By Eyecare NG
Visual acuity is a measure of how well the eye sees. It is usually tested by positioning a standard chart at a distance of 20 feet or 6 metres and asking the person to identify the letters or figures on the chart. Normal visual acuity is 20/20 or 6/6 which means that the patient was able to see at 20 feet (6 metres) the size of letters that are meant to be seen at that distance.
Having a normal visual acuity (20/20 acuity), however, does not necessarily mean good or perfect vision. The results of the visual acuity test only account for the extent the eye sees with the central part of the retina (central vision or macular vision). It does not include the peripheral vision and does not tell how well the brain processes what the eyes see and coordinates with other parts of the body.
The visual system is very complex and visual acuity is just a small part of that system. There are other visual abilities and skills that are required for learning. To learn effectively, the brain needs to process and interpret what the eyes see. It also requires coordinated input from other parts of the body. Therefore, a person with a disorder that interferes with visual processing, interpretation or coordination with other parts of the body will have problems during learning even in the presence of 20/20 acuity.