Effects of age and disc area on optical coherence tomography measurements and analysis of correlations between optic nerve head and retinal nerve fibre layer.

BACKGROUND

The aim here was to investigate whether optic nerve head (ONH) parameters or retinal nerve fibre layer (RNFL) thickness correlate with age or disc area and whether the neuroretinal rim correlates with RNFL thickness.

METHODS

This cross-sectional study enrolled 133 healthy subjects and analysed one randomly selected eye of each subject. All measurements of ONH parameters (including neuroretinal rim, disc and cup areas and cup-to-disc ratios) and RNFL thickness (global and quadrants) were taken by a single experienced operator using optical coherence tomography (OCT).

RESULTS

Of the rim parameters analysed, average nerve width (the height of the nerve fibre bundle) was independent of age or disc area (p > 0.05). Disc area correlated positively with cup area (p < 0.05) but not with cup-to-disc ratios (p > 0.05). Of the RNFL thickness measurements analysed, temporal RNFL was independent of both age and disc area (p > 0.05). According to the analysis of the correlation between RNFL thickness and neuroretinal rim, global or non-temporal RNFL correlated positively with horizontal integrated rim width (p < 0.05, F > 4.000) and temporal RNFL was independent of all rim parameters (p > 0.05, F < 4.000).

CONCLUSION

Aging effect on neuroretinal rim loss or RNFL thickness change is non-uniform, and age is not a constant confounder when using OCT. The temporal RNFL is independent of age, disc area and neuroretinal rim.