A randomized, double-blind, placebo controlled study to investigate the long-term effect of Cyclospasmol R (cyclandelate) on the abnormal permeability of the blood-retinal barrier was performed in 26 patients with insulin-dependent diabetes mellitus for at least 1 year and minimal retinopathy. Cyclospasmol 400 mg or placebo capsules were taken 4 times daily for 12 months by equal numbers in both groups.
Each patient underwent a routine ophthalmoscopic examination, retinal fluorescein angiography and quantitative vitreous fluorophotometry to assess the permeability of the blood-retinal barrier just before the trial and following 6 and 12 months of therapy. Laboratory tests for determining blood and urine glucose levels and blood HbA;levels were also carried out at these assessments.
Statistically significant changes in diabetic control, in HbAclevels or in the frequency of retinal microaneurysms could not be shown in either treatment group during the trial, nor were there any significant differences in these parameters between the two groups. Analysis of fluorophotometric data on fluorescein penetration into the left posterior vitreous demonstrated significant reductions in this parameter during the trial compared to the pretreatment level in Cyclospasmol treated diabetics. These changes in the pretreatment level after 6 and 12 months also differed significantly between the two groups.
However, this statistically significant beneficial reduction in fluorescein penetration into the left posterior vitreous did not occur in the right eye in the Cyclospasmol group.
In placebo treated patients a consistently deleterious trend for this parameter was observed for both eyes during the one year study. The consistently beneficial trend in the right eye following Cyclospasmol and the consistently deleterious trend in both eyes following placebo with regard to the abnormal permeability of the blood-retinal barrier of diabetics with minimal retinopathy could probably be explained by the small number of patients in both groups. No side-effects were reported.