EFFECTS OF PANRETINAL PHOTOCOAGULATION ON CHOROIDAL THICKNESS AND CHOROIDAL BLOOD FLOW IN PATIENTS WITH SEVERE NONPROLIFERATIVE DIABETIC RETINOPATHY.

PURPOSE: To evaluate the choroidal thickness and choroidal blood flow in the subfoveal region quantitatively after panretinal photocoagulation (PRP) in eyes with severe nonproliferative diabetic retinopathy.

METHODS: This was a prospective comparative study of 24 eyes of 24 patients with type II diabetes and severe nonproliferative diabetic retinopathy with no macula edema. The foveal retinal thickness and choroidal thickness were measured by enhanced depth imaging optical coherence tomography. The subfoveal choroidal blood flow was represented by the mean blur rate obtained by laser speckle flowgraphy. The intraocular pressure, blood pressure, pulse rate, and hemoglobin A1c level (HbA1c) were also measured before and after PRP.

RESULTS: The mean foveal retinal thickness did not change significantly during the follow-up period. The mean subfoveal choroidal thickness was reduced significantly from 327.4 μm at the baseline to 286.3 μm at 1 month and 285.0 μm at 3 months after PRP. The mean blur rate ratio decreased significantly to 87.5% at 1 month and 86.0% at 3 months of the baseline values. There was a significant correlation between the subfoveal choroidal thickness and subfoveal choroidal blood flow after PRP. After PRP, the best-corrected visual acuity, intraocular pressure, mean arterial pressure, ocular perfusion pressure, pulse rate, and HbA1c did not change significantly.

CONCLUSION: The success of PRP in treating eyes with severe nonproliferative diabetic retinopathy is probably due to the significant reduction of the subfoveal choroidal thickness and subfoveal choroidal blood flow after PRP.