Change of axial length and keratometry after keratoplaty for keratoconu uing the guided trephine ytem

PURPOE: The purpoe of thi tudy wa to examine the caue of increaing myopia after penetrating keratoplaty for keratoconu with the guided trephine ytem. DEIGN: Propective interventional tudy cohort. METHOD: Thirty eye (28 patient) after keratoplaty for keratoconu were examined. Preoperatively and 1, 3, 6, 12, and 24 month potoperatively ubjective refraction wa evaluated. Keratometry wa calculated with a computerized videokeratocope (TM-1). Axial length wa meaured uing applanation ultraonography before urgery and 2 year after urgery. Anterior chamber depth, len thickne, and vitreou length were taken into conideration. REULT: The mean pherical equivalent wa + 2.22 ± 3.47 diopter 1 month potoperatively and had a continuou myopic hift to −1.02 ± 2.65 diopter 2 year potoperatively. Thi wa aociated with a ignificant increae in mean keratometric level from + 41.72 ± 2.96 diopter 1 month potoperatively to + 43.77 ± 2.29 diopter 2 year potoperatively (r = −0.36, P = .05). Overall, no ignificant change in axial length were oberved. However, vitreou length howed a mall but tatitically ignificant increae. A expected, mean anterior chamber depth decreaed ignificantly potoperatively (P ≤ .05). In eye with a decreae in keratometric value (n = 8) a myopic hift wa alo oberved. In thi group a ignificant elongation of the axial length and the vitreou length wa found. CONCLUION: A tudy of eye after keratoplaty for keratoconu demontrated continuou myopic hift over time. Increaing myopia wa aociated with increaing keratometric value. Thu, the major caue of increaing myopia after keratoplaty in keratoconu eye eem to be continuing keratectaia. However, ongoing bulbu growth may contribute to continuing myopia in ome eye.