Purpose
The aim of this study is to investigate the rule of multifocal electroretinogram (mfERG) to follow-up patients with Stardgardt’s disease in order to provide prognostic information.
Methods
We followed up 15 patients (9 female and 6 male) with ABCA4-related Stardgardt disease for three years by performing the following examinations: ophthalmoscopic exam, best corrected visual acuity (BCVA), full field electroretinogram (ERG) and mfERG. BCVA was measured with Early Treatment Diabetic Retinopathy Study (ETDRS) charts. The fundus lesion were classified according to Fishman stages. ERGs and mfERGs were recorded following International Society for Clinical Electrophysiology of Vision standard guidelines. The ERG responses were categorized according to Lois’s classification. In mfERGs a stimulus array of 103 hexagons was adopted, the responses were spatially averaged in six rings and the amplitude and latency parameters of the three waves (N1, P1 and N2) were computed.
Results
The patients had the following demographic characteristics: age 15-50 yrs, disease length 1-23 yrs, age of onset 12 - 38 yrs. The BCVA ranged from 0 to 1.82 logMar (0.84 ± 0.33 logMar). Fundus lesions were classified as Fishman stage I, II and III in 12, 2 and 1 patients, respectively. ERG responses belonged to Lois class I, II and III in 12, 2 and 1 patients, respectively. None of the patients showed a normal mfERGs in any rings. In the fifty per cent of patients a subnormal but recordable response was assessed in the last three rings. We observed significant differences (p-value < 0.05) in some parameters of mfERG responses between baseline and last follow-up measurements (peak amplitude of N1 wave, latency and peak amplitude of N2 wave in Ring 6, and peak amplitude of N2 wave in Ring 5). Moreover, we observed a significant correlation between BCVA and amplitude of P1 wave in Ring 6 (rho=-0.30; p=0.03). Finally, we observed significant correlation between BCVA lost in the three year follow-up and the amplitude of N1 wave in Ring 6 (rho=0.397;p=0.046).
Conclusions
This study revealed significant differences in mfERG responses after three year follow-up. Selected mfERG parameters, recorded at the baseline, seemed to have a prognostic value to predict the visual acuity lost in the following three years. Further studies on a larger sample of patients would be needed to confirm the prognostic value of mfERG in Stardgardt disease.
Keywords: 494 degenerations/dystrophies •
696 retinal degenerations: hereditary •
509 electroretinography: clinical