• Users Online: 444
  • Home
  • Print this page
  • Email this page
Home Current issue Ahead of print Search About us Editorial board Archives Submit article Instructions Subscribe Contacts Login 

 Table of Contents  
ORIGINAL ARTICLE
Year : 2018  |  Volume : 111  |  Issue : 4  |  Page : 137-143

Evaluation of the anterior chamber angle and filtering bleb morphology after phacotrabeculectomy by using anterior segment optical coherence tomography


1 A Resident at Minia General Ophthalmology Hospital, Minia University, Egypt
2 Assistant Professor of Ophthalmology, Ophthalmology Department, Minia University, Egypt

Date of Web Publication13-Feb-2019

Correspondence Address:
Ahmed Mostafa Eid
Ophthalmology Department, Minia University
Egypt
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ejos.ejos_22_18

Rights and Permissions
  Abstract 

Purpose Evaluating the anterior chamber angle (ACA) and filtering bleb following phacotrabeculectomy by using anterior segment optical coherence tomography (AS-OCT).
Patients and methods This is a retrospective study that included 30 eyes of 30 patients with cataract and glaucoma of both sexes and aged from 42 to 72 years. Patients attended the Ophthalmology Department of Minia University Hospital between June 2016 and November 2017. The duration of follow-up was 6 months. The patient’s underwent preoperative clinical and AS-OCT examination, followed by phacotrabeculectomy, and then postoperative AS-OCT to evaluate the angle and the filtering bleb.
Results A total of eight patients were diagnosed with primary open-angle glaucoma and 22 with primary closed-angle glaucoma. Overall, eight (26.7%) eyes had closed angle in two quadrants: six (20%) eyes with closed superior and inferior quadrants and two (6.7%) eyes with closed nasal and temporal quadrants. Closed ACAs in three quadrants of the eye, the superior, nasal, and temporal quadrants, were found in six (20%) eyes. Closed ACAs in the four quadrants of the eyes were observed in eight (26.7%) eyes. Cystic blebs are highly elevated and hyporeflective (30% of cases). Diffuse blebs are moderately elevated with moderate reflectivity (50% of cases). Flat blebs are low with hyperreflectivity (20% of cases).
Conclusion AS-OCT is an optimistic tool to investigate the filtering blebs. It was able to detect angle changes preoperatively and postoperatively and show the features of the bleb that are not properly detected by the slit lamp examination. It has the advantage over ultrasound biomicroscopy in being a noncontact, noninvasive procedure, allowing early postoperative examination.

Keywords: angle in glaucoma, anterior segment optical coherence tomography, filtering bleb, phacotrabeculectomy


How to cite this article:
AbdElHakam OO, Abdelrahman RM, Abdelrazek ST, Eid AM. Evaluation of the anterior chamber angle and filtering bleb morphology after phacotrabeculectomy by using anterior segment optical coherence tomography. J Egypt Ophthalmol Soc 2018;111:137-43

How to cite this URL:
AbdElHakam OO, Abdelrahman RM, Abdelrazek ST, Eid AM. Evaluation of the anterior chamber angle and filtering bleb morphology after phacotrabeculectomy by using anterior segment optical coherence tomography. J Egypt Ophthalmol Soc [serial online] 2018 [cited 2019 May 21];111:137-43. Available from: http://www.jeos.eg.net/text.asp?2018/111/4/137/252176


  Introduction Top


Cataract and glaucoma are important factors that cause blindness worldwide. The incidence of both is increasing with age [1].

Glaucoma surgery aims to make the intraocular pressure (IOP) low enough to guard against or slow down the further progression of optic nerve damage and visual field deterioration. Many patients present with cataract and glaucoma; however, there is no general agreement on surgical management of coexisting cataract and glaucoma. The combined cataract and glaucoma surgery has been the subject of some controversy [2].

Angle assessment techniques are important in the management of glaucoma [3]. These techniques include the following:
  1. Gonioscopy: assessment of anterior chamber angle (ACA) findings by goniolens, which is considered as a standard method [4].
  2. Anterior segment optical coherence tomography (AS-OCT) is a noninvasive, noncontact, in-vivo imaging technique based on low-coherence interferometry [5]. AS-OCT provides clear images of the anterior part of the eye, including the angle and the filtering bleb [6]. It uses the infrared light to provide real-time images and allows objective and qualitative evaluation of ACA [7]. It is a very good tool for the routine clinical assessment and early postoperative examination when gonioscopy is not possible or difficult and dangerous [8].



