Comparison of Visual Evoked Potential and Electro-oculogram Tests in Early Detection of Hydroxychloroquine Retinal Toxicity

To compare the sensitivity of visual evoked potential (VEP) and electro-oculogram (EOG) tests in early detection of hydroxychloroquine (HCQ) retinal toxicity.Patients and

In this prospective cross-sectional study, 100 consecutive patients (age range: 18 to 30) with juvenile rheumatoid arteritis (JRA) and a cumulative hydroxychloroquine dosage of at least 200gr were included.  In addition 100 healthy individuals with matched age and sex were included as controls. Ocular examinations including visual acuity testing, refractive errors measurement, applanation tonometry, slit lamp biomicroscopy fundus ophthalmoscopy and electrophysiological examinations (EOG and VEP) were performed in both groups. Scores of less than 1.8 for the Arden Index in EOG (AI), as well as less than 4mv of P100 amplitude and more than 110ms of P100 latency in VEP were considered abnormal.

The mean cumulative dosage of HCQ among participants was 262.4±31.9g (95% CI: 256.1 to 268.8g). The mean measurement of AI (EOG), P100 latency and amplitude of VEP were 1.8±0.4, 112.7±10.1ms and 3.7±2.1mv, respectively. There was a significant difference between case and control groups in all parameters (p<0.001 for all). There was not any significant difference between AI (EOG), P100 latency and amplitude of VEP in detecting the ocular toxicity due to HCQ.

We conclude that AI (EOG), P100 amplitude and latency of VEP can all be useful parameters to detect HCQ retinal toxicity, and we did not detect any difference between these two methods.