In vivo confocal microscopy study of blebs after filtering surgery

Ocular surface and glaucoma, a mutual relationship. Practical suggestions for classification and management

The chronic use of glaucoma medications could improve the development of an ocular comorbidity, the glaucoma therapy-related ocular surface disease. This could be related to the exposure of the conjunctiva to preservatives, but also active compounds such as prostaglandin analogues may improve the risk of ocular surface inflammation. Inflammation has a negative impact on tolerability and adherence to eyedrops and to the outcome of filtration surgery as well. A stratification of glaucoma patients based not only on visual field progression but also on glaucoma therapy-related ocular surface disease would be desirable for a strategic management. Early diagnosis, individualized treatment, and safe surgical management should be the hallmarks of glaucoma treatment. One of the main issues for the proper and successful management of patients is the right timing, effectiveness and safety for both medical and surgical treatment options leading to a precision medicine in glaucoma disease as the best modern treatment.

Multi-Quantitative Assessment of AS-OCTA Complemented AS-OCT for Monitoring Filtering Bleb Function After Trabeculectomy

Purpose

The purpose of this study was to explore a quantitative grading system of the filtering bleb combined anterior segment optical coherence tomography angiography (AS-OCTA) vascular features and optical coherence tomography (OCT) morphological features.

Methods

One hundred three eyes of 103 patients diagnosed with primary open-angle glaucoma and undergone trabeculectomy over 6 months were divided into success and failure groups according to postoperative intraocular pressure (IOP) level. Vessel density (VD) and vessel diameter index (VDI) were examined by AS-OCTA. Bleb's morphology, including bleb height (BH), and microcyst-structure (MCS) were detected by AS-OCT. Multi-vascular model score (MVMS) was calculated by comprehensive factor analysis, and the comprehensive grading system (MVMS-MCS-BH) was analyzed by linear regression. The efficiency our method was verified by receiver operating characteristic (ROC) analysis.

Results

The VD and VDI were higher in the failure group and closely related to post-trabeculectomy IOP (all P = 0.000). The MVMS was mostly consisted of VD in all regions, and VDIs of nasal, central, and temporal positions in sequence. MVMS ≥0, BH <1.33, and non-MCS were significantly associated with IOP increasing (coefficient = -3.23, -3.69, and 8.10, all P = 0.000). MVMS-BH-MCS got a higher area under curve (AUC), sensitivity, and specificity (0.92, 100%, and 80.30%) than the slit-lamp method (0.62, 72.20%, and 46.43%, respectively).

Conclusions

The quantitative vascular characteristics detected by AS-OCTA were significant for the bleb monitor. The MVMS-BH-MCS grading system had achieved outstanding accuracy in reflecting the surgical results.

Translational Relevance

The multi-vascular biomarker and comprehensive evaluation combined vascular and morphological parameters yield useful information on surgical outcomes, and help ophthalmologists to monitor patients effectively.

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.

Safety and Efficacy of Three Variants of Canaloplasty with Phacoemulsification to Treat Open-Angle Glaucoma and Cataract: 12-Month Follow-Up

Background: A single-center prospective randomized observational study to compare three types of canaloplasty, i.e., ab externo (ABeC), minicanaloplasty (miniABeC) and ab interno, (ABiC) combined with cataract surgery in primary open-angle glaucoma (POAG) patients over 12 months. Methods: 48 POAG patients underwent one of three canaloplasty procedures: ABeC (16 eyes), miniABeC (16 eyes) or ABiC (16 eyes) or combined with phacoemulsification. Patients were assessed at baseline, at day 0–1–7 and at month 1–3–6–12. Successful treatment was defined as unmedicated IOP reduction ≥20%. Complete surgical success was defined as an IOP ≤ 15 mmHg without medications, and a qualified surgical success as IOP ≤ 15 mmHg with or without medications. Results: Pre-washout IOP median values (mmHg) were 17 (ABeC), 18 (miniABeC) and 17 (AbiC) and decreased at 12-month follow up postoperatively to 13 (p = 0.005), 13 (p = 0.004) and 14 (p = 0.008), respectively—successful treatment was achieved in approximately 100% of patients for ABeC and in 93.8% for both miniABeC and AbiC groups. Preoperatively, the median number of medications was 2.0 (range 1–3) (ABeC), 2.0 (1–3) (miniABeC) and 2.0 (0–4) (ABiC); 12-month post-operatively, all medications were withdrawn except in two patients (followed miniABeC and AbiC). Conclusions: The three variants of canaloplasty significantly reduced IOP and the number of medications in patients with mild to moderate POAG and gave no significant complications.

Comparison of Ex-PRESS implantation versus trabeculectomy combined with phacoemulsification in primary open-angle glaucoma: a retrospective in vivo confocal microscopy study

BACKGROUND

To compare the efficacy of Ex-PRESS implantation versus trabeculectomy combined with phacoemulsification.

METHODS

A retrospective 12-month study on patients with coincident primary open-angle glaucoma (POAG) and cataract. The patients underwent combined phacoemulsification and Ex-PRESS implant (Phaco-ExPRESS, n = 35) or phacotrabeculectomy (Phaco-Trab, n = 35). The morphological structures of the filtering bleb were examined by slit-lamp, anterior segment optical coherence tomography (AS-OCT) and in vivo confocal microscopy (IVCM). Complete success was defined as postoperative intraocular pressure (IOP) < 18 mmHg without the use of anti-glaucoma medication. Qualified success was defined as postoperative IOP < 18 mmHg with or without anti-glaucoma medications. The data were collected preoperatively and postoperatively at 2 weeks, 1 month, 3 months, 6 months, and 12 months.

RESULTS

No significant difference in the variables such as age, IOP and perimetry was found between the groups of Phaco-ExPRESS and Phaco-Trab. At the one-year postoperative visit for filtering blebs, Phaco-ExPRESS increased the mean area of epithelial microcysts significantly from 0.10 ± 0.05 to 0.20 ± 0.09 μm² per μm², while Phaco-Trab decreased the mean area significantly from 0.08 ± 0.04 to 0.04 ± 0.06 μm² per μm². Notably, the hyperreflective dots detected by IVCM decreased by 84.9% in Phaco-ExPRESS but increased by 36.3% in Phaco-Trab. The hyperreflective dots were further identified as neutrophil- and monocyte-like cells. The number of these cells were negatively correlated with the microcysts area (r =  - 0.7, P < 0.01) but positively associated with the grade of connective tissue (r = 0.5, P < 0.01). By creating different microstructural changes in the filtering blebs, Phaco-ExPRESS produced a higher complete success rate (84.9% vs. 41.2%, P < 0.01) and significant decrease in the number of anti-glaucoma medications (P < 0.01) when compared with those in Phaco-Trab. However, the qualified success showed no significant difference between the two groups (100.0% vs. 91.2%, P = 0.24).

