Comparison of Two Clinical Bleb Grading Systems

Needle bleb revision with bevacizumab and mitomycin C compared with mitomycin C alone for failing filtration blebs

PURPOSE

To report the 6-month comparative outcomes and bleb morphology for needle revision with bevacizumab and mitomycin C (MMC) versus MMC alone of failed trabeculectomy and ExPRESS shunt blebs.

METHODS

Patients undergoing bleb needle revision procedures were enrolled in this study. All patients received a subconjunctival injection of 0.1 mL MMC (0.4 mg/mL) mixed with 0.1 mL preservative-free lidocaine (1%) at the beginning of the procedure. The patients were randomized into 2 cohorts assigned to receive either 1.0 mg (0.04 mL of 25 mg/mL) subconjunctival bevacizumab (treatment group) or 0.04 mL of balanced salt solution (control group) injected in an identical manner posterior to the bleb after the bleb needling. Success was defined as ≥20% reduction in intraocular pressure (IOP) without any IOP-lowering medications. Qualified success was defined as ≥20% reduction of IOP with IOP-lowering medications. Failure was defined as IOP>21 mm Hg, IOP reduction <20%, or need for additional surgery. Bleb morphology was classified using the Indiana Bleb Appearance Grading Scale.

RESULTS

Six months postoperatively, in treatment group (n=29), 57% of patients achieved complete success, and 43% failed. In control group (n=29), 41% of patients achieved complete success, 7% achieved qualified success, and 52% failed. The difference in success rates between the 2 groups was not statistically significant (P=0.35). At 6 months, the mean IOP was 11.52 in treatment group and 12.83 in control group (P=0.45); patients in treatment group were on a mean of 0.16 medications as compared with 0.58 medications in control group (P=0.058). For bleb morphology of treatment group compared with control group, the blebs had less vascularity (0.76 vs. 1.20, respectively, on a scale of 0 to 4, P<0.05) and greater extent (2.68 vs. 2.36, on a scale of 0 to 3, P=0.022) in treatment group.

CONCLUSIONS

There was no significant difference between the success rates and IOPs at postoperative month 6 between treatment and control groups. Postoperative blebs in the treatment group were less vascular and had greater extent.

Rosmarinic Acid Suppresses Subconjunctival Neovascularization in Experimental Glaucoma Surgery

PURPOSE

Excessive subconjunctival scarring is associated with increased angiogenesis and leads to filtration failure in glaucoma surgery. In this study, we describe that rosmarinic acid (RA) has anti-angiogenic activity during wound healing in a rabbit model of glaucoma surgery.

METHODS

Forty New Zealand rabbits underwent an experimental trabeculectomy and were randomly allocated into two treatment groups: RA group - treated with subconjunctival injections of 0.1 ml RA (15 mg/ml; n = 20) - and control group - treated with subconjunctival injections of 0.1 ml balanced salt solution (n = 20). The in vivo effect of RA was investigated after 5 and 15 d by measuring the intraocular pressure (IOP; with Tonopen) and bleb area and vascularity (using the Moorfields Bleb Grading System). Vascularization was also studied by counting histological blood vessels and by immunohistochemistry of vascular endothelial growth factor (VEGF) at the surgical site and by quantification of vessels in chicken's chorioallantoic membrane (CAM), treated with AR 500 μg/ml for 48 h.

RESULTS

On the fifth day, eyes of RA group displayed higher bleb area (3.6 ± 0.2 versus 1.8 ± 0.2; p = 0.004) and lower vascularity (3.0 ± 0.5 versus 4.0 ± 0.4; p = 0.009) than controls; however, difference in IOP reduction was not significant (-1.4 ± 0.3 versus -0.8 ± 0.3 mmHg; p = 0.226). Proportion of vessels/field (4.6 ± 0.5 versus 10.4 ± 0.9; p = 0.008) and VEGF immunostaining (15,347 ± 3788 versus 31,043 ± 3230; p = 0.019) also declined with RA treatment. However, at the 15th day, none of the parameters were different between the groups, except for vessels/field proportion (5.4 ± 1.0 versus 10.6 ± 1.6; p = 0.035). CAM exposed to AR inhibited vascularization (-45.67 ± 4.74%; p < 0.001).

