Abstract
Abstract: :
Purpose: To evaluate the effect of astigmatic keratotomy (AK) on cylinder and refractive error in patients with LASIK-induced mixed astigmatism. Methods: We performed a retrospective chart review of patients who underwent AK for mixed astigmatism after LASIK by one surgeon (R.P.) at the Massachusetts Eye & Ear Infirmary. Patients were excluded if they had AK for mixed astigmatism not related to previous LASIK, or if the LASIK was performed elsewhere and no data was available. Vector analysis was used to calculate the surgically induced refractive change (SIRC). Results: Eight eyes of 7 patients met the criteria and were included in the study (4 female and 3 male). The average age of the patients was 51.5 years. AK was performed using a standardized technique. The surgical incisions were determined using the Lindstrom surgical nomogram for astigmatism with a 7mm optical zone. The interval between LASIK and AK ranged from 4.2 to 14.2 months (average: 10.1 months). In all the patients, refractive stability was documented prior to proceeding to AK. The average follow-up after AK was 3.4 months (range 0.3 to 8.7 months). The mean manifest spherical equivalent (SE) prior to AK was -0.11±0.20D. The mean manifest SE post-AK was -0.36±0.30D (average change in SE was -0.20±0.21D). The mean prepoperative and postoperative refractive cylinder was -1.53±0.38D and -0.59±0.35D respectively. The average % cylinder correction from the AK, as calculated using vector analysis, was 84.8%±31.2%. The average axis error was 8.87±7.45. No complications were seen in any of the patients. One patient lost one line of best spectacle corrected visual acuity (BSCVA). Postoperative BSCVA≥20/20 was achieved in 6 eyes (75%) and BSCVA≥20/25 in 7 eyes (87.5%). Uncorrected visual acuity (UCVA)≥20/20 was achieved in 3 eyes (37.5%) and UCVA≥20/25 in 5 (62.5%). Conclusion: AK is a safe and effective procedure for treating mixed astigmatism after LASIK. Larger studies are needed to compare AK and keratoablative procedures in the management of these patients.
Keywords: 325 astigmatism • 544 refractive surgery