الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
As the cornea constitutes the major refractive surface ,any change in its curvature, power or thickness affects the visual acuity. This justifies the proper detailed study of the corneal surface. Studying the topography of normal cornea enabled to diagnose corneal shape anomalies and to understand the rule that such anomalies play in the distortion of image formed and deterioration of vision. Studying the corneal topography is helpful in early diagnosis and follow up of some corneal disorders such as keratoconus, pellucid marginal degeneration, and terrien degeneration contact lens induced wrapage. This work presents different techniques available for studying the corneal surface as well as their advantages and diagnostic value. The simplest form of instruments used for corneal topography is the hand-held placido’s disc which allows only qualitative evaluation of the central 4 -6 rom zone of the corneal surface. The photokeratoscope allowed a permanent record with further evaluation of the map.