CONCLUSION

These data indicate RA has a short-term anti-angiogenic effect and could be a potential modulator of neovascularization during subconjunctival healing at glaucoma filtration surgical sites.

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.

Correlation between filtering bleb morphology, expression of inflammatory marker HLA-DR by ocular surface, and outcome of trabeculectomy

PURPOSE

To correlate clinical bleb characteristics and the expression of human leukocyte antigen (HLA)-DR by conjunctiva with the outcome of trabeculectomy.

PATIENTS AND METHODS

In this cross-sectional study, bleb morphology was assessed at slit lamp using the Moorfields Bleb Grading System in 85 eyes of 85 patients. Conjunctival specimens were collected from superior conjunctiva by impression cytology and analyzed for the expression of HLA-DR on epithelial and antigen-presenting cells. The success of trabeculectomy was defined as intraocular pressure <21 mm Hg without antiglaucoma drops. Differences in bleb characteristics and expression of HLA-DR between eyes with surgical success and failure were examined.

RESULTS

Fifty-eight of 85 eyes with successful trabeculectomy had significantly greater central and maximal area of the bleb (P<0.001) with decreased vascularity of the central (P=0.02) and peripheral part of the bleb (P=0.03). The expression of HLA-DR on conjunctival epithelial cells and antigen-presenting cells was not different between the eyes with successful and failed trabeculectomy and also not between the eyes with and without topical glaucoma medication or topical corticosteroid eye drops.

CONCLUSIONS

Successful trabeculectomy was associated with greater area and decreased vascularity of the bleb but not with diminished expression of inflammatory marker by ocular surface. Presence of subclinical inflammation in eyes without eye drops may result from the transcellular aqueous pathway towards the ocular surface, especially in functioning blebs with adjunctive mitomycin C.

Tear fluid signs associated with filtration blebs, as demonstrated by three-dimensional anterior segment optical coherence tomography

Purpose

To determine the clinical features of tear fluid signs associated with filtration blebs via three-dimensional anterior segment optical coherence tomography (3D AS-OCT).

Methods

In total, 152 eyes (130 patients) with glaucoma that underwent trabeculectomy with mitomycin C were evaluated retrospectively. We investigated tear fluid signs associated with filtration blebs, using 3D AS-OCT with custom software, and compared the findings of lower tear meniscus. We also analyzed postoperative intraocular pressure and the bleb parameters of filtration blebs between eyes with and without tear fluid signs.

Results

We found tear fluid signs associated with filtration blebs in 45 (30%) of 152 eyes. The mean postoperative intraocular pressure of the eyes with the tear fluid sign in a filtration bleb was significantly lower than that in eyes without the tear fluid sign (P<0.001). Blebs with tear fluid signs have more frequent identifiable filtration openings, greater total height, increased fluid-filled cavity height, and less wall intensity compared with blebs without these signs.

Conclusion

We identified tear fluid signs in AS-OCT images on or along filtration blebs that depended on bleb morphology. The occurrence of these signs may be related to the presence of functional blebs, which may thereby control postoperative intraocular pressure.

Monocyte chemotactic protein-1 level in the aqueous humour as a prognostic factor for the outcome of trabeculectomy

BACKGROUND

The aim of this study was to elucidate the effects of the aqueous humour monocyte chemotactic protein-1 level on the surgical outcome of trabeculectomy in cases of phakic glaucoma.

DESIGN

Retrospective study.

PARTICIPANTS

Fifty-three cases of open-angle glaucoma.

