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Anomalies of the Cornea

Corneal anomalies are conditions in which the structure or function of the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy is impaired due to various congenital Congenital Chorioretinitis or acquired pathologies. Corneal anomalies are classified based on anomalies of size, clarity, ectatic anomalies, corneal dystrophies, and acquired conditions. Pathological changes can result in opacity Opacity Imaging of the Lungs and Pleura or clouding of the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy and, hence, reduce visual acuity Visual Acuity Clarity or sharpness of ocular vision or the ability of the eye to see fine details. Visual acuity depends on the functions of retina, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast. Ophthalmic Exam. Corneal anomalies are usually diagnosed based on clinical findings. Management includes correction of refractive errors Refractive errors By refraction, the light that enters the eye is focused onto a particular point of the retina. The main refractive components of the eye are the cornea and the lens. When the corneal curvature, the refractive power of the lens, does not match the size of the eye, ametropia or a refractive error occurs. Refractive Errors and treatment of the underlying conditions.

Last updated: 17 Mar, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Overview

Cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy

The cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy is a transparent, avascular Avascular Corneal Abrasions, Erosion, and Ulcers, watch glass-like structure that covers the iris Iris The most anterior portion of the uveal layer, separating the anterior chamber from the posterior. It consists of two layers – the stroma and the pigmented epithelium. Color of the iris depends on the amount of melanin in the stroma on reflection from the pigmented epithelium. Eye: Anatomy, anterior chamber Anterior chamber The space in the eye, filled with aqueous humor, bounded anteriorly by the cornea and a small portion of the sclera and posteriorly by a small portion of the ciliary body, the iris, and that part of the crystalline lens which presents through the pupil. Eye: Anatomy, and pupil Pupil The pupil is the space within the eye that permits light to project onto the retina. Anatomically located in front of the lens, the pupil’s size is controlled by the surrounding iris. The pupil provides insight into the function of the central and autonomic nervous systems. Pupil: Physiology and Abnormalities.

  • Curvature of the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy is > the rest of the globe.
  • 5 histological layers:
    • Epithelium Epithelium The epithelium is a complex of specialized cellular organizations arranged into sheets and lining cavities and covering the surfaces of the body. The cells exhibit polarity, having an apical and a basal pole. Structures important for the epithelial integrity and function involve the basement membrane, the semipermeable sheet on which the cells rest, and interdigitations, as well as cellular junctions. Surface Epithelium: Histology
    • Bowman’s membrane Bowman’S Membrane Corneal Abrasions, Erosion, and Ulcers 
    • Stroma
    • Descemet’s membrane
    • Endothelium Endothelium A layer of epithelium that lines the heart, blood vessels (vascular endothelium), lymph vessels (lymphatic endothelium), and the serous cavities of the body. Arteries: Histology

Classification of corneal abnormalities

  • Cryptophthalmos
  • Anomalies of size:
    • Microcornea
    • Megalocornea
  • Ectatic anomalies:
    • Keratoconus
    • Keratoglobus
  • Anomalies of clarity:
    • Peters anomaly
    • Sclerocornea
  • Corneal dystrophies:
  • Acquired conditions:
    • Corneal keloids
    • Band-shaped keratopathy

Cryptophthalmos

Cryptophthalmos is an autosomal recessive Autosomal recessive Autosomal inheritance, both dominant and recessive, refers to the transmission of genes from the 22 autosomal chromosomes. Autosomal recessive diseases are only expressed when 2 copies of the recessive allele are inherited. Autosomal Recessive and Autosomal Dominant Inheritance congenital Congenital Chorioretinitis anomaly associated with systemic anomalies and is characterized by an uninterrupted continuity of the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions extend­ing from the forehead Forehead The part of the face above the eyes. Melasma to the malar region.

Epidemiology

  • The incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency of cryptophthalmos is unknown.
    • May occur in isolation
    • Also associated with Fraser syndrome, an autosomal recessive Autosomal recessive Autosomal inheritance, both dominant and recessive, refers to the transmission of genes from the 22 autosomal chromosomes. Autosomal recessive diseases are only expressed when 2 copies of the recessive allele are inherited. Autosomal Recessive and Autosomal Dominant Inheritance malformation disorder presenting with:
      • Cryptophthalmos
      • Syndactyly Syndactyly A congenital anomaly of the hand or foot, marked by the webbing between adjacent fingers or toes. Syndactylies are classified as complete or incomplete by the degree of joining. Syndactylies can also be simple or complex. Simple syndactyly indicates joining of only skin or soft tissue; complex syndactyly marks joining of bony elements. Development of the Limbs
      • Abnormalities of the respiratory and urogenital tracts
  • Bilateral > unilateral

Clinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor

Three forms:

