The Effect Of Different Sequence Of PRP And Grid Laser Photocoagulation On The Diabetic Retinopathy With CSME

Objective:To investigate the effect of different sequence of pan-retinal photocoagulation (PRP) and grid laser photocoagulation on the diabetic retinopathy with clinically significant diabetic macular edema (CSME) by multifocal electroretinogram (mfERG) and Optical Coherence Tomography (OCT), to analyze the changes of macular function and structure after laser photocoagulation.Methods:1.35 eyes of healthy subjects were recruited as the control. They underwent a comprehensive ophthalmic examination as well as mfERG2.40 eyes of 26 patients who were diagnosed as severe non-proliferative diabetic retinopathy (NPDR) with CSME were recruited and divided into two groups, group A and group B, there were 20 eyes in each group. Eyes in group A were treated by PRP three weeks prior to grid laser photocoagulation while group B treated by the laser photocoagulation in a contrary sequence. All the eyes were examined by mfERG and OCT before treatment and 1 week,1 month,2 month,3 month after treatment.3. Statistical method:the data were analyzed by 11.5 statistical software with methods of independent-sample t test, repeated measure ANOVA, P＜0.05 as the standard of significant difference in statistic.Results:1.Compared with control, P1 amplitude decreased significantly in ring1,3,5 and QuadrantⅠ,Ⅳ(P＜0.05) in mERG of DME; N1 amplitute decreased significantly in ring3,5 and QuadrantⅡ,Ⅳ(P＜0.05); P1 and N1 implicit time had significant delayed in ring2-ring5,QuadrantⅡ,Ⅲand ring4,Quarent I separately(P＜0.05).2.After the laser photocoagulation, the P1,N1 amplitude decreased significantly and reach the lowest level at 1 week post-treatment and recovered gradually from 1 month to 3 month post-treatment. Compared to the group B, the P1,N1 amplitude decreased more significantly in group A and recovered more slowly. The P1,N1 implicit time had significant delayed in both group A and B, the recover of P1,N1 implicit time in group better than group A. 3. Among different periods of observation, the changes of macular fovea thickness after treatment had significant difference (P＜0.05) and decreased than pre-treatment in both groups. At the early stage of post-treatment, the macular edema in group A was more significant than group B and decreased more slowly, but there was no significant difference between two groups among different periods of observation (P>0.05).Conclusion:As for the eyes with severe NPDR and CSME, the structure of macular had been destroyed while the macular function had been damaged for some time, all kinds of response in mfERG had decreased. After laser photocoagulation treatment, the extent of the macular edema aggravated and the macular function significantly decreased in a short period because of the effects of laser damage, then it seems to recovery in the following observation period.However, in a long period follow up, it was still lower than that of pre-treatment, though the thickness of macular decreased compared to pre-treatment. Among the patients of severe NPDR with CSME, the increase of macular thickness and deterioration of macular function of those who underwent PRP prior to grid laser photocoagulation were more significant than those who underwent contrary sequence of photocoagulation at earlier stage post-treatment. However, the different therapeutic sequence might have no dramatic influence in a long time follow up.