Anterior segment optical coherence tomography imaging of conjunctival filtering blebs after glaucoma surgery

Bleb vessel density as a predictive factor for surgical revisions after Preserflo Microshunt implantation

PURPOSE

Bleb failure is a common complication after glaucoma filtration surgery. Different bleb classification schemes incorporating filtration bleb vascularization have been proposed, but the reported correlation with intraocular pressure (IOP) has been variable, possibly because of subjective vascularization grading. The purpose of the present study was to evaluate bleb vascularization after Preserflo Microshunt (PM) implantation using anterior segment OCT-angiography (AS-OCTA) as a biomarker for bleb failure.

METHODS

Twenty-three eyes of twenty-three patients underwent PM implantation. Up to 12 months after surgery PM scleral passage-centred AS-OCTA measurements (PLEX Elite 9000) for bleb-vessel density (BVD) determination were performed and IOP as well as necessity for surgical revisions (needling and open revision) were documented. After multi-step image analysis (region of interest definition, artefact removal, binarization, BVD calculation), the predictive value of early postoperative BVD for surgical revisions was assessed using logistic regression modelling.

RESULTS

Baseline IOP (23.57 ± 7.75 mmHg) decreased significantly to 8.30 ± 2.12, 9.17 ± 2.33 and 11.70 ± 4.40 mmHg after 1, 2 and 4 week(s), and 13.48 ± 5.83, 11.87 ± 4.49, 12.30 ± 6.65, 11.87 ± 3.11 and 13.05 ± 4.12 mmHg after 2, 3, 6, 9 and 12 month(s), respectively (p < 0.001). Nine patients (39%) needed surgical revisions after a median time of 2 months. Bleb vessel densities at 2 and 4 weeks were significantly associated with future surgical revisions upon logistic regression analysis (2 W/4 W likelihood-ratio test p-value: 0.0244/0.0098; 2 W/4 W area under the receiver operating characteristics curve: 0.796/0.909).

CONCLUSION

Filtration bleb vessel density can be determined using AS-OCTA in the early postoperative period and is predictive for bleb failure after PM implantation.

Comparison of the Intrableb Characteristics of Anterior Segment Optical Coherence Tomography Imaging in Trabeculectomy according to Amniotic Membrane Transplantation

INTRODUCTION

The purpose of this study was to compare the characteristics of filtering bleb with anterior segment optical coherence tomography (AS-OCT) according to amniotic membrane transplantation (AMT).

METHODS

One hundred and sixteen eyes of 103 glaucoma patients who underwent trabeculectomy with (AMT group; 85 eyes) or without AMT (control group; 31 eyes) were included. Intrableb parameters were evaluated with AS-OCT. Surgical success was defined as an intraocular pressure (IOP) ≤18 mm Hg and IOP reduction ≥20% without medication at the time of AS-OCT examination. Logistic regression analyses were performed to determine factors associated with IOP control.

RESULTS

In the eyes with successful IOP control, the fluid-filled space area, score, and height were greater for the AMT group than the control group (all ps < 0.001), while stripping layer thickness was greater and bleb wall reflectivity was lower for the control group than the AMT group (all ps < 0.001). Surgical success in the AMT group was associated with greater fluid-filled space score, lower bleb wall reflectivity, and microcyst formation (odds ratio [OR] = 8.016, 0.913, and 16.202, respectively, all ps ≤ 0.041). Lower bleb wall reflectivity alone was associated with surgical success in the control group (OR = 0.815, p = 0.019).

CONCLUSION

The extent of the fluid-filled space was associated with successful IOP control after trabeculectomy with AMT. Hyporeflective bleb wall was associated with successful IOP control in AMT and control groups.

Clinical value of anterior segment optical coherence tomography‑assisted Wuerzburg bleb classification system for bleb assessment following trabeculectomy

The Wuerzburg bleb classification system (WBCS) is an established tool for evaluating filtering blebs, while anterior segment optical coherence tomography (ASOCT) provides detailed information on inner bleb structure. The present study aimed to investigate the clinical value of ASOCT-assisted WBCS following trabeculectomy (TRAB). The present prospective, observational study included eyes that underwent TRAB. Bleb assessments using the WBCS were based on the image acquired by ASOCT. The WBCS scores were assessed at postoperative week 2 and postoperative month (POM) 1, 2, 3, 6 and 12. The surgical outcomes at 1 year were determined as success or failure. Spearman's analysis explored the correlation of WBCS scores with intraocular pressure (IOP) and surgical outcome. A total of 32 eyes from 32 patients were included in the present study. The WBCS total score significantly correlated with IOP at POM 1, 2, 3, 6 and 12 (P<0.05). For single parameters, microcysts demonstrated a good correlation with IOP at POM 1, 2, 3, 6 and 12 (P<0.05). The WBCS total score correlated well with surgical outcome at POM 2, 3, 6 and 12 (P≤0.005). Microcysts, vascularity and encapsulation significantly correlated with surgical outcomes (P<0.05). The results of the present study suggest that ASOCT-assisted WBCS is a simple and effective measurement system for blebs after TRAB in clinical practice, which correlates well with IOP and surgical outcomes. Blebs with a higher WBCS total score and microcysts score in the early postoperative period, such as at POM 2 and 3, are less likely to have surgical failure in the long term.

Plasma Rich in Growth Factors as an Adjuvant Agent in Non-Penetrating Deep Sclerectomy

BACKGROUND

The purpose of this study is to evaluate the utility and safety of plasma rich in growth factors immunosafe eye drops (is-ePRGF) in the postoperative treatment of non-penetrating deep sclerectomy (NPDS).

