Trabecular meshwork in neovascular glaucoma eyes after the intravitreal injection of bevacizumab

Aqueous Inflammation and Ischemia-Related Biomarkers in Neovascular Glaucoma with Stable Iris Neovascularization

Purpose: To characterize the aqueous levels of inflammation and ischemia-related biomarkers in a spectrum of retinal ischemic conditions, including neovascular glaucoma (NVG) with stable iris neovascularization after pan retinal photocoagulation (PRP) and anti-VEGF treatment. Methods: Aqueous samples were collected from 139 eyes including NVG (n = 12), stable NVG (n = 26), CRVO (n = 11), NPDR (n = 18), PACG (n = 18), PDR (n = 25), BRVO (n = 7) and cataract (n = 22). The levels of VEGF-A, IL-8 and EPO were measured with ELISA. Results: Aqueous VEGF-A significantly decreased after anti-VEGF and PRP, from 983.79 ± 821.16 pg/ml in the NVG group (n = 11) to 256.50 ± 51.14 pg/ml in the stable NVG group (n = 24) (P = .015). Aqueous VEGF-A in stable NVG group (256.50 ± 51.14 pg/ml, n = 24) was significantly higher (ANOVA, P < .001) than in CRVO (212.10 ± 19.84 pg/ml, n = 7, P = .017), NPDR (221.18 ± 38.21 pg/ml, n = 14, P = .015), BRVO (213.14 ± 48.50 pg/ml, n = 6, P = .028) and cataract group (185.30 ± 34.35 pg/ml, n = 22, P < .001). Aqueous IL-8 in stable NVG group (74.82 ± 10.78 pg/ml, n = 24) was significantly higher (ANOVA, P < .001) than in CRVO (65.19 ± 15.34 pg/ml, n = 11, P = .032) and cataract group (54.11 ± 12.28 pg/ml, n = 22, P < .001). Aqueous EPO in stable NVG group (17.48 ± 3.02 pg/ml, n = 24) was significantly higher (ANOVA, P < .001) than in BRVO (14.98 ± 2.57 pg/ml, n = 7, P = .034) and cataract group (13.50 ± 2.65 pg/ml, n = 22, P < .001). Aqueous concentrations of VEGF-A and IL-8 correlated positively with IOP (r = 0.413, P < .001, r = 0.349, P < .001, respectively, r = correlation coefficient). VEGF-A correlated positively with IL-8 and EPO (P < .001, P = .002, respectively). IL-8 correlated positively with EPO (P < .001). Conclusions: The aqueous levels of VEGF-A, IL-8 and EPO in NVG patients with stable iris neovascularization, who had received PRP and anti-VEGF, were still significantly higher than in control groups with some retinal ischemic conditions.

Prognostic Factor Analysis of Intraocular Pressure with Neovascular Glaucoma

Purpose. To perform multivariate analysis for identifying independent predictors of elevated intraocular pressure (IOP) with neovascular glaucoma (NVG), including antivascular endothelial growth factor (VEGF) intravitreal injections. Methods. We retrospectively reviewed 142 NVG patients (181 eyes) with ischemic retinal diseases [proliferative diabetic retinopathy (PDR) in 134 eyes, retinal vein occlusion (RVO) in 29, and ocular ischemic syndrome in 18]. We analyzed age, gender, initial/final LogMAR VA, initial/final IOP, extent of iris and/or angle neovascularization, treatments, preexisting complications, concurrent medications, and follow-up duration. Results. The mean follow-up duration was 23.8 ± 18.8 months. At the final follow-up, 125 (72.3%) eyes had IOP ≤ 21 mmHg. NVG patients with RVO had a higher degree of angle closure and higher IOP. NVG with PDR had better IOP and LogMAR VA. Angle closure had the greatest impact on final IOP. Greater than 90% of patients treated with trabeculectomy with mitomycin C (LEC) had persistent declines in IOP (≤21 mmHg). Stand-alone and combination anti-VEGF therapies were not associated with improved long-term prognosis of IOP. Conclusions. Angle closure was found to have the greatest effect on NVG-IOP prognosis. When target IOP values are not obtained after adequate PRP with or without anti-VEGF, early LEC may improve the prognosis of IOP.

[Effect of Intravitreal Bevacizumab Injection on Iris and Iridocorneal Angle Neovascularization in Neovascular Glaucoma]

Neovascular glaucoma is a serious complication associated with retinal ischemic changes, which increase the production of vascular endothelial growth factor. Vascular endothelial growth factor has been implicated as a key molecule in the development of newly formed vessels and neovascular glaucoma. Intravitreal injection of bevacizumab, a full-length humanized anti-vascular endothelial growth factor monoclonal antibody, leads to a dramatic regression of the new iris and iridocorneal angle vessels on slitlamp examination. However, anterior segment angiography reveals that bevacizumab does not cause a regression of the neovascular vessels themselves but reduces vascular permeability while newly formed vessels are still present in the iris and iridocorneal angle. This review focuses on the pathology and diagnosis of neovascula glaucoma and the effect of intravitreal bevacizumab on the iris and iridocorneal angle neovascularization.

Alteration of UCP2 and ZO-1 expression in trabecular meshwork of neovascular glaucoma patients

PURPOSE

The aim of this study was to investigate the expression of uncoupling protein 2 (UCP2) and zonula occludens-1 (ZO-1) in the trabecular meshwork (TM) of neovascular glaucoma (NVG) patients treated with trabeculectomy.

MATERIALS AND METHODS

Six eyes with NVG underwent trabeculectomy for therapeutic purposes. The data consisted of patient demographics, presurgical and postsurgical visual acuity, intraocular pressure, gonioscopy, and neovascularization of iris and/or the anterior chamber angle. TM samples were obtained from the NVG eyes that had undergone surgery. Immunofluorescence and confocal laser scanning microscopy were carried out to determine the expression of UCP2 and ZO-1 in the TM cells.

RESULTS

The baseline median visual acuity was light perception, and the mean intraocular pressure (standard error) was 52.5 (8.3) mm Hg. All eyes displayed neovascularization of the iris and the anterior chamber angle. The expression of UCP2 was significantly decreased in TM cells of NVG compared with the control (P=0.000), whereas increase in ZO-1 expression was detected in staining cells with NVG in comparison with the control (P=0.000). The necrotic cells in the TM were increased (P=0.000), whereas the viable cells were reduced (P=0.000) in comparison with the control.

CONCLUSIONS

The decreased UCP2 expression and increased ZO-1 expression suggest that the oxidative stress-induced mitochondrial dysfunction and tight junction formation may play pivotal roles in the progress of NVG.

[Neovascular glaucoma treatment in 2012: role of anti-VEGF agents]

Neovascular glaucoma is a serious pathology with a variety of causes. It results from the secretion by hypoxic retinal tissue of growth factors, including vascular endothelial growth factor (VEGF). Anterior segment involvement begins in the iris, followed by the development of a fibrovascular membrane in the angle, with resultant goniosynechiae. Treatment of the underlying disease consists most often of panretinal photocoagulation. As for the secondary sequelae, current treatment consists of intravitreal injection of anti-VEGF agents. The most utilized agent is bevacizumab or Avastin, off-label. Avastin is effective against neovascularization and ocular hypertension, especially in the early stages. It also represents an adjunct to filtering surgery. It appears to be very well tolerated.

Anti-VEGF Agents for Ocular Angiogenesis and Vascular Permeability

We review articles describing intravitreal injection of anti-VEGF drug trials, while discussing the mechanisms of the action of anti-VEGF antibodies, and also evaluating their outcomes. Intraocular injections of anti-VEGF drug are considered to be an effective treatment for macular edema after retinal vein occlusion, however, recurrent/persistent edema is common. The recent reports may lead to a shift in treatment paradigm for DME, from laser photocoagulation, to newer approaches using anti-VEGF drugs. There have been several well-publicized prospective, randomized studies that demonstrated the efficacy of intravitreal injection of anti-VEGF drugs for patients with AMD. Adjuvant bevacizumab for neovascular glaucoma may prevent further PAS formation, and it is likely to open up a therapeutic window for a panretinal photocoagulation and trabeculectomy. Intravitreal injection of bevacizumab (IVB) results in a substantial decrease in bleeding from the retinal vessels or new vessels during a standard vitrectomy. IVB has also been reported to be effective for inducing the regression of new vessels in proliferative diabetic retinopathy. The use of bevacizumab in stage 4 or 5 retinopahty of permaturity (ROP) is to reduce the plus sign to help reduce hemorrhage during the subsequent vitrectomy. Some authors reported cases of resolution of stage 4 A ROP after bevacizumab injection.

Effect of intravitreal bevacizumab on vascular endothelial growth factor expression in patients with proliferative diabetic retinopathy

PURPOSE

To investigate the effect of bevacizumab (Avastin; Genentech, San Francisco, CA, USA) on vascular endothelial growth factor (VEGF) expression and inflammation in fibrovascular membranes in patients with proliferative diabetic retinopathy (PDR).

MATERIALS AND METHODS

Fibrovascular membranes from 19 eyes of 18 patients with PDR were studied using immunohistochemistry and analyzed in the following 3 groups; group 1: 4 inactive PDR eyes, group 2: 10 active PDR eyes treated preoperatively with adjunctive intravitreal bevacizumab, group 3: five active PDR eyes not treated preoperatively with bevacizumab. Immunohistochemical staining for VEGF, CD31 and CD68 were done.

RESULTS

The immunoreactivity to VEGF and CD 31-positive blood vessels was significantly higher in membranes from group 3 than group 1 (p = 0.007 for VEGF, 0.013 for CD 31-positive vessels). Intravitreal bevacizumab caused a reduction in VEGF expression and vascular densities in 4 out of 10 (40%) excised membranes from eyes with PDR. However, six membranes (60%) in group 2 still demonstrated relatively strong VEGF expression and high vascular density. Infiltration of macrophages was observed in 16 out of the 19 membranes, and the density of macrophages was increased in group 2 compared with group 1 (p = 0.043).

CONCLUSION

Intravitreal bevacizumab injections caused some reduction in VEGF expression and vascular densities in a limited number of active PDR patients. A single intravitreal bevacizumab injection may not be enough to induce complete blockage of VEGF and pathologic neovascularization in active PDR patients. Repeated injections, panretinal photocoagulation and/or PPV may be necessary following intravitreal bevacizumab to reinforce the anti-VEGF effect of the drug.

Histopathology of neovascular tissue from eyes with proliferative diabetic retinopathy after intravitreal bevacizumab injection

PURPOSE

To examine the histopathologic effect of a single intravitreal injection of bevacizumab on newly formed vessels in eyes with proliferative diabetic retinopathy (PDR).

DESIGN

Interventional case series and laboratory investigation.

METHODS

Two days after intravitreal injection of bevacizumab (1.25 mg/eye), pars plana vitrectomy or trabeculectomy was performed for the treatment of PDR or neovascular glaucoma (NVG) associated with PDR. Ten surgically removed preretinal proliferative tissues and 6 deep scleral flaps containing trabecular meshwork were fixed in 2% glutaraldehyde or 4% paraformaldehyde and were subjected to transmission electron microscopic analysis, immunohistochemical analysis, and terminal deoxyuridiine triphosphate (dUTP) nick-end labeling staining. Two surgically removed preretinal proliferative tissues and 2 deep scleral flaps from patients with PDR and NVG, but without preoperative intravitreal injection of bevacizumab (IVB), served as controls.

RESULTS

In control tissues, vascular endothelial cells possessed many fenestrations and were accompanied by pericytes. Apoptotic vascular endothelial cells frequently were observed in tissue after intravitreal injection of bevacizumab, whereas they were not observed in control tissues. Additionally, no apparent fenestration was observed in newly formed vessels from either proliferative tissue or trabecular meshwork after intravitreal injection of bevacizumab. In both PDR and NVG tissues after intravitreal injection of bevacizumab, overexpression of smooth muscle actin was observed in newly formed vessels, suggesting that the treatment may have increased pericytes on the vasculature as compared with control tissue.

CONCLUSIONS

Intravitreal injection of bevacizumab may induce changes in immature, newly formed vessels of PDR or NVG tissue, leading to endothelial apoptosis with vascular regression, while inducing normalization of premature vessels by increasing pericyte coverage and reducing vessel fenestration.

Histology of fibrovascular membranes of proliferative diabetic retinopathy after intravitreal injection of bevacizumab

PURPOSE

The purpose was to study the histology of the fibrovascular membranes in proliferative diabetic retinopathy (PDR) with an intravitreal injection of bevacizumab.

METHODS

Light and electron microscopic studies were performed on surgical specimens obtained during a pars plana vitrectomy from 6 PDR eyes after intravitreal injection of bevacizumab. The patients had preoperatively received no or scant retinal photocoagulations. The presence and distribution of CD34 was assessed as a marker of vascular endothelium using immunostaining. The presence of vascular endothelial growth factor was stained with a method of immunostaining. As controls, we examined 7 surgical specimens from 7 PDR eyes obtained during pars plana vitrectomy without bevacizumab therapy. All control patients had preoperatively received full or nearly full pan retinal photocoagulations.

RESULTS

Light microscopy showed that the CD34-positive vascular endothelial cells formed capillarylike structures in the fibrovascular membranes of all 13 PDR eyes. Vascular endothelial growth factor was positively stained in the vascular endothelium of both groups; however, the number of vascular endothelial growth factor-positive vascular endothelial cells significantly decreased in the fibrovascular membranes with intravitreal injection of bevacizumab. Electron microscopy showed the newly formed vascular endothelial cells with junctional complex in both groups.

CONCLUSION

The vascular endothelial cells with decreased expression of vascular endothelial growth factor are still present in the fibrovascular membranes of patients with PDR after intravitreal injection of bevacizumab.