Wound Healing Modulation in Glaucoma Filtration Surgery- Conventional Practices and New Perspectives: Antivascular Endothelial Growth Factor and Novel Agents (Part II)

Efficacy and safety of intraoperative injection of mitomycin C during trabeculectomy: a systematic review and meta-analysis

PURPOSE

Trabeculectomy, a primary surgical treatment for glaucoma, often employs mitomycin C (MMC) to reduce scar formation and improve surgical outcomes. However, the optimal application method of MMC, whether by injection or sponge, remains a subject of debate. This meta-analysis aims to compare injectable and sponge-based MMC application in terms of efficacy and safety, focusing on various clinical outcomes in glaucoma patients.

METHODS

A comprehensive literature search of Scopus, MEDLINE, EMBASE, Ovid, Chinese biomedical literature database, China National Knowledge Infrastructure, and Cochrane Library was done for eligible studies that report data of glaucoma patients who were administered MMC by injection or sponge application during trabeculectomy. Outcomes of interest included intraocular pressure (IOP) reduction, bleb appearance grading (height, extent, vascularity), use of anti-glaucoma medications, and rates of complete success, qualified success, and failure. Data were reported as weighted mean differences (WMD) or odds ratios (OR) with confidence intervals (CI). The random-effects inverse-variance model with DerSimonian-Laird estimate of tau2 was employed, with continuity correction applied where necessary.

RESULTS

A total of 15 studies with 1276 participants were included. The meta-analysis revealed no significant difference in IOP reduction between patients treated by MMC injection and sponge application (WMD = - 0.434). Significant differences were observed in bleb appearance grading scores for height (WMD = - 0.170) and extent (WMD = 0.174), with substantial heterogeneity. The use of anti-glaucoma medications was significantly lower in the injection group (WMD = - 0.274). However, there were no significant differences in the rates of complete success, qualified success, and failure. The study demonstrated moderate to high heterogeneity across various outcomes.

CONCLUSION

This meta-analysis indicated that while both injection and sponge methods of MMC application during trabeculectomy were equally effective for IOP reduction, they differ in their impact on bleb morphology and postoperative medication requirement. The findings highlight the need for individualized treatment approaches in glaucoma surgery, taking into account the specific needs and characteristics of each patient.

Meldonium Inhibits Cell Motility and Wound-Healing in Trabecular Meshwork Cells and Scleral Fibroblasts: Possible Applications in Glaucoma

Meldonium (MID) is a synthetic drug designed to decrease the availability of L-carnitine-a main player in mitochondrial energy generation-thus modulating the cell pathways of energy metabolism. Its clinical effects are mostly evident in blood vessels during ischemic events, when the hyperproduction of endogenous carnitine enhances cell metabolic activities, leading to increased oxidative stress and apoptosis. MID has shown vaso-protective effects in model systems of endothelial dysfunction induced by high glucose or by hypertension. By stimulating the endothelial nitric oxide synthetase (eNOS) via PI3 and Akt kinase, it has shown beneficial effects on the microcirculation and blood perfusion. Elevated intraocular pressure (IOP) and endothelial dysfunction are major risk factors for glaucoma development and progression, and IOP remains the main target for its pharmacological treatment. IOP is maintained through the filtration efficiency of the trabecular meshwork (TM), a porous tissue derived from the neuroectoderm. Therefore, given the effects of MID on blood vessels and endothelial cells, we investigated the effects of the topical instillation of MID eye drops on the IOP of normotensive rats and on the cell metabolism and motility of human TM cells in vitro. Results show a significant dose-dependent decrease in the IOP upon topic treatment and a decrease in TM cell motility in the wound-healing assay, correlating with an enhanced expression of vinculin localized in focal adhesion plaques. Motility inhibition was also evident on scleral fibroblasts in vitro. These results may encourage a further exploration of MID eye drops in glaucoma treatment.

ZD6474 attenuates TGF-β1-induced fibrosis in human Tenon fibroblasts and inhibits neovascularization via AKT-mTOR signaling pathway

PURPOSE

To investigate the anti-fibrotic effect of ZD6474 (a novel inhibitor of VEGF and EGF) in TGF-β1 stimulated human Tenon's capsule fibroblasts (HTFs) and the anti-angiogenetic role in HUVECs, compared to that of mitomycin C (MMC).

