Macular Hole Formation after Vitrectomy: Preventable?

PURPOSE: To evaluate the causes of secondary macular hole after vitrectomy and the possibility of their prevention. METHODS: 27 patients (28 eyes) who experienced macular hole formation after vitrectomy were reviewed retrospectively. Age, sex, operation methods, duration between the vitrectomy and the secondary macular hole surgery and causes of the primary vitrectomy were recorded. Best-corrected visual acuity (BCVA) before and after primary vitrectomy; preoperative and postoperative macular findings with optical coherence tomography and fundus examination; and BCVA before and after macular hole surgery were analyzed. RESULTS: Of the 2945 eyes that had undergone vitrectomy, 28 eyes (0.96%) experienced macular hole formation. As causes of primary vitrectomy, 12 eyes had proliferative diabetic retinopathy, 6 eyes had rhegmatogenous retinal detachment, 2 eyes had branch retinal vein occlusion, 3 eyes had age-related macular degeneration and 5 eyes had trauma such as eyeball rupture or intraocular foreign body. The mean duration between primary vitrectomy and macular hole formation was 20.4 months (4 days-115 months). The estimated causes of macular hole formation included cystoid macular edema (CME) (n = 13), thinning of the macula (n = 6), thickening of internal limiting membrane or recurrence of preretinal membrane (PRM) (n = 7), recurrence of subretinal hemorrhage (n = 1) and macular damage during vitrectomy (n = 2). Final BCVA after macular hole surgery decreased in most cases compared to BCVA before macular hole formation except in 7 eyes (25%). CONCLUSIONS: Close observation of the macula after primary vitrectomy especially in eyes with continuous CME, and recurrent PRM and proper management on them including timely removal of the tangential traction force are necessary for preventing macular hole formation. In addition, surgeons should make efforts not to exert excessive tractional force on the macula to avoid iatrogenic damage during removal of the preretinal membrane.

Application of avastin in vitrectomy for proliferative diabetic retinopathy and its mechanism / 中华实验眼科杂志

Background Researches demonstrated that avastin-assisted vitrectomy for serious proliferative diabetic retinopathy can decrease intra-operation complication and bring down difficulty of surgery.It is speculated that this is associated with suppression of avastin on neovascularization.However,the evidence of its pathology is lack.Objective The aim of this study was to evaluate the application and mechanism of avastin in vitrectomy for severe proliferative diabetic retinopathy. Methods Twenty-four eyes from consecutive 24 patients with vitrectomy for severe proliferative diabetic retinopathy were enrolled in this study.Fourteen eyes received all intravitreal injection of 0.06 ml avastin(1.5 mg)14 days prior to vitrectomy。And the other 10 eyes underwent only vitrectomy without avastin injection as controls,Preretinal membranes were collected during vitrectomy for histopathologic examination by hemotoxylin and eosin staining.The differences in the density of the neovessels and micro-neovessels between the two groups were observed by detecting the expression of CD34 in vesse]endothelial cells using immunohistochemistry.Written informed consent was obtained from each patient before surgery. Results No statistically significant differences were found in the demography and eye manifestations between only vitreetomy group and avastin+vitrectomy group(P＞0.05).The neovessels with grade three was in 10 eyes in only vitrectomy group and 1 eye in avastin+vitrectomy group(P＜0.01).More capillary-like neovascularization with single vascular endothelial cells,obvious hemorrhage and inflammatory cells infiltration were observed on preretinal membranes in vitrectomy group.However,there were less hemorrhage,ceUular components and few capillary-like neovascularization but more hyaline degeneration of fibrous tissue were observed in avastin+vitrectomy group under the light microscope.Immunochemistry revealed that CD34 was positively expressed in vascular endothelial cells on preretinal membrane in both two groups.The neovessels density and miero-neovessels density were 15.40±7.42/field and 1.88±1.70/field in avastin+vitrectomy group and those in vitreetomy group were 18.00±3.80/field and 0.45±0.56/field respectively,showing significant differences between these two groups(neovessels density:Z=-4.102,P＜0.01;micro-neovessels density:Z=-4.137,P＜0.01).Conclusion As an adjunct drug during the vitrectomy for proliferative diabetic retinopathy, avastin can improve the successful rate of surgery by inhibiting the neovascular formation and alleviating retinal edema.

Ultrastructure of Rapidly Proliferating Preretinal Membrane of Very Extensive Ischemic Diabetic Retinopathy

PURPOSE: Using transmission electron microscopy (TEM), we studied the ultrastructures of rapidly proliferating preretinal membranes of young patients with very extensive ischemic proliferative diabetic retinopathy and diabetes with uncontrollable blood sugar level. METHODS: Nine cases of preretinal membranes were obtained from six eyes of five patients with rapidly progressed proliferative diabetic retinopathy (mean age, 35 years) during vitrectomy. We obtained each preretinal membrane bimanually as one single sheet membrane using intraocular scissors and forceps. Each tissue was fixed in 3% glutaraldehyde in the operating room. All specimens were prepared and studied using TEM. RESULTS: The preretinal membranes were composed of blood vessels and some interstitial cells. The blood vessels within the preretinal membranes varied in developmental stages, from the immature stage to the mature stage. The blood vessels were highly active, in that primitive cells showed a large nucleus and prominent chromatin clumping with abundant cytoplasm. Highly active fibroblast-like cells were also noted. CONCLUSIONS: We observed highly active angiogenesis in preretinal membranes, which rapidly proliferated in cases of severe retinal ischemia in young diabetes patients. This is the first report of such a finding, which may help to explain the poor prognosis of this disease modality.

