Anterior-segment OCT (AS-OCT) and Intraoperative OCT (iOCT) for Trans- Conjunctival Needle Revision (TCNR) of Trabeculectomy Bleb
Phase: NA
Conditions: Glaucoma, Glaucoma Following Surgery
Sponsor: Northwestern University

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PROTOCOL TITLE: Anterior-segment OCT (AS-OCT) and intraoperative OCT (iOCT) for trans-
conjunctival needle revision (TCNR) of trabeculectomy bleb
PRINCIPAL INVESTIGATOR:
Angelo P. Tanna, MD
Department of Ophthalmology
Northwestern University Feinberg School of Medicine
Telephone Number: 312-908-8152
Email Address: atanna@northwestern.edu
VERSION DATE: 04/16/2021
STUDY SUMMARY:
Investigational Agent(s) 
(Drugs or Devices)
N/A
IND / IDE / HDE # 
Indicate
Special Population(s)
Children 
 Children who are wards of the state 
 Adults Unable to Consent  
 Cognitively Impaired Adults 
 Neonates of Uncertain Viability 
 Pregnant Women 
 Prisoners (or other detained/paroled individuals) 
 Students/Employees
Sample Size
Prospective study: 25 Subjects  
Retrospective study (historical controls): 25 subjects
Funding Source
Department of Ophthalmology
Illinois Society for the Prevention of Blindness
Indicate the type of consent 
to be obtained
Written 
Verbal/Waiver of Documentation of Informed Consent
Waiver of HIPAA Authorization 
Waiver/Alteration of Consent Process  
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Site
 Lead Site ( For A Multiple Site Research Study)
 Data Coordinating Center (DCC)
Research Related Radiation 
Exposure
Yes 
 No
DSMB / DMC / IDMC
Yes 
No
OBJECTIVES:
The aim of the research is to assess the surgical success, feasibility and utility of pre-operative 
Anterior Segment Optical Coherence Tomography (AS-OCT) and intraoperative Optical 
Coherence Tomography (iOCT) in trans-conjunctival needle revision (TCNR) of trabeculectomy 
bleb. Furthermore, we want to assess whether AS-OCT can be used to identify characteristics of 
trabeculectomy blebs that are associated with successful surgical outcomes. 
To undergo this study, we will conduct a prospective study of patients who consent to AS-OCT 
and iOCT revision of TCNR. We will compare the outcomes of these patients with 
retrospectively identified, historical controls (i.e. patients who underwent TCNR by the same 
surgeon without AS-OCT or iOCT assistance). 
We hypothesize that information gained from pre-operative AS-OCT and intraoperative OCT 
will aid with intraoperative decision-making for TCNR of trabeculectomy bleb and will thereby 
improve surgical outcomes. We also hypothesize that preoperative AS-OCT can be used to 
identify features of trabeculectomy bleb that can predict success with iOCT-assisted TCNR. 
More specifically, we hypothesize that filtering blebs with more extensive scarring as seen on 
pre-operative AS-OCT will benefit from iOCT. 
BACKGROUND:
Trabeculectomy is one of the most commonly performed glaucoma procedures performed to 
control IOP with approximately 18,000 operations performed in US Medicare beneficiaries 
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alone in 2012.1 One complication of trabeculectomy surgery is the formation of subconjunctival 
and episcleral fibrosis, which occurs as part of the wound healing process and can result in 
fibrosis of the filtering bleb and failure. Transconjunctival needle revision (TCNR) aims to lyse 
subconjunctival adhesions and reestablish adequate aqueous humor flow from the anterior 
chamber to the subconjunctival space. One study reported 17% of trabeculectomies require 
bleb-needling revision.2 During TCNR the surgeon is able to visualize the trajectory of the 
needle or blade under the conjunctiva; however, detection of the fibrotic tissue and 
determination as to whether that tissue has been adequately lysed is difficult, limiting the 
success rate of the procedure. 
