Changes in Corneal Endothelial Cell Density After Transscleral ab Interno Glaucoma Gel Stent Implantation
Conditions: Glaucoma, Endothelial Cell Loss, Corneal
Sponsor: Paracelsus Medical University

Changes in corneal endothelial cell density 
after transscleral ab interno glaucoma gel stent  implantation 
 
STUDY SPONSOR: 
Dept. Ophthalmology and Optometry, Paracelsus Medical University Salzburg 
Muellner Hauptstrasse 48 
5020 Salzburg 
Austria 
 
NCT04547036 
 
PROTOCOL DATE:  
October 15th, 2018  
REV. A 
  
Please Note:  Confidential information contained herein is made available to you in 
your capacity as Investigator, Medical Advisor, or Consultant.  It is provided only for 
review by you, your staff, Ethics Committee members, or other regulatory authority.  
Except as necessary to obtain properly informed consent for participation, it is 
expected that there will be no disclosure to other persons.  
Investigator Statement of Compliance  
As an Investigator, I agree to:  1) Implement and conduct this study diligently and in strict 
compliance with this protocol, applicable government laws and regulations, conditions of 
approval imposed by the reviewing ethics committee or competent authority, the  
Declaration of Helsinki and Good Clinical Practice / ICH Guidelines.  2) Supervise all testing 
of the device involving human subjects, 3) Ensure that the requirements for  
obtaining informed consent are met and 4) Maintain all information supplied by the 
Sponsor in confidence and, when this information is submitted to an EC or any other group, 
it will be submitted with a designation that the material is confidential.  
  
  
 _____________________________________                      _____________________  
 
Investigator Signature   
  
  
  
  
      Date  
 
 

REVISION HISTORY  
  
Date  
Revision  
October 15th, 2018  
A  
 
 
 
 
  
  
 
 

Protocol Outline 
 
Protocol Title: “Changes in corneal endothelial cell density after transscleral ab interno glaucoma 
gel stent  implantation” 
Protocol Version: A 
Protocol Date: October 15st 2018 
Principal Investigator: Prof. Dr. H. Reitsamer 
Research Team: Prof. Dr. H. Reitsamer, Doz. Dr. W. Hitzl, Dr. M. Lenzhofer 
 
 
I. 
Abstract 
 
  
 
STUDY  
OBJECTIVE  
Corneal endothelial cell loss is a known sequela of glaucoma tube shunt 
implantation. Big tube shunts show a decrease of endothelial cell count 
postoperatively (-11.5% after Ahmed glaucoma valves and -12.4% after 
Molteno shunt 2 years postoperatively). The objective of this study is 
to evaluate the change of endothelial cell count after XEN45 in patients 
with or without cataract operation.  
PATIENT  
POPULATION  
In 140 open angle eyes central endothelial cell counts were recorded 
preoperatively, before the XEN45 implantation was performed in Dept. 
Ophthalmology at Paracelsus Medical University Salzburg. XEN45s 
were already performed in the year 2013-2017 (so up to 5 years) in 
open angle glaucoma eyes in combination with or without cataract 
operation. In these eyes central endothelial cell count and central 
corneal thickness was measured preoperatively and documented in 
patients records. 
 
STUDY DESIGN  
A prospective, observational, monocentric trial to evaluate the course 
of endothelial cell density after the XEN implant. The study will take 
place in the Dept. Ophthalmology at Paracelsus Medical University 
Salzburg/SALK. 
Up to 140 consecutive patients with preoperatively recorded 
endothelial cell counts will be summoned to a consecutive endothelial 
cell count record and measurement of central corneal thickness 

postoperatively. Informed consents will be obtained from patients, 
who are interested in participating in the study. 
Patients will be assessed for endothelial cell density and the position 
of the XEN45 measured by anterior segment optical coherence 
tomography. The distance of the XEN45 to cornea, the angle of the 
tube, and the tube length in the anterior chamber will be recorded with 
anterior segment optical coherence tomography. Endothelial cell 
density will be measured on 3 positions: central, superior-nasal 
(location of XEN45 implantation), infero-temporal (far away for the 
XEN45 implant). 
    
