2 - Visual Field Deficits Flashcards
Fovea
Only cones, avascular; surrounded by macula lutea
Optic Disc (papilla)
“blind spot” where vessels/Retinal Ganglion Cell acons enter/leave eye
Circular orange/pink disc
Where is the only place to visualize CNS from the exterior?
Neural retina
Clinical: Papilledema
Indicates increased intracranial pressure; can result in visual blurring or vision loss
Clinical: Optic Disc Swelling
Hypertension
Bilateral swelling; chronic hypertension presents in retinal vessels
Clinical: Optic Disc Swelling
Optic Neuritis
Inflammation of the optic nerve
Common presenting sign of Multiple Sclerosis
Abnormal pupillary light reflex, sluggish compared to unaffected eye (relative afferent pupillary defect [RAPD])
Relative Afferent Pupillary Defect (RAPD)
Abnormal pupillary light reflex, sluggish compared to unaffected eye
Clinical: Arterior-Venous (AV) Nicking
Chronic hypertension stiffens and thickens arteries, leading to vain indention & displacement
Clinical: Cotton Wool Spots
Microinfarcts result in axonal damage; axoplasmic material builds up in nerve fiber layer
Clinical: Emboli and Infarcts
Hollenhorst plaque from embolus
Clinical: Retinal Detachment (general)
Posterior neural retinal separates from Retinal Pigment Endothelial (RPE) layers
Symptoms: Sudden blindness in part of visual field, white spots
Causes: Boxers, complications to cataract surgery, shaken baby syndrome`
Clinical: Retinal Detachment
Rhegmatogenous
Most common; hole or tear in retina that allows fluid to accumulate underneath
Increased risk with aging (liquefaction of the vitreous)
Clinical: Retinal Detachment
Tractional
Scar tissue growing on surface of retina; typically in people with poorly controlled diabetes
Clinical: Retinal Detachment
Exudative
Fluid accumulation beneat retina without hole or tear; can be caused by age-related macular degeneration, eye injury, tumor, or inflammatory disease
Clinical: Retinal Vein Occlusion
Arterial atheroschlerosis causes blockage of nearby retinal vein
Results in hemorrhage and edema
Clinical: Visual Field Defects
Scotoma
Abnormal blind spot in the visual field; caused by retinal lesions
Clinical: Visual Field Defects
Monocular Visual Loss
Optic nerve lesion leads to complete blindness in one eye
Clinical: Visual Field Defects
Hemianopia (hemianopsia)
Homonymoius vs Heteronymous
Loss of half of the visual field along the vertical midline
- - -
Homo (most common) - loss on same side in both eyes
Hetero - Loss on both temporal halves (bitemporal hemianopia) or both nasal halves (binasal hemianopia)
Clinical: Visual Field Defects
Quadrantanopia (Quadrantic hemianopia)
Decreased vision or blindness in 1/4 of the visual field
Clinical: Visual Field Defects
Macular Sparing
Preservation of the center of the visual field, due to redundant blood supply to the occipital pole by branches of the MCA / PCA
Clinical: Visual Field Defects
Binasal Hemianopia
Lesion of uncrossed temporal retinal fibers, results in loss of nasal visual field
Uncommon due to anatomical organization
Causes: Congenital hydrocephalus, atherosclerosis of internal carotids
Clinical: Visual Field Defects
Bitemporal Hemianopia
Lesion of crossed nasal retinal fibers, resulting in loss of the temporal visual field
Most common
Causes: Damage to optic chiasm; usually as a result of pituitary adenoma, meningioma, or hypothalamic glioma
Clinical: Visual Field Defects
Contralateral Superior Quadrantanopia
“Pie in the Sky” visual defect
Causes:
1. Temporal Lobe Lesions (MCA inferior territory; lower optic radiations affected at Meyer’s Loop)
- PCA infarct (lower bank of calcarine fissure)
Clinical: Visual Field Defects
Contralateral Inferior Quadrantanopia
“Pie on the Floor” Visual Defect
Causes:
- Parietal Lobe Lesions (MCA superior territory; upper optic radiations affected)
- PCA infarct (upper bank of calcarine fissure)
