| Popis: |
Background: To evaluate the accuracy of intraocular lens power (IOL) calculation using Scheimpflug tomography and OKULIX ray tracing software in corneal scarring. Methods: This study was conducted on 40 consecutive eyes, 20 cases with corneal scarring and coexisting cataract, and 20 controls with clear cornea, which underwent uneventful phacoemulsification and IOL implantation following Scheimpflug tomography and OKULIX ray tracing software and third generation IOL power calculation formulas for IOL power calculation. Accuracy of IOL power calculation was evaluated by subtracting expected and achieved spherical refraction 3 months postoperatively and was recorded as mean absolute error (MAE). Distance uncorrected visual acuity (UCVA) for each eye was measured using Snellen chart preoperatively and 3 months postoperatively; visual acuity was scored and converted to the logarithm of the minimum angle of resolution (LogMar).Values were recorded as mean ±SD (standard deviation). Student t-test (t) and Mann Whitney test (U) were used for parametric comparison of the means. Intra class Correlation (ICC) coefficient and Pearson correlation Coefficient (r) were used to assess agreement. A P value less than 0.05 was considered statistically significant. Results: In cases of corneal scarring, 20 eyes (100 %) yielded a postoperative spherical refraction which differed less than 1 diopter (D) from predicted, in 16 eyes (80 %) the postoperative spherical refraction was within 0.50 D from expected. The MAE was 0.2 D in cases, which did not differ significantly compared to controls (MAE 0.1 D). In corneal scarring cases, distance UCVA showed significant improvement from 1.3 Log Mar (Snellen equivalent 20/400) preoperatively to 0.5 Log Mar (Snellen equivalent 20/60) 3 months postoperatively. Conclusion: Scheimpflug tomography combined with OKULIX ray tracing software for calculation of IOL power provides accurate results in cases of corneal scarring. |