METHODS

This is a case-control study in patients with open-angle glaucoma. Group one (control) was not treated with is-ePRGF, while group two (is-ePRGF) was treated (four times a day for four months). Postoperative evaluations were performed at one day, one month, three months and six months. The main outcomes were: intraocular pressure (IOP), microcysts in blebs with AS-OCT and the number of hypotensive eye drops.

RESULTS

Preoperatively, group one (n = 48 eyes) and group two (n = 47 eyes) were similar in age (71.5 ± 10.7 vs. 70.9 ± 10.0 years; p = 0.68), IOP (20.6 ± 10.2 vs. 23.0 ± 9.0 mmHg; p = 0.26) and number of hypotensive drugs (2.7 ± 0.8 vs. 2.8 ± 0.9; p = 0.40). The IOP at six months dropped to 15.0 ± 8.0 mmHg (IOP reduction: -27.2%) and 10.9 ± 4.3 mmHg (IOP reduction: -52.6%) for group one and group two, respectively (p < 0.01). At six months, blebs with microcysts were 62.5% (group one) and 76.7% (group two). Postoperative complications were observed in 12 eyes (25%) for group one and in 5 eyes (11%) for group two (p = 0.06). No specific complications related to the use of is-ePRGF were identified.

CONCLUSIONS

Topical is-ePRGF seems to reduce IOP and the rate of complications in the medium term after NPDS, so it can be considered as a possible safe adjuvant to achieve surgical success.

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.

Does mitomycin-C concentration have any influence on XEN45 gel stent outcomes in a real-world setting?

BACKGROUND

To compare the effectiveness and safety of XEN45 implanted with mitomycin-C (MMC) 0.01% versus (vs) XEN45 implanted with MMC 0.02%.

METHODS

Retrospective and single-center study conducted on consecutive patients with open-angle glaucoma or ocular hypertension who underwent XEN45-implant, either alone or in combination with cataract surgery. The primary end-point was the mean change in intraocular pressure (IOP) from baseline to the last follow-up visit.

RESULTS

Fifty-five patients (63 eyes) were included. Thirty-seven (58.7%) eyes underwent surgery with MMC 0.01% and 26 (41.3%) ones with MMC 0.02%. In the overall study sample, the mean (standard error) IOP was significantly lowered from 17.6 (0.7) mm Hg at baseline to 12.6 (0.3) mm Hg at month 12. The IOP was significantly lowered from 17.3 (15.4 to 19.2) mm Hg and 17.9 (16.1 to 17.8) mm Hg at baseline to 12.3 (11.3 to 13.3) mm Hg and 13.1 (12.3 to 13.9) mm Hg at month 12 in the MMC 0.01% and MMC 0.02% groups, respectively; p < 0.0001 each. The mean number of ocular-hypotensive medications significantly decreased from 2.1 (1.9 to 2.3) at baseline to 0.2 (0.04 to 0.3) at month 12, p < 0.0001, with no significant differences between MMC 0.01% and MMC 0.02% groups, p = 0.5181. At month 12, 50 (80.6%) eyes had functioning blebs. Regarding safety, 18 (28.6%) eyes have experience adverse events.

CONCLUSION

XEN45, either alone or in combination with cataract surgery, showed a good effectiveness and safety profile. MMC dose had no influence on the IOP lowering, which may support the use of the lowest dose.

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

The formation of filtration blebs is the main drainage mechanism for reducing intraocular pressure after traditional incisional glaucoma surgery such as trabeculectomy and non-penetrating deep sclerotomy. Early and short-lasting blebs may also occur after canaloplasty. Bleb formation also plays an important role after the implantation of glaucoma drainage devices, including Minimally Invasive Glaucoma Surgery devices. Anterior segment optical coherence tomography (AS-OCT) is a rapid and non-invasive high-resolution imaging technique that has evolved in recent years to become a routine examination. Anterior segment optical coherence tomography (AS-OCT) provides key information in the assessment and follow-up of glaucoma surgery, especially in the assessment of filtration blebs. Thus, bleb morphology can be qualitatively classified into diffuse, cystic, encapsulated and flattened, and AS-OCT imaging can also provide several quantitative parameters of the bleb, such as total bleb height, bleb fluid-filled cavity height, bleb wall thickness, number of microcysts and trabeculectomy opening size. These parameters could have an impact on clinical management during follow-up because they may predict the success or failure of the surgery in the early and late postoperative periods. Additionally, they may also guide the procedures used to increase filtration and reduce intraocular pressure, such as bleb needling and laser suture lysis.

[Studying the condition of filtering bleb after glaucoma surgery using optical coherence tomography]

PURPOSE

To compare the optical coherence tomography (OCT) findings on the condition of filtering bleb (FB) in patients with primary open-angle glaucoma (POAG) who used different local therapy before glaucoma surgery.

MATERIAL AND METHODS

The study included a total of 82 patients (82 eyes) followed up after glaucoma surgery: 50 patients (50 eyes) who received preservatives-containing drugs before glaucoma surgery; 32 patients (32 eyes) - who were on preservative-free drug treatment before glaucoma surgery. The examinations were carried out 7 days, 1 and 3 months after micro-invasive sinus trabeculectomy. The condition of filtering bleb was studied using the Visante AS-OCT device, as well as with a slit lamp for clinical observation. Corneal-compensated intraocular pressure (IOPcc) was determined by bi-directional pneumatic applanation of the cornea using the Ocular Response Analyzer (ORA).