Anterior segment optical coherence tomography (AS-OCT) allows for detailed assessment of the 
internal morphology of the bleb. Studies have utilized AS-OCT to assess morphological features 
of the bleb and correlate it with surgical success.3,4,7 A small case series reported the utility of 
AS-OCT for pre-operative planning for bleb revision, in particular, identifying safe access sites 
and minimizing conjunctival dissection.5
More recently, real time OCT integrated with operative microscope has become available. 
Intraoperative OCT (iOCT) has been utilized extensively in retinal surgery and corneal surgery.6 
Dada et al., described performing iOCT-guided TCNR in 2 patients with failed trabeculectomy 
blebs without intraoperative or postoperative complications.7 These authors report they were 
able to obtain a detailed view of the bleb wall and assess the depth and location of the needle, 
which permitted better lysis of adhesions. A pilot study by Kumar et al., reported one case of 
TCNR in which iOCT was used to demonstrate the extent of adhesions and loculations inside the 
bleb at the beginning of the procedure, and the lysis of these adhesions and formation of large 
single hyporeflective cavity inside the bleb at the end of the procedure.8 These small case 
studies suggest a role of iOCT imaging for TCNR, however, further research is needed to assess 
its feasibility and utility for routine use.
STUDY ENDPOINTS:
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Results from the following tests obtained as part of this study: 
1. Spectralis Anterior-segment OCT (AS-OCT)  (Heidelberg Engineering) available in Lavin 15th 
floor Ophthalmology clinic
2. Digital microscope integrated with Intraoperative OCT (Zeiss Artevo 800, Carl Zeiss Meditec 
AG) available in the Lavin 11th floor operating room 
The primary outcome will be surgical success, defined as a 20% reduction in unmedicated IOP 
below the pre-operative baseline at the post-operative visits (POD1, POM1, POM3). The success 
rate will be compared to a cohort of historical controls comprised of a consecutive series of 
age- and race-matched subjects who underwent TCNR in the operating room by the same 
surgeon, with the same intraoperative anti-fibrotic therapy, without AS-OCT or iOCT imaging 
during a five-year time period from 6/1/2015 to 6/1/2020.
The secondary outcomes will be feasibility and utility of intraoperative OCT. Feasibility will be 
defined as the percentage of cases with successful imaging of the bleb with iOCT. Utility will be 
defined as the percentage of cases in which iOCT changed surgical decision-making. 
Intraoperative OCT will be used to determine whether adhesions have been completely lysed 
and/or whether further lysis of adhesions is necessary. A survey with set of questions based on 
prior literature6 will be used to assess these parameters.  
We will also assess whether findings seen with pre-operative AS-OCT can predict what type of 
blebs will benefit from iOCT-assisted TNCR. Features of AS-OCT and iOCT imaging that will be 
assessed include quality of image capture, visualization of surgical site, and characteristics of 
the bleb. Characteristics of the surgical site include bleb height, internal reflectivity, location 
and number of adhesions, and presence of cysts, cavities, and fistulas.
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STUDY INTERVENTION(S) / INVESTIGATIONAL AGENT(S):
This prospective study will include approximately 25 patients with open-angle glaucoma who 
will undergo TCNR of trabeculectomy bleb by a glaucoma specialist at Northwestern Medicine. 
These patients will have a history of glaucoma and failed trabeculectomy bleb (as evidenced by 
clinical features and elevated IOP). During routine clinic visit, the patient will undergo lit lamp 
grading of bleb by Indiana Bleb Appearance Grading Score (IBAGS).4,9 Subjects who agree to 
participate and provide written informed consent will undergo AS-OCT imaging (Spectralis OCT, 
Heidelberg) of the bleb. During their operation, the Zeiss Artevo digital microscope integrated 
with iOCT (Zeiss Artevo 800, Carl Zeiss Meditec AG), a commercially available device will be 
utilized to visualize and evaluate the morphology of the trabeculectomy bleb at the start and 
conclusion of the case. 