CONCLUSIONS

At the one-year follow-up, Phaco-ExPRESS generated better filtering bleb with larger area of microcysts, looser connective tissues, and less inflammation than that of Phaco-Trab, providing adequate IOP control and less IOP-lowering medications. These findings indicate that Phaco-ExPRESS could be more preferred than Phaco-Trab for the treatment of patients with coincident POAG and cataract.

Preparing the ocular surface for glaucoma filtration surgery: an unmet clinical need

The mutual relationship among medical therapy, ocular surface (OS) and filtration surgery (FS) represents one of the most crucial issues in glaucoma management. As the long-term use of intraocular pressure-lowering medications significantly affect the OS health, patients with an uncontrolled disease frequently undergo glaucoma surgery in less-than-ideal conditions. As we known, OS changes strongly affect the post-operative bleb filtration capability. Therefore, improving the OS conditions before proceeding with FS is needed. Currently, given the rapid diffusion of new surgical procedures, this need is even more perceived. Nevertheless, despite surgeons retain the OS preparation of primary importance, and recognize the OS disease (OSD) as the only modifiable risk factor for filtration failure, there is no agreement on which strategies should be preferred to prepare patients. This is largely due to the lack of validated guidelines, which forces clinicians to adopt personal approaches based on evidence derived from low-quality studies. In this review, we provided an overview of risk factors involved in the FS failure, with particular attention to those depending on OS changes, and how OSD negatively affects the aqueous humor resorption after surgery. Moreover, we reported the most exploited measures to mitigate the OSD before surgery, the possible reasons underlying the absence of shared approaches, and the upcoming area of intervention to preserve the OS health during glaucoma management. Finally, based on the current evidence, we proposed a pre-operative outline reporting the main risk factors that should be considered before surgery, and the therapeutical options available to improve the OS.

Effects of Valproic Acid and Mitomycin C Combination Therapy in a Rabbit Model of Minimally Invasive Glaucoma Surgery

Purpose

This study aimed to compare the effectiveness of combination therapy consisting of low-dose mitomycin C (MMC) and valproic acid (VPA) against high-dose MMC for improving the scar phenotype in minimally invasive glaucoma surgery (MIGS).

Methods

A rabbit model of MIGS incorporating the PreserFlo MicroShunt was treated with high (0.4 mg/mL) or low (0.1 mg/mL) doses of MMC or with combination therapy consisting of low-dose (0.1 mg/mL) MMC and VPA. Operated eyes were examined by live ocular imaging, histochemical evaluation, multiphoton quantitation of collagen characteristics, and molecular analyses.

Results

Although high-dose MMC obliterated the vasculature, combination therapy vastly improved the postoperative tissue morphology by maintaining the vasculature without increased vascularization. Combination therapy also altered collagen morphology and reduced encapsulation of the MicroShunt distal end, which remained at risk with MMC treatment alone. Multiphoton quantitation indicated that the combination therapy significantly reduced collagen density and fiber dimensions compared with monotherapy. At the molecular level, combination therapy significantly reduced Vegfa, Vegfc, and Vegfd expression and inhibited Col1a1 upregulation from baseline levels, all of which low-dose MMC alone was unable to achieve. Notably, COL1A1 protein levels appeared more consistently suppressed by combination therapy compared with high-dose MMC alone.

Conclusions

Compared with high-dose MMC, combination therapy was less toxic by sparing the vasculature and potentially more effective in reducing scarring via the regulation of collagen content and organization.

Translational Relevance

VPA may be combined with low-dose MMC to replace high-dose MMC to deliver safe and effective anti-scarring outcomes.

Effect of valproic acid on functional bleb morphology in a rabbit model of minimally invasive surgery

Purpose

To determine the effect of valproic acid (VPA) on bleb morphology and scar characteristics in a rabbit model of minimally invasive glaucoma surgery (MIGS).

Methods

Nine New Zealand white rabbits were subjected to MIGS with intraoperative implantation of the PreserFlo MicroShunt. Rabbits were then administered with subconjunctival injections of phosphate buffered saline (PBS) (n=4) or with VPA (n=5). Bleb morphology was examined by slit-lamp biomicroscopy and in vivo confocal microscopy. Postoperative day 28 tissues were examined by immunohistochemical evaluation and label-free multiphoton microscopy to visualise the collagen matrix, by terminal deoxynucleotidyl transferase dUTP nick-end labelling assay and immunofluorescent labelling for Ki67 expression to detect apoptosis and cell growth, and by real-time quantitative PCR to measure Col1a1, Fn, and Smad6 transcript expression.

Results

VPA-treated blebs were detectable on day 28, while the PBS-treated blebs were not detectable by day 14. VPA-treated blebs were diffuse, extended posteriorly with near normal conjunctival vascularity and featured a combination of reticular/blurred stromal pattern with evidence of relatively large stromal cysts. Instead of the deposition of thick, disorganised collagen fibres characteristic of the PBS bleb, the VPA bleb contained conspicuously thinner collagen fibres which were associated with similarly thinner fibronectin fibres. In corroboration, Col1a1 and Fn mRNA expression was reduced in the VPA blebs, while increased Smad6 expression implicated the disruption of the transforming growth factor beta pathway. Apoptosis and cell growth profiles appeared similar with both treatments.

Conclusions

The results support the application of VPA to enhance bleb morphology associated with good bleb function in MIGS with no apparent cytotoxicity.

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.

