The objective of this study is to determine the optimal background light intensity for the examination of the visual field with a perimetry test and to confirm the de Vries-Rose, Weber's and Ferry-Porters law in patients with glaucoma.
ID
Source
Brief title
Condition
- Glaucoma and ocular hypertension
Synonym
Research involving
Sponsors and support
Intervention
Outcome measures
Primary outcome
Measurement of (1) the visual field, (2) contrast sensitivity and (3) the
critical flicker frequency in different light intensities.
(1) The visual field is determined by offering points in different places of
the visual field, which increase in light intensity. By repeating the test with
grey filters, the influence of the background light on the outcome of the
visual field test can be determined.
(2) The contrast sensitivity is measured with a set spatial frequency. By
repeating the test with grey filters, the influence of the background light on
the contrast sensitivity can be determined. This results in a function
(contrast sensitivity as a function of light intensity) from which the de
Vries-Rose and Weber's law can be confirmed.
(3) For the measurement of the critical flicker frequency, the frequency where
the flickering light becomes a continue signal is determined. By repeating the
test with grey filters, the influence of the background light on the critical
flicker frequency can be determined. This results in a function (critical
flicker frequency as a function of light intensity) from which Ferry-Porter's
law can be confirmed.
Secondary outcome
N/A
Background summary
Many patients with glaucoma experience difficulties when going from light to
dark and vice versa. These difficulties are not only present in patients with
severe glaucoma, but also in patients with a normal visus and an intact visual
field.
The standard perimetry test which is used to diagnose glaucoma has a set
background light intensity. It has never been researched if this intensity
gives optimal results for the the examination of the visual field in patients
with glaucoma.
When healthy persons see in different light intensities, several psychophysical
laws are applicable [Van Hateren 1992]. These concern the de Vries-Rose and
Weber's law (contrast sensitivity in different light intensities) and
Ferry-Porter's law (critical flicker frequency in different light intensities).
It is yet unclear whether these laws are still applicable in patienst with
glaucoma.
Study objective
The objective of this study is to determine the optimal background light
intensity for the examination of the visual field with a perimetry test and to
confirm the de Vries-Rose, Weber's and Ferry-Porters law in patients with
glaucoma.
Study design
Case-control study.
Study burden and risks
A single visit, in which several psychophysical tests are performed and a few
extra tests to check the healthy state of the eye. Total time invested is 1.5
to 2 hours. In health subjects, it is possible that an eye disease is
discovered during the course of this study. The resulting psychological stress
to the subject can be a disadvantage. However, the advantage is an early start
of adequate treatment. All measurements are conducted using optical techniques
that do not touch the eye and therefore are completely harmless and so there is
no risk during the experiments. No mydriasis (pupil dilation) will be
implemented.
Hanzeplein 1
Groningen 9713 GZ
NL
Hanzeplein 1
Groningen 9713 GZ
NL
Listed location countries
Age
Inclusion criteria
Glaucoma patients aged 18 years or older who visit the ophthalmology outpatient department of the UMCG, provide written informed consent form and meet the inclusion-exclusion criteria.;Healthy subjects will consist of people who have signed in, without ophthalmic abnormalities and provide written informed consent.
Exclusion criteria
Glaucoma patients:
- Visual acuity below 0.8 (above 50 years) or below 1.0 (below 50 years of age)
- Any other eye disease than glaucoma;Healthy subjects:
- Visual acuity below 0.8 (above 50 years) or below 1.0 (below 50 years of age)
- Any other eye disease
Design
Recruitment
Followed up by the following (possibly more current) registration
No registrations found.
Other (possibly less up-to-date) registrations in this register
No registrations found.
In other registers
| Register | ID |
|---|---|
| CCMO | NL50290.042.14 |