[The ERG contribution in early diagnosis of chloroquine and hydroxychloroquine maculopathy]

Derivates of chloroquine (Plaquenil, Delagil), used for long-term treatment of rheumatic diseases, may cause clinically proven irreversible maculopathy, which may progress even after the discontinuation of their application. The optimal early diagnosis of ocular toxicity of chloroquine or hydroxychloroquine drug remains controversial up to now. The aim of this review paper was to evaluate how appropriate is the indication of the electroretinographic (ERG) examination due to the early diagnosis of cumulative drug-related maculopathy. Photopic, pattern, and multifocal ERG (Retiscan, according to the ISCEV methodology) were examined in 10 patients (20 eyes) treated by means of antimalarics, 9 due to the rheumatoid arthritis (RA) and 1 due to the systemic lupus erythremathodes (SLE). The average age of the patients was 60 +/- 15 years, the treatment period was 10 +/- 11 years; the median of the treatment period was 5 years. The control group consisted of 12 healthy, age matched patients (20 eyes) without any obvious ocular pathology. In all of them, the complete ophthalmologic examination was performed: the best corrected visual acuity (BCVA) for far using the Snellen charts, intraocular pressure (IOP) measured by means of the non contact tonometer NIDEK NT-2000, the Amsler grid test, examination of the anterior segment and the posterior segment with the slit lamp. The entry criteria in both groups were BCVA 5/7,5 (0.67) and better, the IOP in the normal range, negative Amsler grid test, anterior segment without significant decrease of the transparency, and physiological posterior segment or with subtle granular pigment dysgrupancies in the macula only. The significant difference between the group treated with chloroquine or hydrochloroquine and the control group at the 1% level of significance was found in following parameters: in the photopic ERG the value of the b wave latency [ms], in pattern ERG, the values of the waves N35 - P50 [microV] and P50 - N95 [microV] amplitudes, and at the 5 % level of significance in photopic ERG, the wave a amplitude value [microV] and in multifocal ERG, the value of the P1 [ms] a N1 [ms] parts latency in the pericentral ring. It follows from the results, that the ERG examination is suitable for the early diagnosis drug cumulative maculopathy caused by chloroquine derivates. Optimal is the individual comparison of the ERG values of the patient before and in certain time intervals after the beginning of the chloroquine derivates treatment.