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Natural history of central islands after laser in situ keratomileusis
1Department of Ophthalmology, China Medical College Hospital, (Tsai), Taichung, Taiwan.
Purpose:
To assess the incidence and natural history of central islands following laser in situ keratomileusis (LASIK) and evaluate the association of central island characteristics with visual acuity.
Setting:
Department of Ophthalmology, China Medical College Hospital, Taichung, Taiwan.
Methods:
A consecutive series of 406 eyes of 212 patients who had LASIK was retrospectively evaluated. Uncorrected visual acuity (UCVA) was measured and corneal topography performed preoperatively and 1 week and 1, 3, 6, and 9 months postoperatively. Best spectacle-corrected visual acuity (BSCVA) was evaluated preoperatively and 1, 3, and 6 months postoperatively.
Results:
The topographic images obtained at 1 week demonstrated central islands in 23 eyes of 20 patients (5.7%). No new cases of central island formation were identified after 1 week. Of the 23 eyes with central islands, the 6 month post-LASIK maps were available in 20 eyes of 18 patients. There was a significant difference in the size and power of the central islands between 1 week and 6 months. However, the power and size decreased slowly. Within 6 months, only 5 of 20 central islands (25.0%) had resolved. Eight eyes were undercorrected, and 1 eye lost 2 lines of BSCVA. Central islands larger than 1.8 mm or 3.0 diopters (D) were significantly correlated with lower UCVA.
Conclusion:
Most central islands that occur with LASIK persist more than 6 months. Large central islands (>/=1.8 mm or >/=3.0 D) are risk factors for lower UCVA. Preventive measures are necessary.