  Aim Top


The aim was to evaluate the angle of the anterior chamber and the filtering bleb following phacotrabeculectomy by using AS-OCT.


  Patients and methods Top


A total of 30 eyes of 30 patients with cataract and glaucoma were evaluated retrospectively. The patients were of both sexes, with age ranged from 42 to 72 years old, who underwent phacotrabeculectomy operation. According to medical ethical committee of Minia University.

Data of the patients attending the Ophthalmology Department of Minia University Hospital between June 2016 and November 2017 for cataract and glaucoma surgery were revised and collected, and then a retrospective study was prepared.

Inclusion criteria

The following were the inclusion criteria:
  1. Patients with both cataract and glaucoma (primary open-angle glaucoma and primary closed-angle glaucoma).
  2. The duration of follow-up was 6 months.


Exclusion criteria

The following were the exclusion criteria:
  1. Patients with a previous ocular surgery.
  2. History of penetrating ocular trauma.
  3. Previous anterior segment laser treatment.
  4. Any corneal opacities.


A full ophthalmological evaluation was done including the following:
  1. Visual acuity and best-corrected visual acuity.
  2. IOP measurement using Goldman applanation tonometer.
  3. Anterior segment examination by slit lamp.
  4. Posterior segment examination.
  5. Gonioscopy preoperatively, using Goldman 3-mirror goniolens (Volk Canada Calarion Medical Technologies Inc.).
  6. AS-OCT preoperatively and postoperatively.


The angle in each quadrant was graded according to Shaffer grading system ([Table 1]). The angle and bleb imaging was obtained by Topcon 3D OCT-2000 (version 8.1×) ([Figure 1]).
Table 1 Summary of Shaffer grading system

Click here to view
Figure 1 Topcon 3D OCT-2000, version 8.1×. OCT, optical coherence tomography.

Click here to view


AS-OCT examination: image acquisition was performed under dark conditions. Patients were instructed to fixate on an external target directed nasally, temporally, superiorly, and inferiorly to assess the ACA of each eye at the horizontal (3 and 9 o’clock positions) and the vertical (6 and 12 o’clock positions) meridians. The eye lids were gently opened to move out of the way by the operator to image the inferior/superior angle to avoid inadvertent pressure on the globe. Then, the analyzed eye was in down-gaze, and the upper eyelid was gently moved up. The bleb and the surrounding conjunctiva were exposed as much as possible. The three-dimensional OCT system shows the three-dimensional anatomic features of the anterior segment, including the angle and the filtering bleb. Each bleb was scanned twice or more, and the best images were selected for subsequent analysis.

Scanning was performed with a vertical 10-mm scan at the center of the bleb. Main outcomes variables were as follows.

The angle was considered to be closed on AS-OCT imaging if contact was found anterior to the scleral spur between the iris and angle wall ([Figure 2]a and b).
Figure 2 AS-OCT imaging showing (a) closed angle and (b) open angle. AS-OCT, anterior segment optical coherence tomography.

Click here to view


The filtering bleb was considered to be cystic if there was reasonable elevation on the scleral bed and considerable subconjunctival space with low reflectivity ([Figure 3]).
Figure 3 A high successful bleb, the bleb wall (W), cavity (C), scleral flab (F), and internal keratotrabeculectomy ostium (O) are clearly seen. AC, anterior chamber; CO, cornea; L, lower lid; PL, peripheral iridectomy; U, upper lid. Cystic spaces within the wall, and these are seen in the superficial and deep region of the wall.

Click here to view


The technique of operation

Phacotrabeculectomy was done by the same surgeon, and the same surgical technique for all cases was applied. Postoperatively, 6-month follow-up was done for all patients.

Statistical analysis

Data were collected, revised, verified, coded, and then entered into PC for statistical analysis using SPSS statistical package, version 20.


  Results Top


This is a retrospective study to detect diagnostic performance of AS-OCT in assessing the ACA preoperatively and postoperatively as well as filtering bleb after phacotrabeculectomy.

