Automated swinging flashlight test in patients with optic nerve disorders

Aim of the study: The swinging flashlight test is an objective method to di agnose a lesion of the anterior visual pathways. However, errors and faults may easily alter the test's results. Hence, the value of the swinging flas hlight test depends highly on the examiner's skills. Therefore an automated and objective procedure was developed which is independent from the examin er. Methods: A binocularly measuring instrument adapted for video pupillography was supplied with two arrays of light emitting diodes in front of each eye of the subject. By means of this illumination, pupillary light reflexes ar e elicited alternately. Pupil size is registered continuously, and after ar tifact elimination, the response amplitudes of the pupils are determined as a mean of right and left pupil. Responses elicited via right and left eye are compared. By varying the stimulus intensitiy it is possible to measure the amount of the relative afferent pupillary defect. The procedure was tes ted in 31 patients with optic nerve disorders. Results: The measurements were easily feasible, stable and reliable. Correl ation between the relative afferent pupillary defect detected manually by g rey filter compensating and with the automated procedure proved to be high. Both variables correlated highly significant with a Spearman rank coeffici ent of 0.65. If the clinical test is regarded as the golden standard, the a utomated swinging flashlight test is able to detect 85% of the relative aff erent pupillary defects greater than or equal to 0.3 logE and 94% of the de fects greater than or equal to 0.6 logE. Conclusion: The automated swinging flashlight test can be recommended to ex clude influences by the examiner or if the exact amount of the relative aff erent pupillary defect is desired, e.g. when monitoring therapeutic effects in optic nerve diseases. Furthermore, an automated swinging flashlight tes t could serve as a screening test.