Purpose:
It was reported familial cases of keratoconus are rare in Japan. In recent years, we often saw familial cases of keratoconus with advanced technology. In this study, we evaluated corneal shape of familial members of keratoconic patients, and consider the inheritance of keratoconus in Japan.
Methods:
We analyzed corneal shape (Keratron Scout and OrbscanIIz) of 161 familial members (6 fathers, 39 mothers, 16 brothers, 18 sisters, 1 twin, 35 sons, 45 daughters, 1 grandmother) of keratoconic patients. With Keratron Scout, we diagnosed keratoconus using the Cone Location and Magnitude Index (CLMI). With OrbscanIIz, we evaluated minimal thickness, central thickness, mean peripheral thickness, anterior BFS, anterior elevation, posterior BFS, and posterior elevation, and diagnosed "keratoconus suspected" when each index is out of normal range (thickness: less than average-2STD, elevation: more than average+2STD).
Results:
With CLMI, we diagnosed 63 eyes (36 members) as keratoconus, and 10 eyes (9 members) as keratoconus suspected. With OrbscanIIz’s indices, a total of 144 eyes (90 members) were diagnosed as keratoconus suspected (minimal thickness: 95 eyes (55 members), center thickness: 87 eyes (51 members), mean peripheral thickness: 65 eyes (35 members), anterior BFS: 20 eyes (14 members), elevation: 81 eyes (57 members), posterior BFS: 20 eyes (16 members), posterior elevation: 85 eyes (56 members).
Conclusions:
These data suggests that the inheritance might be one of the major causes of keratoconus in Japan.
Keywords: keratoconus • topography • genetics