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Colin E Brown, Mollie Myers, Lance Kugler, Srividhya Vilupuru; A Method to Measure Objective Refraction in Small-Aperture Corneal Inlay Patients. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1141.
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© ARVO (1962-2015); The Authors (2016-present)
Small-aperture corneal inlay (KAMRA, AcuFocus Inc., Irvine CA) improves near vision in presbyopic patients by extending depth of focus in the inlay eye. At present, it can be difficult for autorefractors to reliably measure objective refraction in eyes implanted with a small-aperture inlay. The AcuTarget HD (ATHD, Visiometrics, Spain), a new diagnostic instrument based on the double-pass technique, measures objective spherical equivalent refraction (SE). The purpose of this study was to determine whether the objective SE measured by ATHD is consistent with the subjective manifest refractive spherical equivalent (MRSE) in eyes implanted with the small-aperture corneal inlay.
In a retrospective study, twelve patients implanted monocularly with a small-aperture corneal inlay were examined at 1, 3 and 6 months postoperatively. A comprehensive eye examination, including uncorrected and best-corrected visual acuities, manifest spherocylinder refraction, ATHD objective refraction and slit lamp examination, was performed at each visit. Refractions were performed by a single refractionist (MM). The subjective MRSE was calculated from the measured manifest spherocylinder refraction. Mean ± Standard deviation (SD) of objective SE, subjective MRSE and correlation between the refractions were determined by analyzing pooled data across all three visits (n = 36) and at each individual visit (n = 12).
For data pooled across visits, the mean ± SD of objective SE and subjective MRSE were -0.27 D ± 0.67 D and -0.44 D ± 0.78 D, respectively. The objective SE was within ± 0.50 D of subjective MRSE in 69.4% and within ± 1.0 D in 91.7% of measurements. Linear regression analysis between objective SE and subjective MRSE showed a statistically significant relationship (R2 = 0.50, F(1, 35) = 33.61, p < 0.0001). Similarly, the two refraction measurements were significantly correlated at month 1 (R2 = 0.66, F(1, 11) = 19.41, p = 0.0013) and month 6 (R2 = 0.74, F(1, 11) = 25.04, p = 0.0007). The two refraction measures showed a weak correlation at month 3 (R2 = 0.19, F(1, 11) = 2.58, p = 0.1365).
The objective refraction measurement from ATHD was found to be similar to the subjective manifest refractive spherical equivalent. The ATHD instrument can be used to estimate the subjective refraction in the patients implanted with the small-aperture inlay.
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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