Week 3 Visual Pathway and Visual field defects Monocular retinal zone Nerve fiber/optic nerve zone Binocular chiasmal zone Post chiasmal zone Fielddefects are found opposite in the VF to the location of the damages in the eye. RETINAL DETACHMENT VISUAL FIELD Choroidal lesions care caused by tumors, inflammations, infection, or fluid leaks. This type of damage does not respect the horizontal or vertical meridian. EPI RETINAL MEMBRANE TEAR WITH BLEEDING HAMANGIOBLASTOMA Damage may be caused by toxicity, inflammation, infections or heredity. A diffuse pattern of field loss ( rod damage) forming a ring a variable scotomas that will expand outward toward the periphery and inward toward the fovea until blindness results. Damage to cone receptors causing damage to the central 5 degrees. Decreased color and VA will result. Retinal layer All defects will be Subretinal layer monocular. Rods and cones Most pathology will be Retinitis pigmentosa visible with a scope. Macular pathology Lesions temporal to the fovea will present nasal on VF. Lesions can cross all meridians. Central scotomas will cause abnormal VA and color vision. Nerve fiber layer. Most common cause is glaucoma. Also may be caused by trauma, blood vessel occlusions, infections, inflammations and tumors (swelling of the disc) Produces a field loss by pushing the surrounding retina out from the disc creating an enlarged blind spot. It will present more concentric than an enlarged blind spot caused by glaucoma. Macular and papillomacular defects create central or ceccocentral scotomas Bjerrum area of nerve fiber layer. 15 degrees off fixation. Defect in this area will cause an arcing VF loss opposite of the damage. Will start small and increase in size over time. Nerve fiber layer All defects are Optic nerve monocular. (papilledema) Defect will point to Nerve fiber pattern the disc since the defects nerve fibers are Bjerrum area defects traveling toward this point. All pathology will be visible with a scope DAMAGE TO NERVE FIBER GLAUCOMATOUS DEFECTS LAYER WILL SHOW ON VF. TEMPORAL WEDGE NASAL STEP OPTIC NERVE CENTRAL SCOTOMA VISUAL FIELD Allwill be monocular Specific areas of only effecting the nerve fibers that have damaged eye. been damaged will Damage to the nerve respect the horizontal fiber layer will be meridian and point in caused by glaucoma. the direction of the The VF will show up disc. opposite of the Disc problems will damaged area. be visible with a scope. Bi temporal VF loss characteristics Caused by pituitary tumors or swelling, Always bi temporal. Not visible with a scope. CT scan or MRI needed to show defect. Bilateral hemianopia (temporal). Will respect vertical meridian. Will start small and gradually increase in size. LATERAL GENICULATE BODY OPTIC RADIATIONS Homonymous defect Not visible with a will always be scope. present. (Same side) Problem will be Will start out small visible with CT or and gradually get MRI scan. larger. Will be hemianopic and will respect the vertical meridian. Followthe pathway- Page 22 in your text. What is this problem? See you next week for Goldmann Perimetry lecture.