Low Vision Is Not Always Indicated by Visual Function Tests

Abstract

The definitions of terms such as“low vision”and“visually handicapped person”are usually based on the visual acuity and visual field measured using visual function tests. Intractable diplopia and visual confusion are not included in this definition, even though they adversely affect the quality of life of patients and exacerbate their mental disorders. Serious photophobia, ocular pain, and blurred vision without any ocular conditions can be considered visual noise caused by higher brain dysfunction. I propose a hypothesis that visual noise represents defects in the commonly used neural circuit. These symptoms are seen in patients with essential blepharospasm, prolonged and delayed symptoms of head/neck injuries, sarin intoxication, psychotic diseases including panic disorder, and adverse effects of psycholytics.
I hypothesize the existence of neural filters in the visual information-processing mechanism, similar to the thalamus functioning as a low-pass filter of sensory input, and that various visual noises are caused by the dysfunction of such filters. Neuro-ophthalmologists should aim to clarify the neural mechanism underlying the visual noise. I also emphasize the importance of raising social awareness regarding the visual disturbance caused by higher brain dysfunction, which is currently being ignored by insurance services and social welfare.