eye pathology

1. Eye Pathology

2. EYE

3. CONJUNCTIVA

Pinguecula � raised, yellow sub epithelial connective tissue at nasal bulbar conjunctiva Associated with sun exposure Pterygium - wing like projection of vascularized tissue that extends onto the nasal cornea Trachoma - major cause of blindness worldwide preventable with tetracycline eye ointment Stage 1 � follicles (inflammatory infiltrates) & Pannus (fibrovascular tissue growth) Stage 2 - florid inflammation -, ? number and size of follicles, Stage 3 - follicles disappear, scarring starts & inversion of upper lid Stage 4 - disease spontaneously arrests, but corneal scarring ? visual loss Carcinoma in situ �opaque, white shiny, fleshy mass arising from epithelium of conjunctiva or cornea, basal membrane intact and the sub-epithelial tissue is not invaded Squamous cell carcinoma - tumor cells invade the sub-epithelial tissue

4. Trachoma

follicles Stage 1 Intense inflammation Stage 2 Scarring Stage 3

5. CORNEA

Keratitis - Inflammation can be noninfectious and infectious, respond to topical antibiotics and steroids residual scarring ?blindness (require transplantation) if stroma is completely lost ?descemetocele (Herniation through the posterior limiting membrane of the cornea) perforation leads to hypotonia invasion of infectious organisms into globe ? loss of the eye Stromal (interstitial) Keratitis - inflammation intact overlying corneal epithelium Ulcer - inflammation with absent overlying epithelium Risk factors = contact lenses, debilitation and immune deficiency states MCC - Herpetic infections unilateral and recur After transplantation, there is no tissue rejection as cornea has no vessels remove cornea from cadaver within 6 hours after death

6. CORNEA

Dystrophies � hereditary corneal disorders Bilateral & symmetric can cause severe visual loss reparable by corneal transplantation Keratomalacia � Vitamin A deficiency Leading cause of blindness in underdeveloped countries Undernourished children, Bacterial infection and ulceration of the cornea keratinization of mucous membrane epithelium Night blindness- earliest symptom After transplantation, there is no tissue rejection as cornea has no vessels remove cornea from cadaver within 6 hours after death

7. UVEA ( Choroid, Ciliary body, Iris)

Granulomatous uveitis - infectious causes, Inflammation may extend from the Uvea, to the retina, vitreous and sclera Bacterial - TB, leprosy, syphilis, tularemia Viral - cytomegalic, inclusion disease, herpes zoster Fungal - blastomycosis, Cryptococcus, coccidioidomycosis Parasitic - onchocerciasis, toxoplasmosis Sarcoidosis � 1/3rd of cases- granulomatous anterior uveitis, Retinal involvement is associated with CNS sarcoidosis (bad prognosis) Sympathetic ophthalmia = penetrating injuries to one eye Rare, bilateral uveitis initial symptoms - loss of accommodation, blurred vision, photophobia , keratic precipitates and choroidal infiltrates in the sympathizing eye, Rx :- prompt removal of injured eye (if blind)

8. UVEA ( Choroid, Ciliary body, Iris)

Uveal melanomas � 79% of all non-skin melanomas present as an episcleral mass, MC in the Choroid, Iris melanoma = pigmented mass, light in color, Choroidal melanoma =cause retinal detachment, macular edema, or choroidal hemorrhage, Rx : - iris melanomas are resected only when intraocular spread causes pain or visual loss, Ciliary body and choroidal melanomas- enucleation or radiation

9. Uveal Melanomas

10. LENS

Cataracts =opacities in the lens major cause of visual loss throughout the world, MC type- senile cataract is idiopathic and develops in older patients posterior sub capsular cataracts (steroid use) -develop anterior to the posterior capsule and spread toward the periphery, cataractous lens may swell osmotically (intumescent cataract), the cortex may liquefy entirely and the sclerotic nucleus may sink into the cortex (morgagnian cataract), long-standing cataractous lenses shrink and lenticular debris diffuses into the aqueous humor (hyper mature cataract)

11. Cataract

12. RETINA

3 basic Zones electrical impulse generated in the photoreceptor cells transmitted to cells of the inner nuclear layer axons of the ganglion cells ? optic nerve 1. Retinopathy of Prematurity (Retrolental fibroplasia) � Cause blindness in infancy In premature infants exposed to O2 Rx. VEGF plays important role in pathogenesis Vaso - obliterative phase = high O2 ?? VEGF production ? endothelial apoptosis ?functional constriction ? structural obliteration of retinal blood vessels Peripheral retina not vascularized Vaso - proliferative phase =Cessation of O2 Rx.? ?? VEGF ? Neovascularization ? fibrosis into the vitreous Cicatricial phase � fibrovascular component shrinks ? hemorrhages

