Updates on the utility of anterior segment optical coherence tomography in the assessment of filtration blebs after glaucoma surgery

Comparison in conjunctival-Tenon's capsule thickness, anterior scleral thickness and ciliary muscle dimensions between Caucasians and Hispanic by optical coherence tomography

PURPOSE

To investigate the differences in the dimensions of the anterior ocular segment, and specifically in conjunctival-Tenon's capsule thickness (CTT), anterior scleral thickness (AST) and ciliary muscle thickness (CMT), between Caucasian and Hispanic subjects using swept-source optical coherence tomography (SS-OCT).

METHODS

Cross-sectional study including 53 Hispanic and 60 Caucasian healthy participants, matched by age, sex and refractive error, who underwent a complete ophthalmological examination. CTT, AST and CMT were manually measured in the temporal and nasal quadrants at 0, 1, 2 and 3 mm from the scleral spur using SS-OCT.

RESULTS

Mean age and refractive error were 38.7 ± 12.3 years and -1.05 ± 2.6 diopters, and 41.8 ± 11.7 years and -0.50 ± 2.6 diopters for the Hispanic and Caucasians, respectively (p = 0.165 and p = 0.244). The CTT was increased in the temporal quadrant in the Hispanic group in the three studied regions (CTT1, CTT2 and CTT3; being the means 223.0 ± 68.4, 215.3 ± 66.4 and 203.8 ± 67.1 µm versus 190.8 ± 51.0, 189.4 ± 53.2 and 187.4 ± 55.3 µm respectively; p < 0.001). Larger AST values were observed in the temporal quadrant in the Hispanic group (AST2: 559.8 ± 80.8 µm and AST3: 591.6 ± 83.0 µm) compared to the Caucasian group (520.7 ± 50.1 and 558.9 ± 54.7 respectively; p ≤ 0.022). No differences were observed in the nasal quadrant for CTT, AST1 and AST3 (p ≥ 0.076). No differences emerged in the CM dimensions (p ≥ 0.055).

CONCLUSION

CTT and AST measurements were thicker in the temporal quadrant of Hispanic patients compared to Caucasians. This could have implications for the pathogenesis of different ocular diseases.

Swept-Source Anterior Segment Optical Coherence Tomography Imaging and Quantification of Bleb Parameters in Glaucoma Filtration Surgery

This paper describes a technique for using swept-source anterior segment optical coherence tomography (AS-OCT) to visualize internal bleb microstructure and objectively quantify dimensions of the scleral flap and trabeculo-Descemet window (TDW) in non-penetrating glaucoma filtration surgery (GFS). This was a cross-sectional study of 107 filtering blebs of 67 patients who had undergone deep sclerectomy surgery at least 12 months prior. The mean post-operative follow-up duration was 6.5 years +/- 4.1 [standard deviation (SD)]. The maximal bleb height was significantly greater in the complete success (CS) blebs compared to the qualified success (QS) and failed (F) blebs (1.48 vs. 1.17 vs. 1.10 mm in CS vs. QS vs. F, one-way ANOVA, p < 0.0001). In a subcohort of deep sclerectomy blebs augmented by intraoperative Mitomycin-C, the trabeculo-Descemet window was significantly longer in the complete success compared to the qualified success group (613.7 vs. 378.1 vs. 450.8 µm in CS vs. QS vs. F, p = 0.004). The scleral flap length, thickness, and width were otherwise similar across the three outcome groups. The quantification of surgical parameters that influence aqueous outflow in non-penetrating GFS can help surgeons better understand the influence of these structures on aqueous outflow and improve surgical outcomes.

Ab-externo canaloplasty with and without suture in highly myopic eyes

PURPOSE

To evaluate the effectiveness of ab-externo canaloplasty using the iTrack canaloplasty microcatheter (Nova Eye Inc, Fremont, California), with or without suture, in glaucoma patients with high myopia.

METHODS

This was a prospective, single-center, single-surgeon, observational study comparing the outcomes of ab-externo canaloplasty performed with a tensioning suture (suture group) and without a tensioning suture (no-suture group) in mild to severe glaucoma patients with high myopia. Twenty-three eyes received canaloplasty as a standalone procedure, 5 in combination with phacoemulsification. Primary efficacy endpoints included intraocular pressure (IOP) and the number of glaucoma medications. Safety was assessed based on reported complications and adverse events.

RESULTS

Twenty-nine eyes of 29 patients with a mean age of 61.2 ± 12.3 years; 19 eyes in the no-suture group and 10 eyes in the suture group. All eyes demonstrated a significant reduction in IOP 24 months postoperatively, from 21.9 ± 7.22 to 15.4 ± 4.86 mmHg in the suture group and from 23.8 ± 7.58 to 19.7 ± 3.68 mmHg in the no-suture group. The mean number of anti-glaucoma medications reduced from 3.1 ± 0.6 to 0.4 ± 0.7 in the suture group and 3.3 ± 0.9 to and 0.2 ± 0.6 in the no-suture group at 24 months. IOP was not significantly different at baseline between the 2 groups, but it was statistically different at 12 and 24 months. There was no statistically significant difference in the number of medications between the groups at baseline, 12 and 24 months. No serious complications were reported.

CONCLUSION

Ab-externo canaloplasty performed either with or without a tensioning suture demonstrated good effectiveness in highly myopic eyes with a significant reduction in IOP and number of anti-glaucoma medications. The suture group achieved a lower postoperative IOP. However, the no-suture modification provides a similar reduction in medications with reduced tissue handling.

Efficacy and Safety of the Intraoperative Application of Mitomycin in Glaucoma Patients with Trabeculectomy: A Systematic Review and Meta-Analysis

What Is Known and Objective. The primary cause of trabeculectomy failure in glaucoma surgery is the imperfect formation of the filter bubble, which blocks the filtration effect. This systematic review and meta-analysis aimed to compare the effects and safety of mitomycin C (MMC) or no antimetabolite in trabeculectomies cases that require needling revision. Methods. We searched PubMed, Cochrane, and EMBASE to identify randomized trials published between the time the databases were built and May 31, 2022. To compare the effectiveness and safety of mitomycin with or without mitomycin in trabeculectomy, intraocular pressure (IOP), the surgical failure rate, and functional follicle formation were used as efficacy indicators, and the occurrence of postoperative complications was used as a safety indicator. Meta-analyses were performed for comparisons. Results and Discussion. After trabeculectomy, MMC was significantly better than a placebo at lowering postoperative IOP (MD = −11.31 mmHg, 95% CI −19.73 to −2.88 mmHg). MMC outperformed the control group in terms of filtering blebs formation (relative risk (RR) = 1.18, 95% CI: 1.09 to 1.27). The surgical failure rate was significantly lower with MMC compared to placebo (RR = 0.35, 95% CI: 0.22 to 0.58). No significant difference was observed between MMC and placebo in terms of hypotony, anterior chamber bleeding, filter bubble leakage, and endophthalmitis, apart from the shallow anterior chamber (RR: 1.51, 95% CI: 1.02 to 2.25). What Is New and Conclusion. The use of MMC in glaucoma trabeculectomy can increase the success rate of the procedure and provide significant patient benefits. However, it is important to be extremely careful and aware of complications such as shallow anterior chambers.

Novel Bleb Classification Following Ab Interno Implantation of Gel-Stent Using Anterior Segment Optical Coherence Tomography

PRCIS

A novel qualitative tomographical classification for bleb after implantation of XEN-Gel-Stent using ab interno approach is presented. Association of anatomic patterns to intraocular pressure (IOP) and success rates (SR) illustrates that anterior segment optical coherence tomography can be useful tool in clinical guidance.

PURPOSE

To present a novel classification of bleb resulting from ab interno implantation of XEN-Gel-Stent and report association of tomographical patterns with IOP and SR.

MATERIALS AND METHODS

A cross-sectional 1-armed study of patients receiving XEN-Gel-Stent. Tomographical changes in the bleb area were studied using swept-source optical coherence tomography in an early (d 29-90 postsurgery) and late (starting from d 91 postsurgery) phase. Frequency of patterns and their association with IOP and SR (defined as IOP<18 mmHg without medications) were studied.

RESULTS

One hundred eleven examinations of 49 blebs (49 patients) were included. Three tomographical patterns at conjunctival, 4 at tenons capsule, and 2 at episcleral level were characterized. Most frequent conjunctival pattern was subconjunctival spaces (56.3% and 53.2% in the early and late phase, respectively) and associated with lower IOP (13.0±6.0 mmHg) and higher SR (89%) but only in the early phase compared with other conjunctival patterns ( P <0.05). At tenons capsule level, the hyporeflective pattern was most frequent (50% and 51.9% in early and late phase) followed by the cavernous pattern. Both patterns associated with lower IOP and higher SR compared with hyper-reflective or loss of tenon changes ( P <0.005). Most blebs showed no episcleral lake (87.5% and 89.9% in early and late phase). No difference of IOP and SR was noted compared with those showing an episcleral lake.

CONCLUSION

A practical and clinically relevant novel classification system is proposed to tomographically describe and classify blebs after implantation of XEN-Gel-Stent. Certain patterns were associated with lower IOP and higher SR.

Characteristic Assessment of Angiographies at Different Depths with AS-OCTA: Implication for Functions of Post-Trabeculectomy Filtering Bleb

This study aimed to analyze the quantitative vascular biomarkers of filtering bleb function at different depths using anterior segment optical coherence tomography angiography (AS-OCTA). This cross-sectional study is registered on Clinicaltrails.gov (NCT 04515017). Forty-six eyes with primary open-angle glaucoma that had undergone trabeculectomy with mitomycin-C for more than six months were included. Vessel density (VD) and vessel diameter index (VDI) in the superficial layer (SL), Tenon’s layer (TL), and deep layer (DL) of the bleb were obtained. The VD and VDI were higher in the failure group (both p = 0.000). Significant correlations were found between the SL, TL, DL’s VDI, and IOP in the success group (p = 0.013, 0.016, 0.031, respectively). The VD of the TL and DL were related to IOP in the failure group (p = 0.012, 0.009). Tenon’s VD (TVD) and Tenon’s VDI (TVDI) correlated with IOP adjusting for TVD, TVDI, and the Indiana Bleb Appearance Grading Scale (IBAGS) (p = 0.009, 0.043) or Kenfeld grading system (KGS) (p = 0.011, 0.016). The area under curve (AUC) of the TVD, TVDI, IBAGS, and KGS to predict surgery failure were 0.960, 0.925, 0.770, and 0.850. AS-OCTA realized the quantitative evaluation of vessels, especially the invisible vascularity beneath the conjunctiva. TVD and TVDI as detected by AS-OCTA better reflected bleb function than conventional grading systems.