There is no agreement about the importance of cylindric errors, and experts differ widely as to how completely they should be corrected. Particularly is this true regarding low power errors. Many authorities make it a practice to undercorrect high astigmatism, and some consider it fussy to pay much attention to errors under 1 D. Abroad, especially, this is considered good practice. In some parts of this country, on the contrary, the teaching is that low errors cause disturbances out of all proportion to their size. Recently Prangen had occasion to take issue with the still more extreme doctrine that small errors are actually more disturbing than large ones. It will be noted that such theories do not take into consideration the fact that patients differ completely in their reaction to the same amount of astigmatism. Some ophthalmologists must share my experience that it is not the size of the error
BEACH SJ. CORRECTION OF LOW ASTIGMATISM: SUBTRACTION TEST. Arch Ophthalmol. 1943;29(5):775–781. doi:10.1001/archopht.1943.00880170095009
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