RESUMO
Purpose: To determine the discriminating ability of retinal nerve fiber layer [RNFL] thickness measured with spectral-domain optical coherence tomography [SD-OCT] in different stages of glaucoma
Patients and methods: Thirty normal, 150 glaucomatous eyes were included. Glaucomatous eyes were graded into early, moderate and severe stages according to one of the global indices called visual field index [VFI]. Complete ophthalmic examination, white on white perimetry and SD-OCT were done for all patients. RNFL thickness of quadrants and average thickness were recorded. Area under receiver operating characteristic curves [AUCs] were used to assess the performance of OCT parameters
Results: Average, inferior and superior RNFL thickness were the best parameters to discriminate normal from early glaucoma [AUC: 0.91-86], early from moderate [AUC: 0.77-0.70] and moderate from severe [AUC: 0.85-83]. Average RNFL loss was 18% in early glaucoma, 28% in moderate glaucoma and 41% in severe glaucoma. Early damage tends to be focal and in the lower quadrant. A significant correlation was detected between mean VFI and mean RNFL loss. Glaucoma was restaged according to average RNFL loss into early: >/=97.5 micro, moderate: <97.5-72.5 micro and severe: <72.5 micro
Conclusion: RNFL thickness measured with SD-OCT could discriminate the three stages of glaucoma. RNFL loss can be correlated to visual field loss. Future OCT-based staging of glaucoma, adjunctive to perimetry is possible