  • Complete = total failure of eyelid formation
    • Most common type
    • Eyelids Eyelids Each of the upper and lower folds of skin which cover the eye when closed. Blepharitis are replaced by a layer of skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions extending from the forehead Forehead The part of the face above the eyes. Melasma to the malar region.
    • Absence or poor development of the eyebrow
    • Cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy is absent or fused with the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions.
  • Partial = result of the eyelid fold developing abnormally
    • Comprises approximately 20% of the cases
    • Rudimentary lids are present with a small conjunctival sac placed laterally. 
    • The globe is small and almost completely covered by skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions.
  • Abortive = The part of the lid fold derived from the frontonasal process fails to develop, whereas the part derived from the maxillary process develops normally.
    • The abnormal upper lid covers and adheres to up to 75% of the upper cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy.
    • No punctum or upper conjunctival fornix Fornix Vagina, Vulva, and Pelvic Floor: Anatomy
    • Normal lower lid

Management

Treatment is aimed at the surgical reconstruction of the eyelids Eyelids Each of the upper and lower folds of skin which cover the eye when closed. Blepharitis to allow for visual development. There is no standard approach, and stepwise surgeries differ according to the severity of the abnormalities and orbit Orbit The orbit is the cavity of the skull in which the eye and its appendages are situated. The orbit is composed of 7 bones and has a pyramidal shape, with its apex pointed posteromedially. The orbital contents comprise the eye, extraocular muscles, 5 cranial nerves, blood vessels, fat, the lacrimal apparatus, among others. Orbit and Extraocular Muscles: Anatomy development.

Bilateral cryptophthalmos anomalies of the cornea

Bilateral cryptophthalmos

Image: “Bilateral cryptophthalmos with microphthalmos into left ocular globe and abnormal right ocular globe in a female infant with Fraser syndrome” by De Bernardo et al AL Amyloidosis. License: CC BY 4.0

Corneal Anomalies of Size

Microcornea

The normal horizontal diameter of the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy at birth is 10 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma. The adult size of about 11.7 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma is normally attained by 2 years of age.

Overview:

  • Microcornea is characterized by a corneal diameter < 10 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma.
  • Can be unilateral or bilateral
  • Can occur as an independent anomaly
  • May be associated with:
    • Microphthalmos: abnormally small globe
    • Nanophthalmos: abnormally small eye with a normal-sized lens Lens A transparent, biconvex structure of the eye, enclosed in a capsule and situated behind the iris and in front of the vitreous humor (vitreous body). It is slightly overlapped at its margin by the ciliary processes. Adaptation by the ciliary body is crucial for ocular accommodation. Eye: Anatomy

Clinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor:

  • Usually associated with myopia Myopia Refractive Errors and microphthalmos
  • May present as isolated microcornea or relative anterior microphthalmos
  • Individuals usually develop glaucoma Glaucoma Glaucoma is an optic neuropathy characterized by typical visual field defects and optic nerve atrophy seen as optic disc cupping on examination. The acute form of glaucoma is a medical emergency. Glaucoma is often, but not always, caused by increased intraocular pressure (IOP). Glaucoma in the 4th decade of life.
Child with microcornea anomalies of the cornea

Child with microcornea (diameters < 10 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma)

Image: “At 12 years of age, the child had horizontal corneal diameters of 10 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma but otherwise unremarkable anterior segments by slit-lamp examination Slit-Lamp Examination Blepharitis” by Hazin R et al AL Amyloidosis. License: CC BY 2.0

Megalocornea

Megalocornea is a bilateral, nonprogressive corneal enlargement characterized by a horizontal diameter of the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy > 12 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma at birth and 13 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma at 2 years of age. 

Overview:

  • Usually, a clear cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy with normal thickness and vision Vision Ophthalmic Exam
  • Inherited as an X-linked recessive X-Linked Recessive Duchenne Muscular Dystrophy trait
  • Systemic associations:
    • Marfan syndrome Marfan syndrome Marfan syndrome is a genetic condition with autosomal dominant inheritance. Marfan syndrome affects the elasticity of connective tissues throughout the body, most notably in the cardiovascular, ocular, and musculoskeletal systems. Marfan Syndrome
    • Ehlers-Danlos syndrome Ehlers-Danlos syndrome Ehlers-Danlos syndrome (EDS) is a heterogeneous group of inherited connective tissue disorders that are characterized by hyperextensible skin, hypermobile joints, and fragility of the skin and connective tissue. Ehlers-Danlos Syndrome
    • Down syndrome Down syndrome Down syndrome, or trisomy 21, is the most common chromosomal aberration and the most frequent genetic cause of developmental delay. Both boys and girls are affected and have characteristic craniofacial and musculoskeletal features, as well as multiple medical anomalies involving the cardiac, gastrointestinal, ocular, and auditory systems. Down syndrome (Trisomy 21)

Pathophysiology:

  • During corneal development, a defect in the formation of the optic cup allows it to overgrow.
  • Considered a primary overgrowth of the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy 
  • Normal endothelial cell density is present. 

Clinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor:

  • Presents after 12 months of age when the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy has fully developed
  • Symmetric, dome-shaped corneas > 13 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma in diameter
  • Reduced visual acuity Visual Acuity Clarity or sharpness of ocular vision or the ability of the eye to see fine details. Visual acuity depends on the functions of retina, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast. Ophthalmic Exam is uncommon.
  • Astigmatism Astigmatism Unequal curvature of the refractive surfaces of the eye. Thus a point source of light cannot be brought to a point focus on the retina but is spread over a more or less diffuse area. This results from the radius of curvature in one plane being longer or shorter than the radius at right angles to it. . Refractive Errors is common.
Megalocornea in a child

Megalocornea in a child with a corneal diameter > 14 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma

Image: “Megalocornea in a child with a corneal diameter greater than 14 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma” by Khan AO et al AL Amyloidosis. License: CC BY 3.0, cropped by Lecturio.

