Fifty-one subjects completed the protocol across 8 weeks. Noncycloplegic spherical equivalent refraction did not differ significantly between right and left eyes (
P = 0.94). Only right eye data are considered further.
Table 1 summarizes sex, age, and refractive and axial length data, and
Table 2 summarizes subjective and objective measures of chronotype, sleep, activity, and light exposure data for all subjects and by refractive group. Briefly, chronotype, sleep quality and duration, and physical activity metrics did not differ significantly between refractive groups. Neither refractive group nor gender were significantly associated with higher proportions of subjects categorized as having “good” or “poor” PSQI sleep quality (χ
2 = .35,
P = 0.56 and χ
2 = .13,
P = 0.72, respectively), and chronotype classification, as determined by the MEQ, was not significantly associated with refractive group (χ
2 = 2.74,
P = 0.26) or sex (χ
2 = 3.12,
P = 0.21). Neither date nor daylength at time of assessment differed significantly between refractive groups (
P = 0.73 for both). As a group, myopes spent statistically more time exposed to “indoor” photopic conditions compared with their nonmyopic peers (
P = 0.05,
Table 3). However, the amount of time individuals spent “indoors” was not significantly correlated to SER or axial length (Spearman’s rank, ρ = –.17,
P = 0.24 and ρ = .20,
P = 0.16, respectively), and no other light exposure parameter differed significantly between groups (
Tables 2 and
3). Of note, MLiT
1000 tended to be earlier for myopes compared with emmetropes, but the difference between refractive error groups did not reach statistical significance (
P = 0.07), and MLiT
1000 was not significantly correlated to either SER or axial length (AL) (Spearman’s rank, ρ = –.17,
P = 0.23 and ρ = –.08,
P = 0.58, respectively).