What is the purpose of a slap test?

The purpose of a slap test is to assess the tear break-up time. This test is crucial for evaluating the stability of the tear film over the surface of the eye, which is important for understanding a patient's tear film quality and diagnosing dry eye conditions. During the slap test, a small amount of fluorescein dye may be applied to the tear film, and the time it takes for the tear film to break up or disappear is measured. A shorter break-up time indicates poorer tear film stability, which can lead to dry eye symptoms and associated discomfort.

The other options relate to different aspects of eye health: measuring eye pressure is done using tonometry, testing visual acuity involves assessing clarity of vision typically through an eye chart, and evaluating pupil response focuses on the reaction of the pupils to light and accommodation. Each of these procedures targets different ocular functions and health assessments, which distinguishes them from the specific purpose of the slap test.