Characteristics of Highly Myopic Eyes : The Beijing Eye Study

ObjectiveTo evaluate factors associated with high myopia (defined as a myopic refractive error exceeding −8 diopters) in a population-based study.DesignPopulation-based prevalence study.ParticipantsThe Beijing Eye Study included 4439 participants from among 5324 individuals from a rural area and an urban region of Greater Beijing, ≥40 years old and invited to participate (response rate, 83.4%).MethodsInterview and detailed ophthalmic examination.Main Outcome MeasuresRefractive error, microvascular retinal abnormalities, optic disc morphometry, amount of cataract, and age-related macular changes.ResultsFundus photographs and data for refractive error were available for 4319 participants (97.3%; 8484 eyes). In binary logistic regression analysis, prevalence of high myopia was significantly associated with low best-corrected visual acuity (P<0.001; 95% confidence interval [CI], 0.15–0.40), large optic disc size (P<0.001; 95% CI, 1.64–2.25), large size of β zone (P = 0.31; 95% CI, 1.45–1.75) and α zone of peripapillary atrophy (P<0.001; 95% CI, 1.20–1.58), and lower macular drusen count (P = 0.020; 95% CI, 0.81–0.98). The highly myopic group had a smaller mean size of macular drusen (P = 0.03; 95% CI, 0.02–0.26) and a smaller area covered by drusen (P = 0.01; 95% CI, 0.03–0.22). In the highly myopic group, the predominant drusen type was significantly (P = 0.01; 95% CI, 0.05–0.41) more often the hard distinct drusen type than the soft drusen type, and visual field defects were significantly more common (P<0.001; odds ratio [OR], 24.0; 95% CI, 13.9–41.4) and larger (P<0.001; 95% CI, −1.67 to −1.13). The frequencies of early macular degeneration (P = 0.03; OR, 3.0; 95% CI, 1.21–7.51) and late macular degeneration (P<0.001; OR, 6.33) were significantly lower in the highly myopic group than in the non–highly myopic group. High myopia was not significantly associated with gender (P = 0.18; 95% CI, 0.76–1.05), focal arteriolar thinning (P>0.35), arteriolar sheathing (P>0.45), arteriovenous crossing abnormalities (P>0.20), self-reported diagnosis of diabetes mellitus (P = 0.54; OR, 1.36; 95% CI, 0.48–3.80), or arterial hypertension (P = 0.34; OR, 0.66; 95% CI, 0.32–1.34).ConclusionsIn the adult Chinese population, high myopia is associated with a lower number, smaller, size and less advanced type of macular drusen, a larger optic nerve head, and decreased best-corrected visual acuity. The risk of early and late macular degeneration was lower for highly myopic participants than for non–highly myopic participants.