I have used the astigmatic chart for several years, and it has given me such satisfaction that I wish to make it known. It is copied after the Verhoeff chart in that there is a movable circular dial impaled by a central brad to a square card.
On the square, as shown in the accompanying figure, the axes are marked and on the circle two lines at right angles to one another are drawn which are 1/32 inch diameter; it is the fineness of these lines that makes it reliable; the patient is never in doubt which line is the heavier. In the center of the circle a small square is drawn with lines 1/64 inch in diameter. The patients' vision must be blurred at all times so that it is just barely possible for them to make out the 20/60 line on the Snellen chart; this may vary a line with some patients, but the 20/60 line will be found to meet most cases.
ODENEAL TH. A NEW ASTIGMATIC CHART. Arch Ophthalmol. 1930;3(2):148–150. doi:10.1001/archopht.1930.00810040026002
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