Corneal Ectatic Anomalies

Keratoconus

Keratoconus refers to the thinning near the center of the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy, resulting in corneal steepening and conical shape.

Overview:

  • Noninflammatory 
  • Progressive disorder
  • Caused by a congenital Congenital Chorioretinitis weakness of the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy
  • Can be secondary to viral keratoconjunctivitis Keratoconjunctivitis Simultaneous inflammation of the cornea and conjunctiva. Stevens-Johnson Syndrome or trauma

Clinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor:

  • Presents at puberty Puberty Puberty is a complex series of physical, psychosocial, and cognitive transitions usually experienced by adolescents (11-19 years of age). Puberty is marked by a growth in stature and the development of secondary sexual characteristics, achievement of fertility, and changes in most body systems. Puberty or in early adulthood
  • Vision Vision Ophthalmic Exam impairment progresses until the 4th decade.
  • Usually bilateral, may often be more severe on 1 side
  • Difficulties in correcting vision Vision Ophthalmic Exam for myopia Myopia Refractive Errors and astigmatism Astigmatism Unequal curvature of the refractive surfaces of the eye. Thus a point source of light cannot be brought to a point focus on the retina but is spread over a more or less diffuse area. This results from the radius of curvature in one plane being longer or shorter than the radius at right angles to it. . Refractive Errors
  • Findings with advanced disease:
    • Munson’s sign: v-shaped indentation of the lower eyelid on downgaze (see image)
    • Vogt striae: deep stromal stress lines that are pathognomonic for keratoconus
    • Fleischer ring: deposition of hemosiderin Hemosiderin Heme Metabolism at the base of the cone 
    • Acute hydrops Hydrops Cholecystitis: Ruptures may develop in the Descemet’s membrane causing the stroma to become suddenly edematous and opaque.
      • Can present with photophobia Photophobia Abnormal sensitivity to light. This may occur as a manifestation of eye diseases; migraine; subarachnoid hemorrhage; meningitis; and other disorders. Photophobia may also occur in association with depression and other mental disorders. Migraine Headache and a sudden painful drop in visual acuity Visual Acuity Clarity or sharpness of ocular vision or the ability of the eye to see fine details. Visual acuity depends on the functions of retina, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast. Ophthalmic Exam
      • Treatments include pressure patching and bandage contact lenses.
      • Topical hyperosmotics, cycloplegics, and steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors are used to decrease edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema, pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways, and inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation.

Diagnosis:

  • Slit-lamp exam: Cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy may appear normal.
  • Keratometry Keratometry Ophthalmic Exam: may show distortion Distortion Defense Mechanisms
  • Corneal topography Corneal Topography Ophthalmic Exam: may aid in the diagnosis and in assessing disease progression

Management:

  • Corneal collagen Collagen A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of skin; connective tissue; and the organic substance of bones (bone and bones) and teeth (tooth). Connective Tissue: Histology crosslinking: A procedure that uses riboflavin drops, UV light UV light That portion of the electromagnetic spectrum immediately below the visible range and extending into the x-ray frequencies. The longer wavelengths (near-uv or biotic or vital rays) are necessary for the endogenous synthesis of vitamin D and are also called antirachitic rays; the shorter, ionizing wavelengths (far-uv or abiotic or extravital rays) are viricidal, bactericidal, mutagenic, and carcinogenic and are used as disinfectants. Bullous Pemphigoid and Pemphigus Vulgaris, and a photosensitizer to strengthen the bonds in the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy and measure progression.
  • Glasses: to correct myopic astigmatism Astigmatism Unequal curvature of the refractive surfaces of the eye. Thus a point source of light cannot be brought to a point focus on the retina but is spread over a more or less diffuse area. This results from the radius of curvature in one plane being longer or shorter than the radius at right angles to it. . Refractive Errors as long as the patient can function
  • Contact lenses: 
    • Rigid gas-permeable lenses neutralize the irregularity of the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy, but may become intolerable.
    • Scleral lenses that sit on the sclera Sclera The white, opaque, fibrous, outer tunic of the eyeball, covering it entirely excepting the segment covered anteriorly by the cornea. It is essentially avascular but contains apertures for vessels, lymphatics, and nerves. Eye: Anatomy without touching the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy may be used.
  • Surgical interventions:
    • Keratoplasty: required in 10%–15% of patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship 
    • Intrastromal corneal ring segments
Munson’s sign in a patient with keratoconus

Munson’s sign in a patient with keratoconus

Image: “Münson’s sign in a keratoconus patient which appears as bulging of the lower lid during downgaze” by BioMed Research Research Critical and exhaustive investigation or experimentation, having for its aim the discovery of new facts and their correct interpretation, the revision of accepted conclusions, theories, or laws in the light of newly discovered facts, or the practical application of such new or revised conclusions, theories, or laws. Conflict of Interest International/Mariam Lotfy Khaled et al AL Amyloidosis. License: CC BY 4.0

Keratoglobus

Keratoglobus is a hemispherical protrusion of the whole cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy with limbus Limbus An annular transitional zone, approximately 1 mm wide, between the cornea and the bulbar conjunctiva and sclera. It is highly vascular and is involved in the metabolism of the cornea. Eye: Anatomy-to- limbus Limbus An annular transitional zone, approximately 1 mm wide, between the cornea and the bulbar conjunctiva and sclera. It is highly vascular and is involved in the metabolism of the cornea. Eye: Anatomy thinning of the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy.

