Degenerative changes in cornea

•Age related corneal degeneration• Arcus senilis

• It is the most common peripheral corneal opacity, frequently occur with predisposing systemic conditions in elderly individuals,occusionaly arcus

associated with familial or non familial dyslipoprotaneamia,it is most frequently bilateral ,unilateral condition is rare and my occur in association with carotid

disease and ocular hypotony• Sign

• Lipid stromal deposit ,form a band in peripheral cornea separated from limbus by clear corneal zone

• Corneal guttata• Consist of focal accumulation of collagen on the posterior surface of descement

membrane, the lesion appear as warts or excencesrese and are secreted by abnormal endothelial cells

• Keratoconus• It is progressive disorder, in which cornea assume irregular conical

shape,,onset around puberty with slow progressive visual impairment• Both eyes are affected in almost all cases, although involvement

commonly asymmetrical• The role of inheritance are not clear,offsprings are affected in about 10%

of the cases• AS. Transmission are proposed• Association1. Systemic disorder,: down ,ehler danlos,marfan syndroms,osteogenesis

imperfecta and mitral valve prolapse2. Ocular association: vernal keratocongectivitis,aniridia,ectopia

lentis,retinitis pigmentosa,rigid contact lens wear and constant eye rubbing

• Presentation

• Unilateral visual impairment due to progressive myopia and astigmatism which subsequently become irregular

• Patient report frequent changes of spectacle

• As a result of asymmetrical nature of the disease the fellow usually have normal vision with negligible astigmatism which however increase as the condition progress

• Sign

• 1-early

• apical corneal protrusion

• Retinoscopy show irregular seizer reflex

• Slit lamp show very fine vertical deep stromal striae called vogt lines

• Corneal topography is the most sensitive method for detection of early keratoconus

• 2-Late sign

• Progressive corneal thinning

• Progressive visual deterioration

• Bulging of lower lid in down gaze (munson sign)

• Epithelial iron deposit (fleischer ring) my surround the base of the cone

• 3-Acute hydropes• Caused by acute influx of aqueous humor into the cornea as aresult of rupture

of descement membrane, causing

• Sudden drop of V.A.

• Discomfort and watering

• Breaks usually heals within 6-10 wks and corneal edema resolved leaving variable amount of stromal scar

• Treatment of acute phase is with hypertonic saline, patching or soft bandage contact lens

• Permanent treatment:keratoplasty

• Treatment of keratoconus• Spectacles. in early cases to correct mild irregular astigmatism

• Rigid contact lens. when astigmatism cannot corrected by spectacles

• Keratoplasty. In advanced progressive cases

• Contact lens• Therapeutic indication• 1-optical:

• A. irregular astigmatism

• B. superficial corneal irregularity

• C. anisometropia, which my fallow cataract surgery

• 2-promotion of epithelial healing

• A. persistent epithelial defect ,to protect the regenerated epithelium from constant rubbing by blinking

• B. recurrent corneal erosion

• 3- pain relief

• A. bulbous keratopathy which condition occur as aresult of loss of endothelial cell leading to development of corneal edema which when rapture cause sever pain with blinking as following complicated cataract surgery

• B. wet filamentary keratitis as in brain stem stroke

• C. Protection of corneal epithelium from aberrant lashes

• 3-preservation of corneal integrity

• A. descematocele which sever corneal thinning which intended to rupture

• B. splinting and apposition of small corneal wound till healing

• 4-miscelenous indication• A.Ptosis prop as in patient with ocular myopathy• B. maintenance of fornices in eyes with cicatrizing conjunctivitis• C. drug delivery• Complication• Conjunctival

1. allergic conjunctivitis

2. Giant papillary conjunctivitis• Corneal complication

1. Epithelial edema due to hypoxia

2. Corneal vascularization due to hypoxia

3. Sterile corneal infiltrate

4. Microbial keratitis

5. Corneal warping, sever and permanent astigmatism my be caused by chronic corneal hypoxia