The effect of simultaneous dual-focus integration on the global flash multifocal electroretinogram in the human eye.

PURPOSE: To investigate the effect of simultaneous dual-focus (DF) on retinal activities measured by global flash multifocal electroretinogram (mfERG). METHODS: Thirty adults were recruited for mfERG measurement under three conditions: in-focus (i.e., no defocus), +2.50 D DF and +7.50 D DF, administered using single vision contact lenses and DF lenses. The direct component (DC) and the induced component (IC) of the mfERG were pooled into central macular (0-8°), para-macular (8-18°) and peri-macular (18-30°) regions, and then compared across the three conditions using two-way, repeated measures ANOVA. RESULTS: Simultaneous DF had a significant effect on the IC amplitude, which was significantly stronger under +7.50 D DF (p < 0.01) than for the in-focus condition, which was mostly derived from the central and para-macular regions. No significant effect was observed for the +2.50 D DF condition. CONCLUSION: Under the effect of relatively strong simultaneous DF integration, the retina showed an enhanced retinal response, which originated from the inner retina. Compared with the peri-macular region, central and para-macular responses appeared to be enhanced.

Community-based diabetic retinopathy screening in Hong Kong: ocular findings.

BACKGROUND: Diabetic retinopathy is one of the most common causes of blindness. Timely retinal evaluation is known to prevent or minimise visual loss. This study compared the prevalence of ocular disorders in patients who have and have not undergone a retinal examination since diagnosis of their type 2 diabetes mellitus (T2DM). Such data might be useful for planning purposes by health care authorities and agencies in Hong Kong. METHODS: Patients with T2DM aged 30 years or over presented for standardised interviews and screening for diabetic retinopathy. The presence of ocular disorders was recorded and the severity of the retinopathy, if any, was graded using the Early Treatment Diabetic Retinopathy Study (ETDRS) classification. RESULTS: For the 1058 subjects who participated in this study, the mean age at examination was 61.8 ± 10.5 (SD) years (range, 31-93 years). For the 891 subjects with known diabetes for one year or longer, 62.7 per cent had never undergone an evaluation for diabetic retinopathy since diagnosis of their T2DM. Of the 891 subjects, gradable fundus photographs were available for 853 subjects and nearly 2.0 per cent of these had sight-threatening retinopathy based on the ETDRS classification. Those who had not had an eye examination since diagnosis of their T2DM were more likely to have sight-threatening retinopathy than those who had a retinal evaluation (2.6 versus 0.6 per cent; p = 0.04). CONCLUSION: In our sample, over 60 per cent of patients with T2DM for one year or longer had not had a retinal assessment since diagnosis. The risk of developing sight-threatening diabetic retinopathy appears to be higher for those who have not had a retinal assessment.