Clinical Trial Details
— Status: Suspended
Administrative data
| NCT number |
NCT04052269 |
| Other study ID # |
19/WE/5104 |
| Secondary ID |
|
| Status |
Suspended |
| Phase |
Phase 3
|
| First received |
|
| Last updated |
|
| Start date |
June 21, 2019 |
| Est. completion date |
October 30, 2022 |
Study information
| Verified date |
January 2021 |
| Source |
Imperial College London |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Interventional
|
Clinical Trial Summary
It is commonly known that high eye pressure is associated with glaucoma. However, there is
also a theory that poor circulation to the eye is a contributing factor. Therefore, if we can
increase the flow of blood to the eye, we may be able to stop people losing vision from this
disease.
Phosphodiesterase inhibitors (for example sildenafil, tadalafil, Viagra®, Cialis®) are drugs
used to improve blood flow to certain parts of the body. They are commonly used on an ad-hoc
basis to treat erectile dysfunction, in addition to problems with blood circulation to the
lungs, fingers and toes.
The majority of previous work in this field has been completed using insensitive, poorly
reproducible techniques such as colour doppler ultrasound. Since then, a new imaging modality
able to image blood flow in blood vessels without the need for the injection of contrast has
entered clinical use.
This initial pilot study is designed as a proof-of-concept study to investigate whether we
can measure detectable changes in the blood flow to the retina and choroid at the back of the
eye following ingestion of a phosphodiesterase inhibitor medication by healthy and
glaucomatous volunteers already taking this medication for erectile dysfunction.
Description:
Hypotheses
This study is examining the hypothesis that Phosphodiesterase inhibitors increase
chorio-retinal blood flow; in other words, we hypothesise that drugs like Viagra that have a
known effect of generally increasing circulation may also increase the blood flow in the back
of the eye -retina, with possible beneficial effect.
Study design
This is a small pilot study which is not expected to produce a definitive answer to our
question -however, if successful this study will enable us to progress to a larger study that
will have much more data to base our conclusions on.
Our present study will, therefore, examine both healthy and glaucomatous eyes with regards to
the level of blood flow in the retina - something that can be measured using optical
coherence tomography (OCT), a safe and non-invasive procedure which has been in use as part
of the standard of care for some time.
Estimated Timeline
Ethics assessment - April 2019 Patient recruitment - June to Sep 2019 Study period - May 2019
to Jan 2020
Setting
Patient encounters will take place at either the eye clinic, level 1, Charing Cross Hospital,
or the iCORG clinical trials unit, Western Eye Hospital.
Encounter 1 - As part of the routine clinic visit potentially eligible patients will be
approached by the members of the regular care team and study discussed with those who are
interested. Patients who are comfortable to proceed (have discussed the study in detail with
the doctor and have had their questions answered satisfactorily)will provide consent which
will be documented in writing; those who wish to have more time will be afforded as much time
as they need to decide whether or not to participate.
Once the patient has consented to participate, the following study procedures will be done as
part of that visit:
Baseline assessment Medical history Baseline assessment Ophthalmic history Baseline
assessment Drug history Baseline assessment Allergy history - all of the above will be
assessed by the study doctor
Baseline assessment Visual acuity - patient reads letters from a chart 10 feet (3 meters)
away to ascertain the quality of vision Baseline assessment Visual field test -non-invasive
test where the study doctor examines how much 'side' vision patient has using a computerized
machine. Lights are flashed on, and patient has to press a button whenever they see the
light.
Baseline assessment Colour vision/contrast sensitivity - patient reads letters /numbers from
a multi coloured picture.
Baseline assessment Intraocular pressure (IOP)- Study Doctor places eye drops which numb the
eyes and measures the pressure in each eye by gently touching the instrument (called a
tonometer) to the front surface of the eye. This is a standard procedure and the numbing
eye-drops are safe and have been part of standard care pathway for some time.
Baseline assessment Slit-lamp examination- study doctor examines eyes using a special lens
and light Baseline assessment Blood pressure (BP)- standard procedure Baseline assessment OCT
and OCTA scan - OCT stands for optical coherence tomography which is a type of imaging
technique that is commonly used to image the eye in the clinic, using light to visualise the
layers of the back of the eye. There are no risks or discomforts associated with this type of
imaging.
Study procedure PDE-5 inhibitor dosing - participants take their drug as per protocol
(according to what drug they have been taking) Study procedure OCTA 30 minutes - as OCT but
done in different time intervals 30min, 60min, 120min.
Study procedure Repeat BP, IOP at 50 minutes - as described above Study procedure OCTA 60
minutes - as described above Study procedure OCTA 120 minutes- as described above
Upon completion of the study, patients from both cohorts(glaucoma and andrology) will
continue their regular care in their usual clinics. The follow-up data routinely generated as
part of the glaucoma care pathway (only)which is stored within the hospital data system e.g
the central macular thickness, visual fields, IOP and other parameters will be accessed for 3
years following completion of participation with a view of correlating initial results with
possible disease progression and other related outcomes. This segment of the study is purely
data-based and does not require any active involvement from the patients; participation in
the data follow-up part of the study is optional and permission to access the relevant data
will be documented in the informed consent form.
Analyses
No interim analyses will take place as they are deemed not needed.
Sampling
Sampling /recruiting for this pilot study will be from consecutive eligible patients from
glaucoma and andrology clinics as well as patients recruited via the Western Eye Hospital
patient database and replies to poster adverts at Imperial College Healthcare NHS Trust.
The sample size target for this pilot study is 30 including 15 glaucoma subjects and 15
non-glaucoma subjects.
No sample size or power calculations are necessary for this pilot study.
Recruitment sources (aim: 15 non glaucoma participants, 15 glaucoma participants)
Glaucoma clinics (Imperial Healthcare NHS Trust) Andrology clinics (Imperial Healthcare NHS
Trust) Western Eye Patient database - potential patients will be contacted by telephone by a
member of the usual care team and given the opportunity to receive more information about
research that we are undertaking.
Poster (attached) advertisements will be strategically placed in andrology and glaucoma
waiting rooms.
They will also have the opportunity to be emailed/posted a patient information sheet and
given the opportunity to ask further questions.
