Abstract
This study is designed to evaluate the visual outcomes, accuracy, and predictability of corneal flaps with different thicknesses created by 60-kHz femtosecond laser according to different corneal thicknesses in the patients with low and moderate refractive error. A total of 182 eyes were divided according to the central corneal thickness (470μm–499 μm in Group A, 500μm–549 μm in Group B, and 550μm–599 μm in Group C) and underwent femtosecond laser-assisted LASIK for a target corneal flap thickness (100 μm for Group A, 110 μm for Group B, and 120 μm for Group C). Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and refractive status were examined. The flap thickness of each eye was measured by anterior segment optical coherence tomography (AS-OCT) on 30 points at 1-month follow-up to assess the accuracy and predictability. Postoperatively, at least 75% of eyes had a UDVA of 20/16 or better, less than 2% of eyes lost one line, over 30% of eyes gained one or more lines in CDVA, at least 95% of eyes had astigmatism of less than 0.25 D, all eyes achieved a correction within ±1.00 D from the target spherical equivalent refraction. The visual and refractive outcomes did not differ significantly in all groups (P >0.05). The mean flap thickness was 100.36± 4.32 μm (range: 95–113 μm) in Group A, 111.64 ± 3.62 μm (range: 108–125 μm) in Group B, and 122.32 ± 2.88 μm (range: 112–128 μm) in Group C. The difference at each measured point among the three groups was significant (P < 0.05). The accuracy and predictability were satisfactory in all three groups. In conclusion, this customized treatment yielded satisfactory clinical outcomes with accurate and predictable flap thickness for patients with low and moderate refractive error.
Highlights
Laser in situ keratomileusis (LASIK) has been the most commonly performed refractive surgical procedure
Femtosecond laser technology has emerged as an alternative way to precisely create the epithelial-stromal flap in LASIK(FS-LASIK), which is crucial for obtaining an appropriate residual stromal thickness and achieving satisfactory visual and refractive outcomes[1,2,3,4]
The percentages of eyes gained 1 or more lines of corrected distance visual acuity (CDVA) ranged from 34% to 49% in the three groups; the percentages of eyes with no change ranged from 50% to 65%; the percentages of eyes lost 1 line ranged from 1% to 2% (Fig. 3)
Summary
Laser in situ keratomileusis (LASIK) has been the most commonly performed refractive surgical procedure. Different femtosecond laser energies [5,6], different femtosecond laser systems[7], corneal flaps with different diameters and cutting edge [8], and corneal flaps with different thicknesses made by femtosecond laser [9,10] were compared. The patients in those studies, were usually grouped by their refractive statuses or corneal flap cutting patterns. Making customized corneal flaps for patients with different corneal thicknesses has not been investigated yet
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