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Visual Agnosia

Visual Agnosia

Visual agnosia is a condition characterized by the inability to recognize visually presented objects despite having normal vision. For instance, a person with visual agnosia can describe the shape and color of an object but cannot identify or name it. This impairment does not affect their visual field, acuity, color vision, brightness discrimination, language, or memory. An example of this condition in a social setting is someone at a dinner party asking for "that silver thing with a round...

Visual System

Visual System

Light enters the eye through the cornea, a transparent, dome-shaped surface covering the surface of the eyeball that helps to direct and focus incoming light. This light is then channeled toward the pupil, an adjustable opening whose size is controlled by the iris. The iris, a pigmented muscle, regulates the amount of light entering the eye by contracting or dilating the pupil, thereby ensuring optimal light levels for clear vision.
Once through the pupil, the light passes through the lens, a...

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Related Experiment Video

Updated: Mar 14, 2026

Development of a Gaze-Contingent Display Framework Designed for Perceptual and Oculomotor Research with Simulated Central Vision Loss

Development of a Gaze-Contingent Display Framework Designed for Perceptual and Oculomotor Research with Simulated Central Vision Loss

Published on: April 11, 2025

Functional and simulated visual loss.

M Dattilo¹, V Biousse², B B Bruce³

¹Department of Ophthalmology, SUNY Downstate Medical Center, Brooklyn, NY, USA.

Handbook of Clinical Neurology

|October 11, 2016

Summary

This summary is machine-generated.

Nonorganic visual loss (NOVL) presents as vision impairment without a clear organic cause. Diagnosis involves ruling out physical issues, with treatment focusing on reassurance and psychiatric referral if needed.

Keywords:

MRI functional visual loss malingering nonorganic visual loss psychogenic visual field testing visual loss

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Area of Science:

Neurology
Ophthalmology
Psychiatry

Background:

Nonorganic visual loss (NOVL) is a common reason for specialist referrals.
It presents a diagnostic challenge at the intersection of neurology, ophthalmology, and psychiatry.
NOVL is defined as visual impairment without an identifiable organic cause after thorough investigation.

Purpose of the Study:

To outline diagnostic approaches for nonorganic visual loss.
To detail methods for differentiating organic from nonorganic visual impairment.
To describe the management strategy for patients diagnosed with NOVL.

Main Methods:

Clinical examination and bedside maneuvers.
Specialized testing including visual field testing, OCT, VEPs, ERG, and MRI.
Exclusion of organic pathology through comprehensive investigation.

Main Results:

Diagnosis relies on the absence of objective findings and confirmation of visual system integrity.
Various clinical and specialized tests aid in distinguishing NOVL from organic causes.
Successful diagnosis requires careful evaluation and exclusion of physical disease.

Conclusions:

NOVL diagnosis is achievable through specific clinical and instrumental methods.
Management involves patient reassurance, close monitoring, and psychiatric consultation.
Patients with NOVL may have associated psychiatric conditions and are at risk for depression and anxiety.