New developments in visual acuity charts.
The Jackson optotype, similar to the illiterate Es, was selected among several orientable optotypes and is proposed for clinical trials. It is unequivocal and compact. Two optotype gradations were derived from the geometrical progression of ratio 4 square root of 2, thus obtaining size steps quite close to those of Monoyer and Snellen. This is an attempt to unify these two gradations. Four charts were made by these gradations, two with Jackson optotypes, two with British Standard letters, and copies are offered free to research centres for trials.
Casellato
L
L
Milan State University, Italy.
D006801:Humans; D014787:Vision Tests / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D014792:Visual Acuity