METHODS

At the time of trabeculectomy, aqueous humour samples were collected before any incisions were made. The monocyte chemotactic protein-1 level was then determined by immunoassay. The Cox proportional hazards test was used to analyse the clinical factors related to failure of trabeculectomy. Subsequently, the success probability was calculated by Kaplan-Meier analysis and cumulative success probabilities were analysed by the log-rank test.

MAIN OUTCOME MEASURES

Probability of success.

RESULTS

In 30 phakic glaucoma and 23 pseudophakic glaucoma cases, the mean monocyte chemotactic protein-1 levels in aqueous humour were 1165.2 and 2152.9 pg/mL, respectively; the difference was statistically significant (P < 0.0001). Univariate analysis showed that the outcomes of surgery were correlated with the monocyte chemotactic protein-1 level, but not with age, gender, diagnosis of exfoliation glaucoma, pseudophakic status or pretrabeculectomy intraocular pressure. Subsequent multivariate analysis revealed that only the aqueous humour monocyte chemotactic protein-1 level was significantly correlated with the outcomes of trabeculectomy (P = 0.043). Among the 30 phakic glaucoma eyes, the success probabilities after trabeculectomy were significantly different between the high and low monocyte chemotactic protein-1 groups (P = 0.018).

CONCLUSION

In open-angle glaucoma patients, the monocyte chemotactic protein-1 level is a prognostic factor for the results of trabeculectomy.

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.

Biodegradable collagen matrix implant vs mitomycin-C as an adjuvant in trabeculectomy: a 24-month, randomized clinical trial

AIM

To verify the safety and efficacy of Ologen (OLO) implant as adjuvant compared with low-dosage mitomycin-C (MMC) in trabeculectomy.

METHODS

This was a prospective randomized clinical trial with a 24-month follow-up. Forty glaucoma patients (40 eyes) were assigned to trabeculectomy with MMC or OLO. Primary outcome includes target IOP at ≤21, ≤17, and ≤15 mm Hg; complete (target IOP without medications), and qualified success (target IOP regardless of medications). Secondary outcomes include bleb evaluation, according to Moorfields Bleb Grading System (MBGS); spectral domain optical coherence tomography (SD-OCT) examination; number of glaucoma medications; and frequency of postoperative adjunctive procedures and complications.

RESULTS

The mean preoperative IOP was 26.5 (±5.2) in MMC and 27.3 (±6.0) in OLO eyes, without statistical significance. One-day postoperatively, the IOP dropped to 5.2 (±3.5) and 9.2 (±5.5) mm Hg, respectively (P=0.009). The IOP reduction was significant at end point in all groups (P=0.01), with a mean IOP of 16.0 (±2.9) and 16.5 (±2.1) mm Hg in MMC and OLO, respectively. The rates and Kaplan-Meier curves did not differ for both complete and qualified success at any target IOP. The bleb height in OLO group was higher than MMC one (P<0.05). SD-OCT analysis of successful/unsuccessful bleb in patients with or without complete success at IOP ≤17  mm Hg indicated a sensitivity of 83% and 73% and a specificity of 75% and 67%, respectively, for MMC and OLO groups. No adverse reaction to OLO was noted.

CONCLUSIONS

Our results suggest that OLO implant could be a new, safe, and effective alternative to MMC, with similar long-term success rate.

Conjunctival and corneal findings in bleb-associated endophthalmitis: an in vivo confocal microscopy study

PURPOSE

To report the conjunctival and corneal findings in delayed onset glaucoma filtering bleb-associated endophthalmitis (BAE), by using in vivo confocal microscopy (IVCM).

METHODS

This was an observational case series. Four eyes of four glaucomatous patients who previously underwent mytomicin C augmented filtering surgery and affected with delayed onset BAE, underwent IVCM of conjunctival bleb and cornea at diagnosis, after 2 and 8 weeks of therapy. The inflammatory status of the conjunctival epithelium and sub-epithelium was microscopically investigated. Corneal epithelial cells, stromal and endothelial morphology were also evaluated. A group of eight patients with functioning conjunctival filtering bleb was used as control.

