Opticians identify low vision by testing visual acuity using a Snellen chart. A patient with low vision may show reduced acuity even with the best optical correction provided by ordinary lenses. Another way of identifying low vision is from the patient's reporting difficulty with everyday tasks such as recognising faces, or mobility - for example, falling over objects they fail to notice around them. Standard tests of contrast sensitivity and visual fields are also useful to find out more about the patient's visual problems.