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Zhenghua Lin, Weizhong Lan, Zhikuan Yang, Pablo Artal; How Orthokeratology affects Peripheral Optics?. Invest. Ophthalmol. Vis. Sci. 2020;61(7):553.
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© ARVO (1962-2015); The Authors (2016-present)
Orthokeratology (OK) is a rather common procedure that uses rigid contact lenses for reshaping the cornea by over-night wearing. Beyond the correction of refractive error, it has been suggested that produces a reduction of myopia progression perhaps due to induced changes in peripheral refraction. Since this hypothesis is not proved yet, our aim here was to explore the changes in peripheral optics after OK treatment in a group of myopic children.
A group of 31 subjects with mean of age: 11.7±1.9 years, ranged from 8 to 17; and mean of central refractive error: -3.5±1D, ranged from -1.6 to -5.5D) were included in the study. Peripheral aberrations were measured under cycloplegia by using an open-view Hartmann-Shack wavefront sensor (VPR, Voptica SL, Murcia, Spain). This instrument allows to measure fast in the horizontal visual field from temporal 30° to nasal 30° every 1°. Two-dimensional (2D) maps were retrieved from a series of horizontal scans taken every 4° from 20° superior to 16° inferior covering a visual field of 60 x 36°. Measurements were taken before and after the OK treatment.
The average central refraction was -3.5±1 D and -0.9±0.6 D before and after OK respectively. As expected, before OK, myopic subjects presented a relative hyperopia at the periphery (around 1.5 D at 30°) in both nasal and temporal directions. After OK, peripheral refraction showed an asymmetric map (see accompanying figures with relative peripheral refractions before (left) and after (right) treatment). In the temporal retina, refraction changed to myopia (near -1.5 D at 30°) while in the nasal retinal reminded approximately as in the fovea. Astigmatism was significantly increased by OK in the periphery specially in the temporal retina, reaching values of -6D at 30°. High-order aberrations were also increased by OK.
OK treatments produced a significant change in the patterns of peripheral optics. The change was strongly asymmetric: 3D toward myopia in the temporal side and 1D in the nasal side. Astigmatism and higher order aberrations also increased in the temporal side. Peripheral optics after OK is different as in normal emmetropic subjects. Further research is required to determine the cause of the pattern found and if this may have an effect in myopia progression.
This is a 2020 ARVO Annual Meeting abstract.
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