Relative peripheral refraction across 4 meridians after orthokeratology and LASIK surgery

Abstract

BackgroundTo characterize the axial and off-axis refraction across four meridians of the retina in myopic eyes before and after Orthokeratology (OK) and LASIK surgery.MethodsSixty 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).ResultsOK 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.ConclusionsThe 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.

IMI – Interventions for Controlling Myopia Onset and Progression Report

“…64 Although the initial goal of such therapies was to eliminate the need for daytime optical corrections, OK has proven to be effective in slowing myopia progression. OK also has been shown to induce relative myopic shifts in peripheral refractive errors in all meridians, 65 consistent with the most popular hypothesis for this myopia control effect, 66 although a role for altered higher-order aberrations cannot be excluded. 67,68 Most studies on the effectiveness and reliability of OK for myopia control have focused on children, 60,[69][70][71][72][73][74][75] with only limited reports on effects in adults.…”

Optical changes and visual performance with orthokeratology

“…Although most studies have only evaluated changes in peripheral refraction in the horizontal meridian, myopic shifts in refraction with orthokeratology have also been reported in the vertical meridian . Kang and Swarbrick measured peripheral refraction along the vertical meridian in 19 myopic subjects before and after 14 nights of orthokeratology.…”

“…Although most studies have only evaluated changes in peripheral refraction in the horizontal meridian, myopic shifts in refraction with orthokeratology have also been reported in the vertical meridian. 67,69 Kang and Swarbrick 67 measured peripheral refraction along the vertical meridian in 19 myopic subjects before and after 14 nights of orthokeratology. Subjects had peripheral myopia in the vertical meridian at baseline, and orthokeratology caused a myopic shift in peripheral refraction that increased the amount of peripheral myopic defocus.…”

Ocular and Corneal Aberrations changes in controlled randomized clinical trial MiSight® Assessment Study Spain (MASS)

“…Accordingly, several studies tested optical interventions to reduce the central hyperopic defocus (accommodative lag) and peripheral hyperopic defocus, essentially by wearing center-distance multifocal contact lenses (MFCL) 14,15 or by orthokeratology. [16][17][18] However, despite the reduction of peripheral hyperopia effectively preventing ocular growth, with an e cacy varying between 30% 19 and 56%, 17 it is not clear if myopia is only regulated by the relative peripheral defocus. As seen above, the HOA, namely SA, could also eventually be involved in the process of controlling ocular growth in myopia.…”