The "sunglasses sign" predicts nonorganic visual loss in neuro-ophthalmologic practice

The aim of our study was to evaluate whether wearing sunglasses (the "sunglasses sign") can be used by neuro-ophthalmologists to predict nonorganic visual loss (NOVL) in their patients.

We prospectively collected information on all new patients seen by us over 13 months. We included all patients who ultimately received a diagnosis of NOVL, and all patients wearing sunglasses in our clinic. We recorded demographics, iris color, number of positive review of systems, ocular examination, precipitating event or trauma, workers' compensation claims, disability and lawsuit related to the visual loss, and the reason for wearing sunglasses.

Among the 1,377 consecutive new patients seen in our clinic during the study, 34 patients wore sunglasses, among whom 7 (20.6%) had organic visual loss. During the study period, 59 patients were diagnosed with NOVL, among whom 27 (45.8%) wore sunglasses. The sensitivity of wearing sunglasses for NOVL was 0.46 (95% CI 0.33 to 0.59). The probability that a patient walking into our clinic had NOVL was 0.043 (95% CI 0.033 to 0.055); it increased to 0.79 (95% CI 0.62 to 0.91) in sunglasses patients. The specificity of sunglasses for the diagnosis of NOVL was 0.995 (95% CI 0.989 to 0.998). At least one of the following characteristics (highly positive review of systems, workers' compensation claim, disability, and lawsuit) was found in 26 of 27 (96.3%) of NOVL patients wearing sunglasses and in none of the sunglasses patients with organic neuro-ophthalmic disorders. All 7 sunglasses patients with organic neuro-ophthalmic disorders had reasonable ophthalmic explanations for wearing sunglasses.

The "sunglasses sign" in a patient without an obvious ophthalmic reason to wear sunglasses is highly suggestive of nonorganic visual loss.