Low vision services: a practical guide for the clinician.

Low vision has been defined by best-corrected visual acuity worse than 20/40 in the better eye, substantial visual field loss, or substantial loss of contrast sensitivity that cannot be corrected by refraction, medical treatment, or surgery. In the United States, low vision is most commonly caused by age-related macular degeneration, glaucoma, and diabetic retinopathy. Most patients with low vision are elderly, although patients of all ages - including pediatric patients - may be affected. Low vision may decrease a patient's quality of life substantially, leading to emotional distress and possibly depression. Low vision specialists aim to maximize the remaining vision of a patient by providing optical aids, orientation and mobility training, psychosocial support, and other methods of rehabilitation. Innovations in technology and devices offer additional options in low vision rehabilitation. Clinicians should consider referral to low vision specialists when a patient has difficulty with reading, mobility, driving, recognizing faces, or suffers from emotional distress due to low vision. Early referral may lead to improved outcomes.