Swinging-Flashlight-Test

The swinging torch test ( literally about, Swinging flashlight test ', also pupil exchange exposure test or SWIFT test ) or pupil comparison test is an eye care routine for quick assessment of Pupillenafferenz, so the the brain afferent nerve fibers.

Investigation

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

Observation

The examiner observes whether a narrowing ( contraction) of the pupils takes place. If so, he compares this contraction with the contralateral ( other ) pupillary contraction. Is evaluated, the rate and extent of pupillary response in comparison to the contralateral pupil. In a healthy person, both pupils contract equally far and fast. When changing from one to the other eye, the pupil as a result of adaptation to the darkness will continue again. Now, the constriction of the pupil may be compared with light of the other eye.

Pathologies

Displays the SWIFT test a pathological result, one speaks of a relative afferent pupillary defect ( RAPD short ). Such a result is deemed to exist if both pupils are not equal narrow fast or far or expanded even under illumination ( " pupillary escape" ). The RAPD is caused by damage to the afferent to the optic nerve or retina.

Deepening and sources of error

If the examiner is not sure if a RAPD is present, it may hold a weak neutral density filter in front of the illuminated eye. The effect is thus strengthened the suspicion is confirmed. Penetrates the effect, the suspicion remains unclear. Through the reproach of different gray filters of RAPD can also be quantified. Ideally, one should distance, angle and light intensity chosen so that the pupil is contracted by about a third. Varies the distance and angle of illumination or the light is too weak or bright, it may lead to incorrect diagnoses. It is important to make sure that the patient makes no fixation change during the test, and exchanges the point in the distance, for example, against a close.