PROCEDURES INVOLVED:
The devices used in the study are commercially available and have been used extensively in 
ophthalmology and intraocular surgery. Therefore, no experimental devices will be used. The 
AS-OCT is routinely obtained and is considered standard of care. The iOCT is commercially 
available and is also utilized routinely in ophthalmic surgery, particularly for retinal surgery. 
The Zeiss Artevo digital microscopy integrated with intraoperative OCT will be used as an 
adjunct to TCNR. Published research4,6 has not shown iOCT to increase risk of complications 
associated with routine TCNR and we believe injury from imaging is not biologically plausible. 
Surgery and iOCT will be recorded and saved to a secure NMH server. The surgical videos will 
only be used for research purposes. 
Review of medical records will be performed for patients who agree to participate in the 
prospective study. Data gathered will include basic demographic information and clinical data 
relevant to glaucoma management (visual acuity, intraocular pressure, medications, disease 
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severity). Post-operative course including intraocular pressure, intraoperative or post-operative 
complications and repeat TCNR or additional surgery will also be collected. 
Furthermore, a retrospective review of medical records will be performed for patients who 
underwent TCNR without iOCT or AS-OCT assistance by the same surgeon during the period 
from June 1, 2015 to June 1, 2020. This group of patients will serve as historical controls. These 
individuals will be identified using Enterprise Data Warehouse and billing data. We aim to 
identify approximately 25 controls. The selection criteria for controls are 1) age within 5 years 
of each study patient 2) same race as study patient 3) diagnosis of open angle glaucoma and 4) 
adequate follow up of at least 3 months. 
DATA AND SPECIMEN BANKING
Participants will be assigned a study ID. The patient identifiers will be stored separately from 
the coded study data.
Data abstracted from the medical record will be collected on a secure sever, with computers 
only accessible with passwords. Only the research team will have access to the identified data.
SHARING RESULTS WITH PARTICIPANTS
The results are part of the standard glaucoma care for each participant and they will be 
discussed with participants as part of the management of the condition. 
STUDY TIMELINES
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The participant will be in the study for the duration of their office visit (with AS-OCT testing) 
and surgery. In the context of this research study, participants will also be followed for 12 
months after surgery to assess their post-operative course. 
It will likely take approximately 12 months to enroll all study participants. The estimated date 
for completion of primary analyses will be 6 months after enrollment of study. 
INCLUSION AND EXCLUSION CRITERIA
Inclusion criteria
-
Briefly, the diagnosis of glaucoma is based on the presence of 2 or more of the following 
findings: 1) glaucomatous optic disc damage, defined as the presence of optic disc 
excavation, diffuse or focal neuroretinal rim thinning or notching, localized or 
generalized RNFL thinning; 2) visual field defects consistent with glaucoma; and 3) IOP ≥ 
22 mmHg. 
-
Patients with glaucoma who have been advised to undergo TCNR of a failed 
trabeculectomy bleb by a glaucoma specialist at Northwestern Medicine
-
History of failed trabeculectomy (based on clinical features of the trabeculectomy bleb 
and elevated intraocular pressure) 
-
Patients can have history of other glaucoma surgery or cataract surgery 
-
The diagnosis of glaucoma is based on the presence of 2 or more of the following 
findings: 1) glaucomatous optic disc damage, defined as the presence of optic disc 
excavation, diffuse or focal neuroretinal rim thinning or notching, localized or 
generalized RNFL thinning; 2) visual field defects consistent with glaucoma; and 3) IOP ≥ 
22 mmHg. 
