CAUSES OF HIGH ASTIGMATISM AFTER PENETRATING KERATOPLASTY

We retrospectively evaluated the factors which might have caused exces sive corneal astigmatism after penetrating keratoplasty (PKP) in 29 ey es, in which surgical correction of astigmatism was indicated. In 18 e yes high astigmatism (5 diopters or more) existed before suture remova l probably due to graft elevation (3x), wound dehiscence (3x), wound c onfiguration abnormalities such as ovality/overcut (8x), and a thin re cipient cornea (2x). The cause was unknown in 2 eyes. In 19 eyes the a stigmatism considerably increased after all sutures were removed; asti gmatism increased an average of 8.8 diopters (range, 5 to 16.5 D). Ten of these 19 patients showed graft elevation, despite the fact that th e sutures were only removed after an average 22.9 months. In 3 other p atients the astigmatism gradually increased over the years, long after suture removal; two of these showed graft elevation. The study demons trates the possible instability of keratoplasty wounds, the change in astigmatism after suture removal, and the late apparently spontaneous changes in astigmatism after PKP in some eyes.