Retina; Change
Conditions
Keywords
Retina, Microperimetry, Visual Fields
Brief summary
Microperimetry is a relatively new and extremely sensitive method of assessing visual function. It projects light stimuli onto a defined area of the retina to map retinal perceptual thresholds. Participants look at a focal point and press a button to indicate when they have seen a light stimulus. The stimuli vary in intensity to find the participant's visual sensitivity. Microperimetry is carried out in low light conditions. Before testing, participants must adapt to the low light conditions in a process called 'dark adaptation.' Currently there is no consensus on the optimal time needed for dark adaptation. Investigators know that visual sensitivity differs in differing light conditions. Failing to sufficiently dark-adapt may therefore adversely affect test results. The aim of this study is to establish the optimal length of dark adaptation for microperimetry performance in healthy volunteers. On day 1, participants will undergo training field tests to reduce a learning effect affecting the results. Tests will then be performed following 5 mins adaptation, 10 mins adaptation and 30mins adaptation, On day 2, participants will perform testing following no adaptation time, 15 mins adaptation, and 20 mins adaptation. Statistics will be used to determine the effect of adaptation time on average threshold measures.
Interventions
None listed
Sponsors
University of Oxford
Study design
Observational model
OTHER
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
* Participant is willing and able to give informed consent for participation in the study. * Male or female. * Age 18 - 60 years. * Best corrected visual acuity of at least Logmar 0.1 in right eye. * Able to tolerate physical requirements of microperimetry testing i.e. able to sit still at the microperimeter in dark environment and indicate when a light stimulus has been seen using the provided button.
Exclusion criteria
* Any co-existing ocular pathology, either pre-existing or identified on initial ocular examination, not including refractive error or previous cataract surgery
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in average threshold of tests following different dark adaptation periods will be compared. | Different time intervals for adaptation prior to testing; 0 minutes, 5, 10, 15, 20 and 30 minutes on day 1 and day 2. | The average threshold for each test is detailed on the microperimetry printout and is measured in dB. This will be measured by testing following each time interval specified. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in fixation stability, as defined by the area in which 95% of the fixation points for any specific test fall, following different dark adaptation periods will be compared. | Different time intervals for adaptation prior to testing; 0 minutes, 5, 10, 15, 20 and 30 minutes on day 1 and day 2 | The fixation stability for each test is detailed on the microperimetry printout and is measured in degrees for the area covering 95% of the fixation points. This will be measured by testing following each time interval specified. |
Countries
United Kingdom
Outcome results
None listed