Orbital Fractures

Overview

Definition

An orbital fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures is a broken bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types involving the eye socket, either in the orbital rim, the orbital floor, or both.

Epidemiology

• Orbital fractures account for approximately 3% of all patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship seen in the ED.
• More common in men than in women (4:1)
• More common in adults than in children
• Average age: 30 years

Etiology

• The most common cause of orbital fractures is blunt force trauma to the eye.
• About 85% of traumatic eye injuries (including orbital fractures) are caused by:
  • Auto accidents: most common cause of maxillofacial trauma Maxillofacial trauma General or unspecified injuries involving the face and jaw (either upper, lower, or both). Basic Procedures
  • Contact sports
  • Occupational accidents
  • Home repair projects
• About 15% are due to violent assaults.
• For fractures in adult women, it is important to assess for domestic violence. 

Anatomy and Pathophysiology

To understand the pathophysiology of orbital fractures, it is important to understand the anatomy of the orbit, the clinical presentation, and the potential consequences of fractures.

Anatomy

The 7 bones of the orbit are:

• Maxilla Maxilla One of a pair of irregularly shaped bones that form the upper jaw. A maxillary bone provides tooth sockets for the superior teeth, forms part of the orbit, and contains the maxillary sinus. Skull: Anatomy
• Zygomatic Zygomatic Either of a pair of bones that form the prominent part of the cheek and contribute to the orbit on each side of the skull. Skull: Anatomy
• Frontal Frontal The bone that forms the frontal aspect of the skull. Its flat part forms the forehead, articulating inferiorly with the nasal bone and the cheek bone on each side of the face. Skull: Anatomy
• Ethmoid
• Lacrimal 
• Sphenoid
• Palatine 

The walls of the orbit are: 

• Superior (roof):
  • Orbital part of the frontal Frontal The bone that forms the frontal aspect of the skull. Its flat part forms the forehead, articulating inferiorly with the nasal bone and the cheek bone on each side of the face. Skull: Anatomy bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types
  • Lesser wing of the sphenoid
• Medial:
  • Frontal Frontal The bone that forms the frontal aspect of the skull. Its flat part forms the forehead, articulating inferiorly with the nasal bone and the cheek bone on each side of the face. Skull: Anatomy process of the maxilla Maxilla One of a pair of irregularly shaped bones that form the upper jaw. A maxillary bone provides tooth sockets for the superior teeth, forms part of the orbit, and contains the maxillary sinus. Skull: Anatomy
  • Lacrimal bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types
  • Orbital plate of the ethmoid bone Ethmoid bone A light and spongy (pneumatized) bone that lies between the orbital part of frontal bone and the anterior of sphenoid bone. Ethmoid bone separates the orbit from the ethmoid sinus. It consists of a horizontal plate, a perpendicular plate, and two lateral labyrinths. Orbit and Extraocular Muscles: Anatomy
  • Sphenoid body
• Inferior (floor):
  • Maxillary bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types
  • Zygomatic bone Zygomatic bone Either of a pair of bones that form the prominent part of the cheek and contribute to the orbit on each side of the skull. Orbit and Extraocular Muscles: Anatomy
  • Palatine bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types
• Lateral:
  • Greater wing of the sphenoid
  • Orbital part of the frontal Frontal The bone that forms the frontal aspect of the skull. Its flat part forms the forehead, articulating inferiorly with the nasal bone and the cheek bone on each side of the face. Skull: Anatomy bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types
  • Frontal Frontal The bone that forms the frontal aspect of the skull. Its flat part forms the forehead, articulating inferiorly with the nasal bone and the cheek bone on each side of the face. Skull: Anatomy process of the zygomatic bone Zygomatic bone Either of a pair of bones that form the prominent part of the cheek and contribute to the orbit on each side of the skull. Orbit and Extraocular Muscles: Anatomy

Pathophysiology

There are 4 main types of orbital fractures, which are classified on the basis of the anatomy involved.

