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Ortho-K lenses alter peripheral refraction along horizontal, vertical meridians
Researchers propose that inducing greater degrees of myopic defocus onto the peripheral retina, more than habitually experienced, may be needed for effective myopia control, according to a study in Optometry and Vision Science.
Kang and colleagues evaluated 19 young adult myopic subjects who were a mean age of 28 years. Central and peripheral refraction and corneal topography measurements were taken before and after 14 nights of orthokeratology (ortho-K) lens wear.
Before ortho-K wear, peripheral spherical equivalent refraction (M) across the horizontal meridian did not vary significantly from center, according to researchers. M across the vertical meridian was found to be more myopic.
Researchers found a hyperopic shift in M at all positions across the horizontal meridian except at 30 degrees and 35 degrees on the temporal retina, while there was a myopic shift and no change in M at 35 degrees on the nasal retina, according to the study.
After ortho-K lens wear, a significant change was found in J180 profile with a significant negative shift in J180 at all positions except at center and 10 degrees on the nasal retina. Peripheral J180 values were relatively more negative at all positions compared with center after ortho-K lens wear, according to researchers.
Along the vertical meridian, ortho-K lens wear caused significant changes in peripheral M profile, with significant hyperopic M shifts at all positions except 30 degrees on the inferior retina. The M was overall more myopic than the center at all positions except at 10 degrees on the superior retina after ortho-K lens wear, where there was no change.
The researchers wrote that greater extent and duration of retinal exposure to myopic defocus will enhance the efficiency of myopic control modalities, including ortho-K. – by Abigail Sutton
Disclosure: The researchers reported no relevant financial disclosures.