Functional and simulated visual loss.

Nonorganic visual loss (NOVL) is the cause of a large number of referrals to neurologists and ophthalmologists and is a frequent area of overlap between neurologists, ophthalmologists, and psychiatrists. NOVL is the presence of visual impairment without an organic cause for disease despite a thorough and comprehensive investigation. A diagnosis of NOVL requires both the absence of any findings on examination and proof of the integrity and functioning of the visual system. Although sometimes a challenging diagnosis to make, there are a number of techniques and maneuvers which can be utilized fairly easily, either at the bedside or in the clinic, to help determine if a patient has NOVL. In some instances specialized testing, such as formal visual field testing, optical coherence tomography, visual evoked responses, electroretinogram, and various imaging modalities (magnetic resonance imaging) are performed to help determine if the cause of visual loss is organic or nonorganic. Once a diagnosis of NOVL is made, treatment centers around reassurance of the patient, close follow-up, and, if necessary, referral to a psychiatrist, as these patients may have underlying psychiatric disorders and a preceding strong emotional event leading to the current symptoms, and may be more likely to develop depression and anxiety.