Background Macular Integrity Assessment (MAIA) microperimetry is increasingly used in clinical and research settings to assess point retinal sensitivity and fixation stability. Testing occurs under mesopic conditions, commonly after a period of dark adaptation. Our aim was to identify the minimum length of adaptation required to optimise microperimetry performance.
Methods MAIA microperimetry using the 10-2 grid was performed on 40 right eyes of 40 healthy participants aged 18–73 with no ocular pathology and vision of at least 0.1 logMAR after ambient light exposure, with 0, 5, 10, 15, 20 and 30 min of adaptation in mesopic settings. Ten right eyes of 10 participants with choroideremia were also tested following 0 and 20 min of adaptation. We further tested 10 right eyes of 10 healthy participants after bright light exposure, with 0, 10 and 20 min of adaptation. We compared changes in threshold sensitivity and fixation stability across time points.
Results Microperimetry performance did not improve with increasing adaptation time in healthy participants or patients with choroideremia after ambient light exposure. After bright light exposure, we found microperimetry thresholds improved after 10 min of adaptation, but did not improve further at 20 min.
Conclusion Mesopic adaptation is not required before MAIA microperimetry after exposure to ambient light. Ten minutes of adaptation is sufficient after exposure to a bright light stimulus, such as ophthalmoscopy or retinal imaging. The brief time of dark adaptation required corresponds to cone adaptation curves and provides further evidence for cone-mediated central retinal function under mesopic conditions.
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Contributors Each of the named authors (RCH, JH, JMG, REM and JKJ) has made substantial contributions to the work, meeting the criteria for authorship. RCH, JKJ and REM were responsible for the conception and design of the work. RCH, JH, JMG and JKJ were responsible for the acquisition of data. RCH and JKJ were responsible for the analysis and interpretation of data. RCH and JKJ were responsible for drafting of the work. All authors were involved in revising the work critically and giving final approval of the version published, and are in agreement to be held accountable for all aspects of the work.
Funding This work was funded by the Oxfordshire Health Services Research Committee (OHSRC) Grant Ref 1173 and supported by the National Institute for Health Research (NIHR) Oxford Biomedical Research Centre based at Oxford University Hospitals NHS Trust and University of Oxford.
Disclaimer The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health. The sponsor and funding organisation had no role in the design or conduct of this research.
Competing interests None declared.
Patient consent Not required.
Ethics approval Oxford Central University Research Ethics Committee granted ethics approval (R43588/RE001).
Provenance and peer review Not commissioned; externally peer reviewed.
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