How do weather conditions influence the HGN test?

Weather conditions significantly influence the HGN test by affecting visibility and focus. In adverse weather situations, such as rain, fog, or snow, the examiner’s ability to accurately observe the subject's eye movements can be compromised. Additionally, external factors like glare or poor lighting may make it difficult for both the tester and the subject to maintain the necessary focus during the test. This environmental context can lead to challenges in performing the test effectively, which is critical for accurate assessments of eye movement and potential impairment due to substances.

Recognizing how these conditions can interfere with the testing process underscores the importance of conducting the HGN test in a controlled environment to ensure reliable results.