THE USEFULNESS OF THE OPHTHALMOMETER.

Abstract

The ophthalmometer has gone through various stages of appreciation, depreciation and overpraise, back and forth over the same ground again and again; and still we have its enthusiastic advocates, claiming that it does away with the necessity of using mydriatics, while others consider it as merely an expensive scientific toy, utterly unreliable and of no practical value. Is it not worth while, then, to give the subject a few minutes of dispassionate consideration? Let us first take up the question: Is the ophthalmometer of any practical use in refraction work? Those who argue against its usefulness base their argument on the ground that it only shows corneal astigmatism. The argument must turn largely, then, on the frequency and amount of lenticular astigmatism. Many authorities state that most of the astigmatism is corneal, and Suter and others explain the subtracting of half a diopter from the finding with the instrument in