In humans, the pattern of peripheral refractive error varies with the central refractive error.
6 8 11 15 39 To examine the relationship between peripheral and central refractive states in infant monkeys, we divided the 58 monkeys into three subgroups based on the degree of central hyperopia. Specifically, the range of central refractive errors was subdivided into thirds, and the data for animals that fell within each of these three equal-dioptric intervals were pooled. Based on this criterion, the average central refractive errors for the animals in the low-, moderate-, and high-hyperopia subgroups were +1.75 ± 0.66 D (range, +0.25 to +2.43;
n = 8), +3.64 ± 0.65 D (range, +2.44 to +4.61;
n = 37), and +5.67 ± 0.57 D (range, +4.62 to +6.81;
n = 13), respectively.
Figure 2Ashows the average refractive errors for these three subgroups plotted as a function of eccentricity, and
Figure 2Bshows the relative peripheral refractive errors for these subgroups normalized to their respective average central refractive errors. A mixed-design, repeated-measures ANOVA revealed that peripheral refraction varied with eccentricity (
F = 41.79,
P = 0.0001) and that there were significant differences in the pattern of relative peripheral refractions between subgroups (
F = 5.82,
P = 0.02) with significant subgroup–eccentricity interactions (
F = 5.03,
P = 0.0001). Specifically, all three subgroups of monkeys showed nasal–temporal asymmetries in peripheral refractive errors (low,
F = 12.82,
P = 0.02; moderate,
F = 113.88,
P = 0.0001; high,
F = 109.59,
P = 0.0001). There were no between-group differences in relative refractions for the temporal field (high versus low,
F = 0.52,
P = 0.48; high versus moderate,
F = 0.81,
P = 0.37; moderate versus low,
F = 0.007,
P = 0.94). However, because there were significant subgroup differences in the nasal field (high versus low,
F = 10.96,
P = 0.002; high versus moderate,
F = 11.65,
P = 0.001; moderate versus low,
F = 1.20,
P = 0.28), the degree of nasal–temporal asymmetries also increased with the degree of central hyperopia. In particular, the relative refractive state in the nasal field correlated significantly with the eye’s vitreous chamber depth at all eccentricities (
r 2 = 0.15–0.22,
P < 0.003) and with the central refractive error at the 30° (
r 2 = 0.14,
P = 0.003) and 45° eccentricities (
r 2 = 0.23,
P < 0.0001), specifically, the shorter and more hyperopic the eye, the higher the degree of relative peripheral myopia in the nasal field. On the other hand, the degree of relative myopia in the nasal field did not correlate with either the central corneal power (
P = 0.14–0.84) or corneal asphericity, as represented by Q values (
P = 0.052–0.26).