Demographic data of the patients

The data of 30 eyes of 30 patients with cataract and glaucoma of both sexes (16 males and 14 females). The patients’ age ranged from 42 to 72 years (mean, 54.68±8.23 years), [Table 2].
Table 2 Demographic data of patients

Click here to view


They all underwent phacotrabeculectomy. A total of eight patients were diagnosed with primary open-angle glaucoma and 22 were diagnosed with primary closed-angle glaucoma.

The following items were compared preoperatively and postoperatively:
  1. Preoperative and postoperative AS-OCT for ACA.
  2. Postoperative AS-OCT for filtering bleb included bleb wall thickness, presence of microcysts, reflectivity, and bleb height. Before doing phacotrabeculectomy, the mean preoperative IOP was 34.3±3.5 mmHg, and the mean postoperative IOP was 17.3±0.95 mmHg, with significant improvement (IOP was controlled in all cases regardless of the type of bleb) (P<0.001).


Gonioscopy

Chamber angle in each quadrant was classified preoperatively according to the Shaffer grading system.

Grade 0 was detected in a total of 16 (13.2%) quadrants, grade 1 in 20 (16.7%) quadrants, grade 2 in 17 (14.2%) quadrants, grade 3 in 26 (21.7%) quadrants, and grade 4 in 41 (34.2%) quadrants.

Anterior segment optical coherence tomography of the angle preoperatively and postoperatively

Angle was assessed in four quadrants and according to the presence of scleral spur (open angle) or absence of scleral spur (closed angle) ([Figure 4]a and b).
Figure 4 A 57-year-old male patient presented with cataract and glaucoma (PCAG). IOP preoperatively was 38 mmHg, and postoperative IOP was 21 mmHg. (a) Preoperative AS-OCT imaging of ACA superior, inferior, and nasal quadrants showed closed angle (absent scleral spur). (b) Postoperative AS-OCT imaging of ACA same quadrants showed open angle (scleral spur present). ACA, anterior chamber angle; AS-OCT, anterior segment optical coherence tomography; IOP, intraocular pressure; PCAG, primary closed-angle glaucoma.

Click here to view


A closed angle in two quadrants was found in eight (26.7%) eyes: six (20%) eyes with closed superior and inferior quadrants and two (6.7%) eyes with closed nasal and temporal quadrants.

Closed angles in three quadrants of the eye (upper, nasal, and temporal) were found in six (20%) eyes. Closed ACAs in the four quadrants of the eyes were observed in eight (26.7%) eyes.

An open angle in the four quadrants of the eyes was observed in eight (26.7%) eyes.

Anterior segment optical coherence tomography in filtering bleb

  1. Cystic blebs are highly elevated and hyporeflective (30% of cases).
  2. Diffuse blebs are moderately elevated with moderate reflectivity (50% of cases).
  3. Flat blebs are low with hyperreflectivity (20% of cases).


The postoperative AS-OCT bleb among the studied individuals (shape), Figure 5.{Figure 5}

Microcysts within the bleb wall were present in 18 (60%) cases.

Thick bleb wall was present in 18 (60%) cases.


  Discussion Top


Ultrasound biomicroscopy (UBM) and OCT for evaluation of the angle and the bleb in glaucoma are important diagnostic methods. AS-OCT can obtain real-time images of the angle and provide a rapid noncontact method for detecting eyes at risk for angle closure [9],[10]. From this study superior quadrants showed the highest rates of closed angles (73%), followed by inferior (66.7%), nasal (53%), and temporal (26.7%), and it showed eight eyes with opened ACA in four (26.7%) quadrants from those 30 eyes..

Sakata et al. [11] found that the ACA is closed most commonly in the superior quadrant on gonioscopy.

Our results were in agreement with Kunimatsu et al. [12] who examined the ACA of 80 patients with a shallow anterior chamber using UBM and found that closed angles on the superior quadrants (79%), followed by the inferior (64%), nasal (33%), and temporal (26%) quadrants.

This study demonstrated that postoperative AS-OCT measurement of ACA in patients who underwent phacotrabeculectomy was opened in four (100%) quadrants in all the studied eyes.

AS-OCT significantly shows cross-sectional images of bleb morphology that was previously not possible by clinical examination [13].

