Innovations in glaucoma surgery from Dr. Rajendra Prasad Centre for Ophthalmic Sciences

Intraocular pressure control efficacy and safety of HA-Mg glaucoma drainage plate implantation in the anterior chamber of rabbit eyes

The current clinical application of glaucoma drainage devices is made of non-degradable materials. These non-degradable drainage devices often trigger inflammatory responses and scar proliferation, possibly leading to surgical failure. We developed a biodegradable material hydroxyapatite-coated magnesium (HA-Mg) as a glaucoma drainage device. Twelve New Zealand white rabbits were randomly assigned to three groups: HA-Mg drainage plate group (6 right eyes), trabeculectomy group (6 right eyes), and control group (12 left eyes). Results showed that all HA-Mg drainage plates were completely degraded ~4 months postoperatively. At the 5th month postoperatively, there was no statistical difference in the corneal endothelium density between the HA-Mg drainage plate group and the control group (p = 0.857). The intraocular pressure (IOP) level in the HA-Mg drainage plate implantation group was lower than in the other two groups. The trypan blue dye still drained from the anterior chamber to the subconjunctiva 5 months after HA-Mg drainage plate implantation. HE staining revealed the scleral linear aqueous humor drainage channel and anterior synechia were observed after drainage plate completely degraded, with no obvious infiltration with the inflammatory cells. This study showed the safety and efficacy of HA-Mg glaucoma drainage plate in controlling IOP after implantation into the anterior chamber of rabbit eyes.

Comparison of Repeat Trabeculectomy Versus Ahmed Valve Implantation After Initial Failed Trabeculectomy Surgery

PRCIS

Repeat trabeculectomy is associated with similar postoperative intraocular pressure (IOP), a lower complication rate, and a lower need for medications when compared with Ahmed valve implantation (AVI) when performed after initially failed trabeculectomy.

OBJECTIVE

The goal of this study was to compare the efficacy of repeat trabeculectomies and AVI after an initial failed trabeculectomy.

METHODS

All studies that investigated the postoperative success of patients who underwent AVI or repeat trabeculectomy with mitomycin- C after a prior failed trabeculectomy with mitomycin- C found in PubMed, Cochrane Library, Scopus, and CINAHL were included. Mean preoperative and postoperative IOP, proportions of complete and qualified successes, and proportions of complications were extracted from each study. Meta-analyses were performed to compare the differences between the two surgical approaches. Methods of measuring complete and qualified success were too heterogeneous among the included studies to allow for meta-analysis.

RESULTS

The literature search yielded 1305 studies, and 14 studies were included in the final analysis. Mean IOP was not significantly different between the two groups preoperatively and then after 1, 2, and 3 years. Mean number of medications between the two groups was similar preoperatively. After 1 and 2 years, the mean amount of glaucoma medications in the AVI group was approximately twice that of the trabeculectomy group; however, this relationship was only significant at 1 year of follow-up ( P = 0.042). In addition, the cumulative proportion of overall and sight-threatening complications was significantly higher in the AVI group.

CONCLUSION

Repeat trabeculectomy with mitomycin- C and AVI may both be considered after failed primary trabeculectomy. However, our analysis suggests that repeat trabeculectomy may be the preferred method as it provides similar efficacy with fewer disadvantages.

Efficacy of Trabeculectomy Combined With Limited Deep Sclerectomy Versus Trabeculectomy Alone: A Randomized-controlled Trial

PRCIS

The addition of limited deep sclerectomy (LDS) to conventional trabeculectomy increases the success rate, especially in pseudophakic eyes.

PURPOSE

This study aimed to evaluate the efficacy of LDS in enhancing the intraocular pressure (IOP)-lowering outcomes of trabeculectomy.

DESIGN

This was a parallel-arm, single-masked, randomized-controlled trial.

METHODS

A total of 68 patients (68 eyes) with moderate to advanced primary open-angle glaucoma or primary angle-closure glaucoma with pseudophakia were recruited at a tertiary eye care center in Northern India and randomized into 2 groups. Thirty-five eyes in group 1 were subjected to trabeculectomy alone and 33 eyes in group 2 were subjected to trabeculectomy with LDS. All cases were supplemented with low-dose subconjunctival mitomycin-C (0.1 mg/mL for 1 min) in both groups. The primary outcome measure was IOP, and success rates were calculated for IOP ≤18/15/12 and ≥5 mm Hg. The secondary outcome measures included evaluation of bleb morphology, presence of an intrascleral aqueous lake, and supraciliary flow on ultrasound biomicroscopy.

RESULTS

The mean postoperative IOP at 12 months was 13.4±1.83 mm Hg in group 1 and 12.5±1.67 mm Hg in group 2 (P=0.04). For IOP cutoff ≤15 mm Hg, absolute success was noted in 11 (31.4%) and 22 eyes (66.6%) in groups 1 and 2, respectively (P=0.004). At 12 months, the intrascleral lake was detected in 2 (6%) eyes in group 1 and in 9 (29%) eyes in group 2 (P=0.02). Supraciliary flow was detected in 2 eyes (6.2%) in group 2 and none in group 1 at 12 months (P=0.02). In the Cox proportional hazard model, trabeculectomy with LDS was associated with a lower rate of failure (hazard ratio: 0.32, 95% confidence interval: 0.13-0.75, P=0.009).

