Citicoline and Vitamin B(12) Eye Drops in Type 1 Diabetes: Results of a 3-year Pilot Study Evaluating Morpho-Functional Retinal Changes

INTRODUCTION: This study aimed to evaluate the effect of treatment with eye drops containing citicoline and vitamin B(12) on changes in function of the inner retina, morphology of the inner and outer retina, and microvascular condition in patients with type 1 diabetes (DM1) with mild signs of non-proliferative diabetic retinopathy (NPDR) during 3 years of follow-up. METHODS: A pilot study with prospective, randomized, and double-masked design was conducted to address the aims. Twenty patients with DM1 were enrolled and randomly divided into two groups: the DC group comprising patients treated with citicoline and vitamin B(12) eye drops (10 patients; mean age ± standard deviation, 46.86 ± 8.78 years) and the DP group comprising those treated with placebo (10 patients; mean age ± standard deviation, 47.89 ± 7.74 years). In the DC group, one eye of each patient was treated with citicoline and vitamin B(12) eye drops (OMK2(®), Omikron Italia srl, Italy, 3 drops/day), while in the DP group, it was treated with placebo (eye drops containing hypromellose 0.3%, 3 drops/day) for a 3-year period. In both groups, Humphrey Matrix frequency doubling technology (FDT), spectral domain optical coherence tomography (SD-OCT) and OCT angiography (OCTA), and adaptive optics (AO) were applied at baseline and 12, 24, and 36 months of the follow-up period. RESULTS: In the results of follow-up evaluation, the DC and DP groups were significantly different: Significant reduction in function in terms of 10-2 FDT mean sensitivity and in morphology reflected by an increase in inner nuclear layer thickness and decrease in other plexiform layer thickness and foveal vessel density were observed in the DP group, while no such significant changes were observed in the DC group in the long term. CONCLUSIONS: This pilot study indicated that patients with DM1 with mild signs of diabetic retinopathy (DR) who underwent treatment with citicoline and vitamin B(12) eye drops for a 3-year duration achieved stabilization or decreased rate of functional impairment, neuroretinal degeneration, and microvascular damage. TRIAL REGISTRATION: ClinicalTrials.gov identifier, NCT04009980.