This new astigmatic chart is durably made of vinylite plastic and hence maintains permanently its cleanliness and contrast. It is a single unit of simple design, easily handled, and requires no computation. The axes are indicated with dual numbering completely around the dial. The outer figures are read when the dial is seen in the mirror, while the inner figures, in parentheses, are noted with direct vision. The use of the dial with a mirror facilitates considerably the examination and is highly recommended. In a lightly decorated examining room the general illumination is usually adequate for the astigmatic test.
The single line cross is most suitable for the determination of cylindric power. For the location of the axis the rotating Maddox V is more efficient, since the astigmatic eye can distinguish best a difference between two lines at an angle of 60 degrees. With an inverted V placed as an
LEBENSOHN JE. A SIMPLIFIED ASTIGMOMETER. Arch Ophthalmol. 1950;43(5):905-907. doi:10.1001/archopht.1950.00910010920015