Relative peripheral refraction across 4 meridians after orthokeratology and LASIK surgery

Background:To characterize the axial and off-axis refraction across four meridians of the retina in myopic eyes before and after Orthokeratology(OK)and LASIK surgery.Methods:Sixty right eyes with a spherical equivalent(M)between−0.75 to−5.25 D(cylinder<−1.00 D)underwent LASIK(n=26)or OK(n=34)to treat myopia.Axial and off-axis refraction were measured with an open-field autorefractometer before and after stabilized treatments.Off-axis measurements were obtained for the horizontal(35°nasal and temporal retina)and vertical(15°superior and inferior retina)meridians,and for two oblique directions(45–225°and 135–315°)up to 20°of eccentricity.The refractive profile was addressed as relative peripheral refractive error(RPRE).Results:OK and LASIK post-treatment results showed an increase of myopic relative refraction at several eccentric locations.At the four meridians evaluated,the M component of the pre-treatment RPRE values was not statistically different(p>0.05)from the post-treatment RPRE within 30°and 20°of the central visual field after LASIK and OK,respectively.These results demonstrated that the treatment zone warrants an optimal central field of vision.Conclusions:The present study gives an overview of RPRE after refractive corneal reshaping treatments(OK and LASIK)across vertical,horizontal and two oblique meridians together.This allows a 3D representation of RPRE at the retina and shows that the myopic shift induced by both treatments is more relevant in horizontal directions.