Multisubstance analysis of reflection spectra before and after laser photocoagulation for proliferative diabetic retinopathy.

OBJECTIVE

The aim of the study was to provide new data that add to the understanding of diabetic retinopathy and its treatment by photocoagulation.

METHODS

Using a spectrometric method, the reflection spectra of the macula in six type II diabetics with proliferative diabetic retinopathy were measured before and after laser photocoagulation and compared with normals. The investigations were done one day before laser photocoagulation and again the day after. Further measurements were made 14 days, 6 weeks and 4 months after coagulation. The reflection spectra were assessed by multisubstance analysis.

CONCLUSIONS

The contents of xanthophyll, melanin and choroidal oxyhemoglobin and the intensity of scattered light were significantly altered after laser coagulation. For example, in patients with proliferative diabetic retinopathy the content of oxyhemoglobin in the choroid was lower than normal, but it rose after laser treatment. This suggests an improved oxygen supply of the choroid after laser coagulation, implying reduced retinal hypoxia.