Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT05895617 |
| Other study ID # |
ETH2021-1765 |
| Secondary ID |
|
| Status |
Completed |
| Phase |
|
| First received |
|
| Last updated |
|
| Start date |
January 15, 2023 |
| Est. completion date |
April 19, 2023 |
Study information
| Verified date |
May 2023 |
| Source |
Occuity Limited |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Observational
|
Clinical Trial Summary
To determine whether the Occuity PM1 device is non-inferior in measuring central corneal
thickness when compared to ultrasound pachymetry, the Lenstar and the Pentacam.
The Investigation aims to assess long-term safety of the Occuity PM1 device when used under
the conditions and for the purposes intended, to ensure it will not compromise the clinical
condition or the safety of patients, or the safety and health of users or, where applicable,
other persons.
The central corneal thickness measurements taken by the three devices: Occuity PM1, the
ultrasound pachymeter and Lenstar. Demonstrating that the Occuity PM1 Pachymeter is not
inferior to the LenStar in terms of equivalency to a 95% confidence level using the Bland
Altmen equation/approach based on +/-20micron equivalency.
The investigators would like to measure the thickness of the cornea, which is the clear
window at the front of the eye. A corneal thickness measurement is important for several
reasons. The measurement can tell an eye care professional if the cornea is swollen, which
may mean the particiapnt have an increase in fluid within the cornea. Also, assessing corneal
thickness can help in the diagnosis of glaucoma and the measurement is important if the
participant is going to have eye surgery.
The instruments that are currently in use are usually very large and quite expensive and
therefore not ideal for use as part of routine eye care. Some instruments require contact
with the surface of the eye, which may be uncomfortable.
Occuity Ltd. is a medical device company based in Reading, which has been investigating this.
They have developed a new instrument (called the 'PM1 Pachymeter') for measuring the
thickness of the cornea. The instrument shines a harmless low power beam into the eye and
then measures the light reflected back from the eye in order to check the thickness of the
cornea. The low power beam is not a visible light and so the participant will not be able to
see it. s study will assess how closely the eye measurements taken from the new PM1
Pachymeter matches eye measurements taken from two other devices that are currently on the
market. The goal is to provide a non-contact, hand-held meter that is fast and easy to use
without the need to contact the eye.
Description:
The cornea is a thin, transparent structure at the front of the eye; its surface, as well as
the overlying tear film, is responsible for the majority of the eye's refractive power.
Accurate and precise measurement of corneal thickness is important in the diagnosis and
management of many ocular diseases. In particular, the central corneal thickness (CCT)
measurement is a key parameter to consider when planning for procedures such as refractive
surgery, and in the diagnosis of glaucoma.
Refractive error is the leading cause of reversible visual impairment worldwide; it is
therefore unsurprising corrective refractive surgery is one of the most widely performed
procedures globally. In the United Kingdom, the most frequently performed refractive surgery
are laser assisted surgical procedures, such as laser assisted in situ keratomileusis
(LASIK), Laser epithelial keratomileusis (LASEK), and Photorefractive Keratectomy (PRK). All
of these techniques involve ablating the cornea with a laser to achieve a specific shape.
Having an accurate measurement of corneal thickness is therefore of utmost importance in the
planning stages, as excessive ablation of the cornea can lead to corneal ectasia, a
significant complication of refractive surgery .
Glaucoma is a progressive disease which causes irreversible vision loss, and with ever aging
populations, it is now one of the leading causes of irreversible blindness worldwide.
Although it is considered to be multifactorial in aetiology, with both genetic and acquired
factors contributing to its development and progressions, it is still widely accepted that
the intraocular pressure (IOP) is the only modifiable factor in its management to prevent or
slow further visual loss. (5).
IOP measurement is typically done in hospital clinics using a Goldmann applanation tonometer.
