Name a factor that can influence HGN test results unrelated to alcohol.

The horizontal gaze nystagmus (HGN) test measures eye movements as an indication of impairment, typically due to alcohol or drugs. However, there are several factors that can influence the accuracy of the HGN test results, unrelated to alcohol consumption. One significant factor is certain medical conditions.

For instance, individuals with eye disorders, neurological conditions, or injuries affecting eye movement may exhibit nystagmus even when they are not under the influence of substances. Conditions such as vestibular disorders or other neurological issues can impact how the eyes respond during the test, potentially leading to a misinterpretation of the results.

Understanding how medical conditions can influence the HGN test is crucial for officers administering the test. It ensures they can properly assess the situation and consider these factors when determining whether a person is impaired or not.