The visual acuity of each eye corrected with a pinhole (or by current corrective refraction, remembering that not all people keep their vision testing current) must be recorded for reading and for distance. The latter is particularly important, because many reading charts in use are not standardized. The severity of impairment varies widely, and acuity is often normal in the early stages of chiasmal compression when only the peripheral field is affected. When field loss splits macular vision, the acuity is usually preserved, but the patient may only read letters on the nasal side of the chart. A reduction of acuity in the absence of refractive error or incidental abnormalities in the media indicates that the field defect has crossed the midline.
Was this article helpful?