THE MOST exhausting activity in the practice of an ophthalmologist is to persuade persons to read the normal line of the visual test chart. Complicated operations and intricate diagnostic problems sometimes seem next to nothing in comparison; but why this keen interest?
Examination of the visual acuity is classified as a subjective test, but in certain circumstances the answers are as sure as objective results. The moment the patient is brought to read the normal line, it is proved with the exactitude of an objective method that the visual acuity of the examined person is normal, and the whole test then changes from a doubtful to an exact one. This result is worth while.
The next question to be discussed is, of course, the normal value for the visual acuity. Ability to recognize letters of 5 minute angle is generally recognized as normal, corresponding to a visual acuity of 1.0
EHLERS H. CLINICAL TESTING OF VISUAL ACUITY. AMA Arch Ophthalmol. 1953;49(4):431-434. doi:10.1001/archopht.1953.00920020441007