June 2022
Volume 63, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2022
Assessment of the bivariate contour ellipse area (BCEA) as a marker of microperimetry reliability
Author Affiliations & Notes
  • Amandeep Singh Josan
    University of Oxford Nuffield Laboratory of Ophthalmology, Oxford, Oxfordshire, United Kingdom
    Oxford Eye Hospital, Oxford, Oxfordshire, United Kingdom
  • Thomas M W Buckley
    Oxford Eye Hospital, Oxford, Oxfordshire, United Kingdom
  • Laura Taylor
    University of Oxford Nuffield Laboratory of Ophthalmology, Oxford, Oxfordshire, United Kingdom
    Oxford Eye Hospital, Oxford, Oxfordshire, United Kingdom
  • Robert E MacLaren
    University of Oxford Nuffield Laboratory of Ophthalmology, Oxford, Oxfordshire, United Kingdom
    Oxford Eye Hospital, Oxford, Oxfordshire, United Kingdom
  • Footnotes
    Commercial Relationships   Amandeep Josan None; Thomas Buckley None; Laura Taylor None; Robert MacLaren None
  • Footnotes
    Support  NIHR Oxford Biomedical Research Centre
Investigative Ophthalmology & Visual Science June 2022, Vol.63, 2244 – F0452. doi:
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    • Get Citation

      Amandeep Singh Josan, Thomas M W Buckley, Laura Taylor, Robert E MacLaren; Assessment of the bivariate contour ellipse area (BCEA) as a marker of microperimetry reliability. Invest. Ophthalmol. Vis. Sci. 2022;63(7):2244 – F0452.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Microperimetry has increased the accuracy in measurement of retinal sensitivity compared with standard perimetry. It is increasingly utilised in assessing the effects of novel therapies. However, errors from loss of fundus tracking has not been quantified resulting in a lack of understanding of the limitations and reliability of any given examination, particularly in those with poor fixation. The currently used measure, fixation losses, only samples the optic nerve approximately once every minute and may lead to erroneous conclusions about reliability. This study quantifies reliability using fixation data gathered in the form of the 63% and 95% fixation bivariate contour ellipse areas (BCEA63 and BCEA95).

Methods : A custom grid of 181 densely arranged points was constructed using the Macular Integrity Assessment System (MAIA; CenterVue, Padova, Italy), (see fig 1). This grid was centred on the optic nerve of 16 healthy participants and the scotoma mapped. The test was repeated with the participant’s gaze directed away from the fixation target in an attempt to reduce fixation performance. Number of false positives and BCEA63 and BCEA95 values extracted for each participant.

Results : Of the 16 participants, four were rejected due to small pupils. A linear mixed effects model with BCEA as the fixed effect independent variable and participant ID as the random effect variable demonstrated a significant (p = 0.006) linear correlation between the number of false positives and the BCEA. A value of 30 percent false positives corresponds to a BCEA95 of 143 degrees^2 and a BCEA63 of 48 degrees^2.

Conclusions : The MAIA microperimeter gathers a significant amount of fixation information during testing. We have shown for the first time that this fixation data is significantly correlated to the reliability of any given examination with BCEA providing a surrogate marker for test accuracy. Further investigations is warranted to determine what an acceptable false positive value should be as the current value of 30% derives largely from historical static perimetry glaucoma studies. This study suggests any examination with a BCEA63 or BCEA95 of greater than 48 and 143 degrees^2 respectively should be viewed with caution and considered potentially unreliable regardless of the quoted level of fixation losses.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Fig 1. Three consecutive examinations with foveal and non-foveal and repeated foveal fixation respectively

Fig 1. Three consecutive examinations with foveal and non-foveal and repeated foveal fixation respectively

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