this test is designed for testing children and adults with visual impairment at a distance of one meter - the largest symbols are 50M in size corresponding to 1m/50M = to 1/50 or decimal visual acuity 0.02 - equivalent values 20/1000, 6/300 - the smallest symbols are 1M in size corresponding to 1m/1M = to 1/1 or decimal visual acuity 1.00 equivalent values 20/20, 6/6 - designed courtesy of August Colenbrander, MD - chart measures 16" x 21.5"(40.7 cm x 54.6 cm)