RESULTS

After 3 months post-op, a functioning FB and intraocular pressure below 15.0 mm Hg were observed in 38 eyes out of 50 (76%) in group 1, in 12 eyes (24%) the FB was nonfuncitonal. In Group 2, 25 eyes out of 32 (78%) had functioning FB and intraocular pressure lower than 15.0 mm Hg; in 7 eyes (22%) the FB was nonfuncitonal. Needling was needed 3 months after the operation in 7 eyes out of 32 (22%) in group 2. The need for needling according to OCT findings in patients of group 1 occurred already one week after surgery for 4 eyes out of 50 (8%), after one month - for 14 eyes (28%).

CONCLUSION

In patients on pre-operative drug therapy with preservative-containing medications, the process of scarring in the FB is faster. The OCT method allows early detection of the initial signs of scarring, as well as determining the need for needling.

Confocal Microscopy and Anterior Segment Optical Coherence Tomography Imaging of the Ocular Surface and Bleb Morphology in Medically and Surgically Treated Glaucoma Patients: A Review

Glaucoma patients often suffer from ocular surface disease (OSD) caused by the chronic administration of topical anti-glaucoma medications, especially in cases of long-term therapy with preserved or multiple drugs. Additionally, glaucoma surgery may determine ocular surface changes related to the formation and location of the filtering bleb, the application of anti-mitotic agents, and the post-operative wound-healing processes within the conjunctiva. Recently, several studies have evaluated the role of advanced diagnostic imaging technologies such as in vivo confocal microscopy (IVCM) and anterior segment-optical coherence tomography (AS-OCT) in detecting microscopic and macroscopic features of glaucoma therapy-related OSD. Their clinical applications are still being explored, with recent particular attention paid to analyzing the effects of new drug formulations and of minimally invasive surgical procedures on the ocular surface status. In this review, we summarize the current knowledge about the main changes of the ocular surface identified at IVCM and AS-OCT in glaucoma patients under medical therapy, or after surgical treatment.

Topical preservative-free ophthalmic treatments: an unmet clinical need

Introduction: The main role of preservatives in eyedrops is to ensure sterility and microbiological integrity of the drug, and to facilitate the penetration of active compounds into the eye. However, several studies documented significant toxic effects induced by preservatives, especially on the ocular surface. Consequently, most of the ophthalmic medications became progressively available in preservative-free (PF) formulations.Areas covered: We analyzed pre-clinical and clinical studies on PF eyedrops with particular attention to common chronic diseases such as dry eye and glaucoma. We discussed about the pros and cons of using PF eyedrops, in terms of efficacy, safety, and social-economic aspects.Expert opinion: There are still unresolved issues that make hard for PF medications to definitively conquer the drug market. Despite robust pre-clinical evidences of less toxicity, the low number of randomized clinical trials does not permit to state that PF eyedrops have, in clinical practice, a similar efficacy or a higher safety compared to preserved forms. These aspects limit their use to chronic diseases requiring long-term therapies with multiple daily instillations, especially in the presence of concomitant ophthalmic diseases that expose to a risk of ocular surface worsening.

Trabeculectomy With Extended Subscleral Tunnel Versus Conventional Trabeculectomy in the Management of POAG: A 1-Year Randomized-controlled Trial

PRECIS

This clinical trial compares a modified trabeculectomy technique [extended subscleral tunnel (ESST)] with conventional trabeculectomy [subscleral trabeculectomy (SST)] in terms of success rate and bleb morphology. ESST showed comparable results, with lower incidence of bleb-related complications and need for postoperative antiglaucoma medications.

BACKGROUND

To evaluate the outcome of modified trabeculectomy with extended subscleral tunnel "ESST" versus conventional subscleral trabeculectomy "SST" in the management of uncontrolled primary open-angle glaucoma.

PARTICIPANTS AND METHODS

This is a randomized clinical trial of 40 eyes (40 patients) divided into 2 equal groups. In the first group, a conventional SST with adjuvant 0.3% mitomycin-C was performed. In the second group, the ESST group, an additional 1.00 mm wide longitudinal scleral groove was dissected and excised in the center of the deep scleral bed extending 1.00 mm beyond the posterior margin of the flap. Patients were examined on days 1, 7, 14, 30, 90, 180, and at 1 year, with a special focus on intraocular pressure and bleb morphology. Postoperative ultrasound biomicroscopy was performed to evaluate the surgical area.

RESULTS

Both groups showed a significant reduction in intraocular pressure, with the ESST group showing significantly lower values on days 7, 14, 30, 90, and 180 (P=0.001, 0.004, 0.026, 0.001, and 0.048), but no significant differences on day 1 and at 1 year (P=0.06 and 0.07). The need for postoperative antiglaucoma medications was significantly lower in the ESST group (P=0.043). Visually significant cataract and bleb related complications were more in the SST group (P=0.044 and <0.001). Significantly more eyes in the ESST group showed normal bleb vascularity and wider extent.

CONCLUSIONS

ESST offers a guarded posterior flow with a success rate comparable to that of conventional SST. ESST could minimize bleb-related complications and bleb-dysesthesia with better long-term bleb morphology and vascularity. It could also minimize the need for further adjuvant postoperative antiglaucoma medications.

