Purpose: Previous studies suggest that the refractive status of the peripheral retina may influence the progression of myopia. Our aim was to investigate peripheral refractions in human eyes with high myopia when corrected with a conventional soft spherical contact lens (CL).
Methods: Ten young adults with high myopia (over -6.00 D) were investigated. An open-field auto-refractor was used to measure on- and off-axis refractions in primary gaze, with and without a CL, every 5° out to 20° horizontally in nasal and temporal retina. Results were analyzed as mean sphere (M) and astigmatic (J(0) and J(45)) vector components. Partial coherence interferometry measures of eye size were also made on- and off-axis at 10 and 20° in nasal and temporal retina.
Results: Subjects (mean age, 22 years; range, 20 to 26 years) had an average on-axis spherical refractive error of -8.31 ± 2.10 D and an average on-axis eye length of 27.39 ± 1.18 mm. Mean sphere exhibited a significant shift from hyperopic relative peripheral refraction (RPR) in the uncorrected state to myopic RPR on correction, in both nasal and temporal retina. Mean RPR of all subjects across all eccentricities was hyperopic when uncorrected (M = +0.20 ± 0.49 D: mean ± 1 SEM) becoming myopic when corrected (M = -0.45 ± 0.56 D: p = 0.0003, reaching -1.21 ± 0.82 D at 20° in the temporal retina). Peripheral J(0) astigmatism also became significantly more negative on correction (p = 0.002), whereas J(45) astigmatism remained unchanged. On- and off-axis measures of eye length indicated a relatively prolate retinal contour. Uncorrected off-axis mean sphere refractive error reduced with eccentricity, and this was accurately predicted (R > 0.98) by the measured retinal contour.
Conclusions: Correcting the foveal refractive error in high myopia with standard spherical soft CLs can result in significant absolute myopic defocus in the peripheral retina. If peripheral refraction does indeed influence myopia progression, then our results suggest that in high myopia, standard soft CLs may be beneficial in reducing myopia progression.