A randomized clinical trial evaluating choroidal blood flow and morphology after conventional and pattern scan laser panretinal photocoagulation

Yuji Mikoshiba,Yoshitaka Ueno,Eimei Ra,Kentaro Yamamoto,Hiroko Terasaki,Takeshi Iwase

doi:10.1038/s41598-018-32487-y

Abstract

We prospectively investigated the changes in choroidal blood flow and morphology after panretinal photocoagulation (PRP) in 39 eyes with severe nonproliferative diabetic retinopathy (S-NPDR). Seventeen eyes underwent PRP by conventional laser and 22 eyes underwent pattern scan laser (PASCAL). The choroidal blood flow was assessed by laser speckle flowgraphy, and the subfoveal choroidal thickness (SFCT) was measured with optical coherence tomography before and 1, 4, 8, and 12 weeks after the two types of PRP treatments. The choroidal mean blur rate (MBR) at the macular region was significantly reduced to 86.4% of the baseline level in the conventional laser group and 85.7% in the PASCAL group at Week 12 (P = 0.001, P < 0.001, respectively). The SFCT was significantly increased at 1 week following PRP but it was significantly reduced at Week 8 (P = 0.001, P < 0.001, respectively) in both groups. The differences in the ratio of the MBR and the SFCT was not significant between the conventional laser and PASCAL groups at any time after PRP. The results suggest that appropriate PRP treatments even by the PASCAL method will reduce the choroidal blood flow and the choroidal morphological components.

Highlights

Diabetic retinopathy is one of the main causes of severe vision loss in the industrialized world
Our results showed that there was a gradual decrease of the choroidal mean blur rate (MBR) for at least 12 weeks following the panretinal photocoagulation (PRP) by the conventional laser or the pattern scan laser (PASCAL) protocols in eyes with severe nonproliferative diabetic retinopathy (S-NPDR)
PRP caused a significant increase of the subfoveal choroidal thickness (SFCT) at 1 week following the completion of the PRP, but the SFCT was significantly reduced after Week 8 in the both groups

Summary

Introduction

Diabetic retinopathy is one of the main causes of severe vision loss in the industrialized world. Studies have demonstrated that panretinal photocoagulation (PRP) treatments were associated with good long-term visual acuity in most patients with proliferative diabetic retinopathy (PDR)[1,2,3] and severe non-PDR (S-NPDR)[4]. Savage et al reported that the choroidal blood flow determined by pulsatile ocular blood flow is decreased in eyes with laser-treated PDR9. Takahashi et al reported that PRP might increase the choroidal blood flow in eyes with S-NPDR11 It has still not been definitively determined whether PRP will alter the choroidal blood flow probably because of the differences in the measurement methods, instruments, measured regions, and stage of the disease process. Okamoto et al reported that there was a significant positive correlation between the percentage reduction of the SFCT and choroidal MBR at 12 weeks after PRP17. The effect of laser treatment on the choroidal blood flow and its relationship to the choroidal thickness is still controversial

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