Experimental models of glaucoma filtration surgery

Glaucoma filtration surgery plays an important role in achieving intraocular pressure (IOP) reduction in patients who have high IOP despite maximum medical therapy. Preclinical experimental models of glaucoma filtration surgery contribute a great deal to our knowledge of the wound healing processes that predispose to scarring and may lead to poor outcomes. However, this research needs to be interpreted in the light of the specific study design, animal model and methods used. We review the existing literature addressing various models of experimental glaucoma filtration surgery, discuss the considerations in assessing these models and describe future steps in evaluating potential therapeutics and bleb characteristics that could impact translational research in this field.

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.

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.

Structural imaging of conjunctival filtering blebs in XEN gel implantation and trabeculectomy: a confocal and anterior segment optical coherence tomography study

PURPOSE

To describe and compare the conjunctival filtering bleb features after XEN gel implantation and trabeculectomy using anterior segment optical coherence tomography (AS-OCT) and in vivo confocal microscopy (IVCM).

METHODS

Fifty-two patients who underwent completely successful trabeculectomy (24 eyes) or completely successful XEN gel implantation (28 eyes) were consecutively enrolled. At the sixth-month follow-up, filtering blebs were analyzed with AS-OCT and IVCM. The main outcomes were the following: (i) bleb-wall epithelium cyst-like structure density and area (BECSD, BSCSA), (ii) bleb-wall sub-epithelium cyst-like structure density and area (BSCSD, BSCSA,), (iii) bleb-wall thickness (BT), (iv) bleb-wall epithelial thickness (BET), (v) bleb-wall reflectivity (BR), and (vi) bleb height (BH), for AS-OCT. Mean microcyst density (MMD) and area (MMA) and stromal meshwork reflectivity (SMR) were the IVCM outcomes.

RESULTS

Six-month intraocular pressure was 11.46 ± 3.09 and 10.06 ± 3.39 mmHg in the XEN gel implantation and trabeculectomy, respectively (p > 0.05). At AS-OCT, XEN gel blebs showed lower BH, BT, BET, BR, (p < 0.001), and BECSA values (p < 0.005), and a higher BECSD (p < 0.05) compared with trabeculectomy blebs. At IVCM, MMA and SMR values were lower in the XEN gel implantation, compared with trabeculectomy (p < 0.05). BECSD and BSCSD negatively correlated with BR (p < 0.01; r = - 0.110; p < 0.01; r = - 0.249), whereas BR strongly correlated with SMR (p < 0.001; r = 0.819).

CONCLUSION

Successful filtering blebs after XEN gel implantation appeared flatter and thinner, with a higher number of epithelial cysts and a hypo-reflective bleb wall compared with trabeculectomy. These aspects may depend on the different intra-operative tissue manipulation and/or on different aqueous humor dynamics in the sub-conjunctiva between surgeries.

In vivo confocal microscopy: qualitative investigation of the conjunctival and corneal surface in open angle glaucomatous patients undergoing the XEN-Gel implant, trabeculectomy or medical therapy

Purpose

Assessing the quality of the ocular surface by in vivo scanning laser confocal microscopy (IVCM) in primary open angle glaucoma (POAG) patients treated by Xen 45 Gel Stent, medical therapy and trabeculectomy.

Methods

Retrospective, single-center, single-masked, comparative study including 60 eyes of 30 patients (mean age 61.16 ± 10 years) affected by POAG. Eyes were divided into 3 groups: Group 1 eyes underwent the Xen 45 Gel Stent procedure, Group 2 eyes were under medical therapy, Group 3 eyes were surgically treated by trabeculectomy. All patients underwent HRT II IVCM analysis of cornea, limbus, conjunctiva, sub-tenionian space and sclera.

Results

The Xen 45 Gel stent, if properly positioned in the sub-conjunctival space preserves goblet cells and limits ocular surface inflammation. Regular corneal epithelial cells with micro-cysts, and normo-reflective sub-epithelial nerve plexus are documented by IVCM. In sub Tenon’s implants an alternative lamellar intra-scleral filtration is detectable. Combined surgical procedures show a noticeable number of inflammatory cells with rare micro-cysts. Post-trabeculectomy inflammatory reaction is more evident than Xen 45 Gel Stent associated surgical procedures, but less than medical therapy where a conspicuous presence of Langerhans cells, peri-neural infiltrates, marked loss of goblet cells and fibrosis is visible.

Conclusion

Ocular surface inflammation was more notable in topical therapy than after trabeculectomy, which itself causes more inflammation than XEN Gel stents.

Optical Coherence Tomography Angiography Evaluation of Conjunctival Vessels During Filtering Surgery

Purpose

To evaluate the changes in conjunctival vascularization with optical coherence tomography angiography (OCT-A) before and after filtering surgery and to correlate these results with filtering surgery success.

Methods

We evaluated 20 blebs of 20 patients after a first-time trabeculectomy. Conjunctival vascularization was quantified using ImageJ software. Eyes were classified into two groups according to the preoperative conjunctival vessel density: hypovascularized conjunctiva (HypoV; 10 eyes) and hypervascularized conjunctiva (HyperV; 10 eyes). The density of intraepithelial microcysts (0 to 3) was also analyzed.

Results

There were significantly more needling procedures in the HyperV group, with 70% of the eyes undergoing needling during follow-up compared to 20% in the HypoV group (P = 0.012). In the HyperV group, 50% of the eyes required IOP-lowering eyedrops after surgery, compared to 10% in the HypoV group (P = 0.029). HypoV showed significantly more intraepithelial microcysts than did HyperV at 1 week (1.1 vs. 0.4, P = 0.0215), 1 month (2.2 vs. 0.4, P = 0.0003), and 6 months postoperatively (2.0 vs. 0.7, P = 0.0068). A statistically significant correlation was found between preoperative conjunctival vascular density and mean IOP at 1 week (r = 0.483, P = 0.038), 1 month (r = 0.714, P = 0.001), and 6 months postoperatively (r = 0.471, P = 0.043). There was no statistically significant correlation between the preoperative conjunctival vascularization density and the eyedrop-year rate (r = 0.036, P = 0.8704) or the preservative-year rate (r = 0.1444, P = 0.5107).

Conclusions

Poor conjunctival vascularization was associated with lower IOP and a higher number of intraepithelial microcysts evaluated with OCT-A. OCT-A provides a simple, noninvasive, and reproducible method to analyze and quantify bleb vessels before and after filtering surgery.

