Correlation between retinal nerve fiber layer thickness and visual field sensitivity: diffuse atrophy imaging study.

BACKGROUND AND OBJECTIVE: To identify the correlation between retinal nerve fiber layer (RNFL) thickness and visual field sensitivity in healthy eyes with preperimetric and perimetric glaucoma and to estimate the functional RNFL loss in eyes with pre-perimetric glaucoma.

PATIENTS AND METHODS: One hundred and two eyes with glaucoma and diffuse RNFL atrophy and 102 healthy eyes were enrolled. The correlation between optical coherence tomography (OCT)-measured RNFL thickness of the superior (clock-hour segments 10, 11, 12, 1, 2, and 3) and inferior (clock-hour segments 5, 6, 7, and 8) area and the average total deviations of the inferior and superior hemifields in standard automated perimetry (SAP) were evaluated using the simple linear model, respectively. The OCT-measured RNFL thickness was assumed to comprise functional and residual thicknesses; the residual thickness was calculated from the simple linear model and the eyes with severe diffuse RNFL atrophy. Functional RNFL thickness was compared between groups.

RESULTS: Twenty-seven eyes had preperimetric and 75 eyes had perimetric glaucoma. The coefficient of determination (R(2)) of the simple linear model was 0.71 to 0.77 for the correlation between RNFL thickness and total deviation of SAP. The estimated residual thickness was 50.4 to 56.5 μm. On comparison with normal eyes, eyes with preperimetric glaucoma were estimated to have 37% to 41% functional RNFL loss.

CONCLUSION: The correlation between RNFL thickness and SAP sensitivity was well explained by the simple linear model. Approximately 40% loss of the functional RNFL was found in preperimetric glaucoma.