RESULTS

At diagnosis, a diffuse inflammatory cell infiltration within the conjunctival epithelium presenting evident microcysts was found; conversely, there were no such alterations in the sub-epithelium. An evident stromal oedema, keratocytes activation and diffuse endothelial inflammatory precipitates were the major corneal hallmarks. After 2 weeks of therapy, besides a remarkable improvement of epithelial inflammation and an evident reduction in endothelial precipitates, dendritic cells appeared within conjunctival sub-epithelium and corneal epithelium showed aspects of cellular disruption. After 8 weeks, the conjunctival and corneal features consistently improved, except for the endothelium which still presented high-reflective residual precipitates.

CONCLUSIONS

In vivo confocal microscopy proved valuable in the analysis of conjunctival bleb and cornea in patients affected with delayed onset BAE, permitting an evaluation of the course of the disease, the response to therapy and the modulation of dose regimen.

Computational modeling of fluid flow and intra-ocular pressure following glaucoma surgery

Background

Glaucoma surgery is the most effective means for lowering intraocular pressure by providing a new route for fluid to exit the eye. This new pathway is through the sclera of the eye into sub-conjunctival tissue, where a fluid filled bleb typically forms under the conjunctiva. The long-term success of the procedure relies on the capacity of the sub-conjunctival tissue to absorb the excess fluid presented to it, without generating excessive scar tissue during tissue remodeling that will shut-down fluid flow. The role of inflammatory factors that promote scarring are well researched yet little is known regarding the impact of physical forces on the healing response.

Methodology

To help elucidate the interplay of physical factors controlling the distribution and absorption of aqueous humor in sub-conjunctival tissue, and tissue remodeling, we have developed a computational model of fluid production in the eye and removal via the trabecular/uveoscleral pathways and the surgical pathway. This surgical pathway is then linked to a porous media computational model of a fluid bleb positioned within the sub-conjunctival tissue. The computational analysis is centered on typical functioning bleb geometry found in a human eye following glaucoma surgery. A parametric study is conducted of changes in fluid absorption by the sub-conjunctival blood vessels, changes in hydraulic conductivity due to scarring, and changes in bleb size and shape, and eye outflow facility.

Conclusions

This study is motivated by the fact that some blebs are known to have ‘successful’ characteristics that are generally described by clinicians as being low, diffuse and large without the formation of a distinct sub-conjunctival encapsulation. The model predictions are shown to accord with clinical observations in a number of key ways, specifically the variation of intra-ocular pressure with bleb size and shape and the correspondence between sites of predicted maximum interstitial fluid pressure and key features observed in blebs, which gives validity to the model described here. This model should contribute to a more complete explanation of the physical processes behind successful bleb characteristics and provide a new basis for clinically grading blebs.

Comparison of the outcomes of limbal-based trabeculectomy with and without anchor sutures

BACKGROUND AND OBJECTIVE

To retrospectively evaluate the efficacy and safety of limbal-based trabeculectomy with anchor sutures compared to standard limbal-based trabeculectomy. Limbal-based trabeculectomy was performed with a new technique using anchor sutures, which involved tying the conjunctiva to the sclera at a deep fornix incision to prevent bleb localization induced by slippage of the conjunctival suture scar toward the scleral flap.

PATIENTS AND METHODS

In this retrospective, comparative, interventional case series, 45 eyes that underwent limbal-based trabeculectomy with anchor sutures and 27 eyes that underwent standard limbal-based trabeculectomy were analyzed (primary surgery).

RESULTS

At a target intraocular pressure of 15 mm Hg, the 3-year survival rate using Kaplan-Meier analysis was 76.2% in the limbal-based trabeculectomy with anchor sutures group and 55.6% in the standard limbal-based trabeculectomy group. Bleb morphology analysis using the Moorfields Bleb Grading System showed that blebs in the limbal-based trabeculectomy with anchor sutures group were more diffused than those in the standard limbal-based trabeculectomy group.