Translational Relevance

Several studies have demonstrated that highly vascularized blebs might be associated with a higher risk of failure. OCT-A may provide a dye-free, noncontact method for monitoring conjunctival vascularization after filtering surgery.

Use of trypan blue to assess lymphatic function following trabeculectomy

IMPORTANCE

To illustrate the importance of lymphatic drainage in assessing trabeculectomy bleb function using intracameral trypan blue.

BACKGROUND

To study the lymphatic drainage of trabeculectomy blebs using trypan blue, correlate with bleb function and classify them accordingly.

DESIGN

Prospective cross-sectional study in a tertiary care centre.

PARTICIPANTS

Thirteen glaucoma patients post-trabeculectomy were studied.

METHODS

Trypan blue was injected into the anterior chamber.

MAIN OUTCOME MEASURES

The duration taken for dye to stain a drainage bleb or lymphatics is recorded. The extent of the lymphatic structures were measured in clock hours. Intraocular pressure (IOP) prior to surgery was recorded.

RESULTS

Eight post-trabeculectomy subjects with dye stained lymphatic vessels had lower IOP (12.6 mmHg, P = .013) compared to the five with no lymphatic vessel staining (mean IOP 23.6 mmHg). Lymphatic extent was inversely related to IOP (P = .021).

CONCLUSIONS AND RELEVANCE

Eyes with lymphatic connections to drainage blebs had lower IOP and reduced requirement for topical medications. The extent of lymphatic connection to drainage blebs is related to lower IOP.

Bleb Morphology After Mitomycin-C Augmented Trabeculectomy

PURPOSE

The main aim of this article was to study the longitudinal correlation between the clinical, morphological appearance of filtering blebs with anterior segment optical coherence tomography (AS-OCT) in the early postoperative period.

METHODS

Thirty eyes of 30 glaucoma patients scheduled for first-time trabeculectomy with 0.02% mitomycin-C were consecutively enrolled. The filtering blebs were evaluated clinically according to a grading system and with AS-OCT at day 1 and weeks 1, 2, 3, 4, and 12 following surgery. Bleb wall thickness (BWT) and bleb cavity height (BCH) were analyzed by means of horizontal and vertical AS-OCT scans.

RESULTS

Nineteen eyes (63%) had functioning blebs without any further surgical intervention. intraocular pressure changed from 18.4±1.3 mm Hg with preoperatively applied glaucoma medication to a mean of 9.75±1.4 mm Hg at all follow-ups postoperatively without medication. Mean BWT during follow-up was 575±47 μm; mean BCH was 295±72 μm. Nine filtering blebs (30%) showed encapsulation requiring a bleb needling. This was recognized clinically at week 3 in 4, and at week 4 in 5 cases. The tendency towards encapsulation was seen much earlier with AS-OCT, already showing a statistically thinner BWT (P=0.036) at week 1 and a higher BCH (P=0.005) at week 2 postsurgery, compared with the group with functioning blebs. As of week 3, intraocular pressure increased and was statistically significantly higher (P=0.016) compared with the group with functioning blebs. Two patients (7%) showed early scarring.

CONCLUSION

AS-OCT allows an analysis of the clinically invisible deeper layers of the filtering bleb. Characteristics of encapsulation, like higher blebs with thinner bleb walls, are sooner recognized than the clinical appearance. This might benefit the management of the postoperative period after trabeculectomy and the long-term outcome.

Corneal esthesiometry and sub-basal nerves morphological changes in herpes simplex virus keratitis/uveitis patients

AIM

To describe and compare corneal sensation and morphological changes of sub-basal corneal nerves by in vivo laser scanning confocal microscopy (LSCM) in herpes simplex virus (HSV) keratitis/uveitis and contralateral, clinically unaffected eyes.

METHODS

A prospective clinical study included 30 HSV eyes and 30 contralateral eyes of 30 patients, diagnosed with unilateral HSV keratitis/uveitis. Both eyes underwent a complete ophthalmological examination, Cochet-Bonnet aesthesiometry and LSCM of the central cornea, using the Heidelberg Retina Tomograph III Rostock Cornea Module. After 6mo, the same examination of the HSV affected and contralateral, clinically unaffected eyes was performed.

RESULTS

HSV eyes, as compared to contralateral eyes, demonstrated a significant decrease in mean corneal sensation (3.1±1.6 vs 5.3±0.8 cm), total nerve fibres number (5.7±4.4 vs 15.1±5.4), nerve branches (3.4±3.0 vs 8.4±4.7), main nerve trunks (2.3±1.6 vs 5.8±2.2), and nerve fibres density (7.5±5.6 vs 18.1±5.3 mm/mm², P<0.05). There was no significant difference between keratitis and uveitis eyes in mean corneal sensation and nerve fibres parameters. After 6mo, corneal sensation and sub-basal nerve fibres parameters were increased significantly, but did not reach the parameters of contralateral, clinically unaffected eyes.

CONCLUSION

Corneal aesthesiometry and LSCM in HSV affected eyes reveals a significant decrease of corneal sensation and sub-basal nerve fibres which recovers at 6mo but does not reach the normal level.

[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.

Three-dimensional Laser Scanning Confocal Analysis of Conjunctival Microcysts in Glaucomatous Patients Before and After Trabeculectomy

BACKGROUND/AIM

In glaucoma, conjunctival epithelial microcysts (CEM) have been extensively investigated by means of laser scanning confocal microscopy. In the present case series, we examined eight glaucomatous patients undergoing trabeculectomy to obtain a 3-dimensional (3-D) characterization of CEM.

MATERIALS AND METHODS

Image acquisition was performed in z-scan automatic volume mode by Heidelberg Retina Tomograph III/Rostock Cornea Module and a series of 40 images of 300×300 μm (384×384 pixels) to a maximum depth of 40 μm were acquired throughout the upper bulbar conjunctiva before (at the site planned for surgery) and eight weeks after trabeculectomy. The 3-D volume tissue reconstruction with maximal size of 300×300×40 μm was obtained.

RESULTS

In the enface view, CEM appeared as empty, optically clear, round or oval shaped sub-epithelial structures. The 3-D spatial reconstruction showed microcysts as oval-shaped and optically clear elements, which were close, but clearly separated from the epithelium. CEM were embedded in the extra-cellular spaces and located about 10 μm below the epithelial surface. After trabeculectomy, CEM increased density and area especially along the horizontal axis.

