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To the Editor.
—Subtle impairment of central visual acuity is sometimes difficult to demonstrate with the Snellen chart. A patient may read the 20/20 line with each eye, but the vision in one eye may be slightly impaired. If a physician suspects a depression in the central vision in an eye, as can occur with a macular or an optic nerve disease, it may be helpful if the patient can determine a subjective difference between the acuity of his two eyes. However, it may be difficult for the patient alternately to occlude the eyes and detect a difference in acuity. Bar reading can be employed to help with this problem.Ordinarily, bar reading is used to determine if binocular vision is being exercised while reading at near distance. However, it can be employed to help determine if a patient sees better with one eye or the other. The subject should
Beasley FJ. Detecting Impaired Central Vision by Bar Reading. Arch Ophthalmol. 1973;89(3):260. doi:10.1001/archopht.1973.01000040262023