Bleb Morphology Using Anterior-Segment Optical Coherence Tomography after Ahmed Glaucoma Valve Surgery with Tenon Capsule Resection

Objectives

To evaluate the internal morphology of blebs using anterior-segment optical coherence tomography (AS-OCT) and the surgical outcomes of Ahmed glaucoma valve (AGV) surgery with Tenon capsule resection compared to conventional AGV surgery in patients with refractory glaucoma. Patients and Methods. This randomised prospective study included 30 eyes from 30 patients (age range: 42-55 y) with refractory glaucoma from March 2018 to February 2020. The study included two groups: AGV with the Tenon capsule resection group (n = 15) and the conventional AGV surgery group (n = 15). Follow-up continued until 6 months after surgery. The primary outcome was intraocular pressure (IOP) and its association with the number of postoperative glaucoma medications, best corrected visual acuity, visual field, and postoperative complications. The internal morphology of the blebs in both groups was evaluated at 1-day, 1-week, 1-month, 3-month, and 6-month follow-up using AS-OCT in terms of the consequent changes in bleb wall thickness, bleb wall reflectivity, and bleb cavity morphology throughout the 6-month follow-up period.

Results

A significant reduction in IOP was found in both groups, with a greater reduction in group I, where the mean IOP decreased from 32.73 ± 2.12 mmHg in the preoperative period to 13.33 ± 1.59 mmHg after 6 months, whereas in group II, the mean IOP decreased from 33.2 ± 2.21 mmHg in the preoperative period to 14.27 ± 1.44 mmHg after 6 months (p value <0.05). The difference between the 2 groups in terms of the decrease in IOP was insignificant except at 1 and 3 months, where there was a significant difference (p value = 0.016 and 0.01 at 1 and 3 months, respectively). The bleb analysis revealed a significant reduction in the wall thickness in both groups at 1 and 3 months, which was mostly associated with the hypertensive phase. In group I, the bleb wall thickness decreased from 754.67 ± 53.93 μm in the first postoperative day to 684 ± 81.66 μm and 671.6 ± 69.48 μm at 1 and 3 months, respectively, while in group II, the bleb wall thickness decreased from 707.13 ± 31.7 μm in the first postoperative day to 499.53 ± 99.1 μm and 506 ± 76.91 μm at 1 and 3 months, respectively. There was a significant reduction in AS-OCT, and bleb reflectivity was insignificant throughout the follow-up period (p value >0.05). Regarding postoperative complications, the hypertensive phase occurred more frequently in group II (6 eyes, 40%) than in group I (2 eyes, 13.3%). Other complications were also reported more frequently in group II such as hypotony, shallow anterior chamber (AC), and tube exposure.

Conclusion

AS-OCT was beneficial in the analysis of bleb morphology after AGV surgery where there were more diffuse functioning multicystic blebs and less thinning in the bleb wall thickness during the hypertensive phase after resection of the Tenon capsule, which might be related to the less incidence of fibrosis around the surgical site.

[Methods of assessing the condition of filtering bleb after glaucoma surgery]

Currently, there is a need to assess the condition of structures at the surgery site after glaucoma intervention due to the necessity to decide further treatment tactics after performed operations, as well as the possibility of developing more advanced methods of surgical treatment of glaucoma. Despite the fact that there are several methods of examining the filtration bleb (FB), some of them have both clear advantages and significant disadvantages. This article reviews the possibilities of using optical coherence tomography (OCT), ultrasound biomicroscopy (UBM), thermography, confocal microscopy, and the Hyperemia-3 program for assessing the structural and functional state of the FB.

Conjunctival thickness as a predictive imaging biomarker for the glaucoma filtration surgery outcome: An optical coherence tomography study

IMPORTANCE

To analyse the preoperative conjunctival thickness in glaucomatous patients undergoing filtration surgery (FS), using optical coherence tomography (OCT).

BACKGROUND

The conjunctival status represents one of the most critical determinants of the FS outcome.

DESIGN

Retrospective study.

PARTICIPANTS

Sixty-seven patients candidate to FS for uncontrolled glaucoma were enrolled.

METHODS

OCT was performed at the superior bulbar conjunctiva before FS, and at bleb site at the last follow-up (LF-up) after surgery.

MAIN OUTCOME MEASURES

Preoperative full, epithelial, and stromal conjunctival thickness (FCT, CET, CST) and reflectivity (CR), and LF-up bleb-wall thickness (BT), reflectivity (BR) and intraocular pressure (IOP), were the major outcomes. The relations between preoperative parameters and LF-up-IOP, BT and BR were calculated.

RESULTS

FS was completely successful in 23 patients (group 1), successful with medications in 22 (group 2), and failed in 22 (group 3). FCT, CET and CST were lower, whereas CR higher, in group 3 compared to groups 1 and 2 (P < .05); BT was lower (P < .001), whereas BR higher (P < .05) in group 3 compared to group 1. FCT and CST were predictors of FS outcome with lower thickness associated with increased odds of failure (odds ratio 0.922, P = .08; 0.941, P = .025). LF-up-IOP inversely correlated with FCT and CST (r = -0.447, P = .003; r = -0.408, P = .007), whereas positively correlated with CR (r = 0.789, P < .001).

CONCLUSIONS AND RELEVANCE

Preoperative conjunctival thickness and reflectivity show significant correlations with the FS outcome, both in terms of IOP and bleb-wall features. Therefore, they may be proposed as predictive imaging biomarkers to estimate the risk of filtration failure.

Angiographic biomarkers of filtering bleb function after XEN gel implantation for glaucoma: an optical coherence tomography-angiography study

PURPOSE

To evaluate, using optical coherence tomography-angiography (OCT-A), the vascular features of good bleb function after XEN gel implantation (XGI) for uncontrolled glaucoma.

METHODS

Forty-three patients (43 eyes), who underwent XGI, were enrolled. According to the intraocular pressure (IOP) reduction, patients were classified into Group 1 (21 eyes; success) and Group 2 (22 eyes; failure). Optical coherence tomography-angiography (OCT-A) was performed to image the vascularization of the conjunctival bleb-wall. The main outcomes were as follows: vessel displacement areas (VDAs), major vessel displacement area (MVDA; mm2 ), non-flow whole area (NFWA; mm2 ) and bleb-wall vessel density (BVD; %). Co-registered B-scans were also considered to evaluate the bleb-wall cyst-like structure density and area (BCSD, cysts/mm2 ; BCSA, mm2 ), and the bleb-wall thickness (BT, µm).

RESULTS

Mean postoperative follow-up was 7.5 ± 0.14 months; Group 1 and 2 IOP were 14.0 ± 2.5 and 25.3 ± 2.1 mmHg, respectively (p < 0.001). Greater VDA (p < 0.001), MVDA (p = 0.046) and NFWA (p = 0.001) values, and lower BVD (p < 0.001) was found in Group 1 compared to Group 2. Group 1 showed higher BSCD, BSCA and BT values compared to Group 2 (p < 0.001). Postoperative IOP positively correlated with BVD (r = 0.567; p = 0.003), but negatively with VDAs, MVDA (r = -0.581, p = 0.002; r = -0.619, p = 0.001, respectively), BCSD, BCSA (r = -0.580; p = 0.002; r = -0.664; p < 0.001) and BT (r = -0.627, p = 0.001).

CONCLUSION

Successful filtration blebs after XGI present numerous and large areas of vessel displacement within the bleb-wall, along with a rarefied vascular network. These OCT-A features can be considered angiographic biomarkers of a good aqueous humour percolation through the bleb-wall layers.

The role of neuroinflammation in the pathogenesis of glaucoma neurodegeneration

The chapter is a review enclosed in the volume "Glaucoma: A pancitopatia of the retina and beyond." No cure exists for glaucoma. Knowledge on the molecular and cellular alterations underlying glaucoma neurodegeneration (GL-ND) includes innovative and path-breaking research on neuroinflammation and neuroprotection. A series of events involving immune response (IR), oxidative stress and gene expression are occurring during the glaucoma course. Uveitic glaucoma (UG) is a prevalent acute/chronic complication, in the setting of chronic anterior chamber inflammation. Managing the disease requires a team approach to guarantee better results for eyes and vision. Advances in biomedicine/biotechnology are driving a tremendous revolution in ophthalmology and ophthalmic research. New diagnostic and imaging modalities, constantly refined, enable outstanding criteria for delimiting glaucomatous neurodegeneration. Moreover, biotherapies that may modulate or inhibit the IR must be considered among the first-line for glaucoma neuroprotection. This review offers the readers useful and practical information on the latest updates in this regard.

Assessing the Status of Filtering Blebs at 5 Year Post- Trabeculectomy

BACKGROUND:

Glaucoma is a common cause of blindness in the world as well as in Vietnam. It is treated by many different methods but trabeculectomy is still the most popular and highly effective surgical method to treat this condition.

AIM:

To analyze the status of 5 years filtering blebs following trabeculectomy and to explore multiple factors associated with filtering blebs.

METHODS:

This is a retrospective, cross-sectional descriptive study. Eyes had been performed trabeculectomy for 5 years were included in these results. The filtering blebs were assessed using slit lamp and OCT. the OCT captured bleb area to evaluate fluid subconjunctival spaces, thickness and height of bleb and to evaluate the related factors

RESULTS:

A group of 106 primary glaucoma eyes of 97 patients (88 patients with 1 eye, 9 patients 2 eyes) had been performed trabeculectomy for 5 years were taken OCT anterior image. The proportion of female patients is 1.5 times that of male patients. IOP was controlled with or without topical medication in all eyes. The filtering bleb had a high echo reflection, which accounted for 42.5%, the average echo reflection was 38.6%, the low echo reflection response of 18.9%. 66% of the eyes had the aqueous space under the conjunctiva, 65.1% have the aqueous space under sclera flap, the average height of the bleb on OCT was 0.4 mm ± 0.3 mm. Young patients often have a higher rate of bleb fibrosis and loss of function than older patients

CONCLUSION:

OCT is capable of assessing the function of bleb. After 5 years of trabeculectomy, on the OCT image, most cases of blebs are maintaining drainage function.

Intra-operative optical coherence tomography in glaucoma surgery-a systematic review

The application of the OCT in clinical ophthalmology has expanded significantly since its introduction more than 20 years ago. There has been recent growing interest in the application of intra-operative optical coherence tomography (iOCT). The iOCT's ability to enhance visualisation and depth appreciation has the potential to be further exploited in glaucoma surgery, especially with the emergence of Minimally Invasive Glaucoma Surgery (MIGS)-to facilitate targeted device placement and fine surgical manoeuvres in the angles, the sub-conjunctival layer and the suprachoroidal space. Hence, this study aims to appraise the current literature on the applications of iOCT in glaucoma surgery. A total of 79 studies were identified following a literature search adhering to PRISMA guidelines. After full text evaluation, 10 studies discussing iOCT use in glaucoma surgery were included. Traditional glaucoma filtering procedures reviewed included trabeculectomy surgery, goniosynechiolysis, bleb needling and glaucoma drainage device implantation. MIGS procedures reviewed included canaloplasty, trabecular aspiration, ab-interno trabectome and the XEN45 gel stent. iOCT use in ophthalmic surgery is becoming increasingly prevalent and has already been applied in various surgeries and procedures in the field of glaucoma. With the greater adoption of MIGS, iOCT may further contribute in facilitating surgical techniques and improving outcomes. While iOCT offers many advantages, there are still limitations to be overcome-iOCT technology continues to evolve to optimise imaging quality and user-experience.

