Shape of the retinal surface in emmetropia and myopia.
OBJECTIVE
To determine and compare the shapes of the retinas of emmetropic and myopic eyes.


METHODS
Nonrotationally symmetrical ellipsoids were mathematically fitted to the retinal surfaces of 21 emmetropic and 66 myopic eyes (up to -12 D) of participants aged 18 to 36 years (mean, 25.5) using transverse axial and sagittal images derived from magnetic resonance imaging.


RESULTS
The shapes of the ellipsoids varied considerably between subjects with similar refractive errors. The shapes were oblate (steepening toward the equator) in most of the emmetropic eyes (i.e., the axial dimensions of the ellipsoids were smaller than both the vertical and horizontal dimensions). As myopia increased, all ellipsoid dimensions increased with the axial dimension increasing more than the vertical dimension, which in turn increased more than the horizontal dimension (increases in approximate ratios 3:2:1). The relative difference in the increase of these dimensions meant that as the degree of myopia increased the retinal shape decreased in oblateness. However, few myopic eyes were prolate (flattening toward the equator). Independent of myopia, the ellipsoids were tilted about the vertical axis by 11 degrees +/- 13 degrees , and ellipsoid centers were decentered horizontally by 0.5 +/- 0.4 mm nasally and 0.2 +/- 0.5 mm inferiorly, relative to the fovea.


CONCLUSIONS
In general both emmetropic and myopic retinas are oblate in shape, although myopic eyes less so. This finding may be relevant to theories implicating the peripheral retina in the development of myopia.
Atchison
David A
DA
Centre for Health Research-Optometry, Queensland University of Technology, Brisbane, Queensland, Australia. d.atchison@qut.edu.au
Pritchard
Nicola
N
Schmid
Katrina L
KL
Scott
Dion H
DH
Jones
Catherine E
CE
Pope
James M
JM
D000293:Adolescent; D000328:Adult; D000869:Anterior Eye Segment / Q000033:anatomy & histology; D001837:Body Weights and Measures; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009216:Myopia / Q000209:etiology*; D012160:Retina / Q000033:anatomy & histology*; D012737:Sex Factors