Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT05147610 |
| Other study ID # |
RBHP 2021 COUTU |
| Secondary ID |
2021-A00556-35 |
| Status |
Completed |
| Phase |
N/A
|
| First received |
|
| Last updated |
|
| Start date |
December 1, 2021 |
| Est. completion date |
July 21, 2022 |
Study information
| Verified date |
July 2022 |
| Source |
University Hospital, Clermont-Ferrand |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Interventional
|
Clinical Trial Summary
In adult patients, intraocular pression readings are often taken with an air puff tonometer
or goldmann tonometer. The current gold standard for IOP measurement is the Goldmann
Applanation Tonometry (GAT). In some patients, measurement of intraocular pressure taken by
applanation or by air puff may prove to be impossible for various reasons (obesity, handicap,
mental disorder, blindness for Air Puff Tonometry, Anxiety, etc).
There are also many other devices that can be used to measure IOP, including those using
rebound tonometry like the Icare 200.
The rebound tonometer would systematize IOP screening because of its ease of use, provided
its measurements are reliable. In this prospective study, investigators will be measuring
participant's IOP with Goldmann Applanation Tonometry, Icare 200 Tonometer and Air Puff
Tonometry to see if there is an agreement in IOP between the different devices. Investigators
will also look if there is a concordance between central corneal thickness and IOP. Moreover,
investigators will look if there is a IOP concordance between the 3 different devices for
hight BMI people. Indeed, higher body mass index tend to have difficulties with proper
positioning at the slit lamp that may lead to inaccurate GAT measurements. Additionally,
stress level of the patients with different tonometry devices will be recorded using a visual
analog scale.
Description:
Goldmann applanation tonometry remains the gold standard for intraocular pressure measurement
in 2021. It provides the most exact approximation of true intraocular pressure based on
Imbert Fick's law. The statistical normal (Gaussian distribution) of IOP is 15.8 plus or
minus 5.14mmHg (2 standard deviations). Thus, an IOP value is considered to be pathological
if it is greater than 21mmHg. In practice, the measurement with the Goldmann tonometer is
done in a seated position due to the need to be installed behind a slit lamp. An anesthetic
drop such as oxybuprocaine or tetracaine is instilled onto the ocular surface followed by a
fluorescein drop. GAT may be associated with discomfort due to the need for topical
anaesthesia which causes a burning sensation during about 30 secondes. Moreover, the patient
must be compliant and the need to be seated makes measurement very difficult for some
patients: pediatric, dementia, hight BMI or elderly people.
Rebound tonometers determine intraocular pressure by bouncing a small plastic tipped metal
probe against the cornea.
As IOP increases, impact time decreases and rebound increases. It is portable, does not
require the use of eye drops and is particularly suitable for children and non-cooperative
patients. The examination is painless and can be performed without contact anesthesia.
Different versions of tonometer using this principle exist. With the Icare 200 six
measurements are taken. The 2 extreme values are eliminated and the average of the 4
remaining values gives the IOP.
In healthy subjects, the Icare tonometer gives results comparable to those of the Goldmann
tonometer (1) with differences of less than 3 mmHg in 80% of cases (2).
In the literature, the type of rebound tonometer differs from that used in our study. Most of
the previous studies compare the Icare RT01i, the Icare PRO, the Icare ONE, the Icare HOME or
even the Icare 100 which are much older versions.
The Icare 200, the most recent model dating from 2018, has benefited from technical
improvements. Intraocular pressure can be taken in any position.
Only one article in the literature has studied the diagnostic performance of Icare200 to
date. In this study, Icare200 was compared with the Perkins tonometer in 2 groups of people,
one group of healthy subjects and one group of patients with congenital glaucoma.
To date, we have no studies investigating the diagnostic performance of the iCare200 compared
to the Goldmann tonometer. It is the interest of this study to compare the relationship of
the IOP measurements obtained by Icare 200, Air Puff Tonometer and Goldmann Applanation
Tonometry.
For this we have chosen to carry out a prospective study. We have chosen to include
consenting adult patients consulting in ophthalmology consultation at Clermont-Ferrand
University Hospital. This results in a large panel of patients with different IOP in order to
observe enough IOP variability.
IOP measurements appear to correlate with corneal pachymetry (3). So, we chose to organize 4
subgroups according to pachymetry estimated by TONOREF III (high pachymetry, i.e. corneal
thickness greater than 560um; low pachymetry, i.e. corneal thickness less than 500um; normal
pachymetry, i.e. corneal thickness between 500 and 560um and subnormal pachymetry, i.e.
corneal thickness between 500 and 520um).
Patient anxiety during tonometry will be measured using a visual analogue scale.
