| Objective:To investigate the characteristics and the tendency of changes in retina function by multifocal electroretinogram (mERG) for diabetic retinopathy (DR) after photocoagulation, combining with optical coherence tomography (OCT) to analyze the changes of macular fovea thickness and whether it has a statistical correlation with correspondent retina function. Discuss the value of mERG in clinical treatment of DR in order to accumulate application experience for further researches.Meathods:1.35 eyes of healthy elders were recruited to undergo examination of mERG , the results recorded were to be as references.2.40 eyes of 30 patients who were confirmed as preproliferative diabetic retinopathy (pre-PDR) and accepted photocoagulation from July 2006 to December 2007 at Tian Jin Medical University Eye Center were examined by mERG and OCT before and 2 days, 1 week, 2 weeks , 3months after treatment.3. Statistical method: the data were analyzed by 11.5 statistical software with methods of independent-sample t test, two-way ANOVA and Pearson correlation, P<0.05 as the standard of significant difference in statistic.Results:1.Compared with normal, P1 amplitude decreased significantly in ring2-ring5,Quadrant II (P<0.05) in mERG of pre-PDR, N1 amplitute decreased significantly in ring3-ring4,QuadrantIII(P<0.05); P1 and N1 implicit time had significant delay in ring3-ring5,QuadrantIII and ring4 ,Quarent I separately(P<0.05).2. In different periods of observation, the P1 amplitude had significant difference in ring1,ring3-ring5,Quadrant I -IV (P<0.05). the N1 amplitude had significant difference in ring1,ring5 and Quadrant II,IV(P<0.05); the P1 implicit time had significant difference in ring3-ring5 and Quadrant I,III(P<0.05),the N1 implicit time had significant difference only in ring5(P<0.05).3.The changes of macular fovea thinkness had significant difference(P<0.05). the mean of fovea thickness is 274.85±108.20μm 2 days after photocoagulation which thickened obviously compared with previous period (P=0.009), and it had no significant difference between the period of before and 3 months after treatment (P=0.884). 4.The correlation indexs between P1 amplitude and macular fovea thinkness were -0.775(P=0.002<0.05) and -0.594(P=0.025<0.05) seperately before and 1 week after photocoagulation ,all above showed significant negative correlation.Conclusion:As for patients with pre-PDR, the retina function had been damaged for some time, all kinds of responses in mERG were decreased to some extent. After photocoagulation, the retina function apperenced significant decrease in short time because of the effects of laser and the lower resistance of retina, then it seemed to be recovery in follwing 2 weeks, After a long time, it still much lower than that of before photocoagulation. At the same time, there was significant correlation between macular fovea thickness and P1 amplitude before and 1 week after photocoagulation, that is to say the heavier in macular edema, the lower in P1 amplitude.In a word, as a new technique , the mERG can examine retinal responses from many localized regions in short time and provide functional assessment of them, and it also has great value in detection of macular disorders. In this study , mERG was used to examine retina function in pre-PDR with photocoagulation ,combining with OCT to observe the macular fovea thickness and the change of correspondent retina function. it can provide not only the basis for diagnosis of tiny maculopathy but also more objective assessment of functional changes. Because of the mERG can record retinal function objectively,precisely,locatedly and quantitatively, it is a effective addition for clinic and researches. With it, we can gain more information on the variation of visual function and detect the change of retina function,disease progress and therapy effects periodically. So mERG is valuable in clinical application for early detection,follow up and selection of further treatment. |
