Validity of screening for glaucomatous optic nerve damage using confocal scanning laser ophthalmoscopy (Heidelberg Retina Tomograph II) in high-risk populations - A pilot study

Purpose: To evaluate whether confocal scanning laser ophthalmoscopy (Heidelberg Retina Tomograph II [HRT II], Heidelberg Engineering, Heidelberg, Germany) is a valid tool for the detection of glaucomatous optic nerve damage. Design: Observational, cross-sectional, nonconsecutive study in Montreal, Canada. Participants: Three hundred three nonconsecutive, high-risk persons were enrolled during a 6-month period. Methods: Participants underwent HRT II testing and a standard ophthalmologic examination, including gonioscopy, intraocular pressure measurement, and optic disc grading. Main Outcome Measures: Positive likelihood ratio (PLR) and negative likelihood ratio (NLR), sensitivities and specificities, positive predictive value (PPV) and negative predictive value (NPV), and K coefficients of agreement of Moorfields regression analysis (MRA), cup shape measure (CSM), height variation contour (HVC), and mean retinal nerve fiber layer thickness (MRNFL). Results: Three hundred three participants were enrolled, and 291 were examined clinically; 21 (7.2%) were found to have glaucoma. Heidelberg Retina Tomograph II testing was performed successfully and was of acceptable quality in 531 of 601 eyes (88%). When MRA was compared with the clinically based diagnosis, the weighted K coefficient was K = 0.567 (95% confidence interval [CI], 0.42-0.71) for the right eye and K = 0.516 (95% Cl, 0.37-0.66) for the left eye. Best K coefficient of agreement was seen when normals were grouped with suspects in both clinical and MRA diagnosis (K = 0.604; 95% CI, 0.409-0.799 in the right eye). Depending on the gold standard and test-positive definitions for glaucoma, specificity ranged from 87% to 97%, sensitivity from 25% to 100%, PPV from 28% to 68%, NPV from 84% to 100%, PLR from 5.0 to 19.2, and NLR from 1.3 to 6.2. When CSM, HVC, and MRNFLT were compared with clinical diagnosis, all outcome measures were found to have lower ranges: specificity from 46.9% to 83.7%, sensitivity from 36.5% to 76.9%, PPV from 6% to 36%, NPV from 80% to 99%, PLR from 0.8 to 4.0, NLR from 0.9 to 3.0. Conclusions: The results of this study suggest that a glaucoma screening program maybe effective in detecting glaucoma when targeting high-risk populations. Heidelberg Retina Tomograph II testing may prove to be a useful tool in detecting glaucomatous optic nerve damage and could be used as part of a complete glaucoma screening protocol.