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Srividhya Vilupuru, Sincere Chen, Corina Van de Pol; Objective evaluation of tolerance to induced astigmatism in presbyopes implanted with the small-aperture corneal inlay. Invest. Ophthalmol. Vis. Sci. 2017;58(8):328.
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© ARVO (1962-2015); The Authors (2016-present)
Small-aperture inlay (KAMRA inlay) extends depth of focus by blocking unfocused peripheral light rays and by allowing only the central light rays to reach the retina. The main purpose of this study was to measure and compare the effect of induced astigmatism on the optical quality of the retinal image between the inlay eye and the fellow eye.
A prospective, comparative pilot study on five subjects that were implanted with the small-aperture inlay in their preferred eye. The post-implantation time varied from 1 month to 10 years. Up to 2.5 D of astigmatic defocus (DC) was induced in 0.50 D steps at both 180° and 90°. AcuTarget HD was used to objectively evaluate the optical quality of the retinal images at all defocus levels. The Strehl ratio, ocular scatter index (OSI), and predicted visual acuity (VA) were measured at each defocus level. All subjects were fully corrected in both eyes. The changes to the Strehl ratio, predicted visual acuity and OSI from the baseline (0 DC) are reported as mean ± std or as percentage of change.
The spherical equivalent was -0.33 D ± 0.78 D and 0.00 D ± 0.09 D in the inlay and the fellow eyes respectively. For up to 1.5 DC of defocus, the mean decrease in Strehl ratio was 11.2% ± 18.8% vs. 33.7% ± 20.7% in the inlay vs the fellow eyes respectively (p < 0.0001). The mean VA loss was 0.07 ± 0.11 and 0.24 ± 0.16 logMAR in the inlay and the fellow eyes (p = 0.0001). The mean decrease in OSI was 18.2% ± 22.9% and 141.3% ± 112.7% in the inlay and the fellow eyes respectively (p < 0.0001). For defocus greater than 1.5 DC, both eyes showed a significant loss in optical quality. The mean changes to the Strehl ratio, OSI and predicted visual acuities for defocus levels greater than 1.5 DC was significantly different between the inlay eye and the fellow eyes (p < 0.05). Inlay eyes were more tolerant to astigmatic defocus induced at 90° vs. 180°.
The optical quality of the retinal images in eyes implanted with the small-aperture inlay showed robust tolerance to astigmatic defocus of up to 1.5 DC. In comparison, the optical quality of the retinal images degraded beyond 0.50 DC of defocus in the fellow eyes. For defocus greater than 1.5 DC, the inlay eyes showed a gradual but significantly lower change to retinal image quality when compared to their fellow eyes.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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