Abstract
Purpose: :
To evaluate the multifocal electroretinography (mfERG) changes in patients on ethambutol therapy.
Methods: :
Seventeen visually asymptomatic patients receiving anti-tuberculosis therapy with ethambutol underwent ophthalmic examination and mfERG recordings. The N1 and P1 response amplitudes and implicit times of six concentric rings were analyzed and compared with 17 age-similar normal control subjects. Correlation analyses were also performed between the patients’ mfERG and ethambutol parameters.
Results: :
No significant differences in the mfERG N1 and P1 response amplitudes were found between patients on ethambutol and controls at all ring eccentricities (all P>0.05). For implicit times, there were significant delays in the mfERG P1 implicit times of rings 4 to 6 in the ethambutol group compared with controls (P=0.012 to P=0.041). Correlation analyses showed no significant correlation between the mfERG parameters and ethambutol dosage and duration (all P>0.05).
Conclusions: :
The mfERG findings showed that visually asymptomatic patients receiving ethambutol therapy might have electrophysiological changes in terms of delayed mfERG P1 implicit times involving the peripheral macula. This study suggested that ethambutol might have some drug effects in influencing the retinal function.
Keywords: electroretinography: clinical • drug toxicity/drug effects • electrophysiology: clinical