Changes in Choroidal Thickness and Volume in Patients with Diabetic Retinopathy after Panretinal Photocoagulation by Using a Choroidal Thickness Map

Objectives: We aimed to investigate the short-term changes in macular choroidal thickness and volume after Panretinal Photocoagulation (PRP) in patients with Proliferative Diabetic Retinopathy (PDR) using a choroidal thickness map with Spectral-Domain Optical Coherence Tomography (SD-OCT). Methods: In this retrospective study, we reviewed the charts of patients who received PRP for diabetic retinopathy. Central volume scans using a 25-scan pattern and macular thickness map protocols were subsequently performed using the Spectralis OCT before and 1 month after PRP. Retinal thickness was measured by automated segmentation and choroidal thickness was obtained using a volume scan program with manual segmentation. For segmentation of the choroidal layer, the reference lines of the retinal boundary were adjusted to the choroidal boundary. Macular thickness maps were divided into nine sectors according to the ETDRS layout and analyzed to evaluate changes in macular thickness and volume. Results: In all, 49 patients (49 eyes) with early PDR were included. The mean central retinal thickness and mean total retinal volume of all ETDRS subfields increased 1 month post-PRP (308.06 +/- 50.75 mu m, 9.72 mm(3)) compared with before PRP (279.84 +/- 26.62 mu m, 9.19 mm3; P<0.001). Mean central choroidal thickness and mean total choroidal volume of all ETDRS subfields showed no significant change 1 month after PRP (302.57 +/- 43.11 mu m, 8.16 mm(3)) compared with before PRP (298.43 +/- 43.67 mu m, 8.12 mm(3); P=0.120 and P=0.353, respectively). In all nine sectors, including the central 1-mm circle, choroidal thickness and volume showed no significant changes post-PRP treatment (P> 0.05). Conclusion: In the macular region, retinal thickness increased and choroidal thickness did not change 1 month after PRP. These results indicate that PRP may have little or no effect on the change in macular choroidal thickness or volume in patients with early PDR, although whether PRP causes a significant change in choroidal blood flow in the macular region is unclear.