Date Published: March 29, 2017
Publisher: Public Library of Science
Author(s): Takeshi Iwase, Misato Kobayashi, Kentaro Yamamoto, Eimei Ra, Hiroko Terasaki, Demetrios G. Vavvas.
To investigate ocular blood flow and correlations between ocular blood flow and variables in patients with severe non-proliferative diabetic retinopathy (S-NPDR) following panretinal photocoagulation (PRP).
In this retrospective, cross-sectional study, the blood flow on the optic nerve head (ONH) and choroid was assessed with laser speckle flowgraphy (LSFG) using the mean blur rate (MBR) in 76 eyes of 76 patients with S-NPDR who underwent PRP, 39 eyes of 39 patients with S-NPDR who did not undergo PRP, and 71 eyes of 71 normal subjects. The correlation between MBR and variables, including visual acuity (VA) and choroidal area determined by binarization method, was analyzed.
The mean age was 62.9 ± 11.9 years in the S-NPDR with PRP eyes, 55.6 ± 11.4 years in the S-NPDR without PRP eyes, and 60.3 ± 11.1 years in the normal subject eyes. The ONH MBR in vessel and tissue areas and the choroidal MBR were significantly lower in the S-NDR with PRP group than in the other groups (p < 0.001, p < 0.001, and p < 0.001, respectively). The luminal and the stromal areas were significantly smaller in the S-NDR with PRP group than in the other groups (p < 0.001 and p < 0.001, respectively). LogMAR best corrected visual acuity (BCVA) exhibited significant negative correlation with the ONH MBR in vessel (r = −0.386, p < 0.001), tissue (r = −0.348, p < 0.001), and the choroid MBR (r = −0.339, p = 0.002) in the S-NDR with PRP group. Stepwise multiple regression analysis demonstrated that BCVA was a common independent factor associated with the ONH MBR in vessel, tissue, and the choroidal MBR in the S-NDR with PRP group. ONH and choroid MBR in addition to choroidal component, including the luminal area, were significantly lower in eyes of patients with S-NPDR after PRP compared with no PRP and normal subjects group. This could suggest that the significantly reduced ocular blood flow in PRP-treated S-NPDR eyes correlated with long-term decreased post-PRP luminal area and visual acuity.
Diabetic retinopathy is one of the leading causes of blindness in the industrialized world. Studies have demonstrated that panretinal photocoagulation (PRP) is a beneficial clinical treatment that reduces the incidence of blindness in patients with proliferative diabetic retinopathy (PDR).[1–3] A five-stage disease severity classification for diabetic retinopathy includes three stages of low risk, a fourth stage of severe non-PDR (S-NPDR), and a fifth stage of PDR. [4, 5] At least one of the following should be present in S-NPDR: a) “severe” haemorrhages and microaneurysms in all four quadrants of the fundus, b) venous beading, which is more marked in at least two quadrants, and c) intraretinal microvascular abnormalities, which are more severe in at least one quadrant. The Early Treatment Diabetic Retinopathy Study subsequently demonstrated PRP to be associated with maintenance of good long-term visual acuity in most patients with S-NPDR or PDR.
Our results showed that ONH and choroidal MBR were reduced in the PRP on eyes with S-NPDR but were not reduced in untreated eyes with S-NPDR. In addition, PRP on eyes with S-NPDR significantly reduced the SFCT and choroidal area as determined by binarization compared with untreated eyes with S-NPDR and normal eyes. Multiple stepwise regression analysis revealed that BCVA was a common independent factor associated with ONH and choroidal MBR in PRP on eyes with S-NPDR.