September 2021
Volume 21, Issue 9
Open Access
Vision Sciences