Clinical trial NCT02729818: Adaptation Time Required for the Optimisation of Maia Microperimetry Visual Field Testing
Official title: Adaptation Time Required for the Optimisation of Maia Microperimetry Visual Field Testing
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Retina; Change
Keywords: Retina
Microperimetry
Visual Fields
Lead sponsor: University of Oxford
Sponsor class: OTHER
First posted: 2016-04-06
Enrollment: 40
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Observational model: OTHER
Time perspective: PROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Forty healthy adult volunteers (over 18) will be recruited from the University of Oxford. They will need to have healthy eyes and good eyesight (better than 6/7.5 Snellen visual acuity), with no eye diseases apart from refractive error (needing to wear glasses or contact lenses). Participants will need to be able to sit upright at the microperimeter (which involves putting their chin on a chin rest and being able to sit still for up to 20 minutes at a time), and be able to press a button to indicate when they have seen a light stimulus.

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.


Eligibility criteria: 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

Primary outcomes:
measure: Change in average threshold of tests following different dark adaptation periods will be compared.
timeFrame: Different time intervals for adaptation prior to testing; 0 minutes, 5, 10, 15, 20 and 30 minutes on day 1 and day 2.
Secondary outcomes:
measure: 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.
timeFrame: Different time intervals for adaptation prior to testing; 0 minutes, 5, 10, 15, 20 and 30 minutes on day 1 and day 2
Other outcomes:
Locations:
city: Oxford
country: United Kingdom
facility: Nuffield Laboratory of Ophthalmology
Study officials:
affiliation: University of Oxford
name: Jasleen K Jolly
role: PRINCIPAL_INVESTIGATOR
References:
citation: Han RC, Gray JM, Han J, Maclaren RE, Jolly JK. Optimisation of dark adaptation time required for mesopic microperimetry. Br J Ophthalmol. 2019 Aug;103(8):1092-1098. doi: 10.1136/bjophthalmol-2018-312253. Epub 2018 Sep 29.