CONCLUSION

Limbal-based trabeculectomy with anchor sutures appears to be an effective method for decreasing intraocular pressure and improving morphology of blebs.

High-definition imaging of trabeculectomy blebs using spectral domain optical coherence tomography adapted for the anterior segment

BACKGROUND

The aim of this work was to image trabeculectomy blebs using spectral domain optical coherence tomography (SDOCT).

METHODS

In this prospective cross-sectional study, patients who had undergone trabeculectomy with at least 3 months of follow up were included. Blebs were imaged using an adapted SDOCT system (Cirrus HD-OCT, Carl Zeiss Meditec Inc., Dublin, CA, USA) and time domain anterior segment optical coherence tomography (ASOCT) (Visante OCT, Carl Zeiss Meditec Inc.). An observer masked to clinical data assessed the utility of SDOCT and ASOCT in visualizing structures in successful and failed blebs.

RESULTS

Fifty-one eyes were imaged, of which 43 (84.3%) were successful. SDOCT showed wall thickening (93.0% vs. 67.4%, P = 0.006) and discrete hyporeflective spaces in the wall (88.4% vs. 14.0%, P < 0.0001) in a greater proportion of successful blebs than ASOCT. SDOCT showed the bleb cavity (23.3% vs. 48.8%, P = 0.02), scleral flap (34.9% vs. 90.7%, P < 0.0001), subflap space (20.9% vs. 72.1%, P < 0.0001) and ostium (9.3% vs. 88.4%, P < 0.0001) in fewer successful blebs than ASOCT. The internal ostium was not visualized in any failed bleb using SDOCT, whereas ASOCT showed the ostium in 87.5% of failed blebs (P = 0.001). SDOCT showed cystic spaces in the bleb wall in a greater proportion of successful blebs than failed blebs (88.4% vs. 37.5%, P = 0.005).

CONCLUSIONS

SDOCT imaging was able to show fine superficial features in the bleb wall. However, SDOCT had limited clinical utility in that it did not provide useful information about deep features such as flap position, bleb cavity formation or patency of the subflap space and internal ostium.

Restricted post-trabeculectomy bleb formation by conjunctival scarring

PURPOSE

To evaluate the effects of radial conjunctival incision during fornix-based trabeculectomy, and conjunctival scarring associated with previous ocular surgeries, for the restriction of bleb formation.

METHODS

Digital photo-slit lamp images of filtering blebs, which had undergone fornix-based trabeculectomy with mitomycin C previously, were analysed. The area and the height of the bleb in the conjunctivae with radial incision (Ain and Hin, respectively) were compared with the area and the height of the bleb in the conjunctivae without radial incision (Ano and Hno, respectively). We compared the parameters of bleb area (total bleb area, Ain and Ano) and bleb height (the bleb height at the centre of the scleral flap; Hc, Hin and Hno) in eyes without previous ocular surgeries, with those in eyes that underwent previous ocular surgeries.

RESULTS

The study population consisted of 51 eyes. The Ano and the Hno were significantly larger than the Ain (p < 0.001) and the Hin (p < 0.001) respectively. Subgroup analyses in eyes without previous ocular surgeries and eyes with phacoemulsification cataract surgery also showed that the Ano was significantly larger than the Ain. However, there was no significant difference between the Ano and the Ain in eyes with previous trabeculectomy. A comparison of bleb formation between eyes without previous ocular surgeries and eyes with cataract surgery showed no significant differences in each of the bleb area and bleb height parameters. By contrast, the total bleb area (p = 0.021), the Ano (p = 0.017) and the Hc (p = 0.045) were significantly smaller in eyes with previous trabeculectomy than in eyes without previous ocular surgeries.

CONCLUSIONS

Our data demonstrate that bleb formation depends on radial conjunctival incision during fornix-based trabeculectomy and surgical conjunctival scarring from previous trabeculectomy.

