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Zyoptix safe in eyes with high myopia, thin corneas, study finds
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A wavefront-guided system for LASIK was safe in eyes with moderate to high myopia and thin corneas, according to a retrospective Israeli study. Significant undercorrection was seen in patients with high myopia, the study authors found.
Israel Kremer, MD, and colleagues at Enaim Laser Medical Center in Tel Aviv analyzed the results of wavefront-guided LASIK in 98 eyes of 49 patients with myopia of –5.2 D to –10.35 D and corneal thickness of 456 µm to 498 µm. All eyes underwent LASIK with the Bausch & Lomb Zyoptix system and were followed for 36 months.
The mean age of the patients was 28 years old, and mean preoperative spherical equivalent refraction was –7.06 D.
Final uncorrected visual acuity ranged from 6/6 to 6/30. The safety index of the technique was 1.03, and the efficacy index was 0.67. Undercorrection of more than 0.5 D was observed in 41.3% of the 58 highly myopic eyes (greater than –7 D) in the study. Of 40 moderately myopic eyes (–5 D to –6.75 D), 10% were undercorrected.
A significant reduction in spherical aberration was found 12 months postoperatively in all eyes, the researchers said. None of the eyes developed corneal ectasia.
“The low rate of night glare and the reduction in spherical aberrations suggest that the use of a small treatment zone diameter (4.3 mm to 5.6 mm) is possible for myopia between –7 D and –10.35 D, although it may result in significant undercorrection in this patient group,” the researchers said in their study, published in the July issue of the Journal of Cataract & Refractive Surgery.
The use of a small optical zone may reduce quality of vision, the authors said, but this would mainly occur under scotopic conditions.