CONCLUSION

The 3-D in vivo confocal reconstruction of CEM permits for better clarification of their microscopic anatomy and patho-physiological significance, confirming their involvement in AH flow through the bleb-wall after filtration surgery for glaucoma.

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.

XEN glaucoma treatment system in the management of refractory glaucomas: a short review on trial data and potential role in clinical practice

The recent development of new devices that are significantly less invasive, collectively termed minimally invasive glaucoma surgery, offers new perspective of intraocular pressure reduction with less risk, short operating times, and rapid recovery. The aim of this work is to provide a panoramic review of the currently published clinical data to assess the potential role of XEN gel stent (Allergan PLC, Irvine, CA, USA) in the management of glaucoma, which is the only filtering minimally invasive glaucoma surgery device that allows the subconjunctival filtration. The ab interno placement of the XEN gel stent offers an alternative for lowering intraocular pressure in refractory glaucoma as a final step, and in patients intolerant to medical therapy as an early surgical approach with minimum conjunctival tissue disruption, restricted flow to avoid hypotony, and long-term safety.

TFOS DEWS II pathophysiology report

The TFOS DEWS II Pathophysiology Subcommittee reviewed the mechanisms involved in the initiation and perpetuation of dry eye disease. Its central mechanism is evaporative water loss leading to hyperosmolar tissue damage. Research in human disease and in animal models has shown that this, either directly or by inducing inflammation, causes a loss of both epithelial and goblet cells. The consequent decrease in surface wettability leads to early tear film breakup and amplifies hyperosmolarity via a Vicious Circle. Pain in dry eye is caused by tear hyperosmolarity, loss of lubrication, inflammatory mediators and neurosensory factors, while visual symptoms arise from tear and ocular surface irregularity. Increased friction targets damage to the lids and ocular surface, resulting in characteristic punctate epithelial keratitis, superior limbic keratoconjunctivitis, filamentary keratitis, lid parallel conjunctival folds, and lid wiper epitheliopathy. Hybrid dry eye disease, with features of both aqueous deficiency and increased evaporation, is common and efforts should be made to determine the relative contribution of each form to the total picture. To this end, practical methods are needed to measure tear evaporation in the clinic, and similarly, methods are needed to measure osmolarity at the tissue level across the ocular surface, to better determine the severity of dry eye. Areas for future research include the role of genetic mechanisms in non-Sjögren syndrome dry eye, the targeting of the terminal duct in meibomian gland disease and the influence of gaze dynamics and the closed eye state on tear stability and ocular surface inflammation.

Evaluation of Bleb Morphology and Reduction in IOP and Glaucoma Medication following Implantation of a Novel Gel Stent

Objective

To evaluate the efficacy and safety of the Xen Gel Stent and provide a macro- and microscopic analyses of bleb morphology.

Methods

A prospective 12-month study on patients with primary open-angle glaucoma. Patients underwent implantation of the XEN Gel Stent (Allergan INC, Dublin, Ireland) either alone or combined with a cataract surgery. Biomicroscopy, in vivo confocal microscopy (IVCM), and anterior segment-optical coherence tomography (AS-OCT) were used to assess bleb morphology. Safety parameters were adverse events, best corrected visual acuity, visual field, and corneal endothelial cell loss. A postoperative IOP ≤ 18 mmHg without or on medications was respectively defined as complete and qualified success while an IOP ≥ 18 mmHg was defined as failure.

Results

Twelve eyes of 11 patients were evaluated. At one year, 5 out of 10 patients available achieved a complete success while five were qualified success. AS-OCT showed that bleb wall reflectivity was significantly higher in the failure group; IVCM revealed that stromal density was significantly lower in the success group. No safety issues were recorded.

Conclusion

Implantation of the XEN Gel Stent appears to be a safe and effective procedure. AS-OCT and IVCM may be helpful in bleb assessment.

Conjunctival fibrosis following filtering glaucoma surgery

Despite advances in surgical technique and postoperative care, fibrosis remains the major impediment to a marked reduction of intraocular pressure without the need of additional medication (complete success) following filtering glaucoma surgery. Several aspects specific to filtering surgery may contribute to enhanced fibrosis. Changes in conjunctival tissue structure and composition due to preceding treatments as well as alterations in interstitial fluid flow and content due to aqueous humor efflux may act as important drivers of fibrosis. In light of these pathophysiological considerations, current and possible future strategies to control fibrosis following filtering glaucoma surgery are discussed.

Morphology of functioning trabeculectomy blebs using anterior segment optical coherence tomography

Purpose:

To image trabeculectomy blebs using anterior segment optical coherence tomography (AS-OCT), and to correlate the bleb morphologic features at one month postoperatively with bleb function at six months.

Materials and Methods:

This prospective, observational study included 56 eyes undergoing trabeculectomy with MMC, followed up for minimum of six months. Postoperatively, bleb imaging was done using AS-OCT at one and six month. Bleb morphology was assessed for bleb wall reflectivity, bleb pattern in multiform reflectivity, visibility of drainage route and presence of hyper-reflectivity area. Bleb function was considered successful if IOP was <18 mmHg without medication at six month. Bleb morphology one month postoperatively was correlated with bleb function at six months.

Results:

At six months successful bleb function was noted in 44 (81.5%) eyes. Morphology of bleb at one month showed uniform bleb wall reflectivity in 6 eyes (11%) and multiform wall reflectivity in 48 eyes (89%). In eyes with multiform wall reflectivity, microcysts with multiple layers was seen in 26 eyes (48%), microcysts with subconjunctival separation in 12 eyes (22%) and only microcyst in 10 eyes (19%). When bleb features at one month were correlated with the bleb function at six months, logistic regression analysis revealed that blebs with multiform reflectivity with multiple internal layers with microcysts were associated with higher chances of success (P < 0.001).

Conclusion:

AS-OCT demonstrated early bleb morphological features that may be used to predict the functioning of a bleb. Multiform bleb wall reflectivity with a pattern of multiple internal layers and microcysts was associated with increased chances of success of a bleb.

Evaluation of Filtering Bleb Function after Trabeculectomy with Mitomycin C Using Biomicroscopy, Anterior Segment Optical Coherence Tomography and In Vivo Confocal Microscopy

OBJECTIVES

To analyze and assess compatibility of trabeculectomy filtering bleb characteristics and appearances using biomicroscopy, anterior segment optical coherence tomography (AS-OCT) and in vivo confocal microscopy (IVCM).

MATERIALS AND METHODS

Twenty-eight eyes of 28 patients who underwent glaucoma filtering surgery with mitomycin C in our clinic between 2009 and 2013 were evaluated. Morphological appearances of the blebs on slit-lamp biomicroscopy were defined according to the Moorfields bleb classification system. For the internal tissue assessment of blebs, AS-OCT and IVCM were performed. Bleb biometric parameters such as length, height and bleb wall thickness were assessed by AS-OCT; conjunctival epithelial-stromal cyst, structural network of conjunctival stroma and vascularisation were examined with IVCM. The relation between biomicroscopic morphological staging and bleb characteristics detected on AS-OCT and IVCM were assessed.

RESULTS

The mean age of the 28 patients (16 male, 12 female) was 57.2±15.9 (19 to 79) years. The mean time elapsed between surgery and examination was 29.2±19.2 (6 to 68) months. According to biomicroscopic appearance, 17 (60.7%) blebs were functional (13 diffuse, 4 microcystic), whereas 11 (39.3%) blebs were non-functional (9 flat, 2 encapsulated). In the comparison of non-functional and functional blebs, functional blebs were found to be superior in terms of biometric parameters on AS-OCT assessment (p<0.05). Higher number of epithelial and stromal cysts and less vascularisation were detected by IVCM in functional blebs when compared with non-functional blebs (p<0.05).

CONCLUSION

Biomicroscopic appearances and characteristics on AS-OCT and IVCM of filtration blebs are consistent with each other. Besides biomicroscopic examination, which is an easy and practical method for determining bleb morphology, cross-sectional images obtained by AS-OCT and IVCM provide objective data regarding internal structure and functional features of blebs.

Thermography: a new option to monitor filtering bleb function?

PURPOSE

To evaluate the filtering bleb function after trabeculectomy using a new ocular surface thermography device.

METHODS

Thirty-five eyes of 35 patients after trabeculectomy were included in this prospective study. The filtering bleb function was tested with a new ocular surface-oriented, infrared radiation thermographic device in a noncontact manner (TG 1000). The eyes were classified into poorly controlled and well-controlled intraocular pressure (IOP) groups according to the patients' postoperative IOP. According to Kawasaki and colleagues, the mean temperature decrease in the filtering bleb (TDB) for evaluating bleb function was used, where TDB=(mean temperature of the temporal and nasal bulbar conjunctiva)-(mean temperature of the filtering bleb). Furthermore, the filtering bleb was evaluated during 10 seconds of eye opening and a new parameter was introduced, the TB10sec. TDB and TB10sec were analyzed statistically.

RESULTS

The TDB was 0.911°C (±0.467) and the TB10sec was -1.027°C (±0.312) in the well-controlled IOP group. The TDB was 0.599°C (±0.499), and the TB10sec was -0.623°C (±0.265) in the poorly controlled IOP group, respectively. The difference in TDB (P=0.045), as well as that of TB10sec (P<0.001), between the well-controlled and poorly controlled IOP groups was significant.

CONCLUSIONS

Temperature decrease in the filtering bleb provides information about its function. Because of the easy handling and reproducible measurements, thermography using Tomey TG 1000 may be a useful tool in the evaluation of filtering bleb function.

Surgery on the Trabecular Meshwork: Histopathological Evidence

Juxtacanalicular (JXT) trabecular meshwork and endothelial lining of Schlemm's canal have been cited as the loci of aqueous outflow resistance, both in a normal as well as a glaucomatous eye. In this review, we attempt to understand the currently available surgical modalities in light of the available histopathological evidence, regarding localization of outflow resistance. How to cite this article: Bhartiya S, Ichhpujani P, Shaarawy T. Surgery on the Trabecular Meshwork: Histopathological Evidence. J Curr Glaucoma Pract 2015;9(2):51-61.

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

Time domain (TD) and spectral domain (SD) optical coherence tomography (OCT) are cross-sectional, noncontact, high-resolution diagnostic modalities for posterior and anterior segment (AS) imaging. The AS-OCT provides tomographic imaging of the cornea, iris, lens, and anterior chamber (AC) angle in several ophthalmic diseases. In glaucoma, AS-OCT is utilized to evaluate the morphology of AS structures involved in the pathogenesis of the disease, to obtain morphometric measures of the AC, to evaluate the suitability for laser or surgical approaches, and to assess modifications after treatment. In patients undergoing surgery, AS-OCT is crucial in the evaluation of the filtering bleb functionality, permitting a combined qualitative and quantitative analysis. In this field, AS-OCT may help clinicians in distinguishing between functioning and nonfunctioning blebs by classifying their macroscopic morphology, describing bleb-wall features, bleb cavity, and scleral opening. This information is critical in recognizing signs of filtration failure earlier than the clinical approach and in planning the appropriate timing for management procedures in failing blebs. In this review, we summarize the applications of AS-OCT in the conjunctival bleb assessment.

In vivo laser scanning confocal microscopy of the ocular surface in glaucoma

Over the past decade, knowledge about the ocular surface in glaucoma has significantly increased through the use of in vivo laser scanning confocal microscopy (LSCM). This in vivo imaging method can show modifications at the cellular level induced by anti-glaucoma drugs on ocular surface structures and adnexa in the eye. High-quality images of the conjunctiva, cornea, limbus, meibomian glands, and lymphoid structures during therapy can be obtained. In addition, LSCM opened new fields of research on the patho-physiology of aqueous humor (AH) hydrodynamics in untreated, and in medically or surgically treated glaucomatous patients. In these conditions, an enhancement of the trans-scleral AH outflow contributed to clarification of the mechanism of action of different anti-glaucoma medications and surgical approaches. Finally, the use of LSCM represented a huge advance in evaluation of bleb functionality after filtration surgery, defining the hallmarks of AH filtration through the bleb-wall and distinguishing functional from nonfunctional blebs. Thus, signs seen with LSCM may anticipate clinical failure, guiding the clinician in planning the appropriate timing of the various steps in bleb management. In this review we summarize the current knowledge about in vivo LSCM of the ocular surface in glaucoma.