13. RETINA

3 2 1

14. RETINA

2. Diabetic Retinopathy =60% of diabetic patients develop retinopathy 15 to 20 years after initial diagnosis Major cause of blindness in US and Europe Background (Nonprolifeative) retinopathy � Micro - aneurysms - earliest change later arteriovenous shunts develop Proliferative retinopathy =response to severe ischemia and hypoxia New capillaries = incompletely formed and poorly supported, extend into the vitreous cavity ? bleeding is common Neovascularization & development of a fibrous component ? retinal detachment

16. RETINA

Hypertensive retinopathy � Grade 1 - generalized narrowing of the arterioles Grade 2 - focal arteriolar spasms Grade 3 - flame-shaped hemorrhages, dot-and-blot hemorrhages, cotton-wool spots and hard waxy exudates Grade 4 - most severe, in addition to grade 3 changes, optic disc edema Copper wire

17. RETINA

Retinitis Pigmentosa � Group of hereditary, bilateral, progressive retinopathies Loss of rods and cones + proliferation of retinal pigment epithelium (pigmentary retinopathy) Night blindness = early symptom, Optic disc =pale & retinal blood vessels are attenuated, minority of patients have also deafness (Usher syndrome) and endocrinologic disturbances (Bardet-Biedl syndrome) AD, AR, XR or maternally inherited (mitochondrial) trait, Molecular mechanism = Mutations in the genes regulate function of photoreceptor (peripherin) and other ocular (opsin) proteins

18. RETINA

Macular degeneration � MCC of decreased vision in the elderly = Age-related macular degeneration (ARMD) Atrophic form, Bruch membrane thickens, the choriocapillaris is often focally obliterated, the pigment epithelium is atrophic and depigmented and the photoreceptors degenerate, new vessels may grow from the choroid through defects in Bruch membrane, Exudative form, the new vessels produce exudates and hemorrhage under the retina, End result = fibrous scar in the macular region degeneration of the neural retina Permanent loss of central vision Retinal detachment Rhegmatogenous break or tear in the retina allows vitreous fluid beneath the retina Serous or exudative fluid accumulates beneath an intact sensory retina Traction fibrous or Glial membranes form in the vitreous

19. Retinal Detachment

traction Serous or Exudative Rhegmatogenous

20. Retinoblastoma

Retinoblastoma True Rosettes Name of the rosettes ? MC malignant eye tumor of childhood

21. OPTIC NERVE

Papilledema =edema of the optic disc Associated with increased intracranial pressure subarachnoid space surrounding the optic nerve is a direct extension of the subarachnoid space around the brain, Acutely =edema and vascular congestion of the nerve head, obliteration of the optic cup, hemorrhages and displacement of the adjacent retina leading to retinal and choroidal folds, Chronically =degeneration of nerve fibers, gliosis and optic atrophy may occur Optic neuritis (neuropathy) � inflammatory or noninflammatory pathologic processes that include demyelinative diseases caused by systemic or ischemic disease, toxic conditions, spread of inflammation and infection Optic atrophy = end-stage of many optic nerve diseases, loss of myelin and axons, glial proliferation, thickening of the pial septa and widening of the subarachnoid space

22. OPTIC NERVE

Tumors � Primary tumors Common ones -Gliomas and meningiomas, Rarely- Hemangiomas & Hemangiopericytomas extraocular spread - fatal Rx Small tumor - Radiation therapy, Laser photocoagulation and Cryotherapy large tumors - enucleation ( removal of the eye) Glaucoma - high intraocular pressure edema of the cornea, degenerative pannus formation, corneal scarring, cataracts, necrosis of the iris and the ciliary body stroma, atrophy, and venous stasis in the retina Primary angle-closure glaucoma � anatomically predisposed eyes, such as small, hyperopic eyes ( canal of schlemm blocked) Open angle glaucoma � poor transport of aqueous humor out of the eye through the angle Congenital glaucoma and juvenile glaucoma � hereditary, caused by defects in genes encoding several classes of molecules (cytochromes and transcription factors)

23. OPTIC NERVE- Glaucomatous Damage

the ganglion layer and the nerve fiber layer are atrophic Normal Glaucomatous

24. NBNB