• Orbital zygomatic Zygomatic Either of a pair of bones that form the prominent part of the cheek and contribute to the orbit on each side of the skull. Skull: Anatomy fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures:
  • Zygomatic Zygomatic Either of a pair of bones that form the prominent part of the cheek and contribute to the orbit on each side of the skull. Skull: Anatomy region of the orbit is the most common location of an orbital rim fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures.
  • Most common cause: a high-impact blow to the lateral orbit
• Nasoethmoid fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures:
  • Fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures of the medial wall of the orbit
  • Often associated with fractures of the orbital floor
  • Due to direct force applied to the nasal bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types
• Orbital roof fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures:
  • Location: frontal Frontal The bone that forms the frontal aspect of the skull. Its flat part forms the forehead, articulating inferiorly with the nasal bone and the cheek bone on each side of the face. Skull: Anatomy bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types (roof of the orbit)
  • Frequently associated with intracranial injuries 
• Orbital floor fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures:
  • “Blowout fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures”
  • Location: maxillary, zygomatic Zygomatic Either of a pair of bones that form the prominent part of the cheek and contribute to the orbit on each side of the skull. Skull: Anatomy, and palatine bones 
  • Ocular motility Motility The motor activity of the gastrointestinal tract. Gastrointestinal Motility may be disrupted, as orbital tissue is commonly involved.

Clinical Presentation

In a patient presenting with possible orbital fractures, it is important to identify life-threatening and/or serious associated injuries, especially intracranial injury and cervical spine Spine The human spine, or vertebral column, is the most important anatomical and functional axis of the human body. It consists of 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae and is limited cranially by the skull and caudally by the sacrum. Vertebral Column: Anatomy fractures.

History and symptoms

• History of blunt (more common) or penetrating trauma
• Diffuse orbital pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways 
• Pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways on movement of the eyes suggests injury to the extraocular muscles.
• Diplopia Diplopia A visual symptom in which a single object is perceived by the visual cortex as two objects rather than one. Disorders associated with this condition include refractive errors; strabismus; oculomotor nerve diseases; trochlear nerve diseases; abducens nerve diseases; and diseases of the brain stem and occipital lobe. Myasthenia Gravis on upward gaze suggests injury to the orbital floor.
• Numbness of the forehead Forehead The part of the face above the eyes. Melasma suggests injury to the orbital roof.
• Nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics can be caused by entrapment of extraocular muscles.

Physical examination findings

• Periorbital Periorbital Orbital and Preseptal Cellulitis 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
• Ecchymosis 
• Diplopia Diplopia A visual symptom in which a single object is perceived by the visual cortex as two objects rather than one. Disorders associated with this condition include refractive errors; strabismus; oculomotor nerve diseases; trochlear nerve diseases; abducens nerve diseases; and diseases of the brain stem and occipital lobe. Myasthenia Gravis: due to mechanical entrapment of both inferior oblique Inferior oblique Orbit and Extraocular Muscles: Anatomy and inferior rectus Inferior rectus Orbit and Extraocular Muscles: Anatomy muscles
• Absent pupillary light reflex Pupillary Light Reflex Constriction of the pupil in response to light stimulation of the retina. It refers also to any reflex involving the iris, with resultant alteration of the diameter of the pupil. Pupil: Physiology and Abnormalities if damage to the afferent Afferent Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology nerves
• Enophthalmos Enophthalmos Recession of the eyeball into the orbit. Marfan Syndrome: posterior displacement Displacement The process by which an emotional or behavioral response that is appropriate for one situation appears in another situation for which it is inappropriate. Defense Mechanisms of the eyeball within the orbit, seen in blowout fractures
• Proptosis Proptosis Retinoblastoma: protrusion of the eyeball, seen in orbital zygomatic Zygomatic Either of a pair of bones that form the prominent part of the cheek and contribute to the orbit on each side of the skull. Skull: Anatomy fractures
• Widened intercanthal distance due to disruption of the medial canthal ligament
• Bradycardia Bradycardia Bradyarrhythmia is a rhythm in which the heart rate is less than 60/min. Bradyarrhythmia can be physiologic, without symptoms or hemodynamic change. Pathologic bradyarrhythmia results in reduced cardiac output and hemodynamic instability causing syncope, dizziness, or dyspnea. Bradyarrhythmias: associated with the “oculocardiac reflex” (a reduction in pulse rate associated with pressure applied over extraocular muscles)

