Astigmatism does not affect the field sobriety test police use to look at your eyes during a DUI stop. The test is called the Horizontal Gaze Nystagmus test, or HGN. People often confuse the two terms because both involve the eyes - but they measure completely different things. Astigmatism is a vision problem corrected by glasses or contact lenses. HGN measures involuntary jerking of the eye when it follows a moving object. Alcohol and certain drugs increase that jerking, which is what the officer is looking for.
Several legitimate medical conditions can cause natural nystagmus that has nothing to do with alcohol - including genuine nystagmus disorders, certain prescription medications, head injuries, neurological conditions, and even fatigue. If you were given an HGN test during a DUI stop and the officer claims it showed signs of impairment, an experienced DUI lawyer can challenge the test results when a legitimate medical explanation exists. Call 401-573-2265 to discuss your case.