Stability of Keratometric Astigmatism After Non-penetrating Femtosecond Laser Intrastromal Astigmatic Keratotomy Performed During Laser Cataract Surgery

PURPOSE: To investigate the stability of keratometric astigmatism after femtosecond laser intrastromal astigmatic keratotomy (ISAK) performed during laser cataract surgery. METHODS: In this prospective comparative case series, data were collected from patients during follow-up 1 and 6 months after laser-assisted cataract surgery. Corneal keratometry was measured preoperatively and postoperatively by Topcon KR8100PA topographer-autorefractor (Topcon Corporation, Tokyo, Japan). Astigmatic analyses were performed by Alpins' method to calculate surgically induced astigmatism (SIA). All operations were performed by a single surgeon. RESULTS: Data were available on 263 eyes, of which 87 had undergone ISAK during cataract surgery for astigmatism management (cases) and 176 had cataract surgery without ISAK (controls). For ISAK cases, comparing the magnitudes of the individual SIA vectors at 1 and 6 months postoperatively showed a 0.09 diopters cylinder (DC) regression (P =.009). Calculating the change in SIA between 1 and 6 months considering both magnitude and angular direction, the mean regression vector was 0.08 DC @ 94 degrees. For controls (without ISAK), comparing the magnitudes of the individual SIA vectors at 1 and 6 months postoperatively showed a 0.11 DC regression (P <.001). Calculating the change in SIA between 1 and 6 months considering magnitude and angular direction, the mean vector was 0.14 DC @ 88 degrees. There was no significant difference in SIA regression magnitudes between cases and controls. CONCLUSIONS: For both cases with and without ISAK, there were small but statistically significant regressions in SIA between 1 and 6 months postoperatively. These values were low and appear to be of little clinical significance.