Efficacy of selective laser trabeculoplasty following incisional glaucoma surgery

Mechanism of selective laser trabeculoplasty: a systemic review

Although selective laser trabeculoplasty (SLT) is a recognized method for the treatment of glaucoma, the exact changes in the target tissue and mechanism for its intraocular pressure lowing effect are still unclear. The purpose of this review is to summarize the potential mechanisms of SLT on trabecular meshwork both in vivo and in vitro, so as to reveal the potential mechanism of SLT. SLT may induce immune or inflammatory response in trabecular meshwork (TM) induced by possible oxidative damage etc, and remodel extracellular matrix. It may also induce monocytes to aggregate in TM tissue, increase Schlemm's canal (SC) cell conductivity, disintegrate cell junction and promote permeability through autocrine and paracrine forms. This provides a theoretical basis for SLT treatment in glaucoma.

Effects of Ripasudil, a Rho-Kinase Inhibitor, on Scar Formation in a Mouse Model of Filtration Surgery

PURPOSE

Glaucoma is a leading cause of blindness worldwide. Characteristic changes occur in the optic nerve and visual field of patients with glaucoma; optic nerve damage can be mitigated by lowering intraocular pressure. Treatment modalities include drugs and lasers; filtration surgery is necessary for patients with insufficient intraocular pressure reduction. Scar formation often contributes to glaucoma filtration surgery failure by increasing fibroblast proliferation and activation. Here, we examined the effects of ripasudil, a Rho-associated protein kinase (ROCK) inhibitor, on postoperative scar formation in human Tenon's fibroblasts.

METHODS

Collagen gel contraction assays were used to compare contractility activity among ripasudil and other anti-glaucoma drugs. The effect of Ripasudil in combination with other anti-glaucoma drugs and transforming growth factor-β (TGF-β), latanoprost and timolol-induce contractions were also tested in this study. Immunofluorescence and Western blotting were used to study the expression of factors relating scarring formation.

RESULTS

Ripasudil inhibited contraction in collagen gel assay and reduced α-smooth muscle actin (SMA) and vimentin (scar formation-related factors) expression, which was inversely promoted by latanoprost, timolol or TGF-β. Ripasudil also inhibited contraction on TGF-β, latanoprost and timolol-induced contraction. Furthermore, we investigated the effects of ripasudil on postoperative scarring in a mouse model; ripasudil suppressed postoperative scar formation by altering the expression of α-SMA and vimentin.

CONCLUSIONS

These results suggest that ripasudil, ROCK inhibitor may inhibit excessive fibrosis after glaucoma filtering surgery vis inhibition the transdifferentiation of tenon fibroblast into myofibroblast and may have a potential effect as anti-scarring for glaucoma filtration surgery.

Selective laser trabeculoplasty as adjunctive treatment for open-angle glaucoma vs following incisional glaucoma surgery in Chinese eyes

BACKGROUND

Selective laser trabeculoplasty (SLT) is a relatively safe and effective therapy in lowering intraocular pressures (IOP) for glaucoma.

AIM

To study the long-term effects of SLT on IOP and number of glaucoma medications used in Chinese eyes.

METHODS

This is a retrospective study in which 75 eyes of 70 patients with open-angle glaucoma (OAG, n =36) and eyes with prior glaucoma surgery (PGS, n =39) were included. Changes in mean IOP and number of glaucoma medications used evaluated at 1 d, 1 wk, 1 mo, 3 mo, 6 mo, 12 mo, and 36 mo after laser treatment.

RESULTS

All patients (33 male, 37 female) were Chinese. The mean age was 44.34 ± 16.14 years. Mean pre-SLT IOP was 22.75 ± 2.08 mmHg in OAG and 22.52 ± 2.62 mmHg in PGS. Mean IOP was significantly reduced 1 d, 1 wk, 1 mo and 3 mo after laser treatment (P < 0.05, respectively). Whereas, there were no significant differences between baseline and SLT treated groups at the 6^th month both in OAG (P = 0.347, P > 0.05) and in PGS (P = 0.309, P > 0.05). Six months after SLT treatment, some patients received retreatment of SLT or were given more topical IOP-lowering medication to control the IOP. By the end of our study, the average IOP decreased to 20.73 ± 1.82 mmHg in OAG and 20.49 ± 1.53 mmHg in PGS groups. The number of glaucoma medications used was significantly reduced until the end of 3 years compared to baseline.

CONCLUSION

SLT could reduce IOP as adjunctive treatment both in OAG and PGS groups. SLT significantly reduced the number of glaucoma medications used 3-years following treatment in glaucoma patients.

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).

