ERG findings in patients using hydroxychloroquine

Area of Science:

• Ophthalmology
• Pharmacology
• Neuroscience

Background:

• Hydroxychloroquine (HCQ) is widely used for autoimmune diseases.
• HCQ retinopathy is a known complication, typically diagnosed through clinical examination and visual field testing.
• Early detection of HCQ toxicity is crucial to prevent irreversible vision loss.

Purpose of the Study:

• To investigate electroretinography (ERG) findings in patients using HCQ.
• To assess both full-field ERG (ffERG) and multifocal ERG (mfERG) in relation to HCQ exposure duration and dose.
• To identify subclinical signs of HCQ toxicity using ERG.

Main Methods:

• Retrospective review of 26 patients (51 eyes) with 1-30 years of HCQ use.
• Analysis of ffERG and mfERG results in conjunction with clinical evaluations.
• Classification of patients into groups based on ERG and clinical findings.

Main Results:

• 13 patients had no abnormalities.
• 2 patients showed cone b-wave delay.
• 6 patients had decreased ERG amplitude.
• 2 patients had borderline toxicity.
• 3 patients exhibited toxicity (bull's-eye maculopathy).
• Decreased oscillatory potential (OP) amplitudes were common, even without other abnormalities.
• mfERGs were normal in asymptomatic patients but showed a bull's-eye pattern in toxic cases.
• ffERG parameters, including OPs, showed minimal correlation with HCQ duration or cumulative dose.

Conclusions:

• A significant number of patients displayed diffuse ERG abnormalities without clinical signs of HCQ toxicity.
• mfERG detected toxicity but its sensitivity for early changes requires further evaluation.
• Distinguishing between HCQ's pharmacological effects, retinopathy from systemic disease, and toxic effects needs more research.