Comparison of spectral domain optical coherence tomography parameters between disc suspects and “pre-perimetric” glaucomatous discs classified on disc photos

PURPOSE: The aim of this study was to compare SD-OCT parameters between disc suspects and “pre-perimetric” glaucomatous discs classified on disc photos. METHODS: Disc photos of suspicious discs with normal Humphrey visual fields (HVF) were graded as normal or pre-perimetric glaucomatous based on the consensus of three masked glaucoma specialists. RNFL and GCL-IPL maps of SD-OCT (Cirrus OCT) of these eyes were studied. Quantitative RNFL parameters were compared. Both groups were also compared with respect to parameters being classified as abnormal (at the 1% level), and the pattern of GCL-IPL and NFL maps were assessed qualitatively and classified as normal or pre-perimetric glaucomatous by a masked glaucoma specialist. RESULTS: The average and inferior RNFL thicknesses were decreased in pre-perimetric glaucomatous eyes compared to normal eyes (p 0.01) The average, minimal, inferotemporal and inferior sector GCL-IPL thicknesses were decreased in pre-perimetric glaucomatous eyes (all P < 0.002) The highest AUC was for the inferior RNFL thickness (0.771) followed by average RNFL thickness (0.757) The sensitivity and specificity for any one abnormal RNFL parameter was 71.9% and 59.7%, for GCL-IPL parameters was 70% and 69.1% The positive (PLR) and negative likelihood ratios (NLR) were 1.78 and 0.47 for RNFL and 2.26 and 0.43 for GCL-IPL parameters. For the qualitative assessment of RNFL and GCL-IPL maps, the sensitivity, specificity, PLR and NLR were 75%, 77.2%, 3.29, and 0.32, respectively. CONCLUSION: Pre-perimetric disc suspects had greater OCT changes compared to normal disc suspects. Qualitative assessment of RNFL and GCL-IPL maps had the highest discriminatory ability.