الفهرس 
Anatomy of the corneaOnly 14 pages are availabe for public view
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Abstract
Summary
Keratoconus is a progressive non-inflammatory ectatic disorder of the cornea. It comprises central and paracentral thinning of the cornea which leads to progressive painless diminution of vision secondary to myopia and irregular astigmatism.
Keratoconus presented at the second decade of life and its incidence ranges from 50-230 per 100.000 person.
Etiology of keratoconus is unknown, but genetic factors, chemical, physical and enzymatic changes in the cornea may be incorporated.
Keratoconus patients always presented by loss of BCVA and occasionally halos and diplopia
Keratometer is used to measure the K reading of the cornea and so the steepness of the cornea. This beside the keratoscope and paccymetry which used to measure the corneal thickness.
Corneal topography is one of the most important investigation which give us a colored map of the cornea and a numerical values of the K reading of the cornea.
Nowadays pentacam is a major diagnostic tool in diagnosis of keratoconus as it can inform us about the posterior surface of the cornea as well as the anterior surface and give a perfect numerical measurement of the corneal thickness at different zones.
Treatment of Keratoconus include:
1. Glasses in early stage of the disease.
2. Hard contact lens
3. INTACS.
4. Keratoplasty (lamellar or penetrating)
5. Collagen cross-linking by using UVA and Riboflavin.
Cross linking is used to stop progression of Keratoconus which is a prefect tool in management of Keratoconus cases.
Some surgeon now prefer to do INTACS to flatten the steep zone of the cornea and then do cross-linking to stabilize this condition.
Mostly endothelium is not affected in cross-linking as long as the corneal thickness not below 400µm .
After cross-linking it is found that there is an increase in collagen diameter in the anterior stroma more than the posterior stroma and so we can use it in treatment of corneal ulcer.
LASIK is a wide spread refractive procedure. It is based on removal of and amount of corneal stroma to change the corneal shape into an oblate or prolate surface leaving RSB which is responsible for resistance against IOP.
And so, if there is low RSB & even occasionally with normal RSB ectasia may occur which is called post-LASIK ectasia which is presented by progressive steepness and loss of BCVA .
Collagen cross-linking is also used in management of post-LASIK ectasia as it increase the corneal stiffness and hence stop its progression.