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Study shows corneal vertex normal as optimal optic zone center in small incision lenticule extraction
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A lenticule center closer to the corneal vertex normal rather than the pupil center yielded better refractive outcomes in small incision lenticule extraction for myopia and myopic astigmatism, according to a study.
The prospective study included 101 eyes of 101 patients who underwent femtosecond laser small incision lenticule extraction for myopia and myopic astigmatism.
The lenticule was centered on the pupil center (PC group) or vertex normal (VNC group).
Investigators assigned patients to four subgroups based on decentration of the lenticule from the pupil center or vertex normal: 1 PC, 2 PC, 1 VNC and 2 VNC. The lenticule was decentered 0 mm to 0.1 mm in the 1 PC and 1 VNC subgroups and more than 0.1 mm in the 2 PC and 2 VNC subgroups.
At 6 months postoperatively, there were no statistically significant differences in uncorrected or corrected distance visual acuity between the 1 PC and 1 VNC subgroups and the 2 PC and 2 VNC subgroups.
Postoperative uncorrected distance visual acuity was 20/20 or better in 97% of eyes in the 1 PC subgroup, 98% of patients in the 1 VNC subgroup, 100% of eyes in the 2 PC subgroup and 97% of eyes in the 2 VNC subgroup.
Root mean square of higher-order aberrations was significantly higher in the 1 PC subgroup than in the 1 VNC subgroup (P = .04) and in the 2 VNC subgroup vs. the 2 PC subgroup (P = .02).
“It is presumed that centering on the PC could not get better visual quality. However, decentering from the VNC would bring more HOAs and get worse visual outcomes,” the authors said. - by Matt Hasson
Disclosure: The authors report no relevant financial disclosures.
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