| Vitrectomy was born in the 1970s, and rapidly carried out in the mid-1980s in China. Nowadays pars plana vitrectomy is widely used, which has become the principal means of treatment of proliferative diabetic retinopathy, complicated retinal detachment, non-absorbent vitreous opacities, intraocular foreign bodies, and so on. Vitrectomy is so complex as to that different operational procedures, intraocular tamponades and other factors will have detrimental impacts on the corneal endothelium.Corneal endothelium consists of monolayer cells by close connections, which form the cornea-aqueous barrier. The pump function of corneal endothelium makes corneal dehydration that can maintain corneal transparency. Intraocular surgery, ocular trauma and intraocular environment changes may affect the corneal endothelial cells. When endothelial cell density less than 400- 700/mm2, then cornea will lost its compensatory ability and will cause corneal edema and bullous keratopathy, lossing vision. Discompensation of corneal endothelial cells after vitrectomy has become one of the reasons for the loss of vision.Diabetes mellitus is a group of abnormal metabolism syndromes caused by the interaction of genetic and environmental factors, whose common clinical feature is long-term high blood sugar. Diabetes can generate serious complications in eyes involving cornea, lens, retina, and other parts. Corneal endothelium change caused by diabetes is likely to result in the cornea tolerance of patients with diabetic to vitrectomy surgery decreased.Previous studies used corneal thickness, corneal endothelial cell density or ultrastructural changes as the observation index. Corneal endothelium microscope is the most reliable method to observe the changes of corneal endothelial cells in vivo at present. When an endothelial cell damages, its surrounding cells will deform and increase to fill the vacancy. That result in reduction of percentage of hexagonal cells and increase of coefficient of variation of cell area. So morphology analysis is better to reflect endothelial cell injury. The size and pleomorphism of corneal endothelial cells reflect the reserve capacity of cells function, whose change may be the early signal of cell loss. Corneal endothelial cell morphology and density is the basis of maintaining cell function, but cell morphology is more sensitive than cell density in reflecting minor damage.In this study, we used non-contact specular microscope to observe pre- and postoperative four morphological quantitative index of corneal endothelial cell, including cell density (CD), average cell size (AVE), coefficient of variation of cell area (CV), hexagonal cell ratio (RHC), and supplemented with slit lamp examination. We aimed to observe the effects of different pars plana vitrectomies, intraocular tamponades and diabetes mellitus on corneal endothelium, so as to improve the quality of operation and reduce complications of the cornea.Object and Method33 Objects of study (36 eyes) were chosen from the patients performed pars plana vitrectomy in Fundus diseases Branch2 in the Second Affiliated Hospital of Jilin University from May 2007 to October 2007. All patients underwent preoperative ocular and systemic examination, to exclude other factors that may affect the corneal endothelium. Patients who had corneal disease, glaucoma history or the history of cataract surgery were not included in the scope of the study. The objects were divided into three groups by surgical method: simple vitrectomy group (8 eyes), C3F8 group (7 eyes), silicone oil group (21 eyes); each group is divided into diabetic group (DM) and non-diabetic group (NDM).We used slit lamp to observe the pre- and postoperative corneal layers, anterior chamber, aqueous, iris and lens of inpatients every day, and non-contact tonometer to observed IOP changes. Preoperative and postoperative seven days CD, CV, RHC and AVE of corneal endothelium were detected by Topcon SP-2000 non-contact specular microscope. All datas were entered into computer processed by SPSS14.0.ResultsUnder postoperative observation by slit lamp, we found different degrees of corneal edema, dust-or pigment-KP, inflammatory or bloody turbidity of aqueous, ooze and bloody material attachment in anterior chamber in few patients. The inflammation in anterior chamber disappeared after a week's drug treatment. Above changes were found in 10 diabetic eyes and 3 non-diabetic eyes. The patients with vitreous cavity temponade almost had an elevation of intraocular pressure. Most of them recovered after drug treatment, except one eye got secondary glaucoma.All the patients in each group didn't remove lens. Postoperative means compared with preoperative of three groups have shown a rising trend in AVE and CD, decreasing in RHC. And the changes in C3F8 group and silicone oil group are greater than simply vitrectomy group. It may relate to postoperative inflam- mation in anterior chamber and increased intraocular pressure caused by vitreous cavity temponade. There was no significant difference (P>0.05) between pre- and postoperative four morpho- logical quantitative indexes of corneal endothelial cell. It tells that different pars plana vitrectomies without lens removal have little effect on the corneal endothelium.DM group compared with NDM in the same surgery, the changes of four indexes show no significant difference (P> 0.05), except for RHC in C3F8 group. RHC in NDM group shows a significant decline compared to DM with C3F8 temponade. I consider that as a small number of samples, the sampling error and systematic error have a greater impact on the results. This study finds that corneal edema and inflammatory response in anterior chamber in diabetic patients is more serious than non-diabetic patients. In addition to the impact of diabetes itself, it may relate to that the diabetes patients can't treat by systemic hormone. Although the function of corneal endothelial cell in diabetic patients is lower than non-diabetic patients, its function could still be compensated in general damage. Total datum indicate that pars plana vitrectomy without lens removal is relatively safe to corneal endothelium of diabetic patients.Conclusion1. There is no significant effect of different pars plana vitrectomies without lens removal on corneal endothelium.2. It is relatively safe to corneal endothelium that diabetic patients perform pars plana vitrectomies without lens removal.Since this study has a small number of samples, the sampling error and systematic error have a greater impact on the results. In order to get a more reliable conclusion, we suggest a large sample in future studies.
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