Peripheral refraction along the horizontal and vertical visual fields in myopia

Abstract

Peripheral refractions were measured to 35 degrees eccentricity using a free-space autorefractor in young adult emmetropic and myopic subjects. Refractions were measured along horizontal and vertical visual fields for 116 subjects and a 43 subject subset, respectively. Along the horizontal visual field, peripheral myopic shifts in spherical equivalent M of emmetropes changed to relative hypermetropic shifts in the myopes, there were temporal-nasal asymmetries of 90 degrees to 180 degrees astigmatism J(180) which decreased as myopia increased, and 45 degrees to 135 degrees astigmatism J(45) was linearly related to field angle. Along the vertical visual field, both peripheral myopic shifts in peripheral M and J(180) asymmetry were unaffected by magnitude of myopia, and J(45) changed at three times the rate as for the horizontal visual field. Myopia has more effect on peripheral refraction of adult eyes along the horizontal than along the vertical visual field. The peripheral variations in refraction match well what is known about the shapes of emmetropic and myopic eyes.

Axial Length in Orthokeratology Patients: Large Case Series

“…Similar to spectacles and contact lenses, Ortho-K creates sharp focus on the central area of the retina (macula and peri-macular area). But, peripheral to the macular area, while spectacle and contact lens correction creates relative peripheral hyperopia, Ortho-K creates relative peripheral myopia [51][52][53][54][55][56]. This relative peripheral myopic defocus inhibits the signaling for the eye to elongate [50].…”

“…Individually designing Ortho-K lenses for optimal myopia control may involve creation of custom lens profiles generated from baseline measurements of posterior retinal shape and peripheral refraction [52][53][54][55][56]. The ideal amount and location of the relative peripheral myopia required for optimal myopia control is not known at this time [57].…”

Relative peripheral defocus and myopic progression in children

“…While the central refraction difference between the two groups was not significantly different, this may be because of the small number in their progressing group; the initial mean refraction for the progressing group was about 1.4 D more myopic than that of the non-progressing group, and this is expected to give more hyperopic relative peripheral defocus [2][3][4]. The similar axial length between the groups means little without information about the gender distribution, because males have about 0.5 mm longer axial lengths than females of similar refractions and age [5][6][7]; also, again, there may have been insufficient children in this group to show a real difference.…”

Do Peripheral Refraction and Aberration Profiles Vary with the Type of Myopia? - An Illustration Using a Ray-Tracing Approach

“…16,18 Considerable human research is being carried out to study the hypothesis that defocus and astigmatism in the retinal periphery may influence the development and progression of myopia. These studies [12][13][14][15][16][17][18][19][20][21] have reported diverse peripheral refraction patterns with various levels of ametropia. However, most suggest that emmetropes and hypermetropes have relative myopic shifts in the periphery, while myopes have relative hypermetropic shifts.…”

“…24,[26][27][28][29][30] Previous research has revealed that myopic progression is probably associated with several factors like environment, studies, lifestyle, genetics, near work [35][36][37][38][39][40][41][42][43][44][45][46] as well as with the optical defocus theory. It is now widely acknowledged that the defocus in the periphery of myopic eyes may stand a stimulus for the axial growth of the eye [17][18][19][20][21] but none has looked into the type of myopia, whether refractive or axial, at the start/detection stage and its capability to provoke eye growth.…”