OUTCOME  
PARAMETERS  
The primary endpoint is the change of central endothelial cell density 
compared to preoperative data. 
Secondary objectives are the differences of supero-nasal and infero-
temporal endothelial cell density compared to the central endothelial 
cell density, and pachymetry compared to preoperative data.  
EXAMINATION 
SCHEDULE  
Subjects will undergo study visits at the following times:  preoperative 
data (2013-2017) out of patient records, postoperative visit in the year
2018-2019 (1-6 years post XEN45 implantation). 
CLINICAL  
PARAMETERS  
 
The following clinical assessments will be performed at the 
postoperative examination:  
1. Endothelial cell count on different locations of the study eye 
2. Central corneal thickness 
3. Anterior segment optical coherence tomography (to determine 
the position of the XEN45) 
4. Slit lamp examination of the cornea, anterior segment including 
gonioscopy (to determine the position of the XEN45), and 
dilated fundus examination 
5. Best corrected visual acuity 
6. Measurement of IOP   
7. Number and frequency of ocular (glaucoma) medications   
8. Ocular symptoms and assessment of complications (especially 
symptoms, which may be a hint for loss of endothelial cell 
count)  

9. Secondary 
surgical 
procedures 
(if 
applicable 
including 
needlings, 
lasers, 
cataract 
operation, 
bleb 
revisions, 
keratoplasty, secondary IOP lowering procedures, other 
operations) 
 
II. 
Background and Significance/Preliminary Studies 
 
Glaucoma is a leading cause for irreversible visual function loss worldwide. 1 However, the 
reduction of intraocular pressure (IOP) is the only proven therapy for glaucoma. To reduce the 
IOP, most patients are treated with IOP lowering eye drops, but there is a rising group of patients, 
which has an unmet need for surgical IOP reduction. 2-6 All members of the commonly performed 
filtering glaucoma surgeries (e.g. trabeculectomy or big tube shunts) are capable to lower the 
IOP. 
 
In the last years, new minimally invasive glaucoma surgeries (MIGS), have been introduced for 
glaucoma therapy.7-9 The XEN Glaucoma Gel Microstent (XEN-GGM, Allergan Plc, USA) is a 
member in the MIGS group. 10 It bypasses aqueous humor from the anterior chamber to the 
subconjunctival space. 11   
 
Corneal endothelial cell loss is a known sequela of glaucoma tube shunt implantation. 12 Big tube 
shunts show a decrease of endothelial cell count postoperatively (-11.5% after Ahmed glaucoma 
valves and -12.4% after Molteno shunt 2 years postoperatively). 13-15 Corneal endothelial cell 
density further progressively decreased after Ahmed glaucoma valve implantation with time. The 
distance of the Ahmed tube tip to the cornea is significantly associated with endothelial cell loss 
in the quadrant of implantation. 13-15 A dramatic decrease of endothelial cells may cause corneal 
edema and affects the patient’s vision. Even a keratoplasty (transplantation of the cornea or the 
corneas’ inner layers) may be necessary due to a massive decrease of endothelial cell density. 
 
Also after classic filtering surgery (trabeculectomy with and without Mitomycin C), a significant 
loss of endothelial cells is reported. 16 
 
The Cypass Implant (Alcon), a minimally invasive glaucoma surgery (MIGS) competitor to the 
XEN45, was withdrawn from global market due to statistically significant endothelial cell loss at 
5 years. (see https://www.alcon.com/news/media-releases/alcon-announces-voluntary-global-
market-withdrawal-cypass-micro-stent-surgical) 
 
Therefore the objective of this study is to evaluate the change of endothelial cell count after 
XEN45 in combination with or without cataract operation. 

III. 
Study Aims 
 
The present study aims to longitudinally evaluate the change of endothelial cell count after 
XEN45 in 2 patient groups: XEN solo procedures and combined XEN with cataract operations. 
 
 
IV. 
Administrative Organization 
 
In 140 open angle eyes preoperative central endothelial cell counts were recorded 
preoperatively, before the XEN45 implantation was performed. XEN45s were already performed 
in the year 2013-2017 (so up to 5 years) in open angle glaucoma eyes in combination with or 
without cataract operation. In these eyes central endothelial cell count and central corneal 
thickness was measured preoperatively and documented in patients records. 
 
The study will take place in the Dept. Ophthalmology at Paracelsus Medical University 
Salzburg/SALK. 
 
