Application of the ISNT Rule to Neuroretinal Rim Thickness Determined Using Cirrus HD Optical Coherence Tomography.

PURPOSE

The study investigated the applicability of the inferior≥superior≥nasal≥temporal neuroretinal rim thickness (ISNT) rule to rim thickness measured using Cirrus high-definition spectral-domain optical coherence tomography (Cirrus HD-OCT) in healthy eyes and eyes with glaucoma.

METHODS

Rim thicknesses of 4 quadrants were investigated using the rim thickness curve of Cirrus HD-OCT for 40 eyes with mild glaucoma (mean deviation ≥ -6 dB), 40 eyes with moderate to advanced glaucoma (mean deviation 0.05). Relative rim loss in the inferior quadrant of the moderate to advanced glaucoma group (63.8%) was greater than that of the mild glaucoma group (53.6%; P=0.010), whereas rim loss in other quadrants was not significantly different between the 2 groups (P>0.05).

CONCLUSIONS

The ISNT rule with rim thickness measured using Cirrus HD-OCT has limited clinical value in the diagnosis of glaucoma. There is a topographic difference in inferior rim loss according to the stages of glaucomatous damage.