In this study, three types of blebs were described, that is, nine cystic blebs associated with large subconjunctival hyporeflective fluid spaces with thick bleb wall, 12 diffuse blebs with one or more small subconjunctival hyporeflectivity to moderate reflectivity fluid spaces, and nine flat blebs with no subconjunctival spaces, but it did not count encapsulated blebs; this finding matched to some extent with Leung et al. [14] who found cystic bleb, described by a thin wall, big subconjunctival space, internal hyporeflectivity and multiloculated fluid collection; diffuse bleb, defined by a thin wall with one or more subconjunctival spaces with low to moderate reflectivity; encapsulated bleb, if it was large and unique subconjunctival space and thick wall; and flattened bleb, when significant signs of subconjunctival space were not present, with the appearance of a complete contact between scleral bed and bleb wall, and more cases were needed to describe all types of filtering blebs.

Leung et al. [14] found that successful bleb has diffuse thickening of the bleb wall, whereas unsuccessful IOP control was accompanied by thin bleb walls.

Phacoemulsification with IOL implantation can lead to widening of the ACA in open angle and closed angle eyes, based on quantitative evaluation of AS-OCT imaging. Moreover, these results can show correlations between IOP reduction and angle widening, as in this study, there were 22 cases with closed-angle glaucoma.

Cataract extraction usually leads to lowering of the IOP. Wide variation in mean IOP reductions (1.1–13.5 mmHg) have been recorded in such studies [15]. In the current study, we found that the postoperative IOP was reduced significantly in all cases. The mean preoperative IOP was 34.3±3.5, and the mean postoperative IOP was 17.3±0.95, with significant improvement (IOP was controlled in all cases regardless the type of bleb) (P<0.001).

Cataract surgery removes the anatomical cause of angle closure, resulting in deepening and widening of the drainage angle. It would be expected that access of aqueous to the filtering portion of the trabecular meshwork would be improved owing to the widening of the drainage angle.

In this study, reduction of IOP was more demonstrated in cases with a closed angle.

The postoperative reduction in IOP was directly proportional to the increase in angle width in open angle and closed angle eyes, and that can be well evaluated with AS-OCT and showing internal bleb morphology using Topcon AS-OCT. AS-OCT can show features of the bleb that cannot be detected by the slit lamp examination. A large fluid-filled cavity, a huge hyporeflective area, and a thick bleb wall and many microcysts were found to be the signs of well-functioning blebs. Both clinical and imaging data could provide a new tool to understand the different surgical outcomes after phacotrabeculectomy, improve understanding of bleb function and may help in making proper decisions for postoperative bleb management. This knowledge could be crucial to improve surgical techniques and evaluate the use of different surgical treatment modalities.As the role of AS-OCT is comparable to UBM, both allow imaging of the iridocorneal angle and, thus, can help in diagnosis and management of glaucoma [16].

UBM and AS-OCT are important methods for planning and guidance of glaucoma surgery including the evaluation of filtering blebs, as well as the diagnosis and postoperative follow-up and evaluation of postoperative complications [17].

OCT has an advantage over UBM in being noncontact and providing finer resolution than UBM, but UBM is superior in visualizing the retroiridal structures [18].


  Conclusion Top


AS-OCT is a reliable tool to image the filtering blebs. It is able to determine the ACA changes preoperatively and postoperatively and demonstrate characters of the bleb that are not apparent at the clinical examination by the slit lamp. It has the advantage over UBM in being noncontact, noninvasive procedure allowing early postoperative evaluation and management.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Friedman DS, Jampel HD, Lubomski LH, Kempen JH, Quigley H, Congdon N et al. Surgical strategies for coexisting glaucoma and cataract: an evidence-based update1. Ophthalmology 2002; 109:1902–1913.  Back to cited text no. 1
    
2.
Stamper RL, Lieberman MF, Drake MV, Becker B. Becker −Shaffer’s diagnosis and therapy of the glaucomas. Elsevier Health Sciences; 2009.  Back to cited text no. 2
    
3.
Gupta SK, Niranjan DG, Agrawal SS, Srivastava S, Saxena R. Recent advances in pharmacotherapy of glaucoma. Indian J Pharmacol 2008; 40:197–208.  Back to cited text no. 3
[PUBMED]  [Full text]  
4.
He M, Foster PJ, Johnson GJ, Khaw PT. Angle-closure glaucoma in East Asian and European people. Different diseases. Eye (Lond) 2006; 20:3–12.  Back to cited text no. 4
    