Immunohistochemical Stain and Electron Microscopic Study on the Pericytes of Fibrovascular Diabetic Preretinal Membrane

Seven fibrovascular diabetic preretinal membranes were examined with lightmicroscophic immunohistochemical stain and electron-microscopy to evaluate the possibility of pericytes to be involved in membrane contraction. Pericytes were positively stained with anti-actin antibody together with some stromal cells thought to be myofibroblasts presumedly. On transmission electron microscopic study, pericytes were highly active with numerous cytoplasmic processes and contained abundant microfilaments considered as actin in their cytoplasm. Pericyte/endothelial cell ratio of vascular channels were increased in some actively proliferative portion of the membranes. Myofibroblasts that contain abundant cytoplasmic microfilaments were also demonstrated in the extravascular stroma of the membranes and were very similar to the pericytes morphologically. Although the evidence that the pericytes are related to the origin of the myofibroblasts could not be demonstrated, this study suggested that the pericytes may play important roles in development and contraction mechanism of fibrovascular diabetic preretinal membranes.

Surgical Prognostic Factors in Proliferative Diabetic Retinopathy(PDR)

The results of diabetic vitrectomy on eyes with severe proliferative fibrovascular membranes are often disappointing, because of difficulties in removing the membranes. But we sometimes observe the regression of the proliferative fibrovascular membranes when the antero-posterior tractional force become released. Hence we compared the surgical prognosis of proliferative diabetic retmopathy according to the severity of proliferation and whether removal of antero-posterior vitreoretinal traction was complete or not. The results showed that the anatomic success rate and final visual acuities(VA) were significantly better in less-severe proliferation group(LSPG) than in severe prolif era tion group(SPG). In SPG, the anatomic success rate and VA tended to be better when we were able to remove the antero-posterior vitreoretinal adhesion completely whether the removal of preretinal membranes was complete or not. When complete removal of the diabetic fibrovascular membrane is difficult due to severe proliferation and broad adhesion, complete removal of anter-posterior traction only could be an alternative in diabetic vitrectomy.

Ultrastructural change of the Muller cell in the culture of sensory retina

This study was performed to investigate the sequential changes of the retinal tissue in tissue culture condition. The human sensory retinal tissues were cultured for up to 2 weeks and 4 weeks, respectively. The initial changes showed the separation of the intercellular space and the consequent widening of the intercellular space with prolapse of cytoplasmic processes into the widened intercellular space. The internal limiting membrane was also separated from the inner retina, which led to the prolapse of the cytoplasm of the Muller cell. The growth of the Muller cell was most prominent during the 4-weeks' tissue culture period. These findings suggest that the Muller cell might contribute to the formation of cellular membrane in case of the defect of the internal limiting membrane in several pathologic conditions.

Vitrectomy for severe proliferative diabetic retinopathy

To analyse the results of diabetic vitrectomy according to the severity of proliferation [severe (SPG) vs. less-severe proliferation group (LSPG)], and methods of the operation, which was complete removal of anteroposterior vitreous traction with or without complete removal of preretinal memebrane, we compared both groups by using anatomic success rate and postoperative visual acuities (VA). The results were as follows: The anatomic success rate and postoperative VA were significantly better in LSPG than in SPG. In SPG, anatomic success rate and postoperative VA tended to be better when complete removal of anteroposterior traction was possible than when impossible. In SPG, postoperative VA tended to be better when complete removal of preretinal membrane was possible, but the anatomic success rate was the same for each group. So, when severe proliferation (including table-top elevation of posterior retina), complete removal of anteroposterior traction only can improve the anatomic success rate of the surgery.

Ultrastructural Studies of Retina and Proliferative Membranes in Coats' Disease Complicated by Proliferative Vitreoretinopathy

Proliferative vitreoretinopathy is the most common complication of retinal reattachment surgery. The condition is characteristerized by the proliferation of cells on both surface of retina resulting in membrane formation and traction on retina. The authors studied the ultrastructural features of preretinal, subretinal membrane and peripheral retinal tissue which were removed during vitreous surgery in eye with Coats' disease complicated by proliferative vitreoretinopathy (Grade D-l). In preretinal membrane, fibrocytes, fibroblasts, myofibroblasts, macrophages and collagen fibrils were observed in central retinal area and fibrocyte, collagen fibril and retinal pigment epithelium in periphe ral retinal area. In subretinal membreane, retinal pigment epithelial cells, macrophage-like cells, fibrin, collagen fibrils and amorphorous materials were observed.