Measurement of Optic Disc Cup Surface Depth Using Cirrus HD-OCT

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Abstract

Purpose:

To introduce the measurement method of optic disc cup surface depth using spectral-domain optical coherence tomography (SD-OCT) and then evaluate the rates of cup surface depression at 3 different stages of glaucoma.

Materials and Methods:

We retrospectively identified 52 eyes with preperimetric glaucoma, 56 with mild-or-moderate glaucoma and 50 with severe glaucoma and followed them for at least 48 months. Eyes were imaged using SD-OCT (Cirrus HD-OCT) at 12-month intervals. The mean cup surface depth was calculated using the following formula: Cup volume/(disc area×average cup-to-disc ratio2)−200 μm.

Results:

The rates of mean cup surface depression (μm/y) were significantly greater in mild-or-moderate glaucoma (−7.96±1.03) than in preperimetric (−3.11±0.61) and severe glaucoma (−0.70±0.12; all P<0.001). The percentile rates of mean cup surface depression (%/y) were significantly greater than those of average of retinal nerve fiber layer (RNFL) thinning (%/y) in preperimetric glaucoma (−1.64±0.12 vs. −1.11±0.07; P<0.001) and mild-or-moderate glaucoma (−4.20±0.33 vs. −3.14±0.19; P<0.001); and conversely, in severe glaucoma, mean cup surface depth changed slower than did average RNFL thickness (−0.64±0.06 vs. −0.75±0.08%/y; P<0.001).

Conclusions:

In early-to-moderate glaucoma, the cup surface depth changed faster than did the RNFL thickness. These results signify the possibility that SD-OCT–based estimation of cup surface depth might be useful for monitoring of glaucoma development and progression.

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