A potential acuity measurement is sometimes appropriate as an estimate of potential vision prior to a surgical procedure, especially cataract surgery. The potential acuity meter (PAM) is a device that is designed to project an eye chart directly onto the retina. This allows the examiner to test the visual acuity without interference from the cloudy lens. The main purpose of performing this test is to get an idea of the visual acuity that the patient can potentially achieve. Prior to committing to cataract surgery, it helps to know that vision improvement is possible (meaning there are no retinal or neurological problems that will not allow vision improvement despite cataract removal).