METHODS

The effects of ZD6474 on cell proliferation or migration in TGF-β1-stimulated HTFs and HUVECs were determined, using CCK8 or wound healing assay, respectively. The typical markers of fibrosis in TGF-β1-stimuated HTFs were detected, vimentin by immunofluorescence, α-SMA and snail by western blot. Tube formation was applied to validate the anti-angiogenesis effect in HUVECs following ZD6474 treatment. Furthermore, phosphorylated AKT and mTOR (p-AKT and p-mTOR) were evaluated, compared to the standardized total AKT and mTOR, using western blot.

RESULTS

There was almost no decreased cell viability in HTFs following ZD6474 (≤ 1 μM/mL) treatment, but MMC (> 50 μg/mL) significantly impaired cell viability. ZD6474 significantly inhibited TGF-β1-stimulated proliferation and migration in HTFs, compared to control group (**P < 0.01). ZD6474 also significantly attenuated the TGF-β1-stimulated expression of vimentin, α-SMA and snail in HTFs. Tube formation was notably interrupted in HUVECs following ZD6474 treatment (**P < 0.01). P-AKT and p-mTOR were significantly decreased in response to ZD6474 treatment in TGF-β1- induced HTFs and HUVECs.

CONCLUSIONS

ZD6474 exerts anti-proliferation and anti-fibrotic effects in TGF-β1-stimulated HTFs perhaps via regulating AKT-mTOR signaling pathway. ZD6474 also inhibited proliferation, migration and tube formation in HUVECs via the same signaling pathway. We concluded that ZD6474 may be potentially a novel agent in preventing bleb dysfunction following glaucoma filtration surgery (GFS).

Fellow-Eye Comparison between Phaco-Microhook Ab-Interno Trabeculotomy and Phaco-iStent Trabecular Micro-Bypass Stent

The aim of this study is to compare the surgical efficacy and safety between microhook ab-interno trabeculotomy (µLOT) and iStent trabecular micro-bypass stent implantation when both were combined with cataract surgery in both eyes of patients. Sixty-four glaucomatous eyes (32 participants; mean age, 75.9 ± 7.6 years; 15 men, 17 women) were included retrospectively. Intraocular pressure (IOP), number of antiglaucoma medications, best-corrected visual acuity (BCVA), anterior chamber flare (ACF) and corneal endothelial cell density (CECD) were evaluated preoperatively, as well as 2, 3, 6, and 12 months postoperatively. Surgical complications and interventions were compared between the procedures. The preoperative IOP and medications with µLOT (18.8 ± 5.7 mmHg and 3.0 ± 1.2, respectively) were higher than with the iStent (15.5 ± 3.4 mmHg and 2.7 ± 1.2, respectively) (p = 0.0001 and p = 0.0437, respectively). At 12 months, the µLOT values (12.6 ± 2.3 mmHg and 2.3 ± 0.9, respectively) were identical to iStent (12.8 ± 2.5 mmHg and 2.3 ± 0.9, respectively) (p = 0.0934 and p = 0.3251, respectively). At 12 months, the IOP decreased more with µLOT (6.2 mmHg, 29.5%) than iStent (2.7 mmHg, 15.6%) (p = 0.0003). The decrease in medications was greater with µLOT (0.7) than iStent (0.4) (p = 0.0437). Survival rate of IOP control ≤15 mmHg and IOP reduction ≥20% was significantly higher after µLOT (40.6% at 12 months) than iStent (18.8%) (p = 0.0277). The frequency of layered hyphema was significantly greater with µLOT (8 eyes, 25%) than iStent (0 eyes, 0%) (p = 0.0048). The increase in the ACF at 2 weeks postoperatively was significantly greater with µLOT than iStent (p = 0.0156), while changes in the BCVA and CECD were identical between groups. The fellow-eye comparison showed that the IOP reduction was greater with µLOT than iStent when combined with cataract surgery.

Experimental models of glaucoma filtration surgery

Glaucoma filtration surgery plays an important role in achieving intraocular pressure (IOP) reduction in patients who have high IOP despite maximum medical therapy. Preclinical experimental models of glaucoma filtration surgery contribute a great deal to our knowledge of the wound healing processes that predispose to scarring and may lead to poor outcomes. However, this research needs to be interpreted in the light of the specific study design, animal model and methods used. We review the existing literature addressing various models of experimental glaucoma filtration surgery, discuss the considerations in assessing these models and describe future steps in evaluating potential therapeutics and bleb characteristics that could impact translational research in this field.

