Evaluation of a Qualitative Approach for Detecting Glaucomatous Progression Using Wide-Field Optical Coherence Tomography Scans

Abstract

Purpose: To determine the effectiveness of detecting glaucomatous progression by a qualitative evaluation of wide-field (12 × 9 mm) scans on optical coherence tomography imaging. This method was compared to a conventional quantitative analysis of the global circumpapillary retinal nerve fiber layer (cpRNFL) thickness.

Methods: A total of 409 eyes with a clinical diagnosis of glaucoma or suspected glaucoma for which two wide-field scans were obtained at least 1 year apart (n = 125) and within one session (n = 284) were included to determine the sensitivity of detecting progression at 95% specificity. Qualitative OCT evaluation was performed in a similar manner to flicker chronoscopy by superimposing the two scans, and the progression probability was graded. A quantitative event-based analysis of the global cpRNFL thickness also was performed.

Results: Thirty-three and 25 eyes were deemed to have progressed based on qualitative and quantitative approaches, respectively (P = 0.152). A post hoc review of cases where the two methods disagreed revealed that all eyes missed by the quantitative analysis had established glaucomatous damage that appeared to show characteristic patterns of progression. All eyes missed by the qualitative evaluation appeared to be free of such established damage, and instead showed a generalized reduction in cpRNFL thickness.

Conclusions: Qualitative evaluation of OCT imaging information more frequently detected change consistent with known patterns of glaucomatous progression than global cpRNFL thickness, warranting further studies to evaluate its value.

Translational relevance: A framework for qualitatively evaluating progressive glaucomatous changes on OCT imaging clinically shows promise.

Keywords: glaucoma; optical coherence tomography; progression; region-of-interest.

Figure 1

Example of the one-page report used for qualitative evaluation of the probability of progression occurring, consisting of a derived circumpapillary circle scan and its corresponding RNFL thickness profile (top left), the corresponding quadrant and clock-hour circumpapillary RNFL thickness values shown using pie charts (bottom middle), an en face slab image of the inner retina and RNFL thickness map (bottom left), RNFL thickness probability map presented in field view, with 24-2 visual field (VF) test locations overlaid (top right), and the macular ganglion cell plus inner plexiform layer (GCL+) thickness map and GCL+ thickness probability map presented in field view, with 10-2 VF test locations overlaid (bottom right). Note: information presented in field view are inverted relative to information presented in retina view.

Figure 2

Proportional Venn diagram illustrating the number of eyes deemed as having progressed with qualitative evaluation of the OCT imaging information (left) and quantitative analysis of the cpRNFL thickness measurements (right) over time.

Figure 3

An example of a case where qualitative evaluation of the OCT imaging information and quantitative analysis of the cpRNFL thickness measurements over time considered the eye as having progressed.

Figure 4

An example of a case where the quantitative analysis of the cpRNFL thickness measurements considered progression to have occurred, but qualitative evaluation of the OCT imaging information did not on the basis that no characteristic pattern of glaucomatous progression was present.

Figure 5

An example of a case where the qualitative evaluation of the OCT imaging information detected progression missed by quantitative analysis of the cpRNFL thickness measurements.