Human Vision Defects,What is 20/20 Vision?

Visual Defects What does 20/20 Vision mean? Visual acuity is expressed as a fraction. The top number refers to the distance you stand from the chart. This is usually 20 feet. The bottom number indicates the distance at which a person with normal eyesight could correctly read the line with the smallest letters. Normal vision is considered 20/20. If your vision is 20/40, the line you correctly read at 20 feet could be read by a person with normal vision …

…astigmatism is LASIK where a cool laser beam then is used to resurface the eye to overcome the irregular curvature seen in astigmatism. References "Vision Care" (2004), [Online] www.visioncare.com.my "Glaucoma", (2003) [Online] www.glaucoma.org.au "All about Eye's" (2004), [Online] www.eye-directory.com "Eye diseases and disorders" in Encyclopaedia of Health, (2003), Vol.7 pp. 300 "Astigmatism" in World Book Encyclopaedia, (2004), Vol.8 pp. 659 TAYLOR, M. (2000), The Human Eye, Collins, Washington. RAGEN, P. (18/3/2001), "Eye Conditions", West. Australia, p.20