Videokeratographic Anomalies in Familial Keratoconus

Abstract

Abstract: : Purpose:Detection of low expressivity forms of keratoconus among relatives of familial keratoconus patients. Methods: A multicentric prevalence study was conducted. The study included 23 families with 55 clinical keratoconus, 89 first degree relatives, 43 other relatives and a control group of 130 subjects. Qualitative and quantitative analysis of corneal shape was performed by videokeratoscopy using a 0.5 diopter increment scale. Videokeratoscopic indices were calculated (K, AST, Srax, I-S and Kisa%) and corneal shapes were sorted according to the Bogan/Rabinowitz classification (Bogan et al., Arch. Ophthalmol., 1990, 108(7):945-9). Statistical comparisons were conducted between first degree relatives and other relatives and a control population. Results: A new corneal pattern was observed: Jinv (a mirror image of the previously described J shape). J and Jinv shapes were over-represented in the relatives of familial keratoconus patients and quantitative analysis revealed that I-S, Srax and Kisa% values were significantly higher for these suspect patterns. Conclusions: Topographic examination of keratoconus families allowed us to detect suspect videokeratoscopic patterns and provides new data for the detection of forme fruste keratoconus wich is a major contraindication for corneal refractive surgery.

Keywords: keratoconus • topography • genetics