Overview:

  • If congenital Congenital Chorioretinitis, the condition is bilateral.
  • Acquired forms have also been seen due to:
    • Keratoconjunctivitis Keratoconjunctivitis Simultaneous inflammation of the cornea and conjunctiva. Stevens-Johnson Syndrome
    • Chronic marginal blepharitis Blepharitis Blepharitis is an ocular condition characterized by eyelid inflammation. Anterior blepharitis involves the eyelid skin and eyelashes, while the posterior type affects the meibomian glands. Often, these conditions overlap. Blepharitis
    • Idiopathic Idiopathic Dermatomyositis orbital inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation
  • Noninflammatory in origin 
  • Progressive in nature
  • Strong association with Ehlers-Danlos syndrome Ehlers-Danlos syndrome Ehlers-Danlos syndrome (EDS) is a heterogeneous group of inherited connective tissue disorders that are characterized by hyperextensible skin, hypermobile joints, and fragility of the skin and connective tissue. Ehlers-Danlos Syndrome type VI
  • Usually associated with defects in collagen Collagen A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of skin; connective tissue; and the organic substance of bones (bone and bones) and teeth (tooth). Connective Tissue: Histology synthesis Synthesis Polymerase Chain Reaction (PCR) or degradation

Clinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor:

  • Clear corneas, unless patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship have episodes of hydrops Hydrops Cholecystitis and scarring Scarring Inflammation
  • High myopia Myopia Refractive Errors with irregular astigmatism Astigmatism Unequal curvature of the refractive surfaces of the eye. Thus a point source of light cannot be brought to a point focus on the retina but is spread over a more or less diffuse area. This results from the radius of curvature in one plane being longer or shorter than the radius at right angles to it. . Refractive Errors
  • Corneal perforations due to extreme thinning

Management:

  • Refractive correction for high myopia Myopia Refractive Errors
  • Protective eyewear reduces the incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency of corneal perforations. 
  • Fitting of customized scleral lenses
Diffuse corneal thinning with outward protrusion of the globe

a: diffuse corneal thinning with outward protrusion of the globe
b: indentation of the lower lid
c & d: stretched out limbus Limbus An annular transitional zone, approximately 1 mm wide, between the cornea and the bulbar conjunctiva and sclera. It is highly vascular and is involved in the metabolism of the cornea. Eye: Anatomy with clear anterior chamber Anterior chamber The space in the eye, filled with aqueous humor, bounded anteriorly by the cornea and a small portion of the sclera and posteriorly by a small portion of the ciliary body, the iris, and that part of the crystalline lens which presents through the pupil. Eye: Anatomy

Image: “Clinical picture of the patient showing diffuse thinning of cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy with outward globular protrusion” by Gupta N et al AL Amyloidosis. License: CC BY 4.0

Anomalies of Corneal Clarity

Peters anomaly

Peters anomaly is a congenital Congenital Chorioretinitis form of anterior segment dysgenesis in which abnormal cleavage of the anterior chamber Anterior chamber The space in the eye, filled with aqueous humor, bounded anteriorly by the cornea and a small portion of the sclera and posteriorly by a small portion of the ciliary body, the iris, and that part of the crystalline lens which presents through the pupil. Eye: Anatomy results in a central defect in the corneal endothelium Endothelium A layer of epithelium that lines the heart, blood vessels (vascular endothelium), lymph vessels (lymphatic endothelium), and the serous cavities of the body. Arteries: Histology and causes leukoma (whitish plaque Plaque Primary Skin Lesions).

Overview:

  • Multiple gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics loci:
    • PAX6
    • PITX2
    • FOXC1
    • CYP1B1
  • Can occur sporadically, but dominant and recessive inheritances are common
  • Systemic associations include:
    • Trisomy 13 Trisomy 13 Trisomy 13, or Patau syndrome, is a genetic syndrome caused by the presence of 3 copies of chromosome 13. As the 3rd most common trisomy, Patau syndrome has an incidence of 1 in 10,000 live births. Most cases of Patau syndrome are diagnosed prenatally by maternal screening and ultrasound. More than half of the pregnancies result in spontaneous abortions. Patau Syndrome (Trisomy 13)
    • Trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 15
    • Partial deletion of chromosome Chromosome In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. Basic Terms of Genetics arm Arm The arm, or “upper arm” in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). Arm: Anatomy 11q
  • Incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency is unknown: part of the congenital Congenital Chorioretinitis corneal opacities seen in 3–6 individuals per 100,000 
  • Pathogenesis: due to a disruption in neural crest Neural crest The two longitudinal ridges along the primitive streak appearing near the end of gastrulation during development of nervous system (neurulation). The ridges are formed by folding of neural plate. Between the ridges is a neural groove which deepens as the fold become elevated. When the folds meet at midline, the groove becomes a closed tube, the neural tube. Hirschsprung Disease migration or separation that occurs in the 7th week of gestation

Clinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor and diagnosis:

  • Central, paracentral, or complete corneal opacity Opacity Imaging of the Lungs and Pleura is always present.
  • Iris Iris The most anterior portion of the uveal layer, separating the anterior chamber from the posterior. It consists of two layers – the stroma and the pigmented epithelium. Color of the iris depends on the amount of melanin in the stroma on reflection from the pigmented epithelium. Eye: Anatomy strands are often seen across the anterior chamber Anterior chamber The space in the eye, filled with aqueous humor, bounded anteriorly by the cornea and a small portion of the sclera and posteriorly by a small portion of the ciliary body, the iris, and that part of the crystalline lens which presents through the pupil. Eye: Anatomy to the posterior surface of the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy.
  • Peters anomaly type 1 Type 1 Spinal Muscular Atrophy:
  • Peters anomaly type 2 Type 2 Spinal Muscular Atrophy:
    • Associated with denser corneal opacification
    • Presents with keratolenticular adhesions
  • Diagnosis: based on clinical findings and confirmed using ultrasonography

Management:

  • Regular Regular Insulin monitoring for glaucoma Glaucoma Glaucoma is an optic neuropathy characterized by typical visual field defects and optic nerve atrophy seen as optic disc cupping on examination. The acute form of glaucoma is a medical emergency. Glaucoma is often, but not always, caused by increased intraocular pressure (IOP). Glaucoma
  • Surgery: full-thickness penetrating keratoplasty plus lensectomy in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with cataract Cataract Partial or complete opacity on or in the lens or capsule of one or both eyes, impairing vision or causing blindness. The many kinds of cataract are classified by their morphology (size, shape, location) or etiology (cause and time of occurrence). Neurofibromatosis Type 2
Corneal opacity seen in a case of peters anomaly

Corneal opacity Opacity Imaging of the Lungs and Pleura in a patient with Peters anomaly

Image: “Photograph of left eye Left Eye Refractive Errors” by Tuli N et al AL Amyloidosis. License: CC BY 2.0

Sclerocornea

With sclerocornea, the limits of the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy and sclera Sclera The white, opaque, fibrous, outer tunic of the eyeball, covering it entirely excepting the segment covered anteriorly by the cornea. It is essentially avascular but contains apertures for vessels, lymphatics, and nerves. Eye: Anatomy are indistinct, resulting in a congenital Congenital Chorioretinitis anomaly of clarity. Irregularly arranged collagen Collagen A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of skin; connective tissue; and the organic substance of bones (bone and bones) and teeth (tooth). Connective Tissue: Histology fibrils are noted.

Overview:

  • Additional ocular anomalies, such as cataracts or coloboma Coloboma Congenital anomaly in which some of the structures of the eye are absent due to incomplete fusion of the fetal intraocular fissure during gestation. Esophageal Atresia and Tracheoesophageal Fistula, are usually present.
  • Nonprogressive
  • Noninflammatory
  • May affect Affect The feeling-tone accompaniment of an idea or mental representation. It is the most direct psychic derivative of instinct and the psychic representative of the various bodily changes by means of which instincts manifest themselves. Psychiatric Assessment the entire cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy or be limited to a part of the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy:
    • Peripheral type of sclerocornea: The affected area is vascularized with superficial scleral vessels.
    • Total sclerocornea: The entire cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy is opaque and vascularized.
  • Etiology:
  • Pathophysiology:
    • Corneal development occurs during the 7th and 8th weeks of gestation.
    • Failure of the mesenchymal cells to differentiate into corneal and scleral cells allows the corneal curvature to exceed that of the sclera Sclera The white, opaque, fibrous, outer tunic of the eyeball, covering it entirely excepting the segment covered anteriorly by the cornea. It is essentially avascular but contains apertures for vessels, lymphatics, and nerves. Eye: Anatomy.

Clinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor:

  • Partial sclerocornea: presence of a peripheral, white, vascularized, 1–2- mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma corneal rim that blends with the sclera Sclera The white, opaque, fibrous, outer tunic of the eyeball, covering it entirely excepting the segment covered anteriorly by the cornea. It is essentially avascular but contains apertures for vessels, lymphatics, and nerves. Eye: Anatomy. The central cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy is generally normal.
  • Total sclerocornea: 
    • Entire cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy is involved.
    • Center is clearer than the periphery.

