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Chronic Visual Disturbance and Visual Loss

Chronic Visual Disturbance and Visual Loss. Setareh Ziai April 2 nd , 2009 sziai@ottawahospital.on.ca. QUICK review. Basic Anatomy. Where is the problem? LMCC Objectives. Pre-retinal: cornea (dystrophy, scarring, edema) lens (age-related, traumatic, steroid-induced)

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Chronic Visual Disturbance and Visual Loss

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  1. Chronic Visual Disturbance and Visual Loss SetarehZiai April 2nd, 2009 sziai@ottawahospital.on.ca

  2. QUICK review

  3. Basic Anatomy

  4. Where is the problem? LMCC Objectives • Pre-retinal: • cornea (dystrophy, scarring, edema) • lens (age-related, traumatic, steroid-induced) • glaucoma • Retinal: • DM (diabetic retinopathy, macular edema) • vascular insufficiency (arterial or venous occlusion) • tumours • macular degeneration • Post-retinal: • anterior to optic chiasm (if optic nerve = monocular) • compressive optic neuropathy (intracranial masses, thyroid eye disease) • toxic/nutritional (nutritional deficiencies, alcohol/tobacco amblyopia) • optic chiasm lesions (pituitary adenoma)

  5. Whereis the problem? • Pre-retinal: • cornea (dystrophy, scarring, edema) • lens (age-related, traumatic, steroid-induced) • glaucoma • Retinal: • DM (diabeticretinopathy, macularedema) • vascularinsufficiency (arterial or venous occlusion) • tumours • maculardegeneration • Post-retinal: • anterior to opticchiasm (if optic nerve = monocular) • compressive opticneuropathy (intracranial masses, thyroideyedisease) • toxic/nutritional (nutritionaldeficiencies, alcohol/tobaccoamblyopia) • opticchiasmlesions (pituitaryadenoma)

  6. Diagnosis based on: • focused ophthalmological history • monocular vs. binocular • acute vs. chronic • painful vs. painless • exam: … start with gross examination • VA • slit lamp biomicroscopy +/- fluorescein • dilated fundus examination • VF testing • fluorescein angiography +/- other tests

  7. **Remember for exam: • sometimes, chronic visual loss in ONE eye is noted incidentally some time later due to occlusion of normal eye…: CHRONIC LOSS OF VISION CAN PRESENT ACUTELY!!

  8. Corneal Causes • dystrophy • scarring • edema

  9. The Cornea - allows light to enter the eye - provides most of the eye’s optical power - 0.5-0.8 mm thick - transparent due to its uniformity, avascularity and deturgescence

  10. Epithelium Stroma Endothelium

  11. Corneal Dystrophies • rare inheriteddisorders • progressive, usuallybilateral • can affect any of the threelayers of the cornea • affect transparency • ageatpresentation: first to fourthdecades

  12. Corneal Dystrophies • dividedinto: • anterior dystrophies: • epithelium • maypresentwithrecurrentcornealerosions • stromal dystrophies: • usuallypresentwithvisualloss • if veryanterior, can cause erosions and pain • posterior dystrophies: • endothelium • vision losssecondary to edema (endothelialdysfx)

  13. CornealScarring • multiple causes: • trauma • infectious (eg., herpes) • post-surgical

  14. CornealEdema • mostoftencaused by dysfunction of the cornealendothelium: • dystrophy • trauma • infectious (eg., herpes) • post-surgical

  15. Corneal Transplantation

  16. If the corneal stroma opacifies due to trauma or infection, or if thereisswelling or an irregularity of the surface of the cornea, light cannotproperlyreach the retina. In some cases, a corneafrom a deceaseddonorcanbetransplanted.

  17. Corneal Transplantation

  18. Lens-Related Causes (cataract) • age-related • traumatic • steroidinduced

  19. The Lens - biconvex, avascular, transparent structure - sits inside a thin capsule, attached to the ciliary body by the zonules - provides the remainder of the eye’s optical power (along with the cornea) Lens

  20. cataractsare due to the opacification of thisnormallyclear structure

  21. Age-RelatedCataract • often affect the nucleus of the lens first: • yellowing, followed by a browning of the lens • eventually, liquefaction • causes myopic changes (increasedrefractive index of the lens)

  22. TraumaticCataract • mostcommon cause of unilateralcataract in youngindividuals • mostoftencaused by direct penetratinginjury to the lens • canalsobecaused by: • concussion • ionizing radiation to oculartumours • infrared radiation (glassblowers)

  23. Steroid-InducedCataract • bothsystemic and topicalsteroidscanbe the culprits • posterior part of lensaffected first • childrenmaybe more susceptible • if lens changes develop, dose shouldbereduced to the minimum necessary • earlyopacitiesmayregresswith discontinuation of therapy

  24. Glaucoma

  25. Glaucoma • disease of the optic nerve, oftencaused by an increase in intraocular pressure due to poor drainage of aqueousfrom the trabecularmeshwork…

  26. Glaucoma • if leftuntreated, glaucomacanlead to permanent damage to the optic nerve and resultantvisualfieldloss • canprogress to blindness

  27. Glaucoma • by definition, glaucomais a trimodaldisease, characterized by: • increased IOP • optic nerve changes • visualfield changes

  28. GoldmannApplanationTonometer

  29. Glaucoma • classification: • primary: open-angle, angle-closure • secondary: inflammatory, traumatic, neovascular, steroid-inducedetc… • congenital

  30. RiskFactors for Glaucoma • age • african-americanheritage • high IOP • familyhistory • myopia

  31. Symptoms of Glaucoma • oftenasymptomatic • withlatedisease, constriction of peripheral, and later central visualfield • withveryhigh IOP, can have blurry vision and halos around lights

  32. Glaucoma: Optic Nerve Changes • increasedcup:disc ratio • thinning of neural rim • progressive loss of nerve fiber layer • flamehemorrhages on disc

  33. Primary Open Angle Glaucoma • mostcommon (90%) • usuallybilateral (canbeasymmetric) • prevalenceincreaseswithage • angle is open, eyeis quiet • increasedresistance to aqueous drainage at the level of the trabecularmeshworkisthought to be the main pathophysiologicfeature

  34. Treatment options • goal is to stabilize the IOP to protect the optic nerve againstfurther damage • options: • drops • laser • surgery

  35. Glaucoma - Medications • mechanism of action: • decreaseaqueous production: • beta blockers: timolol • alpha agonists: brimonidine • carbonicanhydraseinhibitors: diamox • increaseaqueousoutflow: • miotics: pilocarpine • epinephrine • prostaglandinanalogs: latanoprost

  36. Glaucoma - Lasers • usuallywhenmedical management fails • ALT (argon laser trabeculoplasty), SLT (selective laser trabeculoplasty): for open angle glaucomas • peripheraliridotomy: for angle-closureglaucomas • highsuccess rate

  37. Glaucoma - Surgery • usuallywhenmedical management and laser treatmentsfail • trabeculectomy: sub-conjunctival shunt of aqueous • drainage devices (valves) • cyclodestruction: last resort – destruction of ciliary body

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