V. 
Study Design 
 
Experimental design of the study  
 
A prospective, observational, monocentric trial to evaluate the course of endothelial cell density 
after the XEN implant. 
 
Up to 140 consecutive patients with preoperatively recorded endothelial cell counts will be 
summoned to a consecutive endothelial cell count record and measurement of central corneal 
thickness postoperatively. Informed consents will be obtained from the patients, who are 
interested in participating in the study. The study will be approved by the local ethics committee. 
 
Patients will be assessed for endothelial cell density and the position of the XEN45 measured by 
anterior segment optical coherence tomography. The distance of the XEN45 to cornea, the angle 
of the tube, and the tube length in the anterior chamber will be recorded with anterior segment 
optical coherence tomography. Endothelial cell density will be measured on 3 positions: central, 
superior-nasal (location of XEN45 implantation), infero-temporal (far away for the XEN45 
implant). 
 
Subjects will undergo study visits at the following times:  preoperative data (2013-2017) out of 
patient records, postoperative Visit in the year 2018-2019 (1-6 years post XEN45 implantation). 
 
2 patient groups will be analyzed separately: patients, who had a solo XEN procedure and 
patients, who had a combined XEN and cataract operation. 
 
Study population general description 
 

This study will include subjects presenting with open angle glaucoma and who meet the following 
inclusion and exclusion criteria.  Any questions regarding a patient’s eligibility should be discussed 
with the sponsor prior to enrollment.  
An inclusion of both eyes of the same patient is possible.  
Inclusion Criteria  
1. 
Open Angle Glaucoma 
2. 
History past XEN45 implantation with or without combined cataract procedure 
3. 
Available preoperative endothelial cell count data not older than 1 year before XEN 
operation without any operation between the day of data record and XEN45 operation. 
4. 
Age 18 years or older and of legal age of consent  
5. 
Signed written informed consent  
6. 
Availability, willingness, and sufficient cognitive awareness to comply with examination 
procedures  
Exclusion Criteria  
1. 
Patients with secondary IOP lowering procedures (excluding SLT, needlings, bleb revisions, 
YAG lasers, Argon lasers) after XEN implantation will be excluded from analysis, because 
the secondary IOP lowering procedures may influence endothelial cell count itself. Cataract 
operations without complications are no exclusion criteria, but have to be recorded. 
 
 
Sample size determination and power analysis 
 
No formal sample size calculation was done due to the unknown effect size. 
 
Description of hypothesis for primary endpoint: 
Null hypothesis: H0: the postoperative mean number of endothelical cells is lower than the 
preoperative. 
Alternative hypothesis: H1: the postoperative mean number of endothelical is larger or equal 
than the preoperative 
 
 
Study outcomes/endpoints 
 
The primary endpoint is the change of central endothelial cell density compared to preoperative 
data. 
 
Secondary objectives are the changes of supero-nasal and infero-temporal endothelial cell 
density compared to the central endothelial cell density, and pachymetry compared to 
preoperative data. 
 

VI. 
Study Procedures 
 
Slit lamp examination 
 
The visibility of the XEN in slit lamp examination in eyes looking directly to the examiner will be 
recorded (yes/no). Beside biomicroscopic slit lamp examination of the cornea and anterior 
segment, signs of inflammation or corneal alterations will be recorded. 
 
 
Gonioscopy 
 
Gonioscopy and angle assessment of XEN quadrant (superior-nasal) by Shaffer Grade. The 
position of the XEN will be noted (anterior Schwalbe line = in cornea, in Schwalbe line, anterior 
to Schlemms Canal, in Schlemms Canal, non pigmented Trabecular meshwork, pigmented 
Trabecular meshwork, posterior pigmented trabecular meshwork, scleral Spur, ciliary body band, 
Iris), the lengh of the XEN stent in anterior chamber will be noted, if there is an endothelial/iris 
touch of the XEN stent will be noted:  
  
FIGURE 1:  Shaffer Angle Grading  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TABLE 1:  SHAFFER GRADE FOR ANGLE EVALUATION  
Shaffer Grade  
Angle  
Grade 4 
45-35° angle 
Grade 3 
35-20° angle 
Grade 2 
20° angle 
Grade 1 
10° angle or less 
Grade 0 
0° angle (closed) 
 
     
 
  
  
  

 
Optical coherence tomography 
 
Anterior segment optical coherence tomography (AS-OCT) is used to determine the position of 
the XEN45 in the anterior chamber. The distance of the XEN45 to cornea, the angle of the tube, 
and the tube length in the anterior chamber will be recorded with anterior segment optical 
coherence tomography.  
 
 
Endothelial cell count 
 
Endothelial cell density will be measured on 3 positions: central, superior-nasal (location of 
XEN45 implantation), infero-temporal (far away for the XEN45 implant). 
 
 
Pachymetry 
 
The central corneal thickness has to be measured in the cornea center. 
 
 
Dilated fundus examination 
 
Per clinical rountine. 
 
 
Measurement of IOP   
 
Goldmann applanation tonometry are used to measure IOP. IOP readings are repeated until 2 
consecutive or nonconsecutive measurements are obtained differing by 1 mmHg or less, and the 
average of the 2 readings serves as the IOP measurement for the visit. 
 
 
Best corrected visual acuity 
 
Before BCVA testing, the investigator performs a manifest refraction. Once the best-corrected 
manifest refraction was determined, best corrected visual acuity on the study eye was 
examined with the patients’ pupils in their natural state. The pinhole method for measuring 
visual acuity is not acceptable. 
The BCVA has to be tested at a single seating by the same experienced investigator in the same 
room from a 4 meters distance with standardized low light conditions. A comfortable seating of 
the patient and to the chart placement at eye level is important while testing visual acuity. The 
patients have to be told not to lean forward. Breaks during the testing are allowed as needed. 17  
18 

FIGURE 2:  ETDRS chars 
 
The ETDRS logMAR charts (Lighthouse International, New York, NY) are used for assessment of 
best corrected distance visual acuity. The chart has five letters per row ranging in size from +1.0 
to -0.30 logMAR at 4 meters. 
 
Testing Paradigm for distance BCVA. Subjects are required to identify each letter on the chart 
until they identified a full row of letters incorrectly, at which point the test was terminated, and 
the acuity calculated. Vision testing starts with the top of the chart. Patients are elated to guess 
if they were not sure of the letter. Only a single reading of the chart is allowed. When a letter is 
read correctly, the examiner circles this letter on a score sheet with a layout identical to that of 
the chart. If visual acuity is poor, the test distance is reduced to 1 meter. Visual acuity as low as 
0,025dec (+1,6logMAR) can be mesasured.  
If patients could not see any letter of EDTRS chart at 1 meter, they are tested for finger count 
(0,01dec, logMAR +2), hand movement (0,001dec, logMAR +3) or light perception visual acuity 
(0,0001dec, logMAR +4) at 0.6 meters. 19 Results are recorded on a sheet. 
 
Scoring Snellen for distance BCVA. Snellen line assignment method is used to score results. 
The smallest line, where a patient has read half or more of the letters correctly, is recorded as 
BCVA in Snellen (decimal).  
 
 
Ocular symptoms and assessment of complications  
 
Especially symptoms, which may be a hint for loss of endothelial cell count have to be recorded. 
 
 
Secondary surgical procedures 
 
If applicable record secondary surgical procedures including needlings, lasers, cataract operation, 
bleb revisions, keratoplasty, secondary IOP lowering procedures, other operations. 
 
 
VII. 
Visit  
 
Subjects will be examined and evaluated according to the following schedule of visit:  

 
Visit  
Exam  
Visit Window  
Preop  
preoperative data  out of 
patient chart records 
(2013-2017) 
PO1 
Visit 
Year 2018-2019 (1-6 years post XEN45 
implantation). 
 
Preoperative Procedures 
 
No subject may be entered into the study who does not meet the inclusion/exclusion criteria. 
The details of the study must be fully explained and informed consent must be signed prior to 
any study-specific examinations being performed.  
  
Visit 
 
The visit will request the following information:  
Exams  
Screening Evaluation  
Informed Consent  
Yes  
Demographic Information  
Yes  
Ocular History and Medications  
Ocular history, including presence of ocular pathology 
and ocular medications  
Glaucoma History and 
Medications  
Including number of IOP Lowering Medications 
Secondary surgical procedures 
if applicable including needlings, lasers, cataract 
operation, bleb revisions, keratoplasty, secondary IOP 
lowering procedures, other operations 
Slit Lamp Exam  
Biomicroscopic slit lamp examination of the cornea and 
anterior segment 
Endothelial cell count  
Endothelial cell density will be measured on 3 positions: 
central, superior-nasal (location of XEN45 implantation), 
infero-temporal (far away for the XEN45 implant). 
 