Diagnosis

Ocular injuries are present in up to 29% of patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with orbital fractures. It is imperative that an ocular exam be done as soon as possible to mitigate the risk of vision Vision Ophthalmic Exam loss.

Ocular examination

• 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
• Ocular motility Motility The motor activity of the gastrointestinal tract. Gastrointestinal Motility
• Intraocular pressure Intraocular Pressure The pressure of the fluids in the eye. Ophthalmic Exam
• Slit-lamp examination Slit-Lamp Examination Blepharitis to visualize any retinal damage
• Visual field Visual Field The Visual Pathway and Related Disorders examination

Imaging

• X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests:
  • Screening Screening Preoperative Care to identify fractures
  • Water’s view (also known as the occipitomental view): X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests beam is angled at 45 degrees and shows “teardrop sign” in antrum.
• CT scan:
  • Gold standard for detection of orbital fractures
  • Thin slices < 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 are preferred. 
  • Coronal Coronal Computed Tomography (CT) and sagittal Sagittal Computed Tomography (CT) views differentiate between periorbital Periorbital Orbital and Preseptal Cellulitis 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 and entrapment of intraocular structures.
• MRI:
  • Determines the extent of soft tissue Soft Tissue Soft Tissue Abscess injury 
  • Assesses damage to the vessels

Management and Complications

Orbital fractures are facial injuries and should be managed emergently. Delay in diagnosis may lead to complications or postoperative complications Postoperative Complications Pathologic processes that affect patients after a surgical procedure. They may or may not be related to the disease for which the surgery was done, and they may or may not be direct results of the surgery. Postoperative Care.

Management

Supportive management:

• Stabilize airway Airway ABCDE Assessment.
• Ensure hemodynamic stability.
• IV fluids IV fluids Intravenous fluids are one of the most common interventions administered in medicine to approximate physiologic bodily fluids. Intravenous fluids are divided into 2 categories: crystalloid and colloid solutions. Intravenous fluids have a wide variety of indications, including intravascular volume expansion, electrolyte manipulation, and maintenance fluids. Intravenous Fluids
• Pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways and nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics medications
• Elevate head. 
• Evaluate for:
  • Cervical spine Spine The human spine, or vertebral column, is the most important anatomical and functional axis of the human body. It consists of 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae and is limited cranially by the skull and caudally by the sacrum. Vertebral Column: Anatomy integrity
  • Possible head injuries 
  • Soft tissue Soft Tissue Soft Tissue Abscess and bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types injuries in the head and neck Neck The part of a human or animal body connecting the head to the rest of the body. Peritonsillar Abscess

Empiric management:

• Antibiotics to cover sinus pathogens
• Advise the patient not to blow the nose Nose The nose is the human body’s primary organ of smell and functions as part of the upper respiratory system. The nose may be best known for inhaling oxygen and exhaling carbon dioxide, but it also contributes to other important functions, such as tasting. The anatomy of the nose can be divided into the external nose and the nasal cavity. Nose and Nasal Cavity: Anatomy, in order to avoid air in the orbital cavity. 
• Reduce periorbital Periorbital Orbital and Preseptal Cellulitis 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:
  • Cold compresses 
  • Oral 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

Urgent ophthalmology consult if:

