Topical Administration of Bevacizumab to Facilitate the Functional Filtering Bleb After Trabeculectomy in the Rabbit

Purpose: To evaluate the effects of bevacizumab in 3 different application methods, subconjunctival injection (SCI), hyaluronic acid retardant (HAR), and eye drop (ED), on attenuating scar formation in the filtering bleb. Methods: Trabeculectomy (TRAB) was performed on New Zealand rabbits. TRAB rabbits were intervened with bevacizumab SCI, HAR, ED, or mitomycin C, respectively. Intraocular pressure (IOP) of 1, 7, 14, and 28 days after TRAB was recorded, and the bleb survival rate was analyzed. Bleb height, area, and vascularization were evaluated using anterior segment optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) at 7, 14 and 28 days after surgery. A histopathology examination of the bleb tissue was performed. The expression levels of vascular endothelial growth factor (VEGF)-A, interleukin (IL)-1α, tumor necrosis factor-alpha (TNF-α), transforming growth factor-β1 (TGF-β1), and α-smooth muscle actin (α-SMA) were measured by Western blot. Results: Bevacizumab significantly reduced postoperative IOP and increased the survival of the filtering bleb, especially in the ED group. Less vascularization was shown in the SCI, HAR, and ED groups. Histopathological results showed the fewest levels of scarring and fibrosis in the ED group. The local VEGF-A, IL-1α, and TNF-α expression levels after bevacizumab ED were decreased, combined with suppression of TGF-β1 and α-SMA. Conclusions: Postoperative use of bevacizumab EDs was an effective application method for improving surgical outcomes after TRAB in rabbits. It might be effective in preventing scarring of the filtering bleb by antivascularization and anti-inflammation.

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.

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.

A modified model of glaucoma filtering surgery in Sprague-Dawley rats

Animal models are useful in glaucoma research to study tissue response to wound healing. Smaller animals such as rats offer additional advantages in terms of availability of detection antibodies and microarrays with cheaper maintenance costs. In this study, we describe a glaucoma filtering surgery (GFS) model in adult Sprague-Dawley rats by performing a sclerostomy using a 26-G needle and additionally placing a silicone tube (27 G) connecting the anterior chamber to the subconjunctival space to maintain a patent fistula for the flow of aqueous humor, thus providing a more definitive bleb. This technique will be useful in identifying and modifying newer targets in the wound healing process in order to improve surgical outcomes following GFS.

Predictive Value of Bleb Vascularity after Mitomycin C Augmented Trabeculectomy

Background: To evaluate the relationship between bleb vascularity and surgical outcome one year after mitomycin C (MMC) augmented trabeculectomy. Methods: This was a prospective study of 51 eyes of 44 patients after MMC-augmented primary trabeculectomy with follow-up of 12 months. The total vessel area of a bleb was measured with ImageJ software on color photographs of the bleb on day 1 and 14, then months 1, 3, 6 and 12 after trabeculectomy. Blebs were classified clinically as successful (intraocular pressure (IOP) ≤ 18 mmHg and a >30% reduction in IOP without antiglaucoma medications or additional surgical interventions) or failed. Linear regression analysis was performed to determine the correlation of bleb vascularity with IOP and outcome. Results: At 1 year, 40 eyes (78.4%) were classified as successful and 11 eyes (21.6%) as failed. The mean bleb vascularity at 1, 3 and 12 months after surgery was significantly higher in failed blebs (16.31% vs. 13.01%, p = 0.005, 14.93% vs. 10.15%, p = 0.001, 8.99% vs. 6.37%, p = 0.011, respectively). There were no significant differences in mean bleb vascularity at 1 and 14 days postoperatively in successful and failed blebs. The results revealed a significant association between vessel area at 1 and 3 months after trabeculectomy with IOP at 6 months postoperatively (p = 0.005 and p = 0.009, respectively). Conclusions: In this prospective study, we demonstrated a strong relationship between bleb vascularity and the surgical outcomes of trabeculectomy. Vascularity of the filtering bleb during early postoperative period was not correlated with IOP or success of trabeculectomy at one year. Increased bleb vascularity 1, 3 and 12 months after trabeculectomy appears to predict surgical failure at 1 year after trabeculectomy.

