Binasal congruous hemianopia secondary to functional visual loss: A case report

Area of Science:

• Ophthalmology
• Neuro-ophthalmology
• Psychiatry

Background:

• Presents an unusual case of binasal congruous hemianopia, a rare visual field defect affecting both nasal visual fields.
• Highlights the importance of differentiating functional visual loss (FVL) from organic causes.

Observation:

• A 24-year-old male presented with bilateral nasal visual field defects, headaches, and weight loss.
• Comprehensive ophthalmic and neuroimaging investigations, including visual fields, OCT, MRI, and syphilis testing, were unremarkable.

Findings:

• Confirmed complete binasal congruous hemianopia through Humphrey and Goldmann visual field testing.
• All organic etiological investigations, including neuroimaging and serology, were negative, supporting a diagnosis of FVL.
• The visual field defects remained stable at one-year follow-up.

Implications:

• This case underscores the necessity of a systematic approach to diagnose binasal field defects, prioritizing exclusion of organic pathologies like syphilis.
• Recommends multimodal investigations including fundus imaging, neuroimaging, and serology before attributing the defect to FVL.
• Suggests neuropsychological evaluation for patients with functional visual loss to address underlying psychological factors.