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Zhichao Wu, Denis S.D. Weng, Rashmi Rajshekhar, Abinaya Thenappan, Robert Ritch, Donald C Hood; Effectiveness of a Qualitative Approach for Detecting Glaucomatous Progression on Widefield Optical Coherence Tomography Scans. Invest. Ophthalmol. Vis. Sci. 2018;59(9):4071.
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© ARVO (1962-2015); The Authors (2016-present)
Optical coherence tomography (OCT) imaging is a powerful tool for detecting glaucoma progression, and we hypothesized that it can be further improved through a qualitative evaluation of its results, by considering the full extent of information available and known patterns of glaucomatous progression. We compared this qualitative approach with the conventional measure of global circumpapillary retinal nerve fiber layer (cpRNFL) thickness using widefield (12 x 9 mm) scans.
Eyes with a clinical diagnosis of glaucoma or suspected glaucoma that either had two widefield scans ≥1-year apart (n = 125 eyes; longitudinal group) or within the same visit (n = 284 eyes; variability group) were examined. The qualitative OCT evaluation was performed in a manner similar to flicker chronoscopy, whereby the two widefield OCT scans were co-registered and the information was presented on customized one-page reports that were superimposed. An experienced examiner then provided a grading of the probability of progression after qualitatively evaluating these reports. This method was compared to an event-based analysis of global cpRNFL thickness, and the proportion of eyes detected as having progressed at 95% specificity was determined for each method.
A total of 32 (26%) and 25 (20%) eyes were deemed to have progressed based on the qualitative evaluation and global cpRNFL thickness measurements respectively (P = 0.152); 17 eyes were deemed to have progressed using both methods. A post-hoc review of the 16 eyes missed by the quantitative approach confirmed that all these eyes showed characteristic patterns of glaucomatous progression on the qualitative evaluation. A review of the 8 eyes missed by the qualitative evaluation instead revealed that all these eyes appeared to exhibit a generalized decline in cpRNFL thickness, without any changes consistent with glaucomatous patterns of progression, suggesting that this quantitative approach may have overestimated the proportion of eyes that had truly progressed.
While both the qualitative and quantitative methods appeared to perform similarly, a closer inspection revealed that a qualitative OCT evaluation could allow true glaucomatous progression to be detected more accurately. Future studies are required to determine the long-term implications of this approach.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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