Trans-conjunctival aqueous humor outflow in glaucomatous patients treated with prostaglandin analogues: an in vivo confocal microscopy study

PURPOSE

To analyze, using in vivo laser scanning confocal microscopy (LSCM), the conjunctival features in glaucomatous patients receiving prostaglandin analogues (PGA).

METHODS

Eighty eyes of 80 consecutive glaucomatous patients naive for therapy were enrolled; 30 eyes of 30 healthy subjects served as a control. Patients were randomized to: preservative-free (PF) and preserved latanoprost (groups 1 and 2, respectively), PF and preserved timolol (groups 3 and 4), and controls to vehicle of latanoprost or physiological buffered saline solution (groups 5 and 6). All subjects underwent LSCM of bulbar conjunctiva at baseline and 3 months after initiating therapy. The main outcomes were: mean density (MMD: cysts/mm(2)) and mean area (MMA: cysts/mm(2)) of epithelial microcysts. The relations between MMA and MMD with intraocular pressure (IOP), age, and mean defect (MD), were analyzed.

RESULTS

At baseline, microcysts were found in all subjects. At month three, MMD did not change in all groups (p > 0.05). MMA significantly increased only in group 1 from 2,158.81 ± 524.09 to 3,877.77 ± 867.31, and in group 2 from 2,019.71 ± 541.03 to 5,560.39 ± 1,176.14, with values significantly higher in group 2 (p < 0.001). Significant relations were not found between MMD and MMA with IOP, MD, and age (p > 0.05).

CONCLUSIONS

PGA increased MMA in therapy-naive glaucomatous patients, indicating a possible enhancement of the trans-conjunctival aqueous humor outflow. Therefore, conjunctiva seems an additional target tissue to evaluate the hydrodynamic pathways in glaucoma and modifications induced by medical therapy.

In vivo confocal microscopy of the ocular surface: from bench to bedside

In vivo confocal microscopy (IVCM) is an emerging technology that provides minimally invasive, high resolution, steady-state assessment of the ocular surface at the cellular level. Several challenges still remain but, at present, IVCM may be considered a promising technique for clinical diagnosis and management. This mini-review summarizes some key findings in IVCM of the ocular surface, focusing on recent and promising attempts to move "from bench to bedside". IVCM allows prompt diagnosis, disease course follow-up, and management of potentially blinding atypical forms of infectious processes, such as acanthamoeba and fungal keratitis. This technology has improved our knowledge of corneal alterations and some of the processes that affect the visual outcome after lamellar keratoplasty and excimer keratorefractive surgery. In dry eye disease, IVCM has provided new information on the whole-ocular surface morphofunctional unit. It has also improved understanding of pathophysiologic mechanisms and helped in the assessment of prognosis and treatment. IVCM is particularly useful in the study of corneal nerves, enabling description of the morphology, density, and disease- or surgically induced alterations of nerves, particularly the subbasal nerve plexus. In glaucoma, IVCM constitutes an important aid to evaluate filtering blebs, to better understand the conjunctival wound healing process, and to assess corneal changes induced by topical antiglaucoma medications and their preservatives. IVCM has significantly enhanced our understanding of the ocular response to contact lens wear. It has provided new perspectives at a cellular level on a wide range of contact lens complications, revealing findings that were not previously possible to image in the living human eye. The final section of this mini-review provides a focus on advances in confocal microscopy imaging. These include 2D wide-field mapping, 3D reconstruction of the cornea and automated image analysis.

In vivo confocal microscopy and histopathology of the conjunctiva in trachomatous scarring and normal tissue: a systematic comparison

AIM

To compare in vivo confocal microscopy (IVCM) with the histopathological examination of tissue and cellular changes in normal and diseased conjunctiva.

METHODS

Participants underwent clinical examination and IVCM of the tarsal conjunctiva. A biopsy of the upper tarsal conjunctiva was collected and stained with tinctorial stains and by immunohistochemical staining for CD45 and CD83. Connective tissue scarring, inflammatory cell density and the presence of dendritiform cells were quantitatively assessed in a masked manner by both IVCM and histological assessments for comparative analysis.

RESULTS

Thirty-four participants with severe trachomatous conjunctival scarring and 33 participants with healthy conjunctiva were recruited. The IVCM connective tissue scarring score was strongly associated with the histological grading of scarring (p<0.001). There was limited evidence of an association between the IVCM inflammatory cell infiltrate and the histological inflammatory cell grade (p=0.05). We did not find any evidence to support the hypothesis that dendritiform cells seen with IVCM are mature, conventional dendritic cells.

CONCLUSIONS

The results show that IVCM can be used to robustly quantitate connective tissue scarring and also has a role in measuring the inflammatory cell infiltrate. The discordance between IVCM dendritiform cells and immunohistochemical dendritic cells may be a result of study limitations or may be because these dendritiform structures represent another cell type, such as fibroblasts, rather than dendritic cells.

Anterior Segment Optical Coherence Tomography and its Clinical Applications in Glaucoma

Anterior segment optical coherence tomography (ASOCT) is an imaging modality that provides both quantitative and qualitative information on the cornea, anterior chamber angle, iris and crystalline lens. ASOCT shows excellent repeatability and reproducibility for the measurement of corneal thickness, anterior chamber angle and anterior chamber depth. With realtime video recording, ASOCT can also effectively capture the dynamic changes of the iris and lens in response to light and eye accommodation. With this additional information, physiological and pathological changes of the anterior segment structures are now better understood. This article aims to provide an overview of the current applications of ASOCT in glaucoma.

HOW TO CITE THIS ARTICLE

Li H, Jhanji V, Dorairaj S, Liu A, Lam DSC, Leung CK. Anterior Segment Optical Coherence Tomography and its Clinical Applications in Glaucoma. J Current Glau Prac 2012;6(2):68-74.

Evaluation of filtering blebs using the 'Wuerzburg bleb classification score' compared to clinical findings

BACKGROUND

To determine the agreement between intraocular pressure and the 'Wuerzburg bleb classification score', as well as between single items of the score and intraocular pressure. Interobserver variability was analyzed.