Evaluation of Functional Filtering Bleb Using Optical Coherence Tomography Angiography

Purpose

This study investigated whether filtering blebs can be evaluated using optical coherence tomography angiography (OCT-A) and compared vascularity parameters with conventional bleb grading systems.

Methods

A total of 92 patients with glaucoma, who underwent mitomycin C–augmented trabeculectomy, were enrolled in this study, and 92 eyes were assessed in total. The participants underwent OCT-A in external mode and anterior segment photography for bleb evaluation. For evaluation of bleb vascularity, a blinded observer carefully drew the bleb area on the original OCT-A image using a semiautomated program that calculated the color and brightness densities of the selected area. A blinded observer also classified the grades of the bleb vessels using the Indiana Bleb Appearance Grading Scale (IBAGS) and Moorfields Bleb Grading System (MBGS). The vascularity parameters using OCT-A were compared with the IBAGS and MBGS results. In addition, the correlation between intraocular pressure (IOP) and the bleb vascularity parameters was assessed.

Results

Vessel density measured by OCT-A demonstrated excellent inter- and intraobserver reproducibility. The color and brightness densities were positively correlated with the IBAGS and MBGS vascularity scores. There was no difference in accuracy when predicting IOP risk using vascularity scores from the IBAGS and MBGS or when estimating IOP risk using the color and brightness densities on the net reclassification index.

Conclusions

Bleb evaluation using OCT-A can evaluate vessel vascularity and showed correlation to the IBAGS and MBGS vascularity grading.

Translational Relevance

Bleb vascularity measurements using OCT-A could potentially provide objective and quantitative vessel parameters for bleb evaluation following trabeculectomy.

Longitudinal bleb morphology in anterior segment OCT after minimally invasive transscleral ab interno Glaucoma Gel Microstent implantation

Purpose

Like the classic trabeculectomy, the minimally invasive, ab interno XEN Glaucoma Gel Microstent (XEN‐GGM) creates a filtration bleb in the conjunctiva. The goal of this study was to investigate internal bleb morphology over time with anterior segment optical coherence tomography (AS‐OCT) after XEN‐GGM implantation.

Methods

In a prospective, single‐centre, single‐armed cohort study, blebs were characterized using AS‐OCT in 78 eyes of 60 patients at day 1, at weeks 1 and 2 and at months 1, 3, 6, 9 and 12 after XEN‐GGM implantation in patients with open‐angle glaucoma. Morphological bleb characteristics were correlated with IOP and surgical success.

Results

Anterior segment optical coherence tomography data indicate early and late bleb changes in the course of 12 months. Uniform blebs in AS‐OCTs showed higher IOPs at all examinations between week 1 (17.7 ± 4.8 mmHg versus 11.3 ± 7.1 mmHg, p = 0.001) and month 3 (16.4 ± 6.1 versus 13.4 ± 6.1, p = 0.04). Subconjunctival tissue separation bleb morphology was associated with lower mean IOPs during the course of 12 months (r = −0.75, p = 0.031). Predictors for surgical failure at month 12 were microcystic multiform bleb morphology in AS‐OCT at month 3 (60% versus 15%, relative risk 4.0, p = 0.043) and uniform bleb morphology at month 9 (33% versus 23%, relative risk 1.4, p = 0.015).

Conclusion

Bleb appearance after XEN surgery seems to be different to classic trabeculectomy literature. The present data suggest correlation of IOP and surgical long‐term success with bleb morphology in AS‐OCT. Prevalence of small diffuse cysts is directly associated with lower IOPs, while cystic encapsulation at 3 months predicts higher surgical failure.

[Optical coherence tomography for examination of glaucoma surgery site]

The article reviews the results of using optical coherence tomography (OCT) - a non-invasive non-contact examination method for obtaining a tomographic slice image of the site of glaucoma surgery. The method helped reveal the functional relationships between the newly created outflow pathways and various parameters of the filtering bleb such as its linear dimensions, wall structure, presence of microcysts, position of drainage, etc. Due to its high resolution and noninvasiveness, OCT can be reliably used to examine the structure of aqueous outflow pathways in different postoperative periods with accuracy close to morphometric. The amount of data that had been obtained with the method has allowed the creation of new classifications and clarification of OCT-relevant prognostic signs for glaucoma surgery site.

The CLASS Surgical Site Characteristics in a Clinical Grading Scale and Anterior Segment Optical Coherence Tomography: A One-Year Follow-Up

Purpose

We combined a clinical grading scale and swept source anterior segment OCT to describe the successful and failed CLASS.

Material and Methods

23 patients in the successful group and 17 patients in the failed group were compared in terms of the IBAGS grades and AS-OCT findings at one, three, and twelve months postoperatively.

Results

The majority in the successful group presented shallow blebs (91%, 57%, and 52% at 1M, 3M, and 12M, resp.). 59% of the failed group presented no bleb (H0 E0) from the early postoperative period with the rate increasing to 88% at 3M and 100% at 12M. The scleral lake was detected in all the successful patients. The successful group showed significantly higher rates of TDM integrity (P < 0.001), IF (P < 0.001), and SCF (P < 0.05), but there were no significant differences in the rates of microcysts between the groups (P > 0.05). We found a significant decrease in the SL anteroposterior extent (P=0.003) and SL height (P < 0.001) over time, with no significant correlation between the above parameters and IOP.

Conclusions

The subconjunctival bleb may be a sign of the successful CLASS when it matches the AS-OCT findings of TDM integrity, maintained scleral lake, and intrascleral fluid. A validated OCT pixel intensity measurement is required to evaluate the bleb reflectivity.

Anterior-Segment Optical Coherence Tomography for Predicting Postoperative Outcomes After Trabeculectomy

PURPOSE

To determine whether anterior-segment optical coherence tomography (AS-OCT) can be used to predict post-trabeculectomy bleb outcomes.

