Prevalence and Cause of Loss of Visual Acuity and Visual Field in Highly Myopic Eyes: The Beijing Eye Study

Abstract

To explore prevalence and causes of loss of visual acuity and visual field in highly myopic eyes. Population-based study. The participants (n=4439) of the Beijing Eye Study underwent an ophthalmological and systemic examination including frequency doubling technology perimetry (FDT). High myopia was defined by a refractive error of ≤-6Dpt or axial length >26.0 mm. Prevalence of vision impairment causes. The study included 212 highly myopic eyes (154 participants;mean age:56.2±9.6 years;refractive error:-9.87±3.70 Dpt;range:-20.87 to -6.00Dpt; axial length:27.2±1.3mm;range:26.01-30.88mm). Moderate/severe vision impairment (MSVI) (best corrected visual acuity (BCVA) from <6/18 to 3/60) and blindness (BCVA <3/60 or <10° visual field around central fixation) was present in 40/212 (18.9%;95%CI:13.6,24.2) eyes, and in 10/212 (4.7%;95%CI:1.8, 7.6) eyes, respectively. BCVA decreased with more myopic refractive error (beta:-0.55;B:-0.08;95%CI:-0.09,-0.06;P<0.001). Primary (i.e., most influential) causes for MSVI and blindness were myopic macular degeneration (MMD) (29/50;58%), age-related macular degeneration (1/50;2%), and branch macular retinal vein occlusion (1/50;2%). Secondary causes were MMD (4/50;8%) and optic nerve atrophy (14/50 (28%), differentiated into a non-glaucomatous type (NGOA) (9/50;18%) and glaucomatous type (GOA) (5/50;10%). Prevalence of MMD as vision impairment cause (mean:40/212 (18.9%;95%CI:13.6,24.2) increased from 1/61 (1.6%;95%CI:0.00,4.9) in the group of -6.00 to ≥-7.00Dpt, to 16/25 (64.0%;95%CI:43.8,84.2) in the group of <-15.0Dpt. Higher MMD prevalence correlated with higher myopic refractive error (OR:0.70;95%CI:0.61;0.81;P<0.001) and higher prevalence of concomitant optic neuropathy (OR:86.2;95%CI:16.1,463;P<0.001). Optic neuropathy prevalence as cause of vision impairment (mean:19/212;9.0%;95%CI:5.0,13.0) increased from 0/61 (0%) in the refractive error group of -6.00Dpt to ≥-7.00Dpt, to 9/25 (36.0%;95%CI:16.0,56.0) in the group of <-15.0Dpt. Higher optic neuropathy prevalence correlated with more myopic refractive error (P<0.001) and older age (P=0.02). GOA prevalence (mean:6/212;2.8%;95%CI:1.0,5.0) and NGOA prevalence (mean:13/212 (6.1%;95%CI:3.0,9.0) increased from 0/61 (0%) in the group of -6.00 to ≥-7.00Dpt, to 4/25 (16.0%;95%CI:1.0,31.0) and 5/25 (20%;95%CI:3.0,37.0), respectively, in the group of <-15.0Dpt. In this population-based recruited, highly myopic cohort, prevalence of optic neuropathy (9.0%) as vision impairment cause was lower than MMD prevalence (18.9%), and it was an important reason for vision impairment in the group of <-15Dpt. MMD was vision impairment cause in 16/25 (64.0%) eyes with <-15.0Dpt refractive error.