Management:

  • Generally, no treatment is required. 
  • Refractive errors Refractive errors By refraction, the light that enters the eye is focused onto a particular point of the retina. The main refractive components of the eye are the cornea and the lens. When the corneal curvature, the refractive power of the lens, does not match the size of the eye, ametropia or a refractive error occurs. Refractive Errors are corrected if present. 
  • Artificial tears may be used. 
  • In generalized sclerocornea, early keratoplasty should be considered to provide and/or preserve vision Vision Ophthalmic Exam.
Peripheral scleral changes seen in a patient with sclerocornea

Peripheral scleral changes seen in a patient with sclerocornea

Image: “Sclerocornea” by Mataftsi A et al AL Amyloidosis. License: CC BY 3.0

Corneal Dystrophies

Congenital Congenital Chorioretinitis stromal corneal dystrophy

A noninflammatory, inherited corneal disorder not usually associated with any other ocular or systemic conditions

Overview:

  • Usually involves the central area of the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy
  • Discrete areas of opacification develop in the superficial layers of the stroma. 
  • Etiology:
    • Caused by mutations in the DCN gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics
    • Autosomal dominant Autosomal dominant Autosomal inheritance, both dominant and recessive, refers to the transmission of genes from the 22 autosomal chromosomes. Autosomal dominant diseases are expressed when only 1 copy of the dominant allele is inherited. Autosomal Recessive and Autosomal Dominant Inheritance

Classification:

  • Lattice dystrophy types I and II 
  • Granular dystrophy types I and II 
  • Macular dystrophy
  • Reis-Bucklers dystrophy

Pathophysiology:

  • Clinical symptoms arise due to atrophy Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation and degeneration of basal epithelial cells.
  • Amyloid and hyaline deposits also contribute to the development of symptoms. 
  • There is an increase in number and density until the Bowman’s membrane Bowman’S Membrane Corneal Abrasions, Erosion, and Ulcers becomes eroded and the epithelium Epithelium The epithelium is a complex of specialized cellular organizations arranged into sheets and lining cavities and covering the surfaces of the body. The cells exhibit polarity, having an apical and a basal pole. Structures important for the epithelial integrity and function involve the basement membrane, the semipermeable sheet on which the cells rest, and interdigitations, as well as cellular junctions. Surface Epithelium: Histology desquamates.
  • Corneal dystrophies can present as granular, lattice, or macular forms.
  • The corneal surface is normal or slightly irregular; small opacities are seen throughout the stroma of the entire cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy and give it a cloudy appearance.

Clinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor and diagnosis:

  • Reduction of vision Vision Ophthalmic Exam due to deposits
  • Strabismus Strabismus Strabismus is the misalignment of the eyes while fixating the gaze on an object. Strabismus can be idiopathic, but it may also be caused by cerebral palsy, uncorrected refractive errors, and extraocular muscle or cranial nerve dysfunction. Strabismus is common.
  • Slit-lamp exam: Anterior cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy displays flaky or feathery opacities.

Management:

  • Glasses or contact lenses for correction of refractive errors Refractive errors By refraction, the light that enters the eye is focused onto a particular point of the retina. The main refractive components of the eye are the cornea and the lens. When the corneal curvature, the refractive power of the lens, does not match the size of the eye, ametropia or a refractive error occurs. Refractive Errors
  • Patching or surgical correction of strabismus Strabismus Strabismus is the misalignment of the eyes while fixating the gaze on an object. Strabismus can be idiopathic, but it may also be caused by cerebral palsy, uncorrected refractive errors, and extraocular muscle or cranial nerve dysfunction. Strabismus
  • Keratoplasty

Congenital Congenital Chorioretinitis endothelial corneal dystrophy (CHED)

Congenital Congenital Chorioretinitis hereditary endothelial dystrophy is a corneal dystrophy characterized by bilateral diffuse clouding of corneas.

Etiology and epidemiology

  • Autosomal recessive Autosomal recessive Autosomal inheritance, both dominant and recessive, refers to the transmission of genes from the 22 autosomal chromosomes. Autosomal recessive diseases are only expressed when 2 copies of the recessive allele are inherited. Autosomal Recessive and Autosomal Dominant Inheritance
  • Mutation Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations on chromosome Chromosome In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. Basic Terms of Genetics 20p13
  • Affected gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics: SLC4A11
  • Incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency: 3 in 100,000 births
  • Children of consanguineous marriages have a comparatively greater incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency.

Classification:

  • CHED
  • Posterior polymorphous corneal dystrophy (PPCD)

Pathophysiology: 

  • The SLC4A11 gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics codes for a transmembrane protein, which acts as a pump Pump ACES and RUSH: Resuscitation Ultrasound Protocols between the endothelium Endothelium A layer of epithelium that lines the heart, blood vessels (vascular endothelium), lymph vessels (lymphatic endothelium), and the serous cavities of the body. Arteries: Histology and corneal stroma.
  • Dysfunction of this protein leads to deposition of material in the layers of the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy and corneal clouding.

Clinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor and diagnosis:

  • History of congenital Congenital Chorioretinitis or perinatal clouding of the corneas bilaterally
  • Physical exam findings:
    • Reduced vision Vision Ophthalmic Exam
    • Amblyopia Amblyopia A nonspecific term referring to impaired vision. Major subcategories include stimulus deprivation-induced amblyopia and toxic amblyopia. Stimulus deprivation-induced amblyopia is a developmental disorder of the visual cortex. A discrepancy between visual information received by the visual cortex from each eye results in abnormal cortical development. Strabismus and refractive errors may cause this condition. Toxic amblyopia is a disorder of the optic nerve which is associated with alcoholism, tobacco smoking, and other toxins and as an adverse effect of the use of some medications. Strabismus 
    • Nystagmus Nystagmus Involuntary movements of the eye that are divided into two types, jerk and pendular. Jerk nystagmus has a slow phase in one direction followed by a corrective fast phase in the opposite direction, and is usually caused by central or peripheral vestibular dysfunction. Pendular nystagmus features oscillations that are of equal velocity in both directions and this condition is often associated with visual loss early in life. Albinism

Management:

  • Surgery is the mainstay of treatment.
  • Penetrating keratoplasty or Descemet’s stripping automated endothelial keratoplasty are used.

Acquired Corneal Conditions

Corneal keloids

Corneal keloids are rare, benign Benign Fibroadenoma, gray-white corneal lesions that result from abnormal fibrous Fibrous Fibrocystic Change tissue proliferation. Accumulation of collagen Collagen A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of skin; connective tissue; and the organic substance of bones (bone and bones) and teeth (tooth). Connective Tissue: Histology and various glycoproteins Glycoproteins Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins. Basics of Carbohydrates results in hyperplasia Hyperplasia An increase in the number of cells in a tissue or organ without tumor formation. It differs from hypertrophy, which is an increase in bulk without an increase in the number of cells. Cellular Adaptation of the epithelium Epithelium The epithelium is a complex of specialized cellular organizations arranged into sheets and lining cavities and covering the surfaces of the body. The cells exhibit polarity, having an apical and a basal pole. Structures important for the epithelial integrity and function involve the basement membrane, the semipermeable sheet on which the cells rest, and interdigitations, as well as cellular junctions. Surface Epithelium: Histology and disruption of the Bowman’s layer.

Overview:

  • Congenital Congenital Chorioretinitis: Bilateral cases of corneal keloids are associated with Lowe syndrome and Rubinstein-Taybi syndrome.
  • Acquired: can develop after ocular trauma Ocular Trauma Cataracts in Children or infection
  • Reported in ages ranging from 2 months to 72 years, but rare overall
  • Majority of corneal keloids occur in the 1st 3 decades of life.
  • Pathogenesis: Corneal stromal overgrowth during the healing process results in the transformation Transformation Change brought about to an organism’s genetic composition by unidirectional transfer (transfection; transduction, genetic; conjugation, genetic, etc.) and incorporation of foreign DNA into prokaryotic or eukaryotic cells by recombination of part or all of that DNA into the cell’s genome. Bacteriology of keratocytes into fibroblasts Fibroblasts Connective tissue cells which secrete an extracellular matrix rich in collagen and other macromolecules. Sarcoidosis and myofibroblasts Myofibroblasts Spindle-shaped cells with characteristic contractile proteins and structures that contribute to the wound healing process. They occur in granulation tissue and also in pathological processes such as fibrosis. Hypertrophic and Keloid Scars, leading to keloid formation.

Clinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor:

  • Most patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship present with a slow-growing corneal lesion that appears to be raised from the corneal surface.
  • Gray-white appearance
  • Painless, progressive loss of vision Vision Ophthalmic Exam
  • Failure to close eyelids Eyelids Each of the upper and lower folds of skin which cover the eye when closed. Blepharitis in the case of large keloids
  • Diagnosis is made using visual acuity Visual Acuity Clarity or sharpness of ocular vision or the ability of the eye to see fine details. Visual acuity depends on the functions of retina, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast. Ophthalmic Exam and slit-lamp exams.

Management:

  • No treatment needed when asymptomatic
  • Close monitoring:
    • Size of the keloid
    • Visual acuity Visual Acuity Clarity or sharpness of ocular vision or the ability of the eye to see fine details. Visual acuity depends on the functions of retina, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast. Ophthalmic Exam
  • Surgery is considered when the keloid causes a decrease in visual acuity Visual Acuity Clarity or sharpness of ocular vision or the ability of the eye to see fine details. Visual acuity depends on the functions of retina, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast. Ophthalmic Exam:
    • Local excision
    • Superficial lamellar or phototherapeutic keratectomy
    • Keratoplasty
Corneal keloids appear as opacities

Corneal keloids appear as opacities that rise from the epicorneal surface.

Image: “Slit-lamp microscopic photographs Photographs Ultrasound (Sonography) of corneal keloids” by BMC Ophthalmology/Hyo Kyung Lee et al AL Amyloidosis. License: CC BY 4.0, cropped by Lecturio.

