Prevalence and Ocular Biometric Characteristics of Myopia in Primary Angle Closure Disease in Rural China: The Handan Eye Study

PURPOSE. The purpose of this study was to determine the prevalence of myopia among patients with primary angle closure disease (PACD) in rural China and their ocular biometric characteristics. METHODS. Study subjects were recruited from the Handan Eye Study. A/B-mode scan (Cine Scan, Quantel Medical, Cedex, France) was used to measure the axial length, anterior chamber depth (ACD), and lens thickness (LT). PACD was defined as the anterior chamber angle being considered closed when 180 degrees or more of the posterior pigmented trabecular meshwork were not visible on the gonioscopy. Myopia was defined as a spherical equivalent (SE) refractive error <=-0.5 diopter (D). Persons who did not meet PACD definition were classified as the open-angle (OA) group. RESULTS. The overall prevalence of myopia in persons with PACD was 13.7% (11.6% in primary angle closure suspect [PACS], 21.6% in primary angle closure [PAC], 62.5% in primary angle closure glaucoma [PACG]). The age-specific prevalence of myopia in PACD eyes was 41.7% at 30 to 39 years old, 12.3% at 40 to 49 years old, 8.7% at 50 to 59 years old, 10.7% at 60 to 69 years old, and 31.7% at age 70 years and over. PACD had shorter AL (22.2 +/- 0.8 vs. 22.9 +/- 0.9 mm, P < 0.001), shallower ACD (2.3 +/- 0.3 vs. 2.8 +/- 0.4 mm, P < 0.001), and greater LT (5.0 +/- 0.5 vs. 4.7 +/- 0.5 mm, P < 0.001). PACD had even thicker lenses and deeper ACD with age than those with OA (all P <= 0.025) from 30 years to 70 years of age and over. CONCLUSIONS. Myopia was common among persons with PACD who were less than 40 years of age in this rural Chinese population, and over half of those with PACG were myopic.