Diagnostic ability of Heidelberg Retina Tomography in detecting glaucoma in a population setting: the Singapore Malay Eye Study

Abstract

Objective: To evaluate the performance of the Heidelberg Retina Tomograph II (HRT II, Heidelberg Engineering, Heidelberg, Germany) in diagnosing glaucoma in a population setting.

Design: Population-based cross-sectional study.

Participants: Of 3280 Malay persons aged 40 to 80 years who participated in the survey, 112 subjects (124 eyes) with glaucoma and a subset of 196 bilaterally normal subjects (392 eyes) were included for the evaluation of diagnostic ability of HRT II.

Methods: All glaucomatous and normal eyes underwent standardized ophthalmic assessment (including automated perimetry) and HRT II. Glaucoma was defined according to International Society for Geographical and Epidemiological Ophthalmology criteria. Area under the curve (AUC) receiver operating characteristic (ROC), sensitivity, and specificity were used to evaluate the diagnostic performance of HRT II algorithms. Marginal logistic regression models were used to evaluate the influence of optic disc size on the results of HRT II algorithms.

Main outcome measures: The HRT II algorithms: linear discriminant functions (LDFs) by Mikelberg et al (LDF1), Burk et al (LDF2), Bathija et al (LDF3), and Moorfields regression analysis (MRA). The MRA was subdivided into MRA1 with "borderline" outcomes as positive and MRA2 with "borderline" outcomes as negative.

Results: Subjects with cataract, visual impairment, astigmatism, and greater negative spherical equivalent, and of older age were more likely to yield lower quality images. For analyses by eye, AUCs were 0.789, 0.704, 0.755, 0.754, and 0.762 for MRA1, MRA2, LDF1, LDF2, and LDF3, respectively. At 85% specificity, sensitivities were 62.1%, 65.3%, and 66.9% for LDF1, LDF2, and LDF3, respectively. At 95% specificity, these figures decreased to 31.5%, 42.7%, and 45.2%, respectively. The sensitivity and specificity were 71.0% and 86.7% for MRA1 and 43.6% and 97.2% for MRA2, respectively. Similar estimates were found for analyses by person. Larger optic disc size was associated with increased sensitivity and false-positive rate for MRA1, LDF1, and LDF2. LDF1 and LDF3 were least affected by optic disc area, but the sensitivities were moderate and the false-positive rates were high across different optic disc areas.

Conclusions: The current HRT II algorithms are of limited value for population-based glaucoma screening in the Malay population and do not account adequately for optic disc size.