June 2022
Volume 63, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2022
Letter-based perimetry: Initial findings
Author Affiliations & Notes
  • Colin Flowers
    Department of Psychology, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States
  • Christian Larson
    Department of Ophthalmology and Visual Neurosciences, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States
  • Gordon E Legge
    Department of Psychology, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States
  • Erik J Van Kuijk
    Department of Ophthalmology and Visual Neurosciences, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States
  • Arthur G Erdman
    Department of Mechanical Engineering, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States
    Earl E. Bakken Medical Devices Center, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States
  • Stephen Engel
    Department of Psychology, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States
  • Footnotes
    Commercial Relationships   Colin Flowers None; Christian Larson None; Gordon Legge None; Erik Van Kuijk None; Arthur Erdman None; Stephen Engel None
  • Footnotes
    Support  NH Grant EY030890; Erickson Family Fund for Vision Research
Investigative Ophthalmology & Visual Science June 2022, Vol.63, 4060 – F0024. doi:
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    • Get Citation

      Colin Flowers, Christian Larson, Gordon E Legge, Erik J Van Kuijk, Arthur G Erdman, Stephen Engel; Letter-based perimetry: Initial findings. Invest. Ophthalmol. Vis. Sci. 2022;63(7):4060 – F0024.

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

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Abstract

Purpose : People with central field loss rely on peripheral vision to read. We introduce a letter-based perimetry method to assess letter recognition over the central region of the visual field (13.5° x 14.9°). Performance is compared with microperimetry (Macular Integrity Assessment; MAIA). We expect that letter-based perimetry can accurately map the scotoma. Reading is influenced by other processes not needed in light detection (e.g., crowding, letter recognition) and letter-based perimetry may be useful in predicting peripheral reading ability.

Methods : We report data from one participant with macular degeneration that completed letter-based perimetry and microperimetry monocularly with their better functioning eye (left). Fixation stability was ‘stable’ (95% BCEA = 1.8°2) with a preferred retinal locus below and to the left of the scotoma (approx. 8° in diameter). For letter perimetry, strings of three randomly chosen letters were presented briefly (200 ms) at controlled locations (n = 117) on a computer. Fixation was confirmed to be at the center of the screen using an eye tracker (Tobii Spectrum Pro; 300 Hz). The participant verbally reported any detected letters. Correct and incorrect responses were summed for each letter location and accuracy was computed. The participant chose a comfortable letter size for reading. For microperimetry, a 10-2 Cartesian grid was used with a 4-2 threshold strategy to obtain light sensitivity thresholds; 60 of these locations overlapped with the tested letter locations. Mean letter recognition accuracy was computed for each of the 60 locations by averaging the recognition accuracies of overlapping letters.

Results : To test how well letter-based perimetry was able to map the scotoma, the letter recognition accuracy for MAIA grid locations with low light sensitivity (<= 13 dB; n = 22 locations; mean = 3.05 dB) were compared to those areas with high light sensitivity (>= 17 dB; n = 38 locations; mean = 21.79 dB). Locations with low light sensitivity had significantly lower letter recognition accuracy (9.1%) than locations with high light sensitivity (41.0%; T(58) = -6.62; p < 0.01).

Conclusions : We introduce a letter-based perimetry task where letter recognition is assessed across the central visual field. Letter recognition for areas with low light sensitivity as measured with microperimetry was significantly lower than areas with high light sensitivity demonstrating that letter-based perimetry is useful to detect scotomas.

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

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