Peripheral refraction profiles in subjects with low foveal refractive errors.
OBJECTIVE
To study the variability of peripheral refraction in a population of 43 subjects with low foveal refractive errors.


METHODS
A scan of the refractive error in the vertical pupil meridian of the right eye of 43 subjects (age range, 18 to 80 years, foveal spherical equivalent, < ± 2.5 diopter) over the central ± 45° of the visual field was performed using a recently developed angular scanning photorefractor. Refraction profiles across the visual field were fitted with four different models: (1) "flat model" (refractions about constant across the visual field), (2) "parabolic model" (refractions follow about a parabolic function), (3) "bi-linear model" (linear change of refractions with eccentricity from the fovea to the periphery), and (4) "box model" ("flat" central area with a linear change in refraction from a certain peripheral angle). Based on the minimal residuals of each fit, the subjects were classified into one of the four models.


RESULTS
The "box model" accurately described the peripheral refractions in about 50% of the subjects. Peripheral refractions in six subjects were better characterized by a "linear model," in eight subjects by a "flat model," and in eight by the "parabolic model." Even after assignment to one of the models, the variability remained strikingly large, ranging from -0.75 to 6 diopter in the temporal retina at 45° eccentricity.


CONCLUSIONS
The most common peripheral refraction profile (observed in nearly 50% of our population) was best described by the "box model." The high variability among subjects may limit attempts to reduce myopia progression with a uniform lens design and may rather call for a customized approach.
Departamento de Física, Laboratorio de Optica, Universidad de Murcia, Campus de Espinardo (Edificio CiOyN), Murcia, Spain. juant@um.es
Juan
J
Tabernero
Arne
A
Ohlendorf
M Dominik
MD
Fischer
Anna R
AR
Bruckmann
Ulrich
U
Schiefer
Frank
F
Schaeffel
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005584:Fovea Centralis / Q000503:physiopathology*; D006801:Humans; D016014:Linear Models; D008875:Middle Aged; D008962:Models, Theoretical; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000145:classification / Q000503:physiopathology*; D012160:Retina / Q000503:physiopathology; D014794:Visual Fields; D055815:Young Adult