27 Retina

Structures

retina: most important structures. Other structures support its function

blue layer: choroid, vasculature

Pathology

Retinitis Pigmentosa

AD, AR, or X-linked.
association with abetalipoproteinemia

no real inflammation, just loss of photoreceptors.

Retinitis

floaters: dark spots in visual field

Hypertensive retinopathy

Hypertensive retinopathy can present with gradual, painless, binocular vision loss and headaches, although most patients have no visual symptoms initially. Characteristic features on funduscopic examination include "copper and silver wiring," hard exudates, flame hemorrhages, arteriovenous nicking, arteriolar narrowing, and ischemic changes ("cotton wool spots").

Diabetic Retinopathy

proliferative vs. nonproliferative

Nonproliferative

most common type
microaneurysm: small outpatchings of blood vessels on retina
cotton wool spot: not unique to diabetes

damage to macula from macular swelling, leads to accumulation of yellow exudates.
most common form

Proliferative

vitrectomy: removal of part of vitrous humor, done when bleeding from new blood vessels or debris accumulation

Retinal Detachment

upper left: retina folded on itself like wrinkled paper.

vitreous humor surrounded by vitreous membrane
pts complain of floaters, flashes of lights before retina detachment

Amaurosis Fugax

transient monocular vision loss via emboli that lasts a few seconds.

Retinal Vein Occlusion

arteriosclerosis association with hypertension
arterioles and veins run in AV sheath. Thickened arterioles compress veins

streaky hemorrhages.

Retinal Artery Occlusion

artery occlusion: ischemia
Tay Sachs: sphingolipid accumulate around macula
patient can have painless vision loss
acute retinal ischemia due to thrombosis or emboli in the central retinal artery (branch of ophthalmic artery). Patients develop sudden-onset, painless loss of vision in one eye, with a cherry red macula and retinal pallor on examination. Additional findings may include a relative afferent pupillary defect (Marcus Gunn pupil).