A preliminary trial to determine whether prevention of dark adaptation affects the course of early diabetic retinopathy

This study was designed to determine whether a new form of treatment of diabetic retinopathy (DR) was acceptable to patients and whether reduction in the maximal activity of rods in diabetes could affect the progress of DR. Methods In 12 patients, trans-lid retinal illumination of one eye was employed during sleep to prevent the depolarisation of rods and thus reduce their metabolic activity. Techniques A headband was used to place a source of chemical light over one eye, with its fellow as a control. Measurements Colour contrast thresholds were measured before and after a period of treatment in treated eyes, and the changes were compared to those in untreated fellow eyes, and areas of 'dark retinal anomalies' (microaneurysms, dot haemorrhages) were measured at the same time points. Results Patients found this intervention to be acceptable, and no adverse effects were noted. In the majority of cases, and for each outcome measure, the treated eyes improved relative to their fellows. The intervention significantly reduced the tritan thresholds in treated eyes relative to their fellows (P = 0.03), and the area of dark retinal anomalies decreased in treated eyes and increased in untreated eyes, with a similar probability. Conclusions The study showed that this intervention is safe. Although the study was not powered to study efficiacy, the results are promising and consistent with other reports that indicate the retina in DR is suffering from hypoxia; however, further trials should be undertaken. Eye (2010) 24, 1149-1155; doi:10.1038/eye.2009.328; published online 5 February 2010