Glaucoma is an optic neuropathy Neuropathy Leprosy characterized by typical visual field Visual Field The Visual Pathway and Related Disorders defects and optic nerve Optic nerve The 2nd cranial nerve which conveys visual information from the retina to the brain. The nerve carries the axons of the retinal ganglion cells which sort at the optic chiasm and continue via the optic tracts to the brain. The largest projection is to the lateral geniculate nuclei; other targets include the superior colliculi and the suprachiasmatic nuclei. Though known as the second cranial nerve, it is considered part of the central nervous system. The 12 Cranial Nerves: Overview and Functions 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 seen as optic disc Optic disc The portion of the optic nerve seen in the fundus with the ophthalmoscope. It is formed by the meeting of all the retinal ganglion cell axons as they enter the optic nerve. Eye: Anatomy cupping on examination. The acute form of glaucoma is a medical emergency. Glaucoma is often, but not always, caused by increased intraocular pressure Intraocular Pressure The pressure of the fluids in the eye. Ophthalmic Exam (IOP). Frequently, there is peripheral vision Vision Ophthalmic Exam loss that eventually leads to loss of central vision Vision Ophthalmic Exam. The 2 main types of glaucoma are open-angle and angle-closure. Overproduction or reduced excretion of the aqueous humor Humor Defense Mechanisms leads to open-angle glaucoma. Onset of symptoms is gradual. Angle-closure glaucoma results from blockage in the angle (of 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 and 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), preventing drainage of the aqueous fluid. Diagnosis involves IOP determination (tonometry) and angle visualization with slit lamp Slit Lamp A microscope with a light source that can be projected into a linear beam. It allows cross-sectional viewing of the aqueous humor; conjuncteiva; cornea; eyelids; iris; and lens of the eye. Ophthalmic Exam (gonioscopy). Treatment includes topical medications that reduce IOP, and eye surgery.
Last updated: 8 Jan, 2021
Anatomy 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. Aqueous humor Humor Defense Mechanisms is produced in the posterior chamber Posterior chamber Eye: Anatomy but travels to 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 (passing through the 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). It is drained from 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 via the trabecular meshwork and ultimately through the canal of Schlemm.
Image by Lecturio.This image shows the fundoscopic changes that occur in glaucoma. Note the normal fundoscopic exam Fundoscopic Exam Head and Neck Examination on the left and the findings consistent with glaucoma on the right, with a large optic cup occupying most of the optic disc Optic disc The portion of the optic nerve seen in the fundus with the ophthalmoscope. It is formed by the meeting of all the retinal ganglion cell axons as they enter the optic nerve. Eye: Anatomy.
Image: “Comparison of the optic disc Optic disc The portion of the optic nerve seen in the fundus with the ophthalmoscope. It is formed by the meeting of all the retinal ganglion cell axons as they enter the optic nerve. Eye: Anatomy area of the a normal and b glaucomatous image” by Manchester Metropolitan University, School of Computing, Mathematics and Digital Technology, Manchester, M1 5GD, UK. License: Open SourceThe progression of glaucoma: (a) shows a normal eye; (b) shows an eye with moderate glaucoma; and (c) demonstrates an eye with severe glaucoma. Note the continuously increasing optic cup-to- optic disc Optic disc The portion of the optic nerve seen in the fundus with the ophthalmoscope. It is formed by the meeting of all the retinal ganglion cell axons as they enter the optic nerve. Eye: Anatomy ratio.
Image: “a Normal eye; b eye with moderate glaucoma; c eye with severe glaucoma” by US National Library of Medicine. License: CC BY 4.0Illustration of the open-angle and free flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure of aqueous humor Humor Defense Mechanisms in open-angle glaucoma. The most common cause is idiopathic Idiopathic Dermatomyositis and related to either increased production or decreased drainage.
Image by Lecturio.The changes that occur with closed-angle glaucoma. In the normal eye (left image), aqueous humor Humor Defense Mechanisms exits from the posterior chamber Posterior chamber Eye: Anatomy and enters 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, where it can drain through the trabecular meshwork and the canal of Schlemm. In patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with closed-angle glaucoma (right image), that pathway is blocked, resulting in an accumulation of aqueous humor Humor Defense Mechanisms and increased intraocular pressure Intraocular Pressure The pressure of the fluids in the eye. Ophthalmic Exam.
Image by Lecturio.The differential diagnoses of glaucoma include the following conditions: