Crosslinked Sodium Hyaluronate Implant in Deep Sclerectomy for the Surgical Treatment of Glaucoma

XEN45 Gel Stent Combined with Healaflow Injectable Viscoelastic Implant

Purpose

To introduce a potential solution for failed glaucoma surgeries by proposing an optional surgical procedure in conjunction with the use of Healaflow (Anteis S.A., Geneva, Switzerland) as a spacer, which may potentially reduce the failure rate. Case Presentation. We present the outcomes of a surgical procedure involving the inferonasal implantation of an ab interno XEN gel stent (Allergan, Dublin, Ireland) in a 74-year-old male patient who was experiencing uncontrolled advanced glaucoma in his left eye. It is important to note that the patient had previously undergone several glaucoma surgeries and procedures in the same eye. During this particular procedure, we utilized Healaflow as a spacer by implanting the stent within a subconjunctival Healaflow "bubble." At 6 months postoperatively, intraocular pressure remained on target. There was no need for additional topical medications, and no change in visual acuity was observed.

Conclusion

For patients with a history of unsuccessful glaucoma surgeries and who are unsuitable candidates for tube shunt procedures or transscleral diode cyclophotocoagulation, an alternative option involves implanting the XEN45 stent in the inferior nasal region in conjunction with the use of subconjunctival Healaflow. This combined approach may provide a potential solution for managing glaucoma in these patients.

Advances in Polysaccharide- and Synthetic Polymer-Based Vitreous Substitutes

The vitreous humour is a gel-like structure that composes the majority of each eye. It functions to provide passage of light, be a viscoelastic dampener, and hold the retina in place. Vitreous liquefaction causes retinal detachment and retinal tears requiring pars plana vitrectomy for vitreous substitution. An ideal vitreous substitute should display similar mechanical, chemical, and rheological properties to the natural vitreous. Currently used vitreous substitutes such as silicone oil, perfluorocarbon liquids, and gases cannot be used long-term due to adverse effects such as poor retention time, cytotoxicity, and cataract formation. Long-term, experimental vitreous substitutes composed of natural, modified and synthetic polymers are currently being studied. This review discusses current long- and short-term vitreous substitutes and the disadvantages of these that have highlighted the need for an ideal vitreous substitute. The review subsequently focuses specifically on currently used polysaccharide- and synthetic polymer-based vitreous substitutes, which may be modified or functionalised, or employed as the derivative, and discusses experimental vitreous substitutes in these classes. The advantages and challenges associated with the use of polymeric substitutes are discussed. Innovative approaches to vitreous substitution, namely a novel foldable capsular vitreous body, are presented, as well as future perspectives related to the advancement of this field.

Long-Term Biocompatibility of a Highly Viscously Thiol-Modified Cross-Linked Hyaluronate as a Novel Vitreous Body Substitute

Purpose: In surgical ophthalmology, the treatment of complicated retinal and vitreous diseases is one of the central challenges. For this purpose, the vitreous body is removed as part of the standard therapy and replaced by a temporary tamponade to stabilize the position of the retina. Since the tamponading properties of previous materials such as silicone oils, gases, or semi-fluorinated alkanes are a combination of their surface tension and their buoyancy vector, they cannot completely fill the vitreous cavity. The aim of this work was to test in vivo a novel vitreous body substitute (ViBos strong) based on cross-linked hyaluronic acid for its compatibility.

Methods: A pars plana vitrectomy with posterior vitreous detachment was performed in the right eye of 18 pigmented rabbits, with subsequent injection of ViBos strong. Follow-up examination included slit-lamp examination, funduscopy, intraocular pressure measurements (IOP), optical coherence tomography (OCT), and electroretinogram (ERG) measurements. The rabbits were sacrificed at three different time points (1, 3, and 6 months; each 6 animals) and examined macroscopically and prepared for histological examination (HE staining) and immunohistochemistry (Brn3a and glial fibrillary acidic protein (GFAP)).

Results: ViBos strong demonstrated good intraoperative handling and remained stable for at least 1 month and degraded slowly over 6 months. IOP was within clinical acceptable values at all follow-up examinations. Retinal function was well preserved after instillation of the hydrogel and comparable to the untreated eye after 6 months in OCT, ERG, and histological examinations. An increase in the GFAP expression was found in the surgery eyes, with a peak in the 3-month group. The Brn3a expression was not significantly affected by vitrectomy with ViBos strong.

Conclusion: Highly viscously thiol-modified cross-linked hyaluronate showed a good biocompatibility in rabbit eyes over 6 months after vitrectomy, making it a promising potential as a vitreous substitute.

Polymeric hydrogel as a vitreous substitute: current research, challenges, and future directions

Vitreoretinal surgery is an essential approach to treat proliferative diabetic vitreopathy, retinal detachment, retinal tear, ocular trauma, and macular holes. The removal of the natural vitreous and the replacement with substitutes are critical steps for retina reattachment. Vitreous substitutes including silicone oil (SiO), air, sulfur hexafluoride (SF₆), and perfluoropropane (C₃F₈), have been widely applied in clinical practice. However, these substitutes are reported to cause complications such as emulsification, high intraocular pressure, and lens opacification. Polymeric hydrogels are a kind of material with favorable physical, mechanical properties, and adaptable biocompatibility, thus being highly expected to be ideal vitreous substitutes. Despite years of research, very few polymeric hydrogels can be applied practically in the vitreous cavity. In this review, we focus on the development of polymeric natural-based hydrogels and synthetic hydrogels. Particularly, we pay attention to recent advances in the novel stimuli-response and self-assembly supramolecular hydrogels. Characterized by easy injectability and long residence time, this kind of hydrogel becomes the potentially promising candidates for ideal vitreous substitutes. Finally, we evaluate the current challenges and provide the future directions of vitreous substitutes.

Cross-linked hyaluronic acid viscoelastic scleral implant in trabeculectomy

Purpose:

Patients with glaucoma undergoing trabeculectomy develop bleb cicatrix causing poor postoperative intraocular pressure (IOP) control and low success rates. Several approaches have been explored over the years for better outcomes. This study assesses the safety, efficacy, and outcome of trabeculectomy with HealaFlow^® (Anteis S. A, Geneva, Switzerland), a high-molecular-weight cross-linked hyaluronic acid viscoelastic gel, and comparing it with the antimetabolite Mitomycin-C (MMC).

Methods:

A prospective, interventional, case-controlled study conducted at a tertiary care hospital in Southern India on 60 eyes of patients requiring trabeculectomy divided in two groups – HealaFlow scleral implant and adjuvant low-dose MMC (0.1 mg/mL). Postoperative IOP reduction along with bleb morphology was assessed over follow-up at 1 week, 1 month, 3 months, 6 months, and 12 months.

Results:

Preoperatively IOP in the two groups was statistically similar. Postoperative IOP on day 1 had statistically significant reduction in both groups with greater reduction in MMC group. However, by 12 months, the IOP reduction was statistically similar in both groups, i.e., 46.24% (to 11.04 ± 2.55 mmHg) and 54.47% (to 11.99 ± 3.37 mmHg) in HealaFlow^® group and MMC group, respectively (P > 0.05). The bleb morphologies were similar and complications were seen equally, which resolved by 4 weeks. A complete success rate of 89.29% and a qualified success rate of 10.71% were observed equally in both groups.

Conclusion:

Absorbable biosynthetic cross-linked hyaluronic acid and low-dose MMC are equally safe and efficacious in trabeculectomy with significant IOP reduction and good bleb morphology. Therefore, it is a novel substitute for MMC.

Alginate- and Hyaluronic Acid-Based Hydrogels as Vitreous Substitutes: An In Vitro Evaluation

Purpose

To study alginate- and hyaluronic acid–based hydrogels in vitro as vitreous substitutes.

Methods

Biopolymeric hydrogels based on high-molecular alginate (0.5% and 1.0%) and hyaluronic acid (1.0% and Healaflow) were compared with extracted human vitreous bodies and silicone oil (SIL-5000) regarding their optical properties (refractive index, transmission) and viscoelastic characteristics (storage modulus G′, loss modulus G″). The cytotoxic (metabolic activity, apoptosis) and antiproliferative profiles were determined using cultured human fibroblasts, ARPE-19, and photoreceptor cells. The hydrogel systems were applied to human fetal retinal pigment epithelial cells cultured for two months until maximum transepithelial electrical resistance (TEER) to investigate the effect of the gel matrices on tight junctions using TEER measurements and immunostainings against the tight junction protein ZO-1.

Results

Tested alginate- and hyaluronic acid–based hydrogels resembled the natural refractive index of human vitreous bodies (1.3356–1.3360) in contrast to SIL-5000 (1.4034) and showed high optical transparency (>90%) within the visible light region. The biopolymeric hydrogels exhibited viscoelastic properties similar to juvenile vitreous bodies with G′>G″ adjustable via different gelation times, contrary to SIL-5000 (G′<G″). The metabolic activity, apoptosis and tight junctions of all tested ocular cells were unaffected by the alginate- and hyaluronic acid–based vitreous substitutes.

Conclusions

The present in vitro study demonstrates good optical, viscoelastic, and biocompatible properties of alginate- and hyaluronic acid–based hydrogels required for their use as vitreous substitutes.

Translational Relevance

Biopolymer-based hydrogels represent a promising vitreous replacement strategy to treat vitreoretinal diseases.

A New Retinal Detachment Treatment Model for Evaluation of Vitreous Tamponades

Purpose: To develop a treatment model of rhegmatogenous retinal detachment (RRD) in which the effects of various vitreous tamponades can be explored. Methods: In a primary session, detachment was produced in the right eye of 24 rabbits using vitrectomy, posterior vitreous detachment, retinal break induction, and subretinal injection of viscoelastic solution. The following day, detachments were treated in 16 eyes using SF6 (n = 8) or Healaflow® (HF, a cross-linked hyaluronic acid hydrogel, n = 8) tamponade. Animals were followed for 1 month and thereafter examined macroscopically and morphologically in hematoxylin and eosin-stained sections. Results: Retinal detachment (RD) was successfully treated using repeated surgery. Two HF eyes developed progressive vitritis and were excluded from further evaluation. Enlargement of the initial retinal rupture with concomitant RD was seen in 4/8 SF6 eyes, while all 6 HF eyes displayed an attached retina. Attached areas showed a normal retinal morphology except for in 1 HF eye with extensive degeneration. Conclusions: The RRD repeat vitrectomy model offers a possibility to explore the efficacy and complications of novel potential vitreous tamponades. Gel-based Healaflow® displays excellent anatomic reattachment, however, vitritis and retinal degeneration in some cases warrants further investigation.

Recent developments in regenerative ophthalmology

Regenerative medicine (RM) is one of the most promising disciplines for advancements in modern medicine, and regenerative ophthalmology (RO) is one of the most active fields of regenerative medicine. This review aims to provide an overview of regenerative ophthalmology, including the range of tools and materials being used, and to describe its application in ophthalmologic subspecialties, with the exception of surgical implantation of artificial tissues or organs (e.g., contact lens, artificial cornea, intraocular lens, artificial retina, and bionic eyes) due to space limitations. In addition, current challenges and limitations of regenerative ophthalmology are discussed and future directions are highlighted.

A novel rat model of ocular hypertension by a single intracameral injection of cross-linked hyaluronic acid hydrogel (Healaflow® )

To create a novel animal model of ocular hypertension via the intracameral injection of Healaflow. Unilateral chronic ocular hypertension model of rats was created by the intracameral injection of 3 μL Healaflow. The IOP of subjects was monitored. Dynamic morphological changes were evaluated by fundus imaging, OCT and histological examination. Visual function changes were measured by electroretinography and flash visual-evoked potentials. 24 and 72 hours after injection, the retinal tissue was collected for transcriptome analysis. The expression levels of related genes and proteins were further evaluated by qRT-PCR and Western blotting. The IOP peaked within 1 day after a single intracameral injection of Healaflow and then decreased gradually within 4 weeks. Furthermore, the persistently degenerating retinal ganglion cells occurred within 4 weeks. The visual function of these rats was also impaired. The results of transcriptome analyses, qRT-PCR and Western blotting showed that the expression levels of B2m, Ikzf1 and Stat3 were up-regulated, while the expression levels of Six3 and Prss56 were down-regulated in the retinal tissues. Intracameral injection of Healaflow is an effective approach to induce glaucomatous neurodegeneration in rats. Six3 and Prss56 may be involved in the pathogenesis of progressive glaucomatous damage.

Five Years' Outcomes of Trabeculectomy with Cross-linked Sodium Hyaluronate Gel Implantation for Chinese Glaucoma Patients

Background:

Trabeculectomy is the most efficient surgical treatment. Prevention failure of bleb cicatrix would lead to unsatisfactory postoperative intraocular pressure (IOP) controlling and unsatisfactory success rate. The aim of this study was to evaluate the 5-year outcomes of trabeculectomy with a cross-linked sodium hyaluronate gel implantation for Chinese glaucoma patients.

Methods:

This is a prospective, case-controlled study. Patients who were to be applied first-time trabeculectomy in the Department of Ophthalmology of Peking University Third Hospital between 2010 and 2012 were included in the study. Totally, 60 eyes were randomly assigned to the trabeculectomy group (TA group) or the trabeculectomy with cross-linked sodium hyaluronate gel implantation group (TH group). Follow-up was finished at 1 week, 1 month, 3 months, 1 year, 3 years, and 5 years after the operation. The statistical index of demographic data, IOP, bleb shape, and any complications or medications or surgical procedures were recorded and assessed by SPSS 19.0 software through independent t-test, one-way analysis of variance (ANOVA) and Pearson's Chi-square test, respectively.

Results:

The baseline IOP was comparable between the two groups (t= −1.00, P= 0.32) while the postoperative IOP was significantly lower in the TH group at 1, 3 and 5 years' time points (P = 0.00, P= 0.01 and P = 0.01, respectively). According to the Indiana Bleb Appearance Grading Scale, the height and extent of bleb were better in the TH group at all follow-up time points (P < 0.05), however, the comparison of bleb vascularity showed no statistical difference (P > 0.05). TA group had a higher percentage of complications (13% vs. 3%) compared to TH group; however, there was no statistical difference in the comparison of each statistical item (P > 0.05, respectively). The complete success at 5 years was higher in the TH group than that in the TA group (78% vs. 54%, P = 0.03).

Conclusion:

Our results suggested that implantation of cross-linked sodium hyaluronate gel with trabeculectomy was more efficient and would improve the prognosis of glaucoma patients.

SUPRACHOROIDAL BUCKLING FOR THE MANAGEMENT OF RHEGMATOGENOUS RETINAL DETACHMENTS SECONDARY TO PERIPHERAL RETINAL BREAKS

PURPOSE

To evaluate functional and anatomical outcomes of eyes undergoing suprachoroidal buckling for the management of peripheral retinal breaks in rhegmatogenous retinal detachment.

METHODS

Retrospective cohort study of 41 eyes of 41 patients undergoing suprachoroidal buckling for the management of rhegmatogenous retinal detachment secondary to single or multiple retinal breaks. Suprachoroidal indentation was achieved through the introduction of filler material using a 23-gauge (23-G) olive-tipped, suprachoroidal cannula. This allowed for the creation of a suprachoroidal dome and chorio-retinal apposition. Healon5 (Abbott Medical Optics) was used as filler material in all eyes. Combined 25-G vitrectomy was performed in 5 eyes. Cryopexy and laserpexy were used in 37 and 4 eyes, respectively.

RESULTS

Mean visual acuity gain was the primary outcome measure. Final retinal reattachment rate, single-surgery reattachment rate, and complications were secondary outcome measures. Mean best-corrected distance visual acuity improved from 20/1,100 to 20/42. Single surgery reattachment rate was 92.7% (38/41 eyes). Final retinal reattachment was achieved in all 41 eyes (100%). There was no statistically significant difference in visual acuity gain or anatomical reattachment in terms of retinal break quadrant or extent. No major complications were observed. Two localized suprachoroidal hemorrhages occurred at the entry site for the cannula. These resolved without further intervention.

CONCLUSION

Suprachoroidal buckling using a specially designed cannula is a safe and effective procedure for the management of rhegmatogenous retinal detachment secondary to peripheral retinal breaks.

Catheter-guided suprachoroidal buckling of rhegmatogenous retinal detachments secondary to peripheral retinal breaks

PURPOSE

To evaluate functional and anatomic outcomes of eyes undergoing suprachoroidal buckling (SCB) using a specially designed catheter for the management of rhegmatogenous retinal detachment (RRD) secondary to peripheral retinal breaks.

METHODS

Retrospective cohort study of 62 eyes of 62 patients. Subjects underwent SCB for the management of RRD secondary to single or multiple retinal breaks. Suprachoroidal indentation was achieved through the introduction of viscoelastic material in the suprachoroidal space overlying the break using an illuminated, 450 μm-wide, flex-tip catheter. This allowed for the creation of a suprachoroidal dome and chorio-retinal apposition. Forty-seven eyes (80 %) underwent SCB alone, while 15 eyes (20 %) were combined with 25-G pars-plana vitrectomy. Cryopexy and laserpexy were used in 38 (61 %) and 24 of eyes (39 %) respectively.

RESULTS

Mean pre-operative best-corrected visual acuity (BCVA) improved from logMAR 0.82 (20/132) to 0.22 (20/33) (p < 0.0001). The single surgery reattachment rate was 92 % (57/62.) Final retinal reattachment was achieved in all eyes (100 %). No significant difference was observed in single-surgery anatomic success rates when stratified by lens status, macular involvement, or break location. There were no major intra- or post-operative complications.

CONCLUSION

Suprachoroidal buckling using a special-design, flexible catheter is a safe and effective procedure for the management of RRD secondary to peripheral retinal breaks.

Canaloplasty versus non-penetrating deep sclerectomy - a prospective, randomised study of the safety and efficacy of combined cataract and glaucoma surgery; 12-month follow-up

PURPOSE

To compare outcomes of phaco-canaloplasty (PC) and phaco-non-penetrating deep sclerectomy (PDS) with a viscoelastic compound.

METHODS

This study included 29 eyes after PC and 30 after PDS. Indications were uncontrolled primary open-angle glaucoma (POAG) and a cataract. Corrected distance visual acuity (CDVA), intraocular pressure (IOP), and number of medications were evaluated. Follow-up examinations were performed on days 1 and 7, and after 1, 3, 6, and 12 months. Complete and qualified success was an IOP ≤ 18 mmHg.

RESULTS

At the 12-month follow-up, mean IOP decreased in the PC group from 19.0 ±6.9 mmHg to 12.6 ±2.7 mmHg, and in the PDS group, from 19.1 ±5.8 mmHg to 14.3 ±3.5 mmHg (P < 0.05). Both groups preoperatively and at 12 months showed no significant differences in IOP (P > 0.05). There was no statistically significant difference between the number of medications used (P > 0.05). Complete and qualified success rates for both groups were 79.0 % and 76.9 % (P = 0.701). The most frequent postoperative PC complication was hyphema (58.0 %); for PDS, bleb fibrosis was most frequent (26.7 %). No PC patients required postoperative management. PDS patients required postoperative interventions 58.7 % of the time, including a 5-fluorouracil (5-FU) injection (58.7 %), suture lysis (48.3 %), and needling (27.6 %).

CONCLUSIONS

Both PC and PDS lead to an effective decrease in IOP on a short-term follow-up basis and demonstrate similar efficacy and safety profiles. PDS patients required additional procedures including 5-FU injections, suture lysis, or needling. PC patients required no additional procedures.

Pilot study of glaucoma drainage implant surgery supplemented with reticulated hyaluronic acid gel in severe glaucoma

PURPOSE

This pilot study, the first of its type, was conducted to determine the clinical outcome of glaucoma drainage implant (GDI) surgery supplemented with injectable crosslinked hyaluronic acid (HA) in patients with severe glaucoma.

METHODS

This was a retrospective chart study involving 10 eyes of 10 patients with severe glaucoma (glaucomatous visual field loss worse than -20 dB) who had previously undergone GDI surgery supplemented with crosslinked HA with a 2-year follow-up. Surgical success was defined as intraocular pressure (IOP) &lt;21 mm Hg with a reduction of ≥40% (definition A) or ≥50% (definition B) from baseline IOP on 2 consecutive follow-up visits, IOP &gt;5 mm Hg on 2 consecutive follow-up visits, and neither reoperation of glaucoma nor loss of light perception vision.

RESULTS

The mean ± SD baseline IOP before GDI was 38.5 ± 10.7 mm Hg, and the mean IOP at the last follow-up visit was 13.0 ± 5.0 mm Hg, with a mean pressure drop of 24.4 ± 10.9 mm Hg (62%; p = 0.005). According to definition A, life-table analysis showed an overall success rate of 80%, while according to definition B, the success rate was 50% after 24 months of follow-up. Complications were infrequent and not serious. No complications resulting from the reticulated HA therapy itself were observed.

CONCLUSIONS

In eyes with severe glaucoma, the intraoperative application of crosslinked sodium HA gel may improve the efficacy of GDI surgery.