Adaptation Time Required for the Optimisation of Maia Microperimetry Visual Field Testing

University of Oxford

Status: Completed

Conditions: Retina; Change

Study type: Observational

Funder types: Other

Identifiers

NCT02729818

DarkAdapt

Details and patient eligibility

About

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.

Enrollment: 40 patients

Sex: All

Ages: 18+ years old

Volunteers: Accepts Healthy Volunteers

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