What is 4.9 vision?

Vision is divided into central vision and peripheral vision, central vision is divided into distance vision and near vision, is the main sign of form perception, is the ability to distinguish the shape and position of two-dimensional objects, representing the visual acuity of the fovea of the retina. Glasses power is diopter, normal adult vision standard is 5.0, below 5.0 is low vision, there is no direct relationship between the number of naked vision and glasses power, can not be converted, so can not judge glasses power according to the number of vision, need to go to the hospital mydriasis optometry examination.