Information loss in 2 bleb grading systems

PURPOSE

To assess the effectiveness of transferring descriptive information from bleb photographs to 2 recently described bleb grading systems: the Moorfields Bleb Grading System (MBGS) and the Indiana Bleb Appearance Grading Scale (IBAGS).

METHODS

Two experienced observers graded 51 clinical bleb photographs with a wide range of appearances using both the MBGS and IBAGS bleb grading systems in random order. Grading scores from the 2 observers were averaged, and these numbers used by a third investigator, who did not view the original photographs, to generate 102 sketched representations of the blebs. The sketches were labeled randomly, and 1 month later presented individually in random order, to mask which grading system was used as source data for each drawing.

MAIN OUTCOME MEASURES

The original graders then used an arbitrary 1-5 scale to rate congruity between sketches and photographs for vascularity and morphology features, and overall agreement of the bleb sketches.

RESULTS

For both the IBAGS and MBGS, interobserver agreement between the Congruity Scores (CS) of the 2 masked graders was excellent, ranging between 92% and 98% for each parameter. Overall CS results were 3.2 (good-very good) for IBAGS and 4.1 (very good-excellent) for MBGS. Vascularity CS scores from IBAGS were 3.0 (good) and those from morphology agreement averaged 3.5 (good-very good). For the MBGS, the respective results were 3.9 (good-very good) and 4.1 (very good-excellent), respectively. Photographic quality (P=0.012) and presence of a limbus-based conjunctival flap scar (P=0.012) had an influence on CS scores from IBAGS but not from MBGS.

CONCLUSIONS

Both the IBAGS and MBGS produced acceptable agreement ratings between the sketches derived from grading system data and the original bleb photographs. These grading systems seem to adequately represent the blebs that are being encoded, without significant information loss from the simplification and translation process. The MBGS tended to have higher CS, and may be less influenced by photograph quality and bleb type, suggesting that bleb photographs may be best encoded for statistical analysis in clinical studies using this system.

Imaging of trabeculectomy blebs using anterior segment optical coherence tomography

OBJECTIVE

To image trabeculectomy blebs using anterior segment optical coherence tomography (AS-OCT).

DESIGN

Prospective cross-sectional study.

PARTICIPANTS

Fifty-five patients who had previously undergone trabeculectomy surgery.

METHODS

All blebs were imaged with a prototype of the AS-OCT. Standardized color monophotographs of blebs were also obtained. Blebs were assessed for the following qualitative features: bleb height, thickness of the conjunctiva in the bleb wall, presence of cystic spaces within the bleb wall, apposition of the scleral flap to underlying sclera, and patency of the internal ostium.

MAIN OUTCOME MEASURES

For blebs with preoperative intraocular pressure (IOP) > 18 mmHg with or without ocular hypotensive medication, success was defined as last recorded IOP< or =18 mmHg without topical glaucoma medication. For blebs with preoperative IOP< or =18 mmHg with ocular hypotensive medication, success was defined last recorded IOP< or =18 mmHg with cessation of ocular hypotensive medication. For blebs with preoperative IOP< or =18 mmHg without ocular hypotensive medication, a 20% drop in IOP with no ocular hypotensive medication was accepted as success.

RESULTS

Seventy-eight blebs in eyes of 55 patients were imaged. There were 32 (58.2%) men and the mean age was 68.9+/-11.5 years. Fifty-seven (73.1%) blebs were classified as successful. Anterior segment optical coherence tomography identified the following bleb characteristics: total bleb height, bleb cavity, bleb wall thickness, tangential and radial dimensions, scleral flap thickness, and patency of the internal ostium. The majority of successful blebs displayed thickening of the bleb wall. Failed blebs were mostly low and were characterized by ostial occlusion, apposition of conjunctiva-episclera to sclera or apposition of the scleral flap to its bed. Thickening of the bleb wall was typically absent.

CONCLUSIONS

AS-OCT is a promising tool to image trabeculectomy blebs. It was able to demonstrate features of bleb morphology not visible with the slit lamp.