Three years ago I read a paper before the ophthalmological section of the American Medical Association, on the value of 0.25 D. cylinder in the correction of the lesser grades of astigmatism. My additional experience confirms the position which I then took.
The annoyance occasioned by eye muscle strain demands recognition from complaining patients whose heads will ache when the eyes are much used. All astigmatic eyes do not suffer in like proportion. There are three factors at work that bring about annoyance. The first is the amount of eye work required by a badly shaped cornea; a second factor is the degree of fault; and a third is found in the nervous susceptibility of the patient.
As to the first condition, the amount of work required. The majority of astigmatic eyes only exhibit the trouble under forced application. Eyes which have done faithful and painless duty for many years