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1.keratoconus 2.pptx...........................
- 1. keratoconus By Dr PriyankaPrasad 3rd semester
- 2. Keratoconus • term usedfor conical shape of cornea due to thinning and protrusion • non inflammatory process • usually bilateral but can be asymmetrical • involves central two third of cornea just below the visual axis • mild to marked visual impairment
- 3. Prevalence ,Distribution, AndCourse • Estimates between 50 and 230 per 100000 • Asians and middle east > Caucasians • No significant gender predominance • Unilaterality 2-4% • Onset at puberty 10-20 years gradual progression rate variable
- 4. Systemic Disorders oAlagille Syndrome oAtopicDermatitis oDowns Syndrome oTurners Syndrome oMarfans Syndrome oEhlers Danlos oCrouzon’s Syndrome oBardet-biedl Syndrome oNail Patella Syndrome oGoltz- Gorlin Syndrome Ocular Disorders oVKC oRP oAniridia oEctopia Lentis oLeber’s Congenital Amaurosis oBlue Sclera
- 5. Biochemical Changes • HighLevels Of Proteases, Cathepsins, Gelatinases • Upregulation Of IL 1 Receptor Expression • Downregulation Of Proteinase Inhibitor • Decreased Levels Of Keratin Sulphate And Collagen • Increased Fibroblastic Activity & Apoptosis
- 6. Pathology • Epithelial changes– elongation of superficial cells at apex tunel positive deeper epithelial cells signifying apoptosis early degeneration of basal epithelial cells & iron deposition disruption of basement membrane • Bowman’s layer & ant stroma – z shaped interruptions collagen fragmentation loss of cohesion & interfibrillar spacing fibroblastic activity • Descemet’s membrane – rupture & fluid influx in hydrops • Endothelium – usually uninvolved pleomorphism and polymegathism are also documented
- 7. Types Of ConesIn Keratoconus • Round or nipple-shaped cones having ,</= 5 mm diameter , centre lies more inferonasally • Oval or sagging cone having > 5mm diameter lies more inferotemporally • Globus type in which ectasia involvs more than 75% of cornea
- 8. Diagnosis • demographic profile •clinical evaluations • slit lamp biomicroscopy • keratometry • keratoscopy • corneal topography • anterior segment oct
- 9. Symptoms • Progressive BlurringAnd/Or Distortion • Photophobia • Glare • Monocular Diplopia • Ocular Irritation • Decrease contrast
- 10. Signs • scissoring reflexin retinoscopy • angulation of lower lid on down gaze also known as munson sign • oil droplet sign (charleux sign) • rizzuti phenomenon
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- 14. Slit Lamp Biomicroscopy •prominent corneal nerves • vogt striae • corneal scarring • thinning of inferior or inferonasal corneal stroma • corneal hydrops • fleischer ring
- 15. Keratometry And Keratoscopy •inferior keratometry in upward gaze will show steepening in inferior cornea
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- 17. Forme Fruste Keratoconus(FFKC) •it is a subclinical disease not a variant of keratoconus in which diagnosis is made with the help of topography unlike keratoconus in which diagnosis is clinical. • two ways to define 1. a normal cornea with fellow eye having keratoconus or family history of keratoconus 2. an abnormal cornea in which corneal topography or corneal hysteresis(ORA) or both are abnormal but there are no obvious clinical signs of keratoconus
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- 22. Treatment • spectacle correction •contact lens • intrastromal ring segments for mild to moderate disease • corneal cross linking • keratoplasty 1. PK 2. DALK
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