The pressure reading is affected by the corneal thickness - a thick cornea will give a
falsely elevated IOP reading, which may result in a patient with healthy eyes being commenced
on unnecessary treatment, while conversely a thin cornea may give a falsely low pressure
reading, which can result in patients with glaucoma not being started on sight-saving
treatment. It has been estimated that a 10% increase in CCT can result in an apparent IOP
increase of 3.4mmHg (2).
Ultrasound Pachymeter The ultrasound pachymeter (UP) is currently the gold standard method ,
as well as the most widely used to measure CCT. In comparative device studies, the ultrasound
pachymeter has been shown to provide the most repeatable measurements . In addition, it is a
small and portable handheld device, which makes it very convenient and timesaving to use
during clinic appointments.
However, there are several negative aspects to the UP. First, it is necessary for the device
to make direct contact with the cornea, which introduces the risk of corneal abrasions and
subsequent infection. Second, anaesthetic eye drops need to be used for the patients to
tolerate the corneal touch, and studies have shown that after instillation of anaesthetic eye
drops, the CCT measurement is increased compared to before the use of anaesthetic, which can
lead to a systematic over-reading of IOP. Third, the UP can be difficult to use, as it is
necessary for the probe to contact the cornea perpendicularly, and exactly at the centre of
the cornea to achieve the most accurate reading, which is difficult to achieve even with good
staff training and experience. Lastly, despite the use of anaesthetic, measurement using this
device is uncomfortable, and sometimes poorly tolerated due to the corneal touch, especially
by the paediatric population.
While there are optical devices available on the market which can measure CCT without the
instillation of anaesthetic or corneal touch, they tend to be bulky machines which are not
portable and require specialist training to use. This makes their use in busy hospital
clinics and community optometry practices less feasible.
There is a clear need to develop a device which can measure CCT accurately without
necessitating corneal touch and use of topical anaesthetic, as well as being easily portable.
There is no such device available on the market currently, and in our search in the clinical
trial databases and Occuity did not identify any active trials investigating similar devices.
Occuity PM1 Pachymeter The Occuity device is a new handheld, non-contact, optical pachymeter,
which utilise a low power, eye safe near infrared (1310nm) beam to measure the corneal
thickness.
The device has an intuitive touchscreen display interface, and a series of 9 LEDs which
provides the illumination needed to align the device in front of the eye. Once alignment is
achieved, the measurement can take place by pressing the start button on the touchscreen
display. During preliminary testing at the parent company, it has been shown the alignment
and measurement process takes less than 10 seconds in total, after which a reading will be
shown on the digital display of the device. The device is reported to have high reliability
(variation of approximately 10um with repeat readings of the same eye), and comparable
results to the Lenstar LS900 Biometer during initial testing.
The LED light system consist of a partial ring of 9 white LEDs at a radius of 8.75mm and
spaced at 30° intervals. The total power is 2.4 mWm-2 which is will within the 10 mWm-2 blue
light hazard eye safety limit. The maximum power of the infrared beam is 50µW, which given
the expected exposure time of less than 10 seconds, is considered Class 1 eye safe according
to BS EN 60825.
Lenstar LS 900 (Haag-Streit AG, Koeniz, Switzerland) The Lenstar is an optical device which
utilises an 820mm super-luminescent diode and allows for high resolution measurements of the
structures in the eye, including CCT. Its use is well established in the hospital clinic
setting, and measurements do not require the use of anaesthetic drops or corneal touch. A
drawback of this device is that it is large and heavy, and therefore not portable or as fast
to use, unlike the ultrasound pachymeter or the Occuity PM1 device.
Pentacam (Oculus Optikgerate GmbH (Germany) Very similar to the Lenstar, the Pentacam is an
optical device which also utilises an 820mm super-luminescent diode and allows for high
resolution measurements of the structures in the eye, including CCT. Its use is well
established in the hospital clinic setting, and measurements do not require the use of
anaesthetic drops or corneal touch. A drawback of this device is that it is large and heavy,
and therefore not portable or as fast to use, unlike the ultrasound pachymeter or the Occuity
PM1 device.
