Visual Outcomes of Conductive Keratoplasty to Treat Hyperopia and Astigmatism After Laser in situ Keratomileusis and Photorefractive Keratectomy

AIM: To determine the effect of conductive keratoplasty (CK) for the treatment of induced hyperopia and astigmatism after complicated myopic laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK). MATERIALS AND METHODS: In this interventional case series, 11 eyes of seven subjects with a history of previous LASIK or PRK with inadequate stromal bed or flaps complications were enrolled. Inclusion criteria included residual spherical hyperopia of 1.00 to 3.00 diopters (D) and cylinder of –0.75 to –3.00 D. The modified Refractec nomogram and the LightTouch technique of CK were performed on all eyes. To treat cylinder, a pair of spots per –0.75 D of cylinder were delivered to the flat meridian. Uncorrected visual acuity at near and far (UCVAN and UCVAF respectively, logMAR), best corrected VA at near and far (BCVAN and BCVAF respectively, logMAR) were measured. Refractive outcome, contrast sensitivity, wave front aberrations were measured preoperatively and postoperatively. Statistical analysis was performed with the Wilcoxon signed rank test and the repeated measures analysis of variance with P<0.05 indicating statistically significant change from preoperatively to 1 year postoperatively. RESULTS: The mean preoperative sphere (MS) was 2.57 ± 1.19 D and cylinder (MC) was –1.5 ± 0.49 D. Postoperatively, there was a significant decrease in MS to 0.36±0.98 D (P=0.003) and MC to –1.25 ± 0.76 D at 1 year (P<0.05, both cases). Spherical equivalent (SE) significantly decreased from +2.13 ± 1.09 D to –0.47 ± 1.29 D (P<0.001). The mean UCVAN significantly improved from 0.56 ± 0.32 preoperatively to 0.17 ±0.16 postoperatively (P=0.003). The mean UCVAF was 0.29 preoperatively and 0.22 postoperatively (P=0.353). Mean BCVAN was 0.18 and 0.02 after surgery, and mean BCVAF for far was 0.07 (P>0.05, both cases). CONCLUSIONS: CK is a predictable and reliable method to correct hyperopia after LASIK and PRK, however cylinder correction may induce irregular and unpredictable outcomes and a modified nomogram is required for further studies.