What does the snap test assess in eyelid function?

The snap test is specifically designed to evaluate the ability of the eyelid to return to its normal position after being pulled away or retracted. This assessment checks the functional integrity of the eyelid and the underlying muscles responsible for eyelid movement, primarily the orbicularis oculi.

A normal snap test indicates that the eyelids can quickly revert to their original position, suggesting good muscle tone and appropriate neuromuscular function. A delay or incomplete return can indicate issues such as muscle weakness or nerve impairment, which may be relevant in conditions like facial nerve palsy.

While the elasticity of the eyelid margin is important for overall eyelid function, it is not what the snap test specifically measures. The presence of infection and the measurement of conjunctival depth are not assessed through this test; rather, those would typically be evaluated through different clinical examinations or tests that target inflammation or structural assessments of the eye itself.