Band-shaped keratopathy

A degenerative change associated with the deposition of calcium Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Electrolytes salts in the Bowman’s membrane and anterior stromal lamellae of the corneal epithelium Epithelium The epithelium is a complex of specialized cellular organizations arranged into sheets and lining cavities and covering the surfaces of the body. The cells exhibit polarity, having an apical and a basal pole. Structures important for the epithelial integrity and function involve the basement membrane, the semipermeable sheet on which the cells rest, and interdigitations, as well as cellular junctions. Surface Epithelium: Histology

Overview:

  • Deposition may be due to a multitude of factors:
    • Precipitation of tears
    • pH pH The quantitative measurement of the acidity or basicity of a solution. Acid-Base Balance change
    • Compromise of endothelial function 
    • Corneal edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema
  • Remainder of the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy is clear.
  • Presents as a band A band Skeletal Muscle Contraction-shaped opacity Opacity Imaging of the Lungs and Pleura in the interpalpebral zone, with a clear interval between the ends of the band and the limbus Limbus An annular transitional zone, approximately 1 mm wide, between the cornea and the bulbar conjunctiva and sclera. It is highly vascular and is involved in the metabolism of the cornea. Eye: Anatomy
  • Caused by chronic ocular inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation due to:
  • May be associated with systemic disorders:
    • Hyperparathyroidism Hyperparathyroidism Hyperparathyroidism is a condition associated with elevated blood levels of parathyroid hormone (PTH). Depending on the pathogenesis of this condition, hyperparathyroidism can be defined as primary, secondary or tertiary. Hyperparathyroidism
    • Vitamin D toxicity Vitamin D Toxicity Hypercalcemia
    • CKD CKD Chronic kidney disease (CKD) is kidney impairment that lasts for ≥ 3 months, implying that it is irreversible. Hypertension and diabetes are the most common causes; however, there are a multitude of other etiologies. In the early to moderate stages, CKD is usually asymptomatic and is primarily diagnosed by laboratory abnormalities. Chronic Kidney Disease
    • Hypophosphatasia Hypophosphatasia A genetic metabolic disorder resulting from serum and bone alkaline phosphatase deficiency leading to hypercalcemia, ethanolamine phosphatemia, and ethanolamine phosphaturia. Clinical manifestations include severe skeletal defects resembling vitamin d-resistant rickets, failure of the calvarium to calcify, dyspnea, cyanosis, vomiting, constipation, renal calcinosis, failure to thrive, disorders of movement, beading of the costochondral junction, and rachitic bone changes. Osteomalacia and Rickets
    • Sarcoidosis Sarcoidosis Sarcoidosis is a multisystem inflammatory disease that causes noncaseating granulomas. The exact etiology is unknown. Sarcoidosis usually affects the lungs and thoracic lymph nodes, but it can also affect almost every system in the body, including the skin, heart, and eyes, most commonly. Sarcoidosis

Clinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor:

  • Decreased visual acuity Visual Acuity Clarity or sharpness of ocular vision or the ability of the eye to see fine details. Visual acuity depends on the functions of retina, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast. Ophthalmic Exam is directly proportional to the amount of calcium Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Electrolytes deposition in the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy.
  • Foreign-body sensation
  • Ocular irritation with conjunctival redness Redness Inflammation
  • Photophobia Photophobia Abnormal sensitivity to light. This may occur as a manifestation of eye diseases; migraine; subarachnoid hemorrhage; meningitis; and other disorders. Photophobia may also occur in association with depression and other mental disorders. Migraine Headache
  • Calcium Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Electrolytes deposition begins in the periphery and progresses inwards.

Management:

  • Superficial debridement Debridement The removal of foreign material and devitalized or contaminated tissue from or adjacent to a traumatic or infected lesion until surrounding healthy tissue is exposed. Stevens-Johnson Syndrome and lamellar keratectomy 
  • Treat the underlying cause, if known, to decrease further calcium Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Electrolytes deposition in the cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy.

References

  1. Ventocilla, M. (2021). Megalocornea clinical presentation: History, physical, causes. Medscape. Retrieved July 5, 2021, from https://emedicine.medscape.com/article/1196299
  2. Sihota, R., Tando, R. (2019). Parson’s Diseases of the Eye (22nd ed. Chapter 15). 
  3. Wallang, B.S., Das, S. (2013). Keratoglobus. Eye (London, England), 27(9), 1004–1012. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3772364/
  4. Ocubillo, M.V. (2018). Congenital clouding of the cornea. Medscape. Retrieved July 3, 2021, from https://emedicine.medscape.com/article/1197148
  5. Trief, D., Ciccone, L. (2021). Congenital hereditary endothelial dystrophy. American Academy of Ophthalmology. https://eyewiki.aao.org/Congenital_Hereditary_Endothelial_Dystrophy
  6. Vu, C.V., Hwang, F.S. (2021). Corneal keloids. American Academy of Ophthalmology. https://eyewiki.aao.org/Corneal_Keloids
  7. Taravella, M. (2018). Band keratopathy. Medscape. Retrieved July 5, 2021, from https://emedicine.medscape.com/article/1194813-overview
  8. Singh, P., Tripathy, K. (2021). Keratopathy. https://www.ncbi.nlm.nih.gov/books/NBK562153/
  9. Katzman, L.R., Reiser, B.J. (2016). Pediatric corneal opacities. Retrieved July 5, 2021, from https://www.aao.org/disease-review/pediatric-corneal-opacities
  10. Reynolds, J.D., Reynolds, A.L. (2019). Overview of glaucoma in infants and children. UpToDate. Retrieved July 3, 2021, from https://www.uptodate.com/contents/overview-of-glaucoma-in-infants-and-children
  11. Corneal diseases in children: Congenital anomalies. https://entokey.com/corneal-diseases-in-children-congenital-anomalies/

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