CONCLUSION

The addition of LDS to trabeculectomy led to lower mean IOP and higher success rates at 12 months, compared with trabeculectomy alone.

Neuroprotective role of epigallocatechin-3-gallate in acute glaucoma via the nuclear factor-κB signalling pathway

Glaucoma is a disease involving impaired visual function accompanied by degeneration and necrosis of the optic nerve. Epigallocatechin-3-gallate (EGCG) exerts a neuroprotective effect against the degeneration of retinal ganglion cells. However, whether EGCG can relieve glaucoma and the possible mechanisms remain unclear. In order to determine the function of EGCG in glaucoma, an acute glaucoma rat model was established. Optic neuropathology was examined by haematoxylin-eosin staining and immunofluorescence staining for class III-β tubulin. The levels of inflammation-associated cytokines, such as interleukin (IL)-4, IL-6, TNF-α, IL-1β, IL-13 and IFN-γ were measured by flow cytometry. T cell proliferation was assessed by the carboxyfluorescein diacetate succinimidyl ester method. Finally, the functional role of EGCG in glaucoma was explored. The levels of the inflammation-associated proteins p-IκBα and p-p65 were measured by western blot analysis. The results showed that optic nerve injury occurred, and elevated levels of the inflammatory cytokines IL-4, IL-6, TNF-α, IL-1β, IL-13 and IFN-γ were observed in the rat model of acute glaucoma. In addition, an increased T lymphocyte proliferation rate and imbalance of Th1/Th2 cytokines were present in the models. Importantly, treatment with EGCG significantly alleviated optic nerve injury. At the molecular level, EGCG decreased the levels of inflammation-associated cytokines, decreased the proliferation rate of T lymphocyte cells, and repaired the imbalance of Th1/Th2 cytokines. Moreover, EGCG inhibited the increase in the phosphorylation of IκBα and p65 caused by modelling and thus suppressed the activation of the nuclear factor (NF)-κB signalling pathway. The findings of the present study indicate that EGCG could attenuate the symptoms of glaucoma and inhibit inflammatory responses by suppressing the NF-κB signalling pathway in a rat glaucoma model.

Intraoperative Optical Coherence Tomography-Guided Bleb-sparing Epithelial Exchange: A Modified Approach

With the advent of newer technologies, real-time anterior segment optical coherence tomography (OCT) integrated with the operating microscope has become possible. We are proposing the technique of bleb revision with greater precision under direct visualization of bleb anatomy and extent of tissue depth allowing better localization and easy maneuvering with lesser complications. In this surgical technique, bleb revision was performed using intraoperative real-time OCT incorporated in OPMI LUMERA 700 microscope. Live surgical and OCT view were seen on a common screen together. A moderately elevated, diffuse functional bleb was noted after three months of bleb revision in both cases with controlled intraocular pressure. Intraoperative OCT-guided bleb-sparing epithelial exchange is an adjunctive technique for bleb repair surgery with an increased precision of surgery which can reduce complications, minimize surgical time and maximize surgical outcome.

Inhibitive effect of TAK-242 on Tenon's capsule fibroblasts proliferation in rat eyes

AIM

To study the inhibition effect of TAK-242 on the proliferation of rat eye Tenon's capsule fibroblasts via the toll-like receptor 4 (TLR4) signaling pathway.

METHODS

SD rat Tenon's capsule fibroblasts were extracted and cultured, then the cells were divided into normal control group, lipopolysaccharide (LPS) group (10 g/mL LPS) and TAK-242 group (1 µmol/L TAK-242, and 10 µg/mL LPS after 30min). The expressions of TLR4, transforming growth factor-β1 (TGF-β1) and interleukin-6 (IL-6) in each group were detected by Western blot and reverse transcriptase-polymerase chain reaction (RT-PCR). Cell proliferation was detected by cell counting kit-8 (CCK-8).

RESULTS

Double immunofluorescent labeling in the extracted cells showed negative keratin staining and positive vimentin staining. Western blot showed that the LPS group had the highest expression of TLR4 and TGF-β1 (P<0.01). Enzyme linked immunosorbent assay (ELISA) also showed that the secretion of IL-6 was the highest in LPS group (P<0.01). But there was no significant difference in TLR4 and TGF-1, as well as IL-6 expressions between the TAK-242 group and the normal control group (P>0.05). RT-PCR showed that the IL-6 mRNA expression in LPS group was the highest in the three groups (P<0.01).

CONCLUSION

TAK-242 inhibits the proliferation of LPS-induced Tenon's capsule fibroblasts and the release of inflammatory factors by regulating the TLR4 signaling pathway, providing a new idea for reducing the scarring of the filter passage after glaucoma filtration surgery.