[Relative afferent pupillary defect in glaucoma]

Background: The aim of this retrospective study was to estimate the frequency of relative afferent pupillary defect (RAPD) in glaucoma and whether its occurrence relates to the severity of the visual field defect and its side asymmetry as detected by standard automated perimetry.

Patients and methods: Among patients with primary open angle glaucoma examined at the glaucoma unit of our university eye hospital patients were identified in whom a swinging-flashlight test as part of their routine examination was carried out. The central 30° visual field was examined by means of static perimetry using the Tübinger Automatic Perimeter or the Octopus Perimeter. The visual field findings and their side difference were compared between patients with and without RAPD by means of the Wilcoxon rank-sum test.

Results: After having taken into consideration the inclusion criteria, 100 glaucoma patients were included in the study, 34 of them had an RAPD (34 %). For the visual field analysis only the data of 85 patients, who received the same perimetric strategy, were used. 25 of them had an RAPD (29 %). The calculated visual field scores in patients with RAPD were significantly higher than those in patients without RAPD (p < 0.01), that means their visual field loss was generally more advanced. Also the side difference in visual field of both eyes was significantly greater in patients with RAPD (p < 0.01). A receiver operating characteristics (ROC) curve showed that the side difference in visual field defect is a good predictor for RAPD with an area under curve (AUC) of 0.81.

Conclusion: RAPD can be diagnosed in about one third of patients with primary open angle glaucoma. It can be found especially with more advanced visual field defects and visual field defects with greater side asymmetry. Its absence does not mean that there is no visual field defect at all. We advise to include the swinging-flashlight test in glaucoma diagnostics.