Nox4 Facilitates TGFβ1-Induced Fibrotic Response in Human Tenon's Fibroblasts and Promotes Wound Collagen Accumulation in Murine Model of Glaucoma Filtration Surgery

Collagen accumulation in sub-conjunctival tissue at the surgical wound is one of the major complications associated with glaucoma filtration surgery (GFS). This process often leads to unwanted fibrotic scar formation at the lesion site and dysfunction of tissues. Previously, we demonstrated that NADPH oxidase 4 (Nox4) is implicated in transforming growth factor-beta (TGFβ)-induced collagen production in ocular fibroblasts and scarring responses in a mouse model of corneal injury. Here, we propose that Nox4 is an important facilitator of TGFβ-induced responses. We tested this hypothesis in human Tenon’s fibroblasts (HTF) and also assessed a role of Nox4 in an experimental mouse model of GFS. TGFβ1 induced Nox4 mRNA expression but downregulated Nox5 in HTF. Targeting Nox4 gene expression with an adenovirus carrying a Nox4 small interfering RNA (siRNA) (Ad-Nox4i) or removal of hydrogen peroxide (H₂O₂) with EUK-134 (25 μM) in HTFs significantly reduced TGFβ1-induced Nox4 expression, H₂O₂ production, and collagen synthesis (p < 0.05, n = 3–6). SIS3 (5 μM) that prevents Smad3 phosphorylation is found to suppress TGFβ1-induced collagen production in HTFs. Furthermore, Ad-Nox4i and EUK-134 both abolished TGFβ1-stimulated proliferation of HTFs. We also compared collagen deposition at the wound arising from GFS between wildtype (WT) and Nox4 knockout (KO) mice. Both collagen deposition and fibrovascularization at the wound were significantly decreased in Nox4 KO mice at 14 days after GFS. Our results provide comprehensive evidence that Nox4 is an important mediator for TGFβ1-induced responses in HTFs and collagen deposition in surgical wound following GFS in mice. As such, pharmacological inhibition of Nox4 would be a viable therapeutic strategy for the control of scarring after glaucoma surgery.

Scleral concave pool trabeculectomy combined phacoemulsification in primary open-angle glaucoma with cataract

Background

To investigate the safety and efficacy of scleral concave pool trabeculectomy (SCPT) combined phacoemulsification for eyes with coexisting cataract and primary open-angle glaucoma (POAG).

Methods

This was a retrospective, controlled, interventional pilot case series. Thirty patients (30 eyes) were diagnosed with coexisting cataract and POAG between May 2015 and April 2018. Fourteen eyes underwent SCPT combined phacoemulsification were set as the study group, and 16 eyes received conventional phacotrabeculectomy were set as the control group. All patients were followed up for at least 6 months. The preoperative to postoperative changes in IOP, glaucoma medication requirements, BCVA, blebs functions, and adverse events were recorded.

Results

The groups were matched for baseline age, BCVA, IOP and types of IOP-lowering medications (all P > 0.05). At 6-month visit, there were no significant difference between control and study group in the improvement of BCVA (0.22 ± 0.24 versus 0.18 ± 0.26, P = 0.718), reduction of IOP (− 11.21 ± 8.61 mmHg versus − 9.19 ± 9.18 mmHg, P = 0.540) and the number of eyes that needed IOP-lowering medications (2 versus 3, P = 0.743). At the last visit, the rate of forming functioning blebs was significantly different between the study and control groups, (92.9% versus 68.7% respectively, P = 0.007). In the study group, 5 eyes developed hypotony, and 1 eye showed limited choroidal detachment, whereas in the control group 1 eye developed malignant glaucoma. All adverse events were successfully managed.

Conclusion

The SCPT combined phacoemulsification seems to be a safe and effective alternative to conventional phacotrabeculectomy for patients with POAG and visually significant cataract in the short-term.