 
Pachymetry 
Will be measured in the cornea center 
 
Anterior segment optical 
coherence tomography 
to determine the position of the XEN45 

Anterior segment optical 
coherence tomography  
Best Corrected distance Visual Acuity (BCVA line 
assignment method):  Monocular best-corrected visual 
acuity should be measured in Snellen line assignment 
method.  
IOP (Medicated)  
Intraocular pressure (IOP) using Goldmann  
Gonioscopy  
to determine the position of the XEN45 
Assessment of Adverse Events 
and Serious Adverse Events  
See Section Adverse Event and Serious Adverse Event 
Reporting  
  
 
 
Safety Monitoring Plan 
 
Definition of adverse events, serious adverse events: 
 
The XEN procedure is standard of care. The XEN implant is CE-marked for the implantation in 
primary open angle glaucoma patients. XEN is used in the treatment of glaucoma worldwide. 
Complications occurring during the study period will be treated in the discretion of the treating 
investigator. In every serious adverse event, appropriate measures should be taken to 
treat/resolve and monitor the subject. Any subjects who are withdrawn from the study due to 
an adverse event shall still be followed until the outcome is resolved. 
 
Before and after the study visit, patients will be followed up in the clinical routine. 
 
The investigators will classify the adverse events based on the following definitions according to 
ISO 14155 (2011). 
 
Adverse Event (AE)  
Any untoward medical occurrence, unintended disease or injury, or untoward clinical signs 
(including abnormal laboratory findings) in subjects, users or other persons, whether or not 
related to the investigational medical device.  
  
Adverse Device Effect (ADE)  
An adverse event related to the use of an investigational medical device.  
  
Device deficiency  
Inadequacy of a medical device with respect to its identity, quality, durability, reliability, safety 
or performance. Device deficiencies include malfunctions, use errors, and inadequate labelling.  
Serious Adverse Event (SAE)  
An adverse event that a) led to death,  
b) 
led to serious deterioration in the health of the subject, that either resulted in  
1) 
a life-threatening illness or injury, or  

2) 
a permanent impairment of a body structure or a body function, or  
3) 
in-patient or prolonged hospitalization, or  
4) 
medical or surgical intervention to prevent life-threatening illness or injury or    
permanent impairment to a body structure or a body function,  
c) 
led to foetal distress, foetal death or a congenital abnormality or birth defect  
 NOTE: Planned hospitalization for a pre-existing condition, or a procedure required by the CIP, 
without serious deterioration in health, is not considered a serious adverse event.  
  
Serious Adverse Device Effect (SADE)  
Adverse device effect that has resulted in any of the consequences characteristic of a serious 
adverse event  
 
 
VIII. Analysis Plan 
 
 
Statistical methods 
Data consistency was checked and data were screened for outliers and normal, Gamma, Log-
normal and Tweedie distributions by using quantile plots. Continuous variables were also tested 
for these distributions by using Kolmogorov-Smirnov test. Depending on data distribution the 
following methods will be used: In case of parametrically testing, mixed models based on normal, 
Gamma and Tweedie distributions will be used to analyze data. Independent and unstructured 
working correlation matrices were used for modeling the corresponding covariance of Endothel 
cell number over time. The model based estimator was used to estimate the covariance matrix. 
The corrected quasi likelihood under independence of model criterion will be used to select the 
final models. 95% confidence intervals will be computed for means and results will be illustrated 
by using Whisker plots. In case of nonparametrically testing, Wilcoxon’s matched pairs test will 
be used. All reported tests will be done one-sided, and p-values < 0.05 were considered as 
statistically significant. All statistical analyses will be performed by use of STATISTICA 13 (Hill, T. 
& Lewicki, P. Statistics: Methods and Applications. StatSoft, Tulsa, OK) and NCSS 10 Statistical 
Software (2015). NCSS, LLC. Kaysville, Utah, USA. 
 
 
IX. 
Literature Cited 
 

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