[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.

Bleb grading by photographs versus bleb grading by slit-lamp examination

PURPOSE

Using a bleb-grading system clinically facilitates long-term follow-up of patients with previous glaucoma surgery. Clinical evaluation of these patients can be challenging for untrained ophthalmologists. Morphological bleb configuration might influence planning of follow-up visits in glaucoma patients due to different and individual prognosis after trabeculectomy. In this study, we compared the MaBAGS (Mainz Bleb Appearance Grading System), a classification system for filtering blebs with other classification systems (MBGS/Moorfields Bleb Grading System, IBAGS/Indiana Bleb Appearance Grading Scale) in reference to usability and reliability and compare it to grading by bleb photographs.

METHODS

Forty-two eyes of 31 patients after trabeculectomy were included. Three observers, two senior and one junior observer, graded all blebs using MaBAGS, MBGS and IBAGS during slit-lamp examination. Bleb photographs were reviewed at least 4 weeks after clinical examination. Statistical analysis was performed to determine agreement between the observers using intraclass correlation coefficients.

RESULTS

With MaBAGS, excellent and good levels of agreement were found for vascularity indices, Seidel test and transparency. Parameters for area and height yielded moderate agreement, while indices for conjunctival mobility and microcysts failed to show satisfying levels of agreement. Using MBGS resulted in excellent and good interobserver consistency for parameters regarding subconjunctival blood, Seidel test, and central and peripheral vascularity. Height and nonbleb vascularity reached moderate levels of agreement. Agreement for area parameters was low. With IBAGS, good levels of agreement were found for height and vascularity, and moderate for extent. In all grading systems, consistency was considerably better between the two experienced observers compared to the inexperienced grader.

CONCLUSIONS

MaBAGS shows good reproducibility. Using such a grading system improves precision of the description of a highly variable clinical finding. The reliability of grading by slit-lamp examination exceeds that of grading on photographs.

Quantitative analysis of functional filtering bleb size using Mask R-CNN

Background

Deep learning has had a large effect on medical fields, including ophthalmology. The goal of this study was to quantitatively analyze the functional filtering bleb size with Mask R-CNN.

Methods

This observational study employed eighty-three images of post-trabeculectomy functional filtering blebs. The images were divided into training and test groups and scored according to the Indiana Bleb Appearance Grading Scale (IBAGS) system. Then, 70 images from the training group were used to train an automatic detection system based on Mask R-CNN and perform a quantitative analysis of the function bleb size. Thirteen images from the test group were used to evaluate the model. During the training process, left and right image-flipping algorithms were used for data augmentation. Finally, the correlation between the functional filtering bleb area and the intraocular pressure (IOP) was analyzed.

Results

The 83 functional filtering blebs have similar morphological features. According to IBAGS, the functional filtering blebs have a high incidence of E1/E2, H1/H2, and V0/V1. Our Mask R-CNN-based model using the selected parameters achieves good results on the training group after a 200-epoch training process. All the Intersection over Union (IoU) scores exceeded 93% on the test group. The Spearman correlation coefficient between the area of functional filtering blebs and the IOP value was −0.757 (P<0.05).

Conclusions

Deep learning is a powerful tool for quantitatively analyzing the functional filtering bleb size. This technique is suitable for use in monitoring post-trabeculectomy filtering blebs in the future.

Prospective study on a novel treatment for leaking cystic bleb: Efficacy and safety of collagen crosslinking

IMPORTANCE

Management of cystic bleb leak is difficult. It would be essential to look for a method to strengthen the original pathological conjunctiva and reverse bleb leak.

BACKGROUND

To evaluate the long-term efficacy and safety of collagen crosslinking in patients with leaking cystic bleb.

DESIGN

Prospective interventional case series at a university-based hospital.

PARTICIPANTS

Twelve eyes in 12 subjects with late-onset bleb leak from cystic bleb, without indications for prompt surgical interventions were included.

METHODS

The subjects underwent crosslinking with 0.1% riboflavin application to bleb surface, followed by ultraviolet irradiation for 30 minutes. The subjects were followed up at baseline and at 1 week, 1 month, 3 months, 6 months post-treatment and then every 6 months afterwards.

