Vision screening to detect amblyopia and strabismus is recommended once for all children prior to entering school, preferably between ages 3 and 4. Clinicians should be alert for signs of ocular misalignment when examining infants and children. Screening for diminished visual acuity with Snellen visual acuity chart is recommended for elderly persons. There is insufficient evidence to recommend for or against screening for diminished visual acuity among other asymptomatic persons, but recommendations against routine screening may be made on other grounds (see Clinical Intervention).