Accuracy of scanning laser polarimetry in the diagnosis of glaucoma

Objective: To determine the diagnostic accuracy of scanning laser polarimetry. Subjects and Methods: A total of 95 healthy subjects and 102 patients with glaucoma met all inclusion criteria. Data collected on each participant included an automated visual field examination, stereoview: optic nerve head photographs, intraocular pressure measurement, and a screening and full scanning laser polarimetry study. Each participant was classified as "normal," "glaucoma," or "uncertain" by each of 3 ophthalmologists based on all available clinical information, with the exception of the scanning laser polarimetry results. Before data analysis, 4 diagnostic algorithms for the full-test mode and 2 for the screening mode were chosen to be evaluated for their sensitivity and specificity in detecting glaucoma. Results: Of the 4 algorithms tested for the full-test mode, "the number" (abnormal test score, greater than or equal to 35) had sensitivities of 57%, 71%, and 81% for early, moderate, and severe glaucoma, respectively. Specificity was 89%. For the screening test, sensitivities were much lower, particularly for those with severe glaucoma damage. Conclusions and Clinical Relevance: Scanning laser polarimetry can help to differentiate subjects with normal findings from patients with glaucomatous damage. Even the best algorithm tested, however, failed to detect a substantial number of subjects with severe damage. Further study is needed before scanning laser polarimetry can be recommended as a screening method for glaucoma.