Care of the patient with low vision.

NOTE: This Quick Reference Guide should be used in conjunction with the Optometric Clinical Practice Guideline on Care of the Patient with Low Vision (Reviewed 2001). It provides summary information and is not intended to stand alone in assisting the clinician in making patient care decisions. Visual impairment is a functional limitation of the eye(s) or visual system that can result in a visual disability (a limitation of the abilities of the individual) or visual handicap (a limitation of personal and socioeconomic independence). Visual impairment may be considered as vision inadequate for an individual's needs. Definitions and classification of the levels of visual impairment and legal blindness vary: ‰ World Health Organization defines blindness as profound impairment – blindness of one eye or blindness of the individual ‰ The United States Social Security Administration defines legal blindness as: Remaining vision in the better eye after best correction is 20/200 or less or contraction of the peripheral visual fields in the better eye (A) to 10 degrees or less from the point of fixation; or (B) so the widest diameter subtends an angle no greater than 20 degrees. Visual impairment may also be classified on the basis of the presence of a visual field defect: ‰ No visual field defect ‰ Central visual field defect ‰ Peripheral field defect B. RISK FACTORS Risk factors for visual impairment are numerous. Etiologies may be: