Aberrant wound-healing response in mitomycin C-treated leaking blebs: a histopathologic study

One-Year Randomized Comparison of Safety and Efficacy of Trabeculectomy with Mitomycin C Sub-Tenon Injection versus Mitomycin C-Infused Sponges

PURPOSE

To compare the safety and efficacy of sub-Tenon injection of mitomycin C (MMC) with application of MMC-infused sponges during trabeculectomy.

DESIGN

Single-center randomized clinical trial.

PARTICIPANTS

A total of 56 eyes of 49 patients with open-angle glaucoma were included in this clinical trial.

METHODS

In this single-center randomized clinical trial, 56 eyes of 49 patients underwent trabeculectomy with MMC for primary open-angle glaucoma. Patients were randomized into 2 groups. The injection group received a sub-Tenon injection of 0.15 ml of 0.01% MMC diluted with preservative free lidocaine 2% (n = 27). In the sponges group, sponges soaked in 0.02% MMC were applied under the Tenon's capsule and the scleral flap for 2 minutes (n = 29). Intraocular pressure, endothelial cell count, best-corrected visual acuity, and number of intraocular pressure (IOP)-lowering medications were assessed before surgery and 1 week; 1, 3, and 6 months; and 1 year after surgery. Complete success was defined as IOP of 14 mmHg or less without medication. Bleb morphologic features were assessed using the Indiana Bleb Appearance Grading Scale bleb grading system.

MAIN OUTCOME MEASURES

Intraocular pressure reduction was the primary outcome. Bleb morphologic features and endothelial cell counts (ECCs) were secondary outcomes.

RESULTS

Mean IOP in the sponges group decreased from 30.5 ± 7.4 mmHg at baseline to 12.6 ± 5.9 mmHg at 1 year (P < 0.001); in the injection group, IOP decreased from 29.3 ± 6.8 mmHg at baseline to 12.7 ± 4.3 mmHg at 1 year (P < 0.001). No difference in IOP between the 2 groups was noted at any visit (P < 0.001). Surgical success was 81.5% and 82.8% in the injection and sponges groups, respectively, at 1 year. Mean ECC values were unchanged from baseline to 1 year after surgery for both groups (P = 0.444). Complication rates were similar in the 2 groups. Bleb morphologic features showed differences in the appearance and grading of the blebs between the 2 groups at 1 year, showing larger extent, lower height, and less vascularization in the injection group.

CONCLUSIONS

Sub-Tenon injection of MMC during trabeculectomy seems to be as safe and as efficacious as conventional application of MMC with sponges at 1 year after surgery. Bleb morphologic features show notable differences that may suggest a better long-term outcome.

Pluripotent epigenetic regulator OBP-801 maintains filtering blebs in glaucoma filtration surgery model

Inhibition of fibrosis is indispensable for maintaining filtering blebs after glaucoma filtration surgery (GFS). The purpose of this study was to investigate the ability of a pluripotent epigenetic regulator OBP-801 (OBP) to ameliorate extracellular matrix formation in a rabbit model of GFS. Rabbits that underwent GFS were treated with OBP. The gene expression profiles and intraocular pressure (IOP) were monitored until 30 postoperative days. The bleb tissues were evaluated for tissue fibrosis at 30 postoperative days. In in vitro models, OBP interfered the functions of diverse genes during the wound-healing process. In in vivo GFS models, the expressions of TGF-β3, MMP-2, TIMP-2 and 3, LOX, COL1A and SERPINH1 were significantly inhibited at 30 postoperative days in the OBP group compared with those in the vehicle control group. OBP treatment involving subconjunctival injection or eye drops showed no adverse effects, and reduced levels of α-SMA and collagen deposition at the surgical wound site. OBP maintained the long-lived bleb without scar formation, and IOP was lower at 30 postoperative days compared with the vehicle control group. These findings suggest that OBP is an effective and useful candidate low-molecular-weight agent for improving wound healing and surgical outcomes in a rabbit model of GFS.

