In glare testing, how many controlled degrees of light does the BAT test deliver when the eye is viewing a Snellen target?

In glare testing, the BAT (Brightness Acuity Tester) is designed to evaluate how glare affects visual acuity when viewing a target, such as the Snellen chart. The methodology of the BAT includes the introduction of controlled light levels to simulate real-world conditions experienced in situations where bright lights could interfere with vision.

The testing setup is designed to measure the visual performance at specific angles of glare while the subject observes the target. In this case, the BAT delivers three degrees of controlled light. This specific degree of light is critical as it allows for a nuanced assessment of how varying levels of glare affect an individual's ability to discern details on the Snellen target. By providing a measure of 3 degrees, the BAT ensures that the evaluation is effective in diagnosing potential visual impairments caused by glare, offering insights into how glare can impact visual clarity and acuity.