Swinging flashlight test

The swinging-flashlight test (literally about, Swinging flashlight test ', also pupil exchange exposure test or SWIFT test) or pupils comparison test is a routine medical examination for the rapid assessment of pupils afference , so the the brain afferent nerve fibers .

examination

In the darkened room, the examiner illuminates the patient's pupils several times alternately with a bright halogen lamp or an ophthalmoscope . The patient fixes a point in the distance, while the examiner illuminates the pupils from below at a 45 ° angle for about 2 to 3 seconds. This process is repeated at least 4 to 5 times.

observation

The examiner observes whether the pupils are constricted (contraction). If so, he compares this contraction with the contralateral (other) pupillary contraction. The speed and extent of the pupil reaction in comparison to the contralateral pupil is assessed. In a healthy person, both pupils contract equally far and quickly. When changing from one eye to the other, the pupils widen again as a result of the adaptation to the darkness. The narrowing of the two pupils can now be compared when the other eye is illuminated.

Pathologies

If the SWIFT shows a pathological result, one speaks of a relative afferent pupillary defect (RAPD for short, also Marcus Gunn pupil sign ). Such a result is available when both pupils do not constrict equally quickly or far or even expand when illuminated (“pupillary escape”). RAPD is caused by damage to the afference of the optic nerve or the retina .

In-depth knowledge and sources of error

If the examiner is not sure whether RAPD is present, he can hold a weak gray filter in front of the illuminated eye. If this strengthens the effect, the suspicion is confirmed. If the effect wanders, the suspicion remains unclear. The RAPD can also be quantified by holding various gray filters. Ideally, you should choose the distance, angle and light intensity so that the pupil contracts by around a third. If the distance and lighting angle vary or if the light is too weak or too bright, incorrect diagnoses can occur. It is important to ensure that the patient does not change the fixation during the test and that the point in the distance is e.g. B. swaps for someone nearby.

Individual evidence

↑ ^a ^b Ulrich Schiefer , Helmut Wilhelm Eberhard Zrenner, Annelie Burk: Practical Neuroophthalmology . 2nd, revised edition. Kaden, Heidelberg 2004, ISBN 3-922777-56-2 , pp. 10 .
↑ Hanns Christian Hopf, Detlef Kömpf (Ed.): Diseases of the cranial nerves . Thieme, Stuttgart et al. 2006, ISBN 3-13-140111-7 , p. 50 .
↑ Automatic swinging flashlight test (SWIFT) ( Memento of the original from October 26, 2010 in the Internet Archive ) Info: The @1@ 2 archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . Steinbeis Transfer Center. Biomedical optics and functional testing.

[Schiefer2004_10-1] Ulrich Schiefer , Helmut Wilhelm Eberhard Zrenner, Annelie Burk: Practical Neuroophthalmology . 2nd, revised edition. Kaden, Heidelberg 2004, ISBN 3-922777-56-2 , pp. 10 .

[2] Hanns Christian Hopf, Detlef Kömpf (Ed.): Diseases of the cranial nerves . Thieme, Stuttgart et al. 2006, ISBN 3-13-140111-7 , p. 50 .

[3] Automatic swinging flashlight test (SWIFT) ( Memento of the original from October 26, 2010 in the Internet Archive ) Info: The @1@ 2 archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . Steinbeis Transfer Center. Biomedical optics and functional testing.