American Chinese glaucoma imaging study: a comparison of the optic disc and retinal nerve fiber layer in detecting glaucomatous damage.

Purpose: To compare the relationships between optic nerve structural measures and visual function, as well as the diagnostic sensitivity for glaucoma detection between the retinal nerve fiber layer (RNFL) and neuroretinal rim measurements.

Methods: A total of 101 normal and 156 glaucomatous eyes of 257 enrolled subjects were examined. RNFL thickness was measured by optical coherence tomography, and the neuroretinal rim (rim area, rim/disc area, and rim volume) was measured with a confocal scanning laser ophthalmoscope. The relationship between the structural measures and visual field sensitivity was evaluated with linear and non-linear-regression (quadratic and logarithmic) models. The coefficient of determination (R2) was calculated, and the regression models were compared with Alkaike's information criteria and the F test. The diagnostic sensitivity for glaucoma detection in each structural measure was determined by the area under the receiver operating characteristic curve (AUC).

Results: The relationship of the RNFL, rim area, rim/disc area, and rim volume with visual function was best described with nonlinear regression models (quadratic regression for the RNFL [R2 = 0.383]), rim area [R2 = 0.303]), and rim/disc area [R2 = 0.265]; and logarithmic regression for rim volume [R2 = 0.175]). The change of visual sensitivity at each level of structural damage was highest for the RNFL. The AUC for the RNFL also was higher than the neuroretinal rim measures. In this study population, at 90% specificity, the diagnostic sensitivities for detecting glaucomatous damage was 82.7%, 67.3%, 67.3%, and 52.6% for the RNFL, rim area, rim/disc area, and rim volume, respectively. (These values would apply only to a group with inclusion criteria and disease severity similar to those of the present cohort.)

Conclusions: The RNFL showed a stronger structure-function association and a higher diagnostic sensitivity for glaucoma detection than did the neuroretinal rim.