Ophthalmoscopic assessment of the retinal nerve fiber layer. The Beijing Eye Study

To examine the retinal nerve fiber layer (RNFL) ophthalmoscopically, to search for localized RNFL defects, and to assess factors associated with RNFL visibility in a population-based setting.

The population-based cross-sectional Beijing Eye Study 2006 included 3251 subjects. Using color fundus photographs, RNFL visibility was assessed in grades from 0 to 8 in 8 fundus sectors. Localized RNFL defects were defined as wedge-shaped defects running towards the optic disc.

After exclusion of subjects with optic media opacities, 2602 subjects (mean age: 58.1±9.0 years) were included. RNFL visibility score was highest (P<0.001) in the temporal inferior region, followed by the temporal superior region, nasal superior region, and nasal inferior region. In multivariate analysis, higher RNFL visibility score was associated with younger age (P<0.001; standardized coefficient beta: -0.44; regression coefficient B: -0.22; 95%CI: -0.24, -0.20), female gender (P<0.001; beta: 0.11; B: 1.00; 95%CI: 0.67, 1.32), higher blood concentration of low-density lipoproteins (P = 0.002; beta: 0.07; B: 0.34; 95%CI: 0.13, 0.56), absence of dyslipidemia (P = 0.001; beta: -0.07; B: -0.58; 95%CI: -0.93, -0.24), lower blood glucose concentration (P = 0.006; beta: -0.05; B: -0.14; 95%CI: -0.24, -0.04), hyperopic refractive error (P<0.001; beta: 0.15; B: 0.45; 95%CI: 0.34, 0.56), smaller optic disc size (P<0.001; beta: -0.08; B: -0.72; 95% CI: -1.04, -0.40), absence of glaucomatous optic neuropathy (P<0.001; beta: -0.06; B: -2.69; 95%CI: -4.18, -1.21) and absence of non-glaucomatous optic nerve damage (P = 0.001; beta: -0.06; B: -4.80; 95%CI: 0. -7.64, -1.96). Localized RNFL defects were detected in 96 subjects (prevalence:3.7±0.45% (95% confidence interval (CI): 3.0, 4.4). In multivariate analysis, prevalence of localized RNFL defects was associated with higher blood pressure (P<0.001; odds ratio (OR): 1.07; 95%CI: 1.03, 1.10), higher concentration of low-density lipoproteins (P = 0.01; OR: 1.42; 95%CI: 1.08, 1.85), higher prevalence of glaucomatous optic neuropathy (P<0.001; OR: 46.8; 95%CI: 19.4, 113) and diabetic retinopathy (P = 0.002; OR: 3.20; 95%CI: 1.53, 6.67), and lower total RNFL visibility (P<0.001; OR: 0.92; 95%CI: 0.88, 0.96).

In Chinese aged 45+ years, a decreased RNFL visibility was associated with older age, male gender, dyslipidemia, hyperglycemia, myopia, larger optic disc, and glaucomatous or non-glaucomatous optic neuropathy. Localized RNFL defects (prevalence: 3.7±0.45%) were correlated mainly with higher blood pressure, higher concentration of low-density lipoproteins, glaucomatous optic neuropathy and diabetic retinopathy. These data are helpful for the routine ophthalmoscopic examination of the RNFL.