• Evidence of globe injury: seen in 30% of orbital fractures
• 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
• Widened intercanthal distance
• Evidence of orbital compartment syndrome Compartment Syndrome Compartment syndrome is a surgical emergency usually occurring secondary to trauma. The condition is marked by increased pressure within a compartment that compromises the circulation and function of the tissues within that space. Compartment Syndrome:
  • Decreased retropulsion
  • “Rock hard” eyelids Eyelids Each of the upper and lower folds of skin which cover the eye when closed. Blepharitis
• Open globe
• Severe vagal symptoms

Surgery to reduce the fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures and prevent future deformities:

• May be deferred up to 14 days if periorbital Periorbital Orbital and Preseptal Cellulitis 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 interferes with visualization and assessment
• Is advised for patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with:
  • Orbital hematoma Hematoma A collection of blood outside the blood vessels. Hematoma can be localized in an organ, space, or tissue. Intussusception
  • CSF leakage
  • Globe displacement Displacement The process by which an emotional or behavioral response that is appropriate for one situation appears in another situation for which it is inappropriate. Defense Mechanisms: exophthalmos or proptosis Proptosis Retinoblastoma
  • Entrapment of infraorbital structures leading to the oculocardiac reflex

Commonly used implants for reconstruction are:

• Bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types autograft Autograft Transplant comprised of an individual’s own tissue, transferred from one part of the body to another. Organ Transplantation:
  • Provides good strength for reconstruction 
  • Commonly used in children < 7 years of age
• Cartilage Cartilage Cartilage is a type of connective tissue derived from embryonic mesenchyme that is responsible for structural support, resilience, and the smoothness of physical actions. Perichondrium (connective tissue membrane surrounding cartilage) compensates for the absence of vasculature in cartilage by providing nutrition and support. Cartilage: Histology:
  • Most biocompatible
  • Undergoes easy resorption 
  • Most commonly used for small fractures
• Alloplast:
  • Titanium mesh: used for large floor defects
  • Porous polyurethane: used for defects with well-defined edges
  • Resorbable sheeting: used in small gaps with well-defined edges

Complications

Complications arising from orbital fractures can be due to the injury itself or to surgery.

Injury-related complications:

• Ruptured globe
• Orbital hematoma Hematoma A collection of blood outside the blood vessels. Hematoma can be localized in an organ, space, or tissue. Intussusception
• 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 sheath hematoma Hematoma A collection of blood outside the blood vessels. Hematoma can be localized in an organ, space, or tissue. Intussusception
• Retinal detachment Retinal detachment Retinal detachment is the separation of the neurosensory retina from the retinal pigmented epithelium and choroid. Rhegmatogenous retinal detachment, the most common type, stems from a break in the retina, allowing fluid to accumulate in the subretinal space. Retinal Detachment
• Hyphema Hyphema Bleeding in the anterior chamber of the eye. Corneal Abrasions, Erosion, and Ulcers
• Muscle entrapment
• Orbital compartment syndrome Compartment Syndrome Compartment syndrome is a surgical emergency usually occurring secondary to trauma. The condition is marked by increased pressure within a compartment that compromises the circulation and function of the tissues within that space. Compartment Syndrome

Surgical complications Surgical complications Surgical complications are conditions, disorders, or adverse events that occur following surgical procedures. The most common general surgical complications include bleeding, infections, injury to the surrounding organs, venous thromboembolic events, and complications from anesthesia. Surgical Complications:

• Intraoperative complications:
  • Globe 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 injury 
  • Inadequate removal of prolapsed tissue
  • Hemorrhage
• Postoperative complications Postoperative Complications Pathologic processes that affect patients after a surgical procedure. They may or may not be related to the disease for which the surgery was done, and they may or may not be direct results of the surgery. Postoperative Care:
  • Permanent vision Vision Ophthalmic Exam loss
  • Persistent diplopia Diplopia A visual symptom in which a single object is perceived by the visual cortex as two objects rather than one. Disorders associated with this condition include refractive errors; strabismus; oculomotor nerve diseases; trochlear nerve diseases; abducens nerve diseases; and diseases of the brain stem and occipital lobe. Myasthenia Gravis
  • Infection
  • Implant extrusion or malposition