landolts chart Time table and standard vision

A Landolt C, also known as a Japanese Vision Test, Landolt ring or Landolt broken ring, is an optotype, i.e. a standardized symbol used for testing vision. It was developed by the Swiss-born ophthalmologist Edmund Landolt. The Landolt C consists of a ring that has a gap, thus looking similar to the letter C. The gap can be at various positions (usually left, right, bottom, top and the 45° positions in between) and the task of the tested person is to decide on which side the gap is. The size of the C and its gap are reduced until the subject makes a specified rate of errors. The minimum perceivable angle of the gap is taken as measure of the visual acuity. It is generally practised in the laboratory.[1] The stroke width is 1/5 of the diameter, and the gap width is the same.[2] This is identical to the letter C from a Snellen chart. The Landolt C is the standard optotype for acuity measurement in most European countries. It was standardized, together with measurement procedures, by the German DIN, as DIN 58220 (now EN ISO 8596). 1909 International Academy of Ophthalmology and the International Organization for Standardization (ISO-International Organization for standardization) randol updated in the ring (Landolt ring or ring randol updated) adopt universal time table, diameter 7.5mm, thickness 1.5mm, thickness 1.5mm of a gap to sipyo jeonghago billed at the unit, based on this, of various sizes were ever write sipyo. 5m distance is smaller than the table when the unit can not read sipyo the unit when read at the table based on the visual acuity of 1.0, and the sight is defined as follows. This minimum time is 1 minute (= 1 '), the visual acuity is 1.0. However, the gap spacing Vision 1.0 sipyo somehow have 1.5mm Let's calculate that. <Picture> measuring distance visual acuity (D) 5m, visual theta = 1 ', y spacing of cracks was established, the following expression can be seen that.  namely, Landolt ring gap spacing in the table when the unit is 1.5mm. standards of human visual acuity is 1.0, but 1.5 also 2.0 if bigger, most people of my eye sight better than the other people think this is a misconception. Most of these people are primitive, myopia and normal eye fatigue than those with sight comes quickly.