MAIN OUTCOME MEASURES

Interval from treatment to cessation of bleb leak, recurrence rate of bleb leak and side effects of treatment.

RESULTS

The mean follow-up after crosslinking was 29.33 ± 12.45 months. Bleb leak subsided in 11 (92%) of 12 patients after a single session of crosslinking, after 1 to 8 weeks (median 3 weeks). Time to leak cessation was significantly correlated with the number of prior glaucoma interventions (R = .71, P = .014). Bleb wall at 3 months was significantly thicker than at baseline (0.70 ± 0.67 vs 0.81 ± 0.62 mm, P = .008). None of the patients experienced any complications.

CONCLUSIONS AND RELEVANCE

Crosslinking achieves resolution of cystic bleb leak which lasts for at least 12 months, without the need of subsequent surgical interventions. Crosslinking is a simple, non-invasive treatment for bleb leak. It aims to restore the integrity of conjunctiva.

[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.

Functional evaluation of the filtering bleb by ultrasound biomicroscopy after trabeculectomy with mitomycin C

AIM

To study the role of ultrasound biomicroscopy (UBM) in the assessment of the bleb function after trabeculectomy with mitomycin C (MMC).

METHODS

This was a cross-sectional study including all cases had undergone trabeculectomy with MMC 0.2 mg/mL for 3min. Participants were recruited from the follow-up cases at Department of Ophthalmology, Tanta University in the period from August 2015 to August 2016. Full history taking and ophthalmological examination were performed. Intraocular pressure (IOP) was measured using Goldmann applanation tonometry and the history of prescribed postoperative antiglaucoma medications was recorded. Accordingly, the trabeculectomy blebs were divided clinically into successful blebs when the IOP post-operative was ≤18 mm Hg without medications. Scanning examination of the filtering bleb using UBM examination was performed at the period from 2 to 36mo after trabeculectomy (13.6±9.7mo).

RESULTS

This study included 33 trabeculectomy filtering blebs of 25 patients (9 males and 16 females). The mean age of patients was 53.2±14.2y (range 25-71y). We had 20 eyes with complete success, 9 eyes with qualified success, and 4 eyes with failure after trabeculectomy with MMC. The blebs were classified into successful blebs (IOP ≤18 mm Hg without antiglaucoma medications), others were classified into qualified successful and failed blebs. There was a significant correlation between certain UBM findings (intra-bleb reflectivity, draining sub-scleral tract, bleb height, and intrableb fluid cysts) and cases with different grades of clinical functional success (P<0.01).

CONCLUSION

UBM is an objective tool in the functional assessment of the post-trabeculectomy filtering bleb through a significant correlation between certain UBM parameters and the different grades of clinical functional success.

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.

Blunt needle revision with viscoelastic materials via the anterior chamber for early failed filtering blebs after trabeculectomy

Purpose

To report a new technique of blunt needle revision with viscoelastic materials via the anterior chamber for the treatment of early failed filtering blebs and elevated intraocular pressure after trabeculectomy, in which digital ocular massage and laser suture lysis have been ineffective.

Methods

A 27-gauge blunt needle attached to a syringe containing viscoelastic material was inserted into the anterior chamber from the inferior paracentesis. The needle tip was inserted into the subscleral flap space from the filtering fistula at the anterior chamber side, and the scleral flap was lifted bluntly. The needle tip was then inserted into the subconjunctival space where the viscoelastic agent was injected and the adhesion between the sclera and conjunctiva was separated bluntly. Blunt needle revision via the anterior chamber was performed 14 times in six eyes of six patients at Saitama Medical Center, Jichi Medical University from January 2007 to May 2009. All procedures were performed within 1 month after trabeculectomy.

Results

The intraocular pressure remained 21 mmHg or lower for more than 6 months in three of six eyes. Slight bleeding from the iris occurred in one of the 14 procedures, and hypotony (intraocular pressure below 5 mmHg) occurred in one of the 14 procedures. No serious complications developed.

Conclusion

Blunt needle revision via the anterior chamber for early failed filtering blebs is a new, simple, and safe procedure.