Selective Laser Trabeculoplasty in the Treatment of Ocular Hypertension and Open-Angle Glaucoma: Clinical Review

Selective laser trabeculoplasty (SLT) is a glaucoma treatment that reduces intraocular pressure (IOP). Its mechanism is based on the biological effects of the selective application of laser energy to pigmented trabecular meshwork (TM) cells, resulting in increased outflow facility. Herein, we review current publications on SLT and summarize its efficacy and safety for different indications in open-angle glaucoma (OAG) and ocular hypertension (OHT) treatment. SLT effectively reduces IOP when used as a primary treatment. In patients whose IOP is medically controlled, SLT helps to reduce medication use, and when maximally tolerated topical therapy is ineffective, SLT facilitates the realization of the target IOP. SLT is a repeatable procedure for which the vast majority of complications are mild and self-limiting. With effective IOP reduction, low complication rates and the potential to repeat the procedure, SLT offers the possibility of delaying the introduction of medical therapy and other more invasive treatment modalities while simultaneously avoiding the accompanying complications. With this knowledge, we suggest that SLT be considered as an essential primary treatment option in OAG and OHT, switching to other treatment modalities only when laser procedures are insufficient for achieving the required target IOP.

Outcome of phacoemulsification in patients with open-angle glaucoma after selective laser trabeculoplasty

Purpose

To investigate the outcome of phacoemulsification in selective laser trabeculoplasty (SLT)-treated eyes.

Methods

This retrospective study included patients who had open angle glaucoma (OAG) with previous SLT who underwent phacoemulsification. We evaluated intraocular pressure (IOP), length of glaucoma control without treatment, and antiglaucoma medication or surgery. SLT-treated eyes that did not receive phacoemulsification were retrospectively chosen as a control. We investigated factors related to outcome of phacoemulsification by multivariate analysis.

Results

42 eyes with previous SLT that underwent phacoemulsification and 40 controls were retrospectively evaluated. Phacoemulsification was performed 52 ± 15 months after SLT. After a mean follow-up of 74 ± 21 months, mean IOP was significantly decreased in the phaco group by 2.2 ± 2.7 mmHg (p < 0.001). In the SLT group, mean IOP was decreased by 0.8 ± 2.8 mmHg (p < 0.001). 9 eyes (16.7%) in the phaco group and 11 eyes (19.0%) of the SLT group needed topical treatment, and no eye needed glaucoma surgery in both groups. The factor related to success was higher baseline IOP (p = 0.002).

Conclusion

Prior SLT didn’t negatively influence phacoemulsification in patients with OAG. Phacoemulsification lowered IOP effectively and safely in OAG patients who were treated with SLT.

An in vitro study of scarring formation mediated by human Tenon fibroblasts: Effect of Y-27632, a Rho kinase inhibitor

Scar formation is the most common cause for failure of glaucoma filtration surgery because of increased fibroblast proliferation and activation. We have now examined the effect of Y‐27632, a Rho‐associated protein kinase (ROCK) inhibitor, on postsurgical scarring formation in human Tenon fibroblasts (HTFs). Collagen gel contraction assay was used to compare contractility activity of Y‐27632 with several antiglaucoma drugs. Immunofluorescence and western blotting were used to examine expression of scar formation–related factors. We found that Y‐27632 inhibited collagen gel contraction, as well as α‐smooth muscle actin and vimentin expression; these were promoted by treatment with latanoprost, timolol, or transforming growth factor (TGF)–β. To investigate the effect of Y‐27632 in postsurgical scarring, we mimicked TGF‐β secretion by stimulating HTFs with TGF‐β prior to Y‐27632 treatment. HTFs cultured in the presence of TGF‐β significantly increased gel contraction. In contrast, when HTFs were treated with 10μM Y‐27632, contraction was significantly inhibited. Furthermore, Y‐27632 reduced TGF‐β–induced phosphorylation of mitogen‐activated protein kinase signalling. These results suggest that ROCK inhibitors may inhibit fibrosis by inhibiting transdifferentiation of Tenon fibroblasts into myofibroblasts and by inhibiting TGF‐β signalling after surgery through mitogen‐activated protein kinase pathway suppression. These results implicate that ROCK inhibitors may improve outcomes after filtering surgery with a potential antiscarring effect, while latanoprost and timolol may induce fibrosis.

Significance of the study

Scar formation is the primary cause of failure after glaucoma filtration surgery. A ROCK inhibitor, Y‐27632, has been introduced as a novel potential antiglaucoma treatment to reduce intraocular pressure. The aim of our study was to elucidate the effect of Y‐27632 on scarring formation after glaucoma filtration surgery, in direct comparison with other antiglaucoma drugs. Our findings thus suggested that Y‐27632 may inhibit fibrosis and improve outcome after glaucoma filtration surgery through inhibition of transdifferentiation of Tenon fibroblasts into myofibroblasts, and the TGF‐β and MAPK signalling after surgery, while latanoprost and timolol may induce fibrosis.