Effect of grape seed proanthocyanidin extract on hard exudates in patients with non-proliferative diabetic retinopathy

PURPOSE: To evaluate the efficacy and safety of orally administered grape seed proanthocyanidin extract (GSPE) in patients with non-proliferative diabetic retinopathy (NPDR). METHODS: In this randomized (1:2:2), multicentre, double-blind trial, patients (n = 124; age: 40–78 years) were administered placebo, calcium dobesilate (CD; 750 mg/d), or GSPE (150 mg/d) orally for up to 12 months. All patients had retinal thickening with hard exudates (HEs) that met predefined criteria; the median best-corrected visual acuity was 0.8, as assessed using the Snellen visual acuity card. The main outcome measure was an improvement in HEs by at least 1 grade on a 10-grade severity scale. This was evaluated using fundus photography over 1 year. RESULTS: The rate of improvement in the HE severity was higher in the GSPE group than in the CD group. No statistically significant difference existed among the study groups in optical coherence tomography parameters, such as central subfield macular thickness and total macular volume (TMV). However, in the GSPE group, TMV after 9 months of treatment was significantly decreased compared with that at baseline. The GSPE group showed a significantly greater improvement in HE severity than did the placebo or CD group. Four cases in the GSPE group and 2 in the CD group were determined to have developed potential treatment-related adverse reactions, which were all gastrointestinal in nature. CONCLUSIONS: Oral GSPE therapy for 1 year improved HEs in patients with NPDR. The efficacy of GSPE for HEs was higher than that of oral CD in the study patients.