| Objective: Macular edema (ME) was the most important problem in patients with diabetic retinopathy (DR), and also was the main cause to visual functional lesion in patients with background retinopathy. ME was influenced by many elements, such as breakdown of the blood-retinal inner and outer barriers, and effects of the whole body, and so on. The main treatment to ME was laser photocoagulation (LP). But to some patients with ME, simple LP had no effect on ME, and some patients even got worse. Recently some researchers inferred that the traction of vitreous cortex to macular region may play an important role in this course. So some foreign researchers used pas plana vitrectomy (PPV) to treat these patients, but no positive reports about it were found at interior of country. In this study, some patients were treated with PPV. They had experienced LP, and after 6 months, their ME made no progress, or even got worse, The preoperative and postoperative visual activity, level of edema, PIoo latency, the mean light sensitivity at central 30' , and FAZ were determined in this study to make sure . Whether there was significant difference between the preoperative andpostoperative levels. Research of immunohistochemistry and electron microscope were also studied. The objective of this study were: 1. To find histochemistric evidence to prove that there was continuous macular traction in patients with DME. 2. To study the nosogenesis in persistent DME. 3. To evaluate the effect of the operation to patients with DME.Methods:l.In 7 patients (10 eyes) with persistent DME (all these patients were treated with PPV),the preoperative visual activity of lm,3m,6m,9m,and fluorescein angiography (FA) were determined. The same targets were also determined postoperatively.2.The preoperative and postoperative area of FAZ were determined in these patients. Significance test was used between the preoperative area of FAZ and postoperative area.3.The 3m P-VEP were determined between preoperation and postoperation. The 6m P-VEP were also determined.4.The pre-and postoperative mean light sensitivity at central 30 were determined in these patients. Significance test was used between the preoperative mean light sensitivity at central 30 and the postoperative level.5. The vitreous specimens were treated with HE dying, immunohistochemistry with light microscope and electron microscope . The cells and extracellar stroma were studied by these ways.Results:l.In 3m test ,visual activity increased (2 lines) in 5 eyes after PPV, 3 eyes kept the same (3/10,30%), and visual activity fell (2 lines) in 2 eyes (2/10,20%).In 6m test ,visual activity increased (2 lines) in 5 eyes (5/7,71.43%), 2 eyes kept the same (2/7,28.57%), no one's visual activity fell (2 lines). There was significant difference between 3m and 6m test.2. There was significant difference between the preoperative 6ME and postoperative 6m ME(P-5.142xl0-15 ).3 .There was significant difference in the 6m area of FAZ between the preoperative and postoperative levels (P=0.0284). There was significance in the 9m area of FAZ between the preoperative and postoperative levels (P=0.029). There was significant difference in the area of FAZ between the patients' preoperative levels and the normal group (P=0.0004), and there was no significant difference in the 9m area of FAZ between the patients' postoperative levels and the normal group's (P=0.0508). The area of FAZ in patients with persistent DME was broader than the area of the normal group.4. There was significant difference in the P100 latency between the preoperative and 3m , 6m postoperative levels (P=0.0099,p=0.0105).5.There was significant difference in the mean light sensitivity at central 30?between preoperative and 6mpostoperative levels (P=0.0049). The postoperative mean light sensitivity at central 30?got better than the preoperative levels.6. Cells were found with light microscope (HE dying) as following: (1) fibroblasts( fusiform cells) (2) neuroglial cells (small, round nucleus,...
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