Purpose: This study examines the ability of time domain optical coherence tomography (Stratus OCT) of the retinal nerve fiber layer (RNFL) to discriminate between normal patients and patients with three stages of glaucomatous vision loss in a US veteran population.
Methods: A review of consecutive patients who underwent automated perimetry and Stratus OCT Fast RNFL scanning within a 6-month period was conducted. Patients with nonglaucomatous ocular disease that might affect the RNFL or perimetry results were excluded. Glaucomatous eyes were staged using the Hodapp-Parrish-Anderson grading system. Average, quadrant, and individual clock hour RNFL thicknesses and normative results between all groups were compared.
Results: A total of 247 normal subjects and 157 glaucoma subjects were included. Significant differences in RNFL thickness measurements were observed between all groups (p < 0.05). Receiver operating curve analysis of highest area under the curve showed average RNFL for normal versus mild glaucoma (0.86), inferior quadrant for mild versus moderate glaucoma (0.80), and superior quadrant for moderate versus severe disease (0.86). Normative results for individual parameters demonstrated high specificity but low sensitivity for mild disease versus normal control subjects with increasing sensitivity and decreasing specificity in subsequent stages of disease. The number of OCT parameters classified as borderline or abnormal increased with advancing disease, but a combination of high sensitivity and specificity was not detected for any stage.
Conclusions: Optical coherence tomography RNFL thickness measurements, individual parameter normative results, and the number of parameters classified as borderline or abnormal poorly distinguished between severities of disease. Significant RNFL thickness overlap and lack of normative parameters demonstrating both high sensitivity and specificity between consecutive stages of disease highlighted the wide variability of structural findings using time domain OCT in the staging of glaucoma.