Accuracy of optical coherence tomography for diagnosing glaucoma: an overview of systematic reviews

Aims: To assess the diagnostic accuracy (DTA) of optical coherence tomography (OCT) for detecting glaucoma by systematically searching and appraising systematic reviews (SRs) on this issue. Methods: We searched a database of SRs in eyes and vision maintained by the Cochrane Eyes and Vision United States on the DTA of OCT for detecting glaucoma. Two authors working independently screened the records, abstracted data and assessed the risk of bias using the Risk of Bias in Systematic Reviews checklist. We extracted quantitative DTA estimates as well as qualitative statements on their relevance to practice. Results: We included four SRs published between 2015 and 2018. These SRs included between 17 and 113 studies on OCT for glaucoma diagnosis. Two reviews were at low risk of bias and the other two had two to four domains at high or unclear risk of bias with concerns on applicability. The two reliable SRs reported the accuracy of average retinal nerve fibre layer (RNFL) thickness and found a sensitivity of 0.69 (0.63 to 0.73) and 0.78 (0.74 to 0.83) and a specificity of 0.94 (0.93 to 0.95) and 0.93 (0.92 to 0.95) in 57 and 50 studies, respectively. Only one review included a clear specification of the clinical pathway. Both reviews highlighted the limitations of primary DTA studies on this topic. Conclusions: The quality of published DTA reviews on OCT for diagnosing glaucoma was mixed. Two reliable SRs found moderate sensitivity at high specificity for average RNFL thickness in diagnosing manifest glaucoma. Our overview suggests that the methodological quality of both primary and secondary DTA research on glaucoma is in need of improvement.