Tests for Miscellaneous Functional Visual Complaints

Abstract

There are many functional complaints in addition to diminished visual acuity. One common complaint is narrowing of the visual field, for which many examiners prefer monocular Tangent Screen visual field testing. In functional disease, the visual field does not expand as would be expected when tested at double the distance with the larger target. Instead, the functional patient frequently exhibits tunnel vision or tubular vision. Another method of testing is a monocular Goldmann visual field examination where a functional patient demonstrates inversion or spiraling of isopters. If the patient complains of night blindness, dark adaptometry or dark-adapted visual evoked response testing can be performed, though many examiners demonstrate other signs of functional disease and treat the patient with reassurance and follow-up. A functional complaint of no depth perception can be evaluated by proving the presence of binocular vision with a number of tests including Titmus Stereoacuity. The examiner can evaluate a complaint of double vision with a colored lens and a prism bar, which will merge or move images closer in true diplopia. Functional ptosis is distinguished from organic ptosis by contraction of the orbicularis in the former and contraction of the frontalis in the latter. Neuropsychological testing can be supportive of a functional diagnosis. Examiners use embedded portions of traditional personality inventories or symptom validity tests to look for inconsistencies and exaggeration.