Three-dimensional anterior segment optical coherence tomography of filtering blebs after trabeculectomy

PURPOSE: To evaluate trabeculectomy blebs by using 3-dimensional anterior segment optical coherence tomography (OCT). METHODS: We prospectively examined 4 eyes of 4 patients who developed filtering blebs after trabeculectomy. A 1310-nm high-speed OCT prototype was used to image the 3-dimensional structure of the filtering blebs. RESULTS: The 3-dimensional structure of the filtering blebs was clearly observed in the OCT images. Three types of filtering blebs were observed: diffuse blebs in 2 eyes, an encapsulated bleb in 1 eye, and a nonfunctioning cystic bleb in 1 eye. The volume of each bleb was 9.97, 1.10, 0.76, and 0.88 mm3, respectively. En-face OCT images clearly showed the aqueous outflow channels at the margins of the scleral flaps. CONCLUSION: Three-dimensional OCT allows objective and noninvasive assessment of filtering blebs after trabeculectomy.     

青光眼术后滤过泡的眼前节光学相干断层扫描研究

目的利用眼前节光学相干断层扫描（AS-OCT）观察青光眼滤过手术后滤过泡的内部形态,探讨AS-OCT在滤过泡功能评价中的意义。方法前瞻性研究。收集已行青光眼滤过手术3个月以上的患者53例（69眼）,术后随诊时间为3~48个月,平均（10.78±11.03）个月。按照van Buskirk分级法将滤过泡分为功能型（Ⅰ、Ⅱ）和非功能型（Ⅲ、Ⅳ）,同时利用AS-OCT获取滤过泡内部形态,根据AS-OCT内部形态特点分为弥散型、微囊型、包裹型、扁平型。比较2种检测方法的一致性。结果69眼平均眼压为（14.9±4.5）mmHg。按照van Buskirk分级法38眼为功能型滤过泡（38/69,55.07%）,31眼为非功能型滤过泡（31/69,44.93%）。AS-OCT示26眼弥散型滤过泡（26/69,37.68%）,平均眼压（13.16±3.77）mmHg;11眼为微囊型滤过泡（11/69,15.94%）,平均眼压（15.36±2.92）mmHg;19眼为包裹型滤过泡（19/69,27.54%）,平均眼压（15.77±5.07）mmHg;13眼为扁平型滤过泡（13/69,18.84%）;平均眼压（16.62±5.33）mmHg;微囊型滤过泡与包裹型滤过泡间的眼压差异有统计学意义（F=3.32,P〈0.05）。对于滤过泡功能性的评价,AS-OCT与裂隙灯显微镜检查法有较好的一致性（χ^2=0.03,P=0.86）。结论AS-OCT具有分辨率高的优点,能清晰地显示滤过泡内部横断面的形态,准确而客观地区分功能型和非功能型滤过泡,且能较早发现滤过泡包裹化的趋势,是青光眼滤过手术效果重要的评价手段。     

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.     

A pilot study on slit lamp-adapted optical coherence tomography imaging of trabeculectomy filtering blebs

Background Our study aims to identify anatomical characteristics of glaucoma filtering blebs by means of slit lamp-adapted optical coherence tomography (SL-OCT) and to identify new parameters for the functional prognosis of the filter in the early post-operative period. Methods Patients with primary open-angle glaucoma, aged 18 years and older, scheduled for primary trabeculectomy at the Department of Ophthalmology, Radboud University Nijmegen Medical Centre, were considered for our study. All patients underwent standardized trabeculectomy with intra-operative application of mitomycin C. The filtering blebs were evaluated clinically and with SL-OCT on day 1 and 1, 2, 4 and 12 weeks following surgery. The resulting data were analysed and weighed against surgical success. To better understand the SL-OCT data a small comparative histologic study was performed. Results The study included 20 eyes of 20 patients. After completion of our study, 15 eyes of 15 patients (mean age±SD 67 ± 16 years) were eligible for data analysis and 5 eyes missed at least one follow-up visit. Filtering surgery was considered successful (intraocular pressure ≤ 21 mmHg without antiglaucomatous medication) in 11 of 15 eyes. SL-OCT frequently demonstrated multiple hypo-reflective layers within Tenon’s capsule (“striping” phenomenon) in the first post-operative week. Presumably, these layers corresponded with drainage channels in the histological specimen. These channels were present in functional filters but not in the failures. In addition, the visualisation of the sclera below the filtering zone was better defined in failures compared with successful filtering blebs (“shading” phenomenon). We observed no differences in the volume and clinical aspect of the blebs in the successful group compared with the unsuccessful group. Conclusions Successful filtering blebs show characteristic optical properties on SL-OCT. These phenomena suggest a diffusely enhanced fluid content and the presence of intra-bleb drainage channels in functional filtering blebs. Meeting presentation Presented in part as a poster at the 1st World Glaucoma Congress, Vienna, Austria, July 2005. Financial disclosure Medical Workshop, Groningen, Netherlands, made the slit lamp-adapted optical coherence tomography device available to one of the authors (T. Theelen) with support from the manufacturer, Heidelberg Engineering, Lübeck, Germany. There are no other competing interests.     

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.     

Stratus optical coherence tomography study of filtering blebs after primary trabeculectomy with a fornix‐based conjunctival flap

Purpose: To investigate the relationship between filtering bleb function and Stratus optical coherence tomography (OCT) images. Methods: We studied 72 eyes of 65 consecutive patients who had a fornix‐based conjunctival flap in primary trabeculectomy with mitomycin C (MMC). Filtering blebs with various types of glaucoma were examined using Stratus OCT. Success rates were defined as intraocular pressure (IOP) ≤ 15 mmHg and IOP reduction ≥ 25% without medication or additional surgery. Success rates among classified groups were compared using Kaplan–Meier survival curves and the log‐rank test. Results: Blebs were classified into three different categories on the basis of the following Stratus OCT patterns: cystoid type (multiple cysts inside the bleb; 17 eyes), diffuse type (low to high reflective areas that were mixed inside the bleb; 31 eyes) and layer type (medium to high reflective layer inside the bleb; 24 eyes). Success rates in the cystoid‐, diffuse‐ and layer‐type blebs were 94%, 97% and 75% (P = 0.02), respectively. Conclusion: In trabeculectomy with MMC and a fornix‐based conjunctival flap, there is a significant association between the success rates and the postoperative Stratus OCT findings of filtering blebs.     

Imaging of trabeculectomy blebs with Visante anterior segment optical coherence tomography after digital ocular compression

Purpose  

We investigated changes in intrableb morphology of functioning trabeculectomy blebs with anterior segment optical coherence tomography (AS-OCT) after digital ocular compression.     

Anterior segment optical coherence tomography imaging of trabeculectomy blebs before and after laser suture lysis

PURPOSE: To image trabeculectomy blebs before and after laser suture lysis (LSL) using anterior segment optical coherence tomography (AS-OCT). DESIGN: Prospective observational study. METHODS: Blebs were imaged with a prototype of the AS-OCT (Carl Zeiss Meditec, Inc, Dublin, California, USA) before and after LSL. Blebs were assessed for bleb height, bleb wall thickness, apposition of the scleral flap to sclera, and patency of the internal ostium. RESULTS: Seven blebs in eyes of seven patients were imaged. Pre-LSL, five blebs were low and two were of moderate height. After LSL, six of seven eyes (85.7%) showed an increase in total bleb height, with increased bleb wall thickness and separation of the scleral flap from sclera. In one eye, there was no discernible change in bleb height, cavity height, or wall thickness. CONCLUSIONS: AS-OCT was able to demonstrate features of bleb morphology that changed after LSL.     

AS-OCT对青光眼滤过术后滤过泡形态及形成过程评估

目的 通过应用眼前节光学相干断层扫描(AS-OCT)对青光眼滤过术后不同时期滤过泡内部结构的观察,了解各种类型滤过泡的内部结构特征和动态变化规律,以期寻找不同形态滤过泡与其功能间关系,为临床诊疗提供客观依据.方法 前瞻性分析研究.对2009年3月至2009年12月在北京大学眼科中心行青光眼滤过手术的患者62例(68只眼),年龄从27 ～ 79岁,平均年龄(62.56±14.06)岁,其中男性26例(29只眼),女性36例(39只眼).在术后1d,1周,1个月,3个月,6个月分别行视力,眼压,裂隙灯显微镜和AS-OCT检查.结果 68只眼中有4只眼在术后6个月时眼压高于20 mm Hg,其余64只眼在随访期间眼压均在正常范围.术后1d至术后6个月,滤过泡的总体高度变化差异无统计学意义(P＞0.05),囊壁厚度逐渐增加(P＜0.05),囊壁回声逐渐增强(P＜0.05).AS-OCT能清晰显示滤过泡的内部结构;量化有效滤过泡的各项指标,包括滤过泡总体高度,囊壁的厚度,巩膜瓣下的滤过通道等;显示滤过手术后不同时期滤过泡的动态变化.结论 AS-OCT是评价青光眼术后滤过泡形态的有效工具.探明滤过泡外观、内部结构及其功能的相互关系,有助于为滤过泡的功能维护提供客观参考.     

前节相干光断层扫描在球结膜及相关疾病中的应用

相干光断层扫描(optical coherence tomography,OCT)自问世以来,以其无创、非接触、高分辨率的优势,迅速在眼科领域推广应用,检查部位从眼后节黄斑、视神经,发展到眼前节结构的观察及相关疾病的诊治,为临床诊疗与科研提供更为可靠、准确的临床资料.近年来,前节OCT技术被应用于球结膜的参数测定(如球结膜厚度测量)、小梁切除术后滤过泡评估,以及结膜松弛症、翼状胬肉、睑裂斑、结膜肿瘤、球结膜淋巴管扩张等球结膜组织结构观察与结膜疾病的诊疗过程中,拓展了前节OCT的应用领域.     

