Abstract

AIMS Abnormalities in colour perception occur early in the development of diabetic retinopathy. Whether these changes can be influenced by increasing circulating oxygen saturation was studied in comparison with non-diabetic controls.

METHODS Protan and tritan colour thresholds were measured using a computer graphics system in 37 insulin dependent diabetic subjects, with no or minimal background retinopathy, and 27 matched controls. Colour thresholds were performed after subjects inhaled either gaseous air or 100% oxygen for a minimum of 5 minutes.

RESULTS Diabetic subjects had higher colour vision thresholds when inhaling air when compared with controls (protan (mean 3.93 (SEM 0.39), v 2.36 (0.16), p<0.0002) and tritan (8.15 (0.62) v 5.42 (0.31), p <0.002)). The colour vision thresholds observed in diabetic subjects inhaling air fell when they inhaled oxygen (protan (3.93 (0.39) v 3.57 (0.33), p <0.025) and tritan (8.15 (0.62) v 7.35 (0.59), p<0.005)). No fall in colour thresholds was seen in non-diabetic controls who inhaled oxygen.

CONCLUSION A small improvement in the colour vision thresholds was observed using computer graphics in diabetic subjects, with minimal or no retinopathy, who inhaled oxygen. This study supports a hypothesis that reduced retinal oxygenation contributes to the colour vision defects in diabetes.