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Ling Lin, Srividhya Vilupuru, Jay Stuart Pepose; Evaluating the effect of corneal inlay implantation depth on visual outcomes and stability. Invest. Ophthalmol. Vis. Sci. 201657(12):.
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© 2017 Association for Research in Vision and Ophthalmology.
The surgical implantation depth and total corneal thickness may have an effect on the visual performance of the eyes implanted with a monocular small aperture corneal inlay in naturally occurring emmetropic presbyopes. These parameters were evaluated in a prospective, international, multicenter, non-randomized clinical trial which treated and followed the patients through five years.
There were 507 implanted patients between 45 years and 60 years old in the study. The eligible eyes had preoperative UNVA between 20/40 and 20/100 and a preoperative spherical equivalent cycloplegic refraction between +0.50 to -0.75 D with no more than 0.75 D of cylinder. The inlay was implanted monocularly in the non-dominant eye into a femtosecond laser created pocket between 200 to 270 microns (µm) using laser settings ≤6X6 micron spot/line separation in 166 patients. Laser settings larger than 6x6 spot/line separation were not included in the following analysis. Uncorrected distance and near visual acuities (UDVA & UNVA) and manifest refractive spherical equivalent (MRSE) were measured preoperatively (n=166) and postoperatively at 3, 6, 9, 12, 18, 24, 30, 36, 48, 60 months (n = 165, 164, 160, 154, 152, 150, 144, 146, 107, 101, respectively). All visits were combined in the following analysis.
The majority of inlays (57%) were implanted at 210 µm, 23% at 200 µm, 5% at 205 µm, 4% at 220 µm and 11% at 270 µm. Mean corneal thickness was 553 ± 28 µm (range: 500-640 µm). Twenty-four percent of the subjects were implanted deeper than 40% of their total corneal thickness, similar to the proportion (20%) implanted in the posterior stroma calculated based on a general anatomy model of the cornea. Results were very similar for both depth group definitions. Analyses showed that the change in MRSE postoperatively was significantly less when implanted deeper than 40% of the cornea in thick corneas (>550 µm) indicating greater refractive stability (t-test, p<.0001). Postoperative UNVA and the improvement in UNVA were also significantly better when implanted deeper in thick corneas (t-test, p<.0001). In thin corneas (≤550 µm) or for UDVA, there was not a significant correlation between the visual outcomes and depth groups.
We conclude that deeper implantation of a small aperture inlay may improve refractive stability and visual outcomes.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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