Anterior segment imaging: ultrasound biomicroscopy and anterior segment optical coherence tomography

PURPOSE OF REVIEW: Recent advances in ocular imaging have included high-resolution techniques for visualizing the anterior segment and angle structures. This review will describe the two main anterior segment imaging modalities and summarize their applications, strengths and weaknesses. RECENT FINDINGS: Ultrasound biomicroscopy and more recently anterior segment optical coherence tomography are imaging modalities that can be used to obtain two-dimensional images of the angle and surrounding structures. Ultrasound biomicroscopy has the advantage of being able to illustrate the ciliary body and therefore give clinicians information on nonpupil block mechanisms of primary angle closure and also diagnose other abnormalities such as cyclodialysis clefts. Anterior segment optical coherence tomography is a noncontact and rapid method of imaging the angle and anterior segment that has great potential in the diagnosis and follow-up of patients with angle closure. This article will discuss these and other applications and compare and contrast the two technologies. SUMMARY: Rapid advances in anterior segment imaging are enlightening clinicians and researchers to the importance in making the diagnosis of primary angle closure, trying to establish underlying causal mechanisms, and evaluating treatments. Although they do not replace conventional angle and anterior segment examination, they hold great potential for the future.     

Filtering bleb functionality: a clinical, anterior segment optical coherence tomography and in vivo confocal microscopy study

PURPOSE: To provide a microscopic and macroscopic analysis by a clinical, in vivo confocal microscopy (IVCM) and anterior segment optical coherence tomography (AS-OCT) assessment of filtering blebs after glaucoma surgery. MATERIAL AND METHODS: We retrospectively analyzed 60 eyes of 48 glaucomatous patients by slit-lamp, IVCM, and AS-OCT examinations. Patients were divided into 2 groups: successful blebs (group 1, 16 patients, 27 eyes) were defined as a one-third reduction in preoperative intraocular pressure without antiglaucoma medications and failed blebs (group 2, 32 patients, 33 eyes) as a less than one-third reduction in preoperative intraocular pressure without therapy. The examinations were performed from 1 to 96 months postoperatively. RESULTS: Diffuse or cystic clinical patterns were indicative for good functionality whereas flat or encapsulation was indicative for poor functionality. When comparing successful with failed blebs, the IVCM analysis showed a greater number (P=0.014), density (P=0.009), and total area of epithelial microcysts (P=0.017) and a lower density of connective tissue (P=0.006). The AS-OCT analysis showed a lower degree of bleb wall reflectivity (P<0.001). A significant correlation was found between the clinical and AS-OCT parameters, particularly for the cystic (100%) and diffuse (74%) patterns. CONCLUSIONS: All IVCM parameters did correlate well with the bleb functionality whereas, among the AS-OCT parameters, only the bleb wall reflectivity was significantly related to the filtering capability. Clinical and AS-OCT bleb classification showed a significant degree of concordance. As a consequence, simultaneous approach by clinical, microscopic, and tomographic assessment improves the clinician's ability in the postsurgery understanding and management of blebs.     

Analysis of bleb morphology after trabeculectomy with Visante anterior segment optical coherence tomography

BACKGROUND: To describe the use of anterior segment optical coherence tomography (OCT) in imaging intrableb morphology after trabeculectomy. METHODS: 14 post-trabeculectomy eyes from 11 primary open angle glaucoma and 3 primary angle closure glaucoma subjects were studied. The blebs were classified with reference to slit lamp morphology and bleb function. They included diffuse filtering (n = 7), cystic (n = 2), encapsulated (n = 2) and flattened (n = 3) bleb types. One eye in each patient was imaged with the Visante anterior segment OCT. A vertical scan line of 10 mm consisting of 512 A-scans was positioned at the centre of the bleb. The images were then analysed by built-in software. Intrableb morphologies and structures, including bleb wall thickness, subconjunctival fluid collections, suprascleral fluid space, scleral flap thickness, intrableb intensity (low, medium or high) and the route under the scleral flap were characterised and measured. RESULTS: Diffuse filtering blebs were found by subconjunctival fluid collections. Suprascleral fluid space and the route under the scleral flap were identified in four of the seven cases. Cystic blebs were composed of a large hyporeflective space with multiloculated fluid collections covered by a thin layer of conjunctiva. Encapsulated blebs had a thick bleb wall with high reflectivity and an enclosed fluid filled space. Flattened blebs demonstrated high scleral reflectivity and no bleb elevation. CONCLUSIONS: Visante anterior segment OCT can be used for bleb imaging. The different patterns of intrableb morphology identified by OCT were related to slit lamp appearance and bleb function. This information may be useful to study the different surgical outcomes and the process of wound healing in trabeculectomised eyes.