METHODS

57 post-trabeculectomy eyes were included. Colour photographs were used to score the filtering bleb in accordance to the Wuerzburg bleb classification score by two different examiners. At the same visit, clinical data such as intraocular pressure, best corrected visual acuity, slit lamp biomicroscopy and medical history were obtained by another examiner.

RESULTS

After trabeculectomy, 42 out of 57 eyes (73.7%) reached the target pressure (≤ 21mmHg, and intraocular pressure reduction of at least 20%, without antiglaucoma medication, and without any additional intervention). Fair agreement was found between intraocular pressure and Wuerzburg bleb classification score ≥ 8 points and ≥ 7 points (kappa 0.24 and 0.27, respectively). Analyzing the subgroups of the morphological criteria, best agreement was found between occurrence of microcysts and target intraocular pressure (к 0.22-0.34).

CONCLUSIONS

Evaluating filtering blebs after trabeculectomy by using the Wuerzburg bleb classification score is a good technique for predicting intraocular pressure control in eyes attaining a minimum score of seven points. The presence of microcysts on the filtering bleb predicts that the eye is likely to attain target pressure.

Conjunctival findings in hyperbaric and low-tension glaucoma: an in vivo confocal microscopy study

PURPOSE

To analyse the epithelial features of the bulbar conjunctiva in hyperbaric and low-tension glaucoma (LTG) using in vivo confocal microscopy (IVCM).

METHODS

Thirty-six eyes of 36 patients [18 affected by primary open-angle glaucoma (POAG) and 18 with LTG] were studied; control group was constituted by 28 eyes of 28 healthy subjects. All eyes were examined using digital confocal laser-scanning microscopy (HRT II Rostock Cornea Module). The main IVCM outcome measurements were mean density (MMD: cysts/mm(2)) and mean total area (MMA: μm(2)) of the epithelial microcysts.

RESULTS

The mean intraocular pressure level (mmHg ± SD) was 15.1 ± 1.7, 16.3 ± 3.1 and 12.6 ± 1.8 in healthy, POAG and LTG eyes, respectively. Conjunctival microcysts were found in all patients and subjects: for healthy subjects, MMD = 10.9 ± 11.1 cysts/mm(2) and MMA = 1501.9 ± 1191.1 μm(2); for patients infected with POAG, MMD = 36.8 ± 28.6 cysts/mm(2) and MMA = 7904.8 ± 7050.5 μm(2); and for patients infected with LTG MMD = 45.6 ± 29.0 cysts/mm(2) and MMA =7946.9 ± 5227.5 μm(2). MMD and MMA were not significantly different between patients infected with POAG and those with LTG, whereas they were significantly greater in patients (fourfold and fivefold, respectively) than healthy subjects.

CONCLUSIONS

The present study demonstrated that conjunctival microcysts represent an in vivo feature in all eyes with medically controlled POAG and LTG. Therefore, conjunctiva deserves careful analysis, because its accurate microscopic definition could help clarify the pathophysiology of aqueous outflow in glaucoma.

In vivo confocal microscopy in scarring trachoma

Objective

To characterize the tissue and cellular changes found in trachomatous scarring (TS) and inflammation using in vivo confocal microscopy (IVCM).

Design

Two complimentary case-control studies.

Participants

The first study included 363 cases with TS (without trichiasis), of whom 328 had IVCM assessment, and 363 control subjects, of whom 319 had IVCM assessment. The second study included 34 cases with trachomatous trichiasis (TT), of whom 28 had IVCM assessment, and 33 control subjects, of whom 26 had IVCM assessment.

Methods

All participants were examined with ×2.5 loupes. The IVCM examination of the upper tarsal conjunctiva was carried out with a Heidelberg Retina Tomograph 3 with the Rostock Cornea Module (Heidelberg Engineering GmbH, Dossenheim, Germany).

Main Outcome Measures

The IVCM images were graded in a masked manner using a previously published grading system evaluating the inflammatory infiltrate density; the presence or absence of dendritiform cells (DCs), tissue edema, and papillae; and the level of subepithelial connective tissue organization.

Results

Subjects with clinical scarring had a characteristic appearance on IVCM of well-defined bands and sheets of scar tissue visible. Similar changes were also seen in some clinically normal subjects consistent with subclinical scarring. Scarred subjects had more DCs and an elevated inflammatory infiltrate, even after adjusting for other factors, including the level of clinical inflammation. Cellular activity was usually seen only in or just below the epithelium, rarely being seen deeper than 30 μm from the surface. The presence of tissue edema was strongly associated with the level of clinical inflammation.

Conclusions

In vivo confocal microscopy can be quantitatively used to study inflammatory and scarring changes in the conjunctiva. Dendritic cells seem to be closely associated with the scarring process in trachoma and are likely to be an important target in antifibrotic therapies or the development of a chlamydial vaccine. The increased number of inflammatory cells seen in scarred subjects is consistent with the immunopathologic nature of the disease. The localization of cellular activity close to the conjunctival surface supports the view that the epithelium plays a central role in the pathogenesis of trachoma.

Financial Disclosure(s)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Birefringence measurement of cornea and anterior segment by office-based polarization-sensitive optical coherence tomography

We present a case series of cornea and anterior segment disorders investigated by an office-based polarization-sensitive optical coherence tomography (PS-OCT). Blebs of glaucoma patients treated by trabeculectomy, and corneas of keratoconus and keratoplasty patients were measured by PS-OCT. Birefringence formations in trabeculectomy bleb were measured in 1 control eye and 3 eyes of trabeculectomy model rabbits. Polarization insensitive scattering OCT and the depth-resolved birefringence were measured simultaneously by PS-OCT. Abnormal birefringence was observed in keratoconus cases with advanced thinning and with a rupture of Descemet's membrane. The graft-host interface of the keratoplasty case showed abnormal birefringence. The appearance of abnormal birefringence in the cornea was likely to be an indication of cross-linking of collagen fibrils. The measurement of rabbit showed abnormal birefringence in the scarring eyes. Wide regions of strong birefringence were observed in the eyes of trabeculectomy patients who had high intraocular pressure. Visualization of scarring in bleb by PS-OCT may be useful for the planning of secondary surgery. PS-OCT showed promising for the study and diagnosis diseases related to abnormal fibrous tissues of the cornea and anterior eye segment.