| Objective: Diabetic retinopathy (DR), especially proliferative diabetic retinopathy(PDR), is the chiefly cause of visual loss in the middle-aged people domestic and overseas. The living quality of those patients with diabetic retinopathy have been affected tremendously. Now panretinal photocoagulation (PRP) is one of the most important measures to prevent blindness caused by PDR. In the treatment of PRP. What the laser light affected directly is retina, otherwise the physiological and biochemical character of vitreous body will be affected by the light and the laser's heat as well. Then the relationship between the vitreous body and retina will be affected either. So posterior vitreous detachment will be occurred or developed. Because there are few studies about the relationship between PRP and the changes of PVD in different stages of DR. Our study is justly selected the patients with preproliferative diabetic retinopathy (PPDR) or the fourth stage of DR (PDR-Ⅳ) who mostly often should be performed PRP treatment. Our aim is to observe the difference of PRP's effect to the PVD of the two stage patients. At the same time , in order to access the effect of PVD's change to the curative effect of PRP, we also observed the new vessels change in the patients with PDR-Ⅳ. We believe the results could give us some information about PVD's function and more instruction to clinical work. Methods: The patients meet eligibility criteria were enrolled in the study and accepted the following examinations and treatments respectively. 1 The condition of vitreous was documented through direct fundus ophthalmoscopy, binocular indirect ophthal-mosopy, slit-lamp biomicroscopy, +90 diopter double aspheric preset lens and B-scan ultrasonography. Based on the examinations we classified the posterior vitreous into no PVD(record as N), partial PVD(record as P) and complete PVD(record as C). 2 Fundus fluorescein angiography(FFA): As a standard time, at the 2ed minute, we saved every patient's FFA images by which we compared the leakage of new vessels before and six months after PRP. On the basis of the comparison we classified the neovascularization change into complete shrinkage, partial shrinkage , no change or extend. 3 Laser photocoagulation: Krypton yellow laser was used for macular grid photocoagulation, the spot should be faint whitish; krypton green laser was used for panretinal photocoagulation ,the spot should be grayish. All patients were accepted both macular grid photocoagulation and PRP. 4 Follow-up: Every patient was examined at the 1st , 3rdand 6th month respectively after laser photocoagulation. At the 6th month we accessed the change of PVD and shrinkage of new vessels by another carefully examination including B-scan ultrasonography and FFA. The change of PVD were classified into N—N: no PVD at both initial and final examinations; N—P: no PVD at initial examination, partial PVD at final examination; N—C: no PVD at initial examination, complete PVD at final examination; P—P: partial PVD at both initial and final examinations; P—C: partial PVD at initial examination, complete PVD at final examination; C—C: complete PVD at both initial and final examinations。Results: 1 The effect of laser photocoagulation to PVD: 43 PPDR eyes and 71 PDR-Ⅳeyes which have no PVD were investigated. After PRP, there were 29(67.45%) PPDR eyes and 24(33.80%) PDR-Ⅳeyes remain no PVD(N—N). There was statistically difference between the two groups(P<0.05); There were 8(18.60%) PPDR eyes and 36(50.70%) PDR-Ⅳeyes showed partial PVD(N—P). Significant statistically difference between the two groups(P<0.01); There were 6(13.95%) PPDR eyes and 11(15.50%) PDR-Ⅳeyes showed complete PVD(N—C). There was no statistically difference between the two groups(P>0.05). Compared with the 5 PPDR eyes which have partial PVD before PRP, there were 25 PDR-Ⅳeyes. After PRP there were 4(80%) eyes in PPDR and 19(76%)in PDR-Ⅳremain partial PVD(P—P).There were only 1(20%) eye in PPDR and 6(24%)eyes in PDR-Ⅳbecame complete PVD(P—C).Both have no statistically difference(P>0.05). There were 10 eyes in PPDR and 9 eyes in PDR-Ⅳshowed complete PVD before and after PRP(C—C). 2 The effect of PVD to the curative effect of laser photocoagulation: There were six kind of PVD changes. N—P and P—P have statistically less shrinkage of neovascularization than other groups(P<0.05). There was no statistically difference between the two groups(P>0.05). Among the other groups, there was no statistically difference between each other(P>0.05). If we classified the eyes into no, partial and complete PVD groups according to the vitreous condition after PRP, we can see that the no PVD and complete PVD groups showed statistically better shrinkage of neovascularization. Conclusions: 1 durig the treatment of laser photocoagul-ation we should pay more attention to PVD, especially the change of PVD. 2 After PRP, the eyes showed no or complete PVD have better curative effect than those showed partial PVD. 3 We should followed the eyes showed partial PVD more constantly after PRP. 4 PRP can cause complete PVD which plays important role in preventing DR from deterioration. This may one of the curative mechanism of PRP. 5 If the laser photocoagulation were performed in the... |
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