5.
Huang D, Swanson EA, Lin CP, Schuman JS, Stinson WG, Chang W et al. Optical coherence tomography. Science 1991; 254:1178–1181.  Back to cited text no. 5
    
6.
Console JW, Sakata LM, Aung T, Friedman DS, He M. Quantitative analysis of anterior segment optical coherence tomography images: the Zhongshan Angle Assessment Program. Br J Ophthalmol 2008; 92:1612–1616. ‏  Back to cited text no. 6
    
7.
Dawczynski J, Koenigsdoerffer E, Augsten R, Strobel J. Anterior segment optical coherence tomography for evaluation of changes in anterior chamber angle and depth after intraocular lens implantation in eyes with glaucoma. Eur J Ophthalmol 2007; 17:363–367.  Back to cited text no. 7
    
8.
Kalev-Landoy M, Day AC, Cordeiro MF, Migdal C. Optical coherence tomography in anterior segment imaging. Acta Ophthalmol Scand 2007; 85:427–430.  Back to cited text no. 8
    
9.
Konstantopoulos A, Hossain P, Anderson DF. Recent advances in ophthalmic anterior segment imaging: a new era for ophthalmic diagnosis. Br J Ophthalmol 2007; 91:551–557.  Back to cited text no. 9
    
10.
Bald M, Li Y, Huang D. Anterior chamber angle evaluation with fourier-domain optical coherence tomography. J Ophthalmol 2012; 2012:103704.  Back to cited text no. 10
    
11.
Sakata LM, Lavanya R, Friedman DS, Aung HT, Gao H, Kumar RS et al. Comparison of gonioscopy and anterior segment ocular coherence tomography in detecting angle closure in different quadrants of the anterior chamber angle. Ophthalmology 2008; 115:769–774.  Back to cited text no. 11
    
12.
Kunimatsu S, Tomidokoro A, Mishima K, Takamoto H, Tomita G, Iwase A, Araie M. Prevalence of appositional angle closure determined by ultrasonic biomicroscopy in eyes with shallow anterior chambers. Ophthalmology 2005; 112:407–412.  Back to cited text no. 12
    
13.
Salim S, Dorairaj S. Anterior segment imaging in glaucoma. Semin Ophthalmol 2013; 28:113–125.  Back to cited text no. 13
    
14.
Leung CK, Yick DW, Kwong YY, Li FC, Leung DY, Mohamed S et al. Analysis of bleb morphology after trabeculectomy with Visante anterior segment optical coherence tomography. Br J Ophthalmol 2007; 91:340–344.  Back to cited text no. 14
    
15.
Huang G, Gonzalez E, Peng PH, Lee R, Leeungurasatien T, He M et al. Anterior chamber depth, iridocorneal angle width, and intraocular pressure changes after phacoemulsification: narrow vs open iridocorneal angles. Arch Ophthalmol 2011; 129:1283–1290.  Back to cited text no. 15
    
16.
Radhakrishnan S, Goldsmith J, Huang D, Westphal V, Dueker DK, Rollins AM et al. Comparison of optical coherence tomography and ultrasound biomicroscopy for detection of narrow anterior chamber angles. Arch Ophthalmol 2005; 123:1053–1059.  Back to cited text no. 16
    
17.
Kawana K, Kiuchi T, Yasuno Y, Oshika T. Evaluation of trabeculectomy blebs using 3-dimensional cornea and anterior segment optical coherence tomography. Ophthalmology 2009; 116:848–855.  Back to cited text no. 17
    
18.
Radhakrishnan S, See J, Smith SD, Nolan WP, Ce Z, Friedman DS et al. Reproducibility of anterior chamber angle measurements obtained with anterior segment optical coherence tomography. Invest Ophthalmol Vis Sci 2007; 48:3683–3688.  Back to cited text no. 18
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
 
 
    Tables

  [Table 1], [Table 2]



 

Top
 
 
  Search
 
Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

 
  In this article
Abstract
Introduction
Aim
Patients and methods
Results
Discussion
Conclusion
References
Article Figures
Article Tables

 Article Access Statistics
    Viewed225    
    Printed38    
    Emailed0    
    PDF Downloaded55    
    Comments [Add]    

Recommend this journal


[TAG2]
[TAG3]
[TAG4]