Diplopia and Eye Muscle Function VA Rating: DC 6090 Ocular Motility Guide

Impairment of extraocular muscle function leads to diplopia (double vision) when the two visual axes fail to align properly. Under 38 CFR 4.78, ocular motility and diplopia must be formally mapped using a tangent screen or Goldmann perimeter at a test distance of 330 mm. The visual field is divided into distinct gaze quadrants: central 20 degrees, upward quadrant, downward quadrant, and lateral quadrants. Because humans look down when reading and walking, downward diplopia causes the greatest functional disability and receives the highest regulatory weight in the rating schedule.

The rating schedule draws a strict distinction between occasional and constant diplopia. In accordance with Diagnostic Code 6090 Note (1) and 38 CFR 4.31, diplopia that is occasional, intermittent, or fully correctable with prism spectacles is assigned a noncompensable 0% disability rating. Only constant diplopia that cannot be corrected by lenses or surgical alignment qualifies for a compensable disability evaluation under the ocular motility schedule.

Diagnostic Code 6090 does not assign direct percentage ratings for double vision. Instead, 38 CFR 4.78 establishes a statutory conversion formula that translates constant uncorrectable diplopia into an equivalent visual acuity for the more impaired eye. Constant diplopia within the central 20 degrees or in the downward field converts to 5/200, 20/100, or 20/70 visual acuity depending on the extent of field involvement. Diplopia restricted to the upward quadrant carries lower impairment weight.

Once the rater converts the diplopia finding into its legal visual-acuity equivalent for the affected eye, that converted value is paired against the fellow eye's true measured visual acuity on the DC 6066 central visual acuity matrix. For example, if constant downward diplopia converts to a 20/70 equivalent and the fellow eye has normal 20/20 vision, the rater locates the intersection of 20/70 and 20/40 (the single-eye rule standard) to assign the final disability rating. This prevents double-counting and adheres to 38 CFR 4.14 anti-pyramiding principles.

Diplopia rarely occurs as an isolated primary condition; it typically stems from cranial nerve injury (oculomotor DC 8203, trochlear DC 8204, or abducens DC 8206), orbital blowout fractures, traumatic brain injury, stroke, or multiple sclerosis. When pursuing secondary service connection for diplopia, medical records must document the underlying neurological or mechanical cause. Under 38 CFR 3.310, Association between conditions does not by itself establish secondary service connection. The evidence must support causation or aggravation in the individual claim.