Exclusion criteria
-
Age younger than 18 years; 
-
Secondary causes of glaucoma (e.g., iridocyclitis, trauma); 
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-
Any evidence of corneal or conjunctival pathology adjacent to filtration bleb that could 
influence AS-OCT image
-
Patients who did not undergo surgery or have adequate follow up
-
Adults unable to consent, individuals who are not yet adults (infants, children, 
teenagers), pregnant women, prisoners and vulnerable populations
VULNERABLE POPULATIONS: NONE
PARTICIPANT POPULATION(S)
Prospective Study Population 
Accrual 
Number:
Category/Group:
(Adults/Children 
Special/Vulnerable 
Populations)
Consented:
Maximum Number to be 
Consented or 
Reviewed/Collected/Screened
Enrolled:
Number to 
Complete the Study 
or Needed to 
Address the 
Research Question
25 adults 
25 adults 
25 eyes
Local
Study-wide
Total:
25 adults
25 adults 
25 eyes
Age and race matched historical controls (identified via retrospective chart review) 
Accrual 
Number:
Category/Group:
(Adults/Children 
Special/Vulnerable 
Populations)
Consented:
Maximum Number to be 
Consented or 
Reviewed/Collected/Screened
Enrolled:
Number to 
Complete the Study 
or Needed to 
Address the 
Research Question
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25 adults 
0 
25 eyes
Local
Study-wide
Total:
25 adults
0 
25 eyes
RECRUITMENT METHODS
Potential participants will be identified from the patients scheduled for follow up in the 
Glaucoma Service at Northwestern Medicine. Potential participants who are already scheduled 
for surgery may be called to gauge interest in the study. If they express interest, the patient will 
return to clinic prior to surgery to review and sign the informed consent and complete pre-
surgery study imaging. Only patients who fit the inclusion/exclusion criteria will be asked to 
participate in the study. 
COMPENSATION FOR PARTICIPATION IN RESEARCH ACTIVITIES
There is no additional cost for the patient to participate in this study. Patients and their
insurance companies will be billed for office visits and procedures that are part of their usual
medical care. There is no compensation made to the study subjects for participating in this
study. Patients will have routine preoperative and postoperative follow up visits as necessary 
based on their clinical course. No extra visits will be required as a result of participation in this
study.
WITHDRAWAL OF PARTICIPANTS
All the participants are free to withdraw at any point of the study.  In case the participants are 
not willing to continue with the study protocol they will be removed from the analysis. 
RISKS TO PARTICIPANTS
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There is a risk of loss of confidentiality of the information that is used in this study.  To minimize 
the risk of breach in confidentiality, the consent process for the prospective study will be done 
in a private room. Patient names will be replaced with arbitrary IDs. For the duration of the 
study, the patients will be referred by their ID. All data will be kept in a password-protected file.
POTENTIAL BENEFITS TO PARTICIPANTS
There may be no direct benefits of this study to the patient. Results of this study may provide 
important knowledge that will be generalizable to the care of other patients with glaucoma.
DATA MANAGEMENT AND CONFIDENTIALITY
PROVISIONS TO MONITOR THE DATA TO ENSURE THE SAFETY OF PARTICIPANTS
For the prospective study, the consent process and all the study procedures will be done in a 
private room/space. To protect participant’s confidentiality, their information and study 
conduct will only be discussed with individuals listed in the study personnel. 
In general, patients’ data and all information pertaining to this study will remain confidential 
and all the study materials will be kept in a password protected computer a password-
protected file and a secure server. Paper files will be kept in a locked drawer. In addition, the 
identifier list will be maintained separately from the study data. This identifier list will be kept in 
a password-protected file on a secure server.
PROVISIONS TO PROTECT THE PRIVACY INTERESTS OF PARTICIPANTS
The study is done in the same facility that glaucoma clinic is located and patients are imaged 
with the AS-OCT device on the same floor. The acquired data with AS-OCT are similar to images 
routinely taken for their glaucoma follow up. The iOCT is attached to the operating microscope 
in the same operating room that is routinely used for ocular surgery. The consent process and 
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all the study procedures for individuals enrolled in the prospective study will be done in a 
private room/space. 
To protect participant’s confidentiality, their information and study conduct will only be 
discussed with individuals listed in the study personnel. Patients’ data and all information 
pertaining to this study will remain confidential and all the study materials will be kept in a 
password-protected computer a password-protected file and a secure server. Paper files will be 
kept in a locked drawer.
COMPENSATION FOR RESEARCH-RELATED INJURY
This study is minimal risk and therefore, there will be no anticipated research related injuries in 
this study or compensation for such injuries
ECONOMIC BURDEN TO PARTICIPANTS
Patients will be billed for the office visit as this was planned in advance. There will be no extra 
cost to patients as a result of this study. The AS-OCT or iOCT that will be performed as part of 
this study will not be billed to the patient or their insurance carrier.
CONSENT PROCESS
Potential participants in the prospective study will be identified from the patients scheduled for 
follow up or surgery in the Glaucoma Service at Northwestern Medicine. Patients will be 
approached verbally about the study during their visits or over the phone by study approved 
personnel. The informed consent process will take place in person in a private room. The 
research team will go over the consent forms with the patients to ensure they understand the 
nature of the research study, its procedures, potential risks and benefits, and their 
responsibilities as participants. The patients will be given as much time as needed to consider 
the study and address any questions or concerns. If patients need additional time to decide 
whether or not to enroll in the study, they will have the option of rescheduling for a later time.
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Throughout the consent process, the research team will stress that participation is completely 
voluntary and that participants may withdraw from the study at any point. Patients will be 
provided a copy of the fully executed, signed consent forms. An additional copy of the signed 
consent forms will be scanned into the patient's electronic medical record and hard copies will 
be maintained in the subject binder.
For the historical control data, a retrospective chart review of glaucoma patients who 
underwent TCNR surgery from June 1, 2015 to June 1, 2020, will be performed. Consent will not 
be obtained for these patients as they will not undergo any further testing or treatments. 
NON-ENGLISH SPEAKING PARTICIPANTS
Only English-speaking patients will be included in this study
WAIVER OR ALTERATION OF CONSENT PROCESS 
Written consent form will be required for all participants; except for patients in the control 
arm.
Waiver of consent is requested for subjects in the control arm.
This research involves no more than minimal risk of harm to the subjects and involves no 
procedure for which written consent is normally required outside the research context. 
Given the retrospective nature of the data collection and de-identified reporting, the waiver 
should not adversely affect the rights or welfare of the participants. Protocols are in place to 
protect information and ensure minimal risk of identifiers being improperly used or disclosed.
The waiver or alteration will not adversely affect the rights and welfare of the participants
Process to Document Consent in Writing
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For the prospective study, the consent process and all the study procedures will be done in a 
private room/space. To protect participant’s confidentiality, their information and study 
conduct will only be discussed with individuals listed in the study personnel. The process will be 
documented using the department's standard consent documentation template. It may also be 
noted in Epic.
Waiver of HIPAA Authorization
Use of PHI described in the protocol is necessary to the research. The research could not 
practicably be conducted without access to and use of the protected health information. 
Protected health information will not be reused or disclosed to any other person or entity, 
except as required by law, for authorized oversight of the research project, or for other 
research for which the use or disclosure of protected health information would be permitted by 
the HIPAA Privacy Rule. 
Given the retrospective nature of the data collection and de-identified reporting, the waiver 
should not adversely affect the rights or welfare of the participants. Protocols are in place to 
protect information and ensure minimal risk of identifiers being improperly used or disclosed.
There is a plan to destroy the identifiers at the earliest opportunity consistent with conduct of 
the research as described in the Access Security and Management section, unless there is a 
health or research justification for retaining the identifiers.
PROTECTED HEALTH INFORMATION 
Participant will be assigned a study ID. The patient identifiers will be stored separately from the 
coded study data.
Data abstracted from the medical record will be collected on a secure sever, with computers 
only accessible with passwords. Only the research team will have access to the identified data
ACCESS SECURITY AND MANAGEMENT
Subjects will be assigned a coded number and a coded identifier list with the corresponding 
name to an identification number will be kept in locked files in the ophthalmology department, 
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of which only authorized research personnel will have access to. The data recorded for the 
study will be kept as a password-protected file on a password protected computer, separate 
from the subject log key. Data will be recorded and analyzed in a coded manner, with only 
authorized research personnel having access to it. Health information collected during the 
study will be stored electronically in password-protected files in the Department of 
Ophthalmology and then will be deleted at the earliest opportunity at the close of the study 
and no later than 10 years.
QUALIFICATIONS TO CONDUCT RESEARCH AND RESOURCES AVAILABLE
We estimate that there are a few patients in each glaucoma clinic that qualify to be included in 
the prospective study. Patients are selected among the patients that are being followed for 
glaucoma in the glaucoma clinic. The clinical examination is done as part of the routine 
glaucoma follow up and imaging will be acquired at the same day. Imaging with devices will 
take few minutes and do not pose any risk to patients. 
The eye clinic at Northwestern University has qualified and trained staff. Dr. Angelo Tanna is a 
Professor and Vice Chairman in the Department of Ophthalmology at Northwestern University 
and has 20 years of experience in Ophthalmology practice. He, along with his team of 
ophthalmologist colleagues and fellows will recruit, verbally consent, collect anonymous 
responses and analyze data.
In addition, Dr. Angelo Tanna and the other co investigators will ensure the proper adherence 
to this protocol and data reviewing. All IRB approved staff involved with the study will be given 
access to the protocol and trained on their roles/responsibilities.
REFERENCES
1.
Arora KS, Robin AL, Corcoran KJ, Corcoran SL, Ramulu PY. Use of Various Glaucoma 
Surgeries and Procedures in Medicare Beneficiaries from 1994 to 2012. Ophthalmology. 
2015;122(8):1615-1624.
2.
Kirwan JF, Lockwood AJ, Shah P, et al. Trabeculectomy in the 21st century: a multicenter 
analysis. Ophthalmology. 2013;120(12):2532-2539.
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3.
Mastropasqua R, Fasanella V, Agnifili L, Curcio C, Ciancaglini M, Mastropasqua L. 
Anterior segment optical coherence tomography imaging of conjunctival filtering blebs 
after glaucoma surgery. BioMed research international. 2014;2014:610623.
4.
Hamanaka T, Omata T, Sekimoto S, Sugiyama T, Fujikoshi Y. Bleb analysis by using 
anterior segment optical coherence tomography in two different methods of 
trabeculectomy. Investigative ophthalmology & visual science. 2013;54(10):6536-6541.
5.
Kojima S, Inoue T, Kawaji T, Tanihara H. Filtration bleb revision guided by 3-dimensional 
anterior segment optical coherence tomography. Journal of glaucoma. 2014;23(5):312-
315.
6.
Ehlers JP, Modi YS, Pecen PE, et al. The DISCOVER Study 3-Year Results: Feasibility and 
Usefulness of Microscope-Integrated Intraoperative OCT during Ophthalmic Surgery. 
Ophthalmology. 2018;125(7):1014-1027.
7.
Dada T, Angmo D, Midha N, Sidhu T. Intraoperative Optical Coherence Tomography 
Guided Bleb Needling. Journal of ophthalmic & vision research. 2016;11(4):452-454.
8.
Kumar RS, Jariwala MU, V SA, et al. A Pilot Study on Feasibility and Effectiveness of 
Intraoperative Spectral-Domain Optical Coherence Tomography in Glaucoma 
Procedures. Translational vision science & technology. 2015;4(2):2.
9.
Cantor LB, Mantravadi A, WuDunn D, Swamynathan K, Cortes A. Morphologic 
classification of filtering blebs after glaucoma filtration surgery: the Indiana Bleb 
Appearance Grading Scale. Journal of glaucoma. 2003;12(3):266-271.
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