The effects of peripapillary atrophy on the diagnostic ability of Stratus and Cirrus OCT in the analysis of optic nerve head parameters and disc size.

PURPOSE: We compared the diagnostic ability of Stratus and Cirrus optical coherence tomography (OCT) in optic nerve head (ONH) analysis, and examined the effects of optic disc size and peripapillary atrophy (PPA) on their diagnostic capacity.
METHODS: Stratus and Cirrus OCT was performed in 28 control and 78 glaucomatous eyes. ONH parameters and diagnostic capacity calculated from the area under the receiver operating characteristics curve (AUC) were compared between the two modalities. Glaucomatous eyes were classified by optic disc size and the presence/absence of PPA, and their AUCs were compared.
RESULTS: Rim area (AUC 0.936) and rim volume (AUC 0.824) showed the best diagnostic capacity in Cirrus and Stratus OCT, respectively. Cirrus OCT showed greater diagnostic ability over Stratus OCT for all ONH parameters. With increasing ONH size, diagnostic ability declined in rim and disc areas, while it improved in average cup-to-disc ratio (CDR), vertical CDR, and cup volume for both modalities. Optic disc size as measured by Stratus OCT was significantly larger than that by Cirrus OCT in glaucomatous eyes with PPA. In addition, the diagnostic capacity of all ONH parameters declined significantly for glaucomatous eyes with PPA, especially for Stratus OCT. In Cirrus OCT, retinal nerve fiber layer (RNFL) thickness showed poorer diagnostic ability than rim area in the glaucoma with PPA group.
CONCLUSIONS: The diagnostic capacity of Cirrus OCT was superior to that of Stratus OCT. Considering the principle of determining the disc margin, as Stratus OCT tends to make excessive measurements of the optic disc in PPA, caution is required in analyzing the results.