Postoperative adjunctive bevacizumab versus placebo in primary trabeculectomy surgery for glaucoma

AIM

To compare the effectiveness of postoperative adjunctive use of subconjunctival bevacizumab in altering the outcome of primary trabeculectomy in terms of sustained lowering of intraocular pressure (IOP) and reduction of postoperative bleb vascularization and fibrosis.

METHODS

A prospective, one center, randomized, placebo-control study. Fifty-nine patients (59 eyes) with uncontrolled IOP under maximal tolerated medical treatment (MTMT) were recruited. A primary trabeculectomy with mitomycin C (MMC) was done and the patients were randomized to either postoperative subconjunctival injection of bevacizumab (1.25 mg/0.05 mL) or balanced salt solution (BSS). Forty-seven patients (47 eyes) completed at least one year of follow up and were included in the study. The main outcome measure was the IOP, and secondary outcome measures include bleb morphology, vascularization, and fibrosis, as well as the need for glaucoma medications and 5-fluorouracil (5-FU) needling.

RESULTS

At 1-year follow up, there was no significant difference between groups for IOP (P=0.65), bleb morphology (P=0.65), and the need for glaucoma medications (P=0.65) or 5-FU needling requirements (P=0.11). However, the bevacizumab group had a higher rate of success results, lower use of glaucoma medications after surgery, and optimal bleb aspect in more patients, but more 5-FU needling procedures required.

CONCLUSION

A bigger sample size is needed in order to determine whether the differences found in the bevacizumab group are statistically significant.

Nintedanib inhibits TGF-β-induced myofibroblast transdifferentiation in human Tenon's fibroblasts

Purpose

This study aimed to investigate the effect of nintedanib on the conversion of human Tenon's fibroblasts (HTFs) into myofibroblasts and reveal the molecular mechanisms involved.

Methods

Primary cultured HTFs were incubated with transforming growth factor β1 (TGF-β1) alone or combined with nintedanib, and cell proliferation and migration were measured by cell counting kit-8 (CCK8) and the scratch wound assay, respectively. HTF contractility was evaluated with a 3D collagen contraction assay. The mRNA and protein levels of α smooth muscle actin (α-SMA) and Snail and the phosphorylation levels of Smad2/3, p38 mitogen-activated protein kinase (p38MAPK), and extracellular signal-regulated kinase ½ (ERK1/2) were determined by quantitative reverse transcription polymerase chain reaction (RT-PCR), western blot, and immunofluorescence staining.

Results

Nintedanib inhibited the proliferation and migration of HTFs in a dose-dependent manner. Furthermore, nintedanib prevented HTF myofibroblast differentiation via downregulation of mRNA and protein expression of α-SMA and Snail. A three-dimensional (3D) collagen gel contraction assay demonstrated that nintedanib effectively inhibits myofibroblast contraction induced by TGF-β1. Mechanistically, we revealed that nintedanib reduces the TGF-β1-induced phosphorylation of Smad2/3, p38MAPK, and ERK1/2, suggesting that nintedanib acts through both classic and nonclassic signaling pathways of TGF-β1 to prevent HTF activation.

Conclusions

Our study provides new evidence that nintedanib has potent antifibrotic effects in HTFs and suggests that it may be used as a potential therapeutic agent for subconjunctival fibrosis.

Prospective pilot study comparing deep sclerectomy outcomes with a long-term and intense corticosteroid treatment versus a standard one

Objective

To compare prospectively intraocular pressure (IOP) results after deep sclerectomy (DS) using a topical short-term corticosteroid treatment (STCT, 1  month) versus a topical long-term and intense corticosteroid treatment (LTCT, 6 months) in a two2  year-follow-up.

Methods

Patients with medically uncontrolled open angle glaucoma were prospectively recruited and underwent a DS.

