RESUMEN
Purpose: To compare the visual outcomes following topography?guided laser in situ keratomileusis (LASIK) treatment using manifest refraction versus a new topography analysis software. Methods: A prospective, randomized, observer?masked contralateral study was conducted in the refractive services of a tertiary eye care hospital in South India. Analysis of visual outcomes, corneal higher?order aberrations, and contrast sensitivity were performed at 3 months postoperative visit following uneventful topography?guided LASIK using the Wavelight EX500. One eye was treated with the Contoura platform using manifest refraction (Contoura), while the contralateral eye was treated using an ablation profile planned by the Phorcides Analytic Engine (Phorcides). Results: Sixty eyes of 30 patients were included in the study. At 3 months postoperative visit, the uncorrected distance visual acuity (UDVA) in the Contoura and Phorcides groups was logarithm of the minimal angle of resolution (logMAR) 0.04 ± 0.07 and logMAR 0.06 ± 0.1, respectively (P = 0.483). Postoperative manifest refractive spherical error (MRSE) was 0.12 ± 0.22 and ? 0.06 ± 0.20 D in the Contoura and Phorcides groups, respectively (P = 0.338). Although higher number of eyes demonstrated a gain in one or more lines of corrected distance visual acuity (CDVA) in the Contoura group (16.6% vs. 6.6%), the difference was not statistically significant (P = 0.361). Vector analysis (Alpins criteria) for postoperative cylinder, contrast sensitivity measurement, and corneal higher?order aberration profile showed no significant difference between the two groups at 3 months postoperative visit (P = 0.213, 0.514, and 0.332, respectively). Conclusion: Quantitative and qualitative visual outcomes with the Phorcides Analytic Software were similar to the Contoura treatment using manifest refraction.
RESUMEN
Purpose: To develop a nomogram in cases with mismatch between subjective and Topolyzer cylinder, and based on the magnitude of the mismatch, customize a treatment plan to attain good visual outcomes post?laser?assisted in situ keratomileusis (LASIK) surgery. Methods: The patients were evaluated preoperatively using corneal tomography with Pentacam. Five optimal corneal topography scans were obtained from the Topolyzer Vario were used for planning the LASIK treatment. For the nomogram purpose, the patients were divided into three categories based on the difference between the subjective cylinder and Topolyzer (corneal) cylinder. The first group (group 1) consisted of eyes of patients, where the difference was less than or equal to 0.4 D. The second group (group 2) consisted of eyes, where the difference was more than 0.4 D and the subjective cylinder was lesser than the Topolyzer cylinder. The third group (group 3) included eyes where the difference was more than 0.4 D but the subjective cylinder was greater than the Topolyzer cylinder. LASIK was performed with the WaveLight FS 200 femtosecond laser and WaveLight EX500 excimer laser. Assessment of astigmatism correction for the three groups was done using Aplins vector analysis. For comparison of proportions, Chi?square test was used. A P value less than 0.05 was considered statistically significant. Results: The UDVA was statistically significantly different when compared between groups 1 and 2 (P = 0.02). However, the corrected distance visual acuity (CDVA) was similar among all the three groups (P = 0.1). Group 3 showed an increase of residual cylinder by ?0.25 D, which was significant at intermediate and near reading distances (P < 0.05). Group 3 showed significantly higher target?induced astigmatism (TIA) compared to groups 1 and 2 (P = 0.01). The mean surgically induced astigmatism (SIA) was the least in group 2, which was statistically significant (P < 0.01). Conclusion: The outcomes for distance vision using our nomogram postoperatively were excellent, but further refinement for improving the near vision outcomes is required
RESUMEN
Background: Topography guided laser-assisted in situ keratomileusis (LASIK) has always been some sort of an enigma in terms of its understanding and interpretation. Contoura LASIK is one such form of FDA approved topography guided LASIK on the Wavelight platform for virgin eyes. Inspite of promising so much, its complete application has not yet been fully understood and cannot be applied for all cases. Purpose: The iSMART Contoura LASIK is a software designed by the author, aimed to specifically to plan and treat eyes with Contoura LASIK. Synopsis: This is computer based software which studies the higher order aberrations being treated by the machine, and applies geometry and vector mathematics to appropriately modify the final treatment refraction so as to completely correct the refractive error. The software guides almost everything related to LASIK planning including safety parameters like percent tissue altered and residual stromal bed, the ring and stop size for microkeratome needed, femto flap diamter and Contoura planning. This software will be a useful tool for all Wavelight EX500 Contoura LASIK users. Highlights: This video demonstrates briefly the overview, working and utility of the iSMART LASIK software along with a quick understanding of how Contoura LASIK planning is done using it.