HRT change analyses show poor agreement with expert-assessed stereophotographs

The purpose of this study was to compare optic disc changes using automated analysis of Heidelberg retina tomograph (HRT) images with assessments by glaucoma specialists of change in optic disc stereophotographs from the same eyes, and to determine which method had the highest concordance with expert assessment of stereophotographs.

They included 56 patients (91 eyes) with high-risk ocular hypertension or early glaucoma who had optic disc stereo photographs and Heidelberg retina tomograph (HRT) imaging at a single center. The selection criteria were sufficiently long, good-quality HRT series (seven visits in at least 70 months of follow-up) and follow-up photographs contemporaneous with the final HRT image.

Using optic disc stereographs, expert observers identified 33 eyes (36 percent) as exhibiting glaucomatous change. Altering HRT progression criteria so that 36 percent of eyes progressed according to each statistical assessment method, stereophotographic assessment agreed with HRT image-derived assessments 54 percent of time for topographic change analysis (TCA), 65 percent of the time for statistic image mapping (SIM), and 67 percent of the time for linear regression of rim area (RALR). Agreement between all three statistical methods for detecting HRT change was 60 percent, and pairwise concordance was 71 percent to 76 percent. Receiver operating characteristic areas under the curve for predicting stereophotographic-assessed change were 0.61 for TCA, 0.62 for SIM, and 0.66 for RALR.

The authors concluded that while the extent to which the HRT measures real change across time has yet to be established, the practical benefits of being able to observe change using automated or semi-automated digital image analysis suggest that it is an important tool for assessing disease progression, especially if a statistical method for best detecting the change can be established.