A clinical and ultrastructural investigation of the cornea in keratoconus

Keratoconus is a non-inflammatory corneal disease that progressively causes topographical alteration of the cornea as a result of thinning, and consequently leads to impaired vision. In this thesis, the clinical studies are showed that the incidence rate and severity of keratoconus in Asir province, Saudi Arabia is high with an early onset and more rapid progress to the severe disease stage at a young age compared to other countries. The result also showed that the disease required different contact lens designs to be available in the clinics and the selection of initial back optic zone radius for multiple contact lens designs should be based in the steepest keratometric reading in early stage, and on average keratometric reading on moderate and advanced stages. However, regardless of the stage of disease, tricurve contact lens design should be selected based on average keratometric reading. Ultrastructure investigation of the anterior surface of Bowman's layer using different microscopes revealed that the changes are not limited to the apical cone only, but extend to the periphery of the cornea especially in the advances stage of keratoconus. Also, although the topographical map is usually used in trephination, it was found that the topographical features alone failed to indicate the full extent of the progress of keratoconus towards the corneal periphery. Data from transmission electron microscopy and high-angle X-ray diffraction suggest that the structural abnormalities in the stromal fibrillar matrix might be influential underlying reasons for topographic changes in the keratoconic-like changes of SPARC-null and JKC mice.EThOS - Electronic Theses Online ServiceGBUnited Kingdo