Results

We operated 45 eyes of 45 patients, 22 in STCT group and 23 in LTCT group. Median preoperative IOP was 27 (22-36.75)  mm Hg for STCT and for 25 (22-28) mm Hg for LTCT group without significant difference (p=0.195). Median postoperative IOP was 4 (3-6.25) mm Hg in STCT group versus 2 (0-5)  mm Hg in LTCT at day 1 (p=0.003); 8.5 (5.75-11.25)  mm Hg (STCT) vs 6 (4-9) mm Hg (LTCT) at week 1 (p=0.079); 17.5 (14.75-22.25)  mm Hg (STCT) vs 13 (10-14) mm Hg (LTCT) at month 1 (p=0.001); 16 (12-20) mm Hg (STCT) vs 12 (10-15) mm Hg (LTCT) at month 3 (p=0.008); 17 (14-20) mm Hg (STCT) vs 12 (10-14) mm Hg (LTCT) at month 6 (p=0.000); 16 (14-20) mm Hg (STCT) vs 14 (10-16) mm Hg (LTCT) at year 1 (p=0.002) and 17.5 (15-19)  mm Hg (STCT) vs 14 (12-16) mm Hg (LTCT) at year 2 (p=0.001). The complete success rate was 54.5 % in STCT and 87 % in LTCT (p=0.018).

Conclusions

A long-term and intensive postoperative treatment enhances success rate in DS compared with a standard protocol.

MEK inhibition prevents TGF‑β1‑induced myofibroblast transdifferentiation in human tenon fibroblasts

Subconjunctival fibrosis represents the primary cause of postoperative failure of trabeculectomy, and at present there is a lack of effective intervention strategies. The present study aimed to investigate the effect of the mitogen‑activated protein kinase kinase (MEK) inhibitor U0126 on human tenon fibroblast (HTF) myofibrosis transdifferentiation, and to illuminate the underlying molecular mechanisms involved. It was demonstrated that U0126 significantly inhibited the proliferation, migration and collagen contraction of HTFs stimulated with TGF‑β1. In addition, U0126 largely attenuated the TGF‑β1‑induced conversion of HTFs into myofibroblasts, as indicated by a downregulation of the mRNA and protein expression of α‑smooth muscle actin and zinc finger protein SNAI1, and by ameliorating the 3D‑collagen contraction response. Mechanistically, U0126 suppressed the TGF‑β1‑stimulated phosphorylation of mothers against decapentaplegic homolog 2/3, P38 mitogen‑activated protein kinase and extracellular signal‑regulated kinase 1/2, indicating that U0126 may inhibit HTF activation through the canonical and non‑canonical signaling pathways of TGF‑β1. Therefore, U0126 exhibits a potent anti‑fibrotic effect among HTFs, and the inhibition of MEK signaling may serve as an alternative intervention strategy for the treatment of trabeculectomy‑associated fibrosis.

Protective effects of biodegradable collagen implants on thinned sclera after strabismus surgery: a paired-eye study

PURPOSE

To determine the efficacy of a biodegradable Ologen (Aeon Astron Europe BV, Leiden, The Netherlands) collagen matrix in reducing the blue color change due to exposed thinned sclera after strabismus surgery.

METHODS

Fourteen patients with intermittent exotropia undergoing symmetric bilateral lateral rectus recession surgery were included in this prospective, randomized, paired-eye controlled study. In each patient, Ologen was implanted at the original rectus insertion site in one randomly selected eye; the other eye underwent conventional surgery. Ologen was inserted under the conjunctiva without suturing, covering the muscle insertion site. Conjunctival color change was analyzed using computer-based image analysis immediately and 1 week, 1 month, and 3 months postoperatively. Slit-lamp photographs of each eye were evaluated using contrast limited adaptive histogram equalization (CLAHE), Canny edge, and the RGB (red-green-blue) model. Secondary outcomes were conjunctival and sclera thickness 3 months postoperatively determined by anterior segment optical coherence tomography.

RESULTS

Immediately and 1 week postoperatively all color models showed no significant differences between Ologen-implanted and control eyes. Three months postoperatively, Ologen-implanted eyes exhibited significantly lower CLAHE (P = 0.041) and RGB model blue color (P = 0.008) values than control eyes. Canny edge (P = 0.061) and RGB model red color (P = 0.152) values did not differ between eyes. Conjunctival stroma and episcleral complex thickness was greater in Ologen-implanted eyes than in controls (P = 0.001).

CONCLUSIONS

Blue color change was significantly less noticeable in Ologen-implanted eyes than in controls. Thus, Ologen implantation helps prevent visible blue sclera at the original rectus insertion site after lateral rectus recession.

Sustained subconjunctival delivery of cyclosporine A using thermogelling polymers for glaucoma filtration surgery

We successfully developed a subconjunctival delivery system of CsA using an injectable thermogel to inhibit post-surgical scar formation after glaucoma filtration surgery.