Central Islands After LASIK Detected by Corneal Topography

A central island is defined as a localized elevated area in corneal topography after excimer laser application for myopic correction. We experienced 15 cases of central islands developed 1 week after LASIK using VISX STAR on corneal topography. The uncorrected visual acuity and best corrected visual acuity were 0.52 ± 0.22, 0.66 ± 0.25 in central islands group and 0.69 ± 0.19, 0.78 ± 0.19 in control group at 1 week after LASIK. The visual acuity in control group was more improved statistically significantly than central islands group (respectively p = 0.01, p = 0.03). There was no statistical significance between the two groups, although the uncorrected visual acuity and best corrected visual acuity were somewhat more increased in control group at 2 months and 6 months after LASIK than in central islands group (respectively p = 0.06, p = 0.24 at 2 months, p = 0.10, p = 0.17 at 6 months). On the changes of spherical equivalent after LASIK, both the central islands group and control group were in hyperopic state at 1 week after LASIK and were somewhat regressed to myopia at 2 months and 6 months after LASIK. But there was no statistical significance between the two groups at different time points(respectively p = 0.15, p = 0.64, p = 0.67). In 12 cases the central islands were disappeared spontaneously at 2 months, but in 3 cases the central islands were remained 6 months after LASIK on corneal topography. In the one case of 3 cases the best corrected visual acuity was 0.5 at 6 months after LASIK, but in the others the best corrected visual acuity was not different from the mean best corrected visual acuity. Most cases in LASIK, the central islands were dissapeared without specific treatments as in PRK. We suggest, in the case of central islands at 6 months after LASIK, that if the patient complain visual discomfort, monocular diplopia, haloes, or ghost images, central reablation with excimer laser should be considered.