Prospective study on a novel treatment for leaking cystic bleb: Efficacy and safety of collagen crosslinking

IMPORTANCE

Management of cystic bleb leak is difficult. It would be essential to look for a method to strengthen the original pathological conjunctiva and reverse bleb leak.

BACKGROUND

To evaluate the long-term efficacy and safety of collagen crosslinking in patients with leaking cystic bleb.

DESIGN

Prospective interventional case series at a university-based hospital.

PARTICIPANTS

Twelve eyes in 12 subjects with late-onset bleb leak from cystic bleb, without indications for prompt surgical interventions were included.

METHODS

The subjects underwent crosslinking with 0.1% riboflavin application to bleb surface, followed by ultraviolet irradiation for 30 minutes. The subjects were followed up at baseline and at 1 week, 1 month, 3 months, 6 months post-treatment and then every 6 months afterwards.

MAIN OUTCOME MEASURES

Interval from treatment to cessation of bleb leak, recurrence rate of bleb leak and side effects of treatment.

RESULTS

The mean follow-up after crosslinking was 29.33 ± 12.45 months. Bleb leak subsided in 11 (92%) of 12 patients after a single session of crosslinking, after 1 to 8 weeks (median 3 weeks). Time to leak cessation was significantly correlated with the number of prior glaucoma interventions (R = .71, P = .014). Bleb wall at 3 months was significantly thicker than at baseline (0.70 ± 0.67 vs 0.81 ± 0.62 mm, P = .008). None of the patients experienced any complications.

CONCLUSIONS AND RELEVANCE

Crosslinking achieves resolution of cystic bleb leak which lasts for at least 12 months, without the need of subsequent surgical interventions. Crosslinking is a simple, non-invasive treatment for bleb leak. It aims to restore the integrity of conjunctiva.

Overhanging-Dissecting Blebs: Immunohistochemical Characterization

PURPOSE

The purpose of this study was to determine if glaucoma filtering blebs migrate over or under the cornea epithelium using histopathologic and immunohistochemical techniques to evaluate the likely origin of the surface epithelium and bleb matrix.

METHODS

Histologic and immunohistochemical evaluations were performed of normal conjunctiva (n=4), corneal overhanging-dissecting blebs (n=4), and leaking blebs over the scleral surface (n=6). Antibodies were used against epithelial [cytokeratin 3 (CK3)+12, CK13] and extracellular matrix [decorin and keratan sulfate (KS)] antigens. Labeling was graded in a semiquantitative manner.

RESULT

The epithelium of dissecting (over cornea) blebs was labeled primarily with CK3+12 antibody. KS staining was faint and comparable in normal conjunctiva, and the stroma of dissecting and leaking blebs (P=0.12). Decorin staining in the normal conjunctival stroma was of moderate intensity and comparable with the dissecting bleb staining and; significantly greater than that in the leaking blebs (P=0.02).

CONCLUSIONS

Histology and ICH indicate that the epithelium of the dissecting blebs has a corneal epithelial phenotype. The extracellular matrix immunophenotype was similar to the normal conjunctival stroma suggesting that dissecting blebs migrate under the corneal epithelium.

Collagen Cross-linking for Late-onset Bleb Leakage: 1-Year Results

PURPOSE

To assess the efficacy of collagen cross-linking in the treatment of late-onset bleb leakage.

METHODS

A retrospective, interventional case-series. Cross-linking was performed for late-onset bleb leakage after failure of standard medical therapy. Primary outcome is measured by complete resolution of bleb leakage. Secondary outcomes including intraocular pressure and corrected distance visual acuity (CDVA) were documented over 1 year and were analyzed using repeated measure ANOVA.

RESULTS

Seven patients underwent cross-linking for bleb leakage between 2012 and 2013. Five (71%) had complete resolution of bleb leakage. Intraocular pressure improved from 3.9±1.0 to 7.4±1.1 mm Hg at 1 to 2 months (P=0.0003) and remained at 9.6±3.0 mm Hg at final visit (P=0.06). The corresponding CDVA also improved from 0.6±0.2 to 0.38±0.37 logMAR (P=0.0069) at 1 to 2 months before stabilizing at 0.38±0.44 (P=0.0021) at 1 year. Two cases (29%) had persistent bleb leakage after treatment. Four patients (57%) had resolved hypotony (≥6 mm Hg) at final visit. No adverse event was reported.

CONCLUSIONS

Collagen cross-linking is a noninvasive treatment offering reasonable success rate for filtering bleb leakage, and may spare patients invasive surgical bleb revisions.

A Novel Method for the Delivery of Antimetabolites During Glaucoma Surgery

Current techniques for the delivery of antimetabolites, such as mitomycin C, tend to be very variable among surgeons and risk uncontrolled contact with the conjunctivae, which may result in delayed wound healing, wound dehiscence, and wound leakage postoperatively. We describe a novel technique which appear to allow a more precise and reproducible delivery of antimetabolite to the target area with minimal contact with the conjunctival edge. The technique involves the injection of an antimetabolite-soaked wick into the subconjunctival space posterior to the scleral flap using an intraocular lens injector system.

[Repair of a leaking bleb filtration with conjunctival and amniotic membrane transplantation]

CLINICAL CASE

A 71-year-old woman presented with a leaking bleb after a combined phacotrabeculectomy performed 13 years ago. To construct a new filtering bleb, the necrotic area was fully excised. The amniotic membrane was inserted over the scleral flap underneath healthy conjunctiva edges. A conjunctiva-Tenon autograft from the contralateral eye was sutured and was sealed with fibrin adhesive.

DISCUSSION

We propose a new surgical technique to repair late leak failures after trabeculectomy with mitomycin C in blebs with a large avascular area. Transplantation of amniotic membrane and conjunctival autograft may be used to repair late leak failures with inadequate conjunctiva to advance.

Inhibitory effects of trehalose on fibroblast proliferation and implications for ocular surgery

Trehalose is a disaccharide which plays an important role in preserving cells from completely dehydrated circumstances. In this study, we investigated effects of trehalose on proliferative activity of fibroblasts and epithelial cells both in vitro and in vivo. As in vitro assessment, normal human dermal fibroblasts and normal human epidermal keratinocytes were cultured in media containing various concentrations of trehalose. Growth activities of cells were evaluated with MTT assay and diff-quick™ staining. Expressions of vimentin and α smooth muscle actin (α-SMA) changed by trehalose were semiquantitatively measured by Western blot. As an in vivo study, 5% or 10% trehalose was topically instilled onto rabbit eyes after simple conjunctival incision or trabeculectomy. Condition of the surgical wound was evaluated by morphologically and immunohistochemically using isolectin B4 and antibodies specific for vimentin and α-SMA. Intraocular pressures (IOPs) after trabeculectomy were compared between eyes treated with trehalose and 0.04% mitomycin C (MMC). Results obtained by in vitro experiments showed that growth activities of cultured fibroblasts and keratinocytes were inhibited by trehalose in a dose-dependent manner. Fibroblasts were strongly inhibited by trehalose concentrations ≧ 5% of trehalose, whereas keratinocytes were less inhibited compared to fibroblasts. Expressions of vimentin and α-SMA were reduced by trehalose. With in vivo experiments, postoperative application of trehalose resulted in less firm adhesion between conjunctiva and sclera compared to controls. Immunohistochemical studies showed reduced staining of isolectin B4, vimentin and α-SMA in conjunctival wounds treated by topical trehalose. Also, after trabeculectomy, IOP remained in a low range during instillation of topical trehalose solution. We concluded that trehalose has inhibitory effects on proliferation of fibroblasts and vascular tissues, partially due to inhibition of transformation of fibroblasts into myofibroblasts in wound tissues. The present results imply that trehalose can be a potential agent for preventing postoperative fibrous scar formation after ocular surgery such as glaucoma filtration surgery.