Clinicopathological Correlates: Chronic Arsenic Toxicity Causing Bilateral Symmetric Progressive Optic Neuropathy

Area of Science:

• Ophthalmology
• Toxicology
• Gastroenterology

Background:

• Bilateral symmetric optic neuropathy can have various causes, including toxic and nutritional factors.
• Diagnostic workups for unexplained visual acuity loss often involve extensive testing to rule out common pathologies.
• Heavy metal toxicity is a less common but critical differential diagnosis in neuro-ophthalmological cases.

Observation:

• A 70-year-old man experienced gradual central visual acuity loss over several years with minimal objective findings on initial examination.
• Extensive investigations, including neuro-imaging and electroretinography, failed to identify the cause of the progressive vision loss.
• Elevated arsenic levels were detected after continued visual deterioration, prompting further investigation into environmental exposures.

Findings:

• The patient had a history of hemorrhagic colitis requiring colectomy 28 years prior, linked to arsenic exposure from well water at a country cottage.
• Analysis of a colonic biopsy from the colectomy revealed significantly elevated arsenic levels, confirming chronic exposure.
• This case establishes a direct link between chronic arsenic exposure from contaminated well water and the development of bilateral optic neuropathy.

Implications:

• Clinicians should consider heavy metal toxicity, particularly arsenic, in the differential diagnosis of unexplained bilateral optic neuropathy.
• Environmental history, including water sources and potential exposures, is crucial in diagnosing chronic toxicities.
• Early identification and removal from the source of arsenic exposure are vital for managing heavy metal-induced visual impairment.