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David A Berntsen; Retinal image quality after orthokeratology. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1748.
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© ARVO (1962-2015); The Authors (2016-present)
Orthokeratology (OK) has been shown to slow myopia progression in children. OK is hypothesized to slow eye growth by inducing spherical aberration (SA) and peripheral myopic retinal defocus caused by corneal reshaping. Certain image quality (IQ) metrics are reported to be highly correlated with changes in low-contrast visual acuity (LCVA). These metrics were used to describe the effect of OK on retinal IQ and explore the relation with spherical aberration (SA).
Twenty myopic adults were fitted with overnight OK contact lenses (Paragon Vision Sciences). Eight cycloplegic aberrometry measurements (right eye) were made using a Complete Ophthalmic Analysis System (COAS) before and 1-month after being fitted with OK lenses. Zernike polynomials were fitted through the 6th radial order over a 5-mm pupil diameter. Retinal IQ was calculated using six metrics (three image plane: logNS, logVSX, and logVSMTF; three pupil plane: logRMSs, logPFSt, logPFSc) using the average higher-order aberrations before and 1-month after OK fitting. Analyses of IQ, SA, and refractive error included paired t-tests and Pearson correlations to evaluate the relation between the change in SA and change in IQ.
The baseline OD spherical refractive error (±SD) and mean age were –2.93 ± 0.98 D (range: –1.25 D to –5.00 D) and 27 ± 5 years, respectively. One month after OK, the OD spherical refractive error was +0.26 ± 0.36 D (change = 3.19 ± 0.90 D; p < 0.0001). SA increased by 0.20 ± 0.12 μm (p < 0.0001). All six metrics showed a reduction in IQ (change ± SD) after OK (all p < 0.0001): logRMSs (0.41 ± 0.21), logPFSt (-0.55 ± 0.28), logPFSc (-0.72 ± 0.49), logNS (-0.43 ± 0.26), logVSX (-0.54 ± 0.34), logVSMTF (-0.39 ± 0.23). Increased positive SA due to OK was associated with reduced IQ (r = 0.58 for logRMSs where positive change is worse IQ and r range from -0.78 to -0.88 for all other IQ metrics where negative change is worse IQ; all p < 0.0001).
Despite reduced IQ, OK has been shown to slow axial eye growth in myopic children and provide good high-contrast visual acuity. Increased SA after OK is associated with reduced retinal IQ and previously has been associated with decreases in LCVA, similar to those reported with soft multifocal lenses. Retinal IQ metrics can be a valuable tool in designing novel designs for myopia control to balance plus introduced on the retina with the impact on visual quality.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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