الفهرس 
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Abstract
Keratoconus is the most common corneal ectasia. It usually appears in the second decade of the life and affects both genders and all ethnicities.
In corneal refractive surgery, early diagnosis of keratoconus (subclinical asymptomatic keratoconus) is of great importance in patients seeking surgery because it can prevent progression of the pathology after surgery and make it symptomatic.
Tomographic-based data have added significantly more information to the screening of corneal ectasia. In addition to anterior corneal analysis, tomography also provides information about the posterior cornea and the pachymetric distribution, which can increase our ability to identify early and subtle corneal changes.
In this study we diagnosed keratoconic cases according to pentacam parameters.
Perhaps corneal volume, as a measure of tissue loss, could be included as a way of classifying the severity of keratoconus and, therefore, used to monitor the progression of this condition.
The present study evaluated corneal volume in subjects with different severities of keratoconus. The volume contained within different diameter discs (3 and 5 diameter) centered on the corneal apex in 20 keratoconic corneas. 10 of them were mild keratoconus (who had steepest keratometry reading lower than 45D) compared to 10 sever cases (who had steepest keratometry greater than 52D).
We evaluated also Corneal thickness at the apex (CTA), Thinnest corneal thickness (TCT), Anterior chamber depth (ACD), Corneal keratometry(K) and Corneal asphericity (Q).
In conclusion, based on the data in our study, we think the effect of keratoconus is not limited to corneal thickness. Rather, it affects all anterior segment parameters of the eye and results in significant alternations with the progression of the disease.
There is a clear reduction of corneal volume in early keratoconus, and such reduction increases significantly with the severity of the disease.
Measurement of corneal volume could prove to be a useful tool to monitor the progression of the disease and in other applications, such as assessing the effect of treatments including corneal collagen crosslinking and Implatation of INTACS