Eye chart smaller towards the bottom of the chart. The person removes any glasses or contact lenses, and stands or sits a standardized distance from the chart (e.g., 20 feet for the Snellen chart). The person is then asked to identify the optotypes on the chart, starting with large rows and continuing to smaller rows until the optotypes cannot be reliably identified any more. The row in which the person can reliably identify symbols defines the visual acuity. One eye is tested at a time. Practically, this is accomplished by covering the other eye with a hand, piece of paper, or a
International Resources for the Improvement of Sight International Resources for the Improvement of Sight International Resources for the Improvement of Sight (IRIS) is an International NGO that specializes in prevention of blindness and restoration of sight. It was founded in 1996 by Michele Claudel and John Stewart. It was initially founded to help people in Cambodia without access to eye care, it has since expanded to Nepal, Lao PDR and Sri Lanka. IRIS equips new eye clinics, strengthens existing ones, conducts eye screening, provides cataract surgery for poor people, primary eye care training for staff. IRIS has partnered with other NGOs to provide funding for services, such