Panretinal Photocoagulation In The Treatment Of Diabetic Retinal Neovascularization At Different Stages

Objectives: To evaluate the effect of panretinal photocoagulation (PRP) ondiabetic retinal neovascularization (RNV) at different stages; to clear the bestindications and opportunities of PRP and predict the effect of treatment.Methods:101eyes of68patients (132RNV) were included in the study.According to the fundus examination, fundus fluorescein angiography (FFA)and optical coherence tomography (OCT), patients were divided into fourgroups. They were pre-proliferative diabetic retinopathy (PPDR) group,RNV-bud group,RNV-leaf group and vitreous-retinal NV group. All thepatients were treated with PRP. Patients with macular edema should be treatedwith focal or grid photocoagulation first, and then treated with PRP. PRP wasfinished in four sessions once a week according to Early Treatment DiabeticRetinopathy Study protocol. Best-corrected visual acuity (BCVA), theregression of RNV leaking area in FFA and the changes of morphology ofRNV in OCT was observed at baseline and at month1.5,3,6after PRP.Results:1. There was no statistical significant difference of BCVA in group PPDR,RNV-bud and RNV-leaf at1.5months after PRP (P>0.05), but statisticalsignificant differences were found between the first three groups andvitreous-retinal NV group (P<0.01). At month3,6after PRP, there was nostatistical significant difference of BCVA in group PPDR, RNV-bud andRNV-leaf (P>0.05), but statistical differences were found between the firstthree groups and vitreous-retinal NV group (P<0.05).6months after PRP, BCVA in group PPDR improved in4eyes (17.4%);was unchanged in15eyes (65.2%); and decreased in4eyes (17.4%). In groupRNV-bud, visual acuity improved in3eyes (12%); was unchanged in17eyes(68%); and decreased in5eyes (20%). In group RNV-leaf, visual acuity improved in6eyes (23.1%); was unchanged in13eyes (50%); and decreasedin7eyes (26.9%). In group vitreous-retinal NV, visual acuity improved in9eyes (33.3%); was unchanged in10eyes (37.1%); and decreased in8eyes(29.6%). χ2test was used to compare effective rate of BCVA at6months afterPRP in four groups. The result revealed that there was no difference ineffective rate of BCVA (P>0.05).2. RNV leaking area of group RNV-bud, RNV-leaf and vitreous-retinal NVgroup was (0.79±0.60)mm~2,(4.39±5.58)mm~2,(3.62±3.40)mm~2. Follow-up ateach time point after treatment compared with the pre-PRP, there weresignificant differences (P>0.01) in four groups after treatment. Lessen of RNVleaking area was obvious at6months after PRP, and the RNV leaking areawas (0.05±0.14)mm~2,(0.87±2.10)mm~2,(2.48±3.42)mm~2in group RNV-bud,RNV-leaf and vitreous-retinal NV respectively.Pairwise comparison of RNV leaking area among groups was done atmonth1.5,3,6. There was no statistical significant difference between groupRNV-bud and RNV-leaf (P>0.05), but there were statistical differencesbetween group RNV-bud and vitreous-retinal NV, group RNV-leaf andvitreous-retinal NV respectively.We analyzed the effective rate of lessen of RNV leaking or NP in differentstages of RNV at6months after PRP. It was showed that there were statisticalsignificant differences between the first three groups and vitreous-retinal NVgroup (P<0.01), but no difference was found among the first three groups(P>0.05).3. OCT images finding: RNV-bud group: The RNV presented aspunctiform or small irregular rounded high reflection signals were on retinalsurface before PRP,39RNV with localized partial PVD,4RNV withcomplete PVD. RNV-leaf group: The RNV presented as linear, strip orirregular rounded high reflection signals were on retinal surface before PRP,and all of them were accompanied with different extent of localized partialPVD. Vitreous-retinal NV group: The base of RNV were presented as striphigh reflection signals on retinal surface, partly stretching to the vitreous cavity, and all of them were with localized partial PVD.There were no significant morphologic changes of RNV in the threegroups after PRP. In RNV-bud group, partial PVD had co-existed with RNVwhich didn't develop a regression or progress on FFA whether PRP wasperformed or not. In all RNV, we only found2clusters of RNV underwent thetransition from partial PVD (before PRP) to complete PVD (after PRP).4. In the study, preretinal hemorrhage occurred in1case in RNV-leafgroup. Vitreous hemorrhage occurred in2cases and tractional retinaldetachment in1case in vitreous-retinal NV group.Conclusions:1. The effect of PRP was better on PPDR, RNV-bud and RNV-leaf, andworse on vitreous-retinal NV.2. PRP should be performed in time to the PPDR patients, in order tostabilize vacuity and patients' conditions.