MATERIALS AND METHODS

We divided 58 eyes of 47 trabeculectomy patients into success or failure groups based on their status at 12 months after surgery. We then compared various AS-OCT measurement parameters between the two groups at 1 and 2 weeks and 1, 3, 6, and 12 months. We also analyzed the early post-trabeculectomy bleb parameters with multiple logistic regression, stepwise multiple regression, and the receiver operating characteristic (ROC) curve, to evaluate the power of these parameters to predict long-term outcomes.

RESULTS

Intraocular pressure 3 or more months after trabeculectomy was significantly lower in the success group than the failure group (all: P < 0.0016). Cleft volume was significantly higher 6 or more months after trabeculectomy in the success group than the failure group (P = 0.0027 and <0.0016). Reflectivity of the bleb wall was significantly higher in the failure group than the success group at 2 weeks and all later time points (all: P < 0.0016). Reflectivity of the bleb wall at 2 weeks after trabeculectomy was a risk factor for failure, with an odds ratio (OR) for failure of 2.48 (95% confidence interval, 1.31-4.68, increasing per 10 AU). The area under the ROC curve for reflectivity of the bleb wall at 2 weeks after trabeculectomy was 0.775 when the cutoff value was set at 122.8, with sensitivity, specificity, and OR of 78.3%, 80.0%, and 14.4, respectively. A stepwise multiple regression analysis showed that reflectivity of the bleb wall at 2 weeks was an independent factor indicating postoperative bleb survival period (β = -0.39, P = 0.007).

CONCLUSIONS

Reflectivity of the bleb wall, measured by AS-OCT, may be an early post-trabeculectomy predictor of bleb outcome.

Qualitative analysis of repaired filtering blebs with anterior segment-optical coherence tomography

OBJECTIVE

To provide a qualitative analysis of filtering blebs after being surgically repaired due to late blebs leaks.

METHODS

Blebs were studied 6 months after surgical reparation using AS-OCT Triton (Topcon^®). An analysis was made of the morphological pattern and internal structures of blebs, including the covering, in 10 patients. The images were obtained using OCTs at a wavelength of 1050nm.

RESULTS

According to the Hirooka classification, three different patterns were found in the structure of blebs, which made it possible to correlate them with their functionality. A full covering was observed in 70% of the cases, and they showed sub-epithelial cysts (cystoid pattern). Two cases showed a full conjunctival retraction without Tenon's covering. The walls were thin, with a de-structured bleb (diffuse pattern) being visualised. In the third group, the image showed a partial conjunctival retraction with Tenon's covering. There were some sub-epithelial diffuse cysts with walls following a laminar pattern.

CONCLUSION

Using AS-OCT, it is possible to study the bleb's characteristics in detail, as well as the cover, in the case of blebs requiring repair due to late leaks, using conjunctival advancement. It allows for the early visualisation of conjunctival retractions that were not visible in a slit lamp, and to predict the functionality of the blebs by their morphology.

Pathogenesis of Uveitic Glaucoma

Uveitic glaucoma consists one of the most serious complications of intraocular inflammation and, despite its rarity, is considered as one of the leading causes of preventable loss of vision worldwide. It has been associated with a wide spectrum of inflammatory diseases, but its pathogenesis is still not fully comprehended. It appears that the type of inflammation, the steroid-response and the anatomical alterations of the anterior chamber play a pivotal role. To our knowledge, the mechanisms may be both acute and chronic. The main targets of the treatment are to control the inflammation and reduce the intraocular pressure (IOP). The management of glaucoma associated with uveitis remains an extremely challenging condition for ophthalmologists. The successful treatment of uveitic glaucoma is inextricably correlated with prompt and immediate therapeutic decisions. Very often a solid collaboration between clinicians from different specialties may be required for treating the underlying disease.

Further understanding of its pathogenesis can indicate therapeutic targets and may lead to the development of new and more efficient therapeutic approaches. New glaucoma surgical modalities may ameliorate the prognosis after surgical intervention, but this calls for further evaluation. This study aims to highlight the complexity of uveitic glaucoma analyzing the main pathogenetic mechanisms and the correlations with the inflammatory response.

In vitro mitomycin C absorption and delivery with different sponge materials used in filtering surgery

PURPOSE

The purpose of this study is to evaluate and compare mitomycin C (MMC) absorption and delivery in different materials used in filtering surgery.

METHODS

This is an in vitro study comparing polyvinyl alcohol triangular sponges (TS6, TS8), polyvinyl alcohol fluid wicks (EFW), and absorbable gelatin sponges (AGS3, AGS5), from which five different types of transport units were obtained. Seven pieces of sponge of each transport unit type were obtained as follows: two transverse strips were obtained at 6 and 8 mm from the apex of TS and divided into three equal pieces; 4×4 mm pieces of EFW; 3×3 and 5×5 mm pieces of absorbable gelatin sponges were cut. Filter paper was placed on a precision scale (0.01 mg). The seven sponge pieces of each type were weighed three times consecutively in dry and wet states, the latter after immersion for 15 seconds in 0.2 mg/mL MMC. The difference between the weights of the dry and wet filter paper at the end of each measurement sequence was also calculated and considered as an estimate of the amount of mitomycin delivered.

RESULTS

The amounts of MMC absorbed by each transport unit were as follows: (mean ± standard deviation) 27.43±5.13 for TS6, 31.91±6.63 for TS8, 15.96±2.23 for EFW, 17.96±2.05 for AGS3, and 33.81±2.05 for AGS5. The amounts of MMC delivered to the filter paper were as follows: 21.70±2.84 for TS6, 23.83±4.03 for TS8, 12.93±1.75 for EFW, 14.69±1.79 for AGS3, and 27.30±1.58 for AGS5.

CONCLUSION

Percentage MMC delivered was similar for all materials, but there was a tendency for greater delivery using larger sponges and greater homogeneity in delivery with AGS5. No statistical differences were found in percentage delivered by the different transport materials.

Visualization of conventional outflow tissue responses to netarsudil in living mouse eyes

Visual impairment due to glaucoma currently impacts 70 million people worldwide. While disease progression can be slowed or stopped with effective lowering of intraocular pressure, current medical treatments are often inadequate. Fortunately, three new classes of therapeutics that target the diseased conventional outflow tissue responsible for ocular hypertension are in the final stages of human testing. The rho kinase inhibitors have proven particularly efficacious and additive to current therapies. Unfortunately, non-contact technology that monitors the health of outflow tissue and its response to conventional outflow therapy is not available clinically. Using optical coherence tomographic (OCT) imaging and novel segmentation software, we present the first demonstration of drug effects on conventional outflow tissues in living eyes. Topical netarsudil (formerly AR-13324), a rho kinase/ norepinephrine transporter inhibitor, affected both proximal (trabecular meshwork and Schlemm's Canal) and distal portions (intrascleral vessels) of the mouse conventional outflow tract. Hence, increased perfusion of outflow tissues was reliably resolved by OCT as widening of the trabecular meshwork and significant increases in cross-sectional area of Schlemm's canal following netarsudil treatment. These changes occurred in conjunction with increased outflow facility, increased speckle variance intensity of outflow vessels, increased tracer deposition in conventional outflow tissues and decreased intraocular pressure. This is the first report using live imaging to show real-time drug effects on conventional outflow tissues and specifically the mechanism of action of netarsudil in mouse eyes. Advancements here pave the way for development of a clinic-friendly OCT platform for monitoring glaucoma therapy.

Quantification of the filtering bleb's structure with anterior segment optical coherence tomography

BACKGROUND

The aim of the study is to determine the relationship between post-trabeculectomy bleb structure evaluated using anterior segment optical coherence tomography (AS-OCT) and postoperative intraocular pressure (IOP).

DESIGN

Rretrospective is showed for the design of this study.

PARTICIPANTS

There are twenty-seven eyes of 27 trabeculectomy patients.

METHODS

We drew contour lines for the bleb and cleft on 8-radius-scanned AS-OCT images, and determined correlations of AS-OCT measurements to postoperative IOP at 6 months.

MAIN OUTCOME MEASURES

The parameter used in this study is an anterior segment optical coherence tomography measurements of bleb structure, including cleft volume, wall volume, and the brightness of the bleb wall.

RESULTS

We found significant correlations between postoperative IOP at 6 months and cleft volume at 3 and 6 months (r = -0.56, P = 0.007 and r = -0.82, P <0.001), bleb wall volume at 6 months (r = -0.48, P = 0.042), bleb vertical brightness at 3 and 6 months (r = 0.73, P < 0.001 and r = 0.49, P = 0.040), and bleb horizontal brightness at 1 week, 2 weeks, 3 months and 6 months (r = 0.49, P = 0.016, r = 0.65, P < 0.001, r = 0.52, P = 0.013 and r = 0.71, P = 0.001). A stepwise multiple regression analysis of bleb structural measurements made ≤2 weeks postoperatively showed that the strongest independent factor indicating postoperative IOP at 6 months was bleb horizontal brightness at 2 weeks (β = 0.50, P = 0.006).

CONCLUSIONS

Early postoperative AS-OCT measurements of blebs, especially horizontal brightness of the bleb wall, were associated with postoperative IOP at 6 months. AS-OCT measurements of blebs may be useful predictors of trabeculectomy outcomes.

Current Approach in the Diagnosis and Management of Uveitic Glaucoma

Uveitic glaucoma (UG) typically is associated with very high intraocular pressure (IOP) and more intense optic nerve damage than other glaucoma types. This secondary glaucoma requires an early diagnosis and adequate management of both uveitis and glaucoma. It is mandatory to identify the mechanisms of IOP elevation that in many eyes have multiple combined mechanisms. Management of these patients commonly requires an interdisciplinary approach that includes a glaucoma specialist and rheumatologist to control the inflammation and IOP. Glaucoma surgery is required early in these patients due to the high IOP usually present and is less successful than in primary open-angle glaucoma. Recurrent uveitic episodes, multiple mechanism, and the complications associated with uveitis make surgical management of UG challenging. In this review, the management and treatment of UG are updated to clarify the pathogenesis and prevent optic nerve damage.

Advanced Morphological and Functional Magnetic Resonance Techniques in Glaucoma

Glaucoma is a multifactorial disease that is the leading cause of irreversible blindness. Recent data documented that glaucoma is not limited to the retinal ganglion cells but that it also extends to the posterior visual pathway. The diagnosis is based on the presence of signs of glaucomatous optic neuropathy and consistent functional visual field alterations. Unfortunately these functional alterations often become evident when a significant amount of the nerve fibers that compose the optic nerve has been irreversibly lost. Advanced morphological and functional magnetic resonance (MR) techniques (morphometry, diffusion tensor imaging, arterial spin labeling, and functional connectivity) may provide a means for observing modifications induced by this fiber loss, within the optic nerve and the visual cortex, in an earlier stage. The aim of this systematic review was to determine if the use of these advanced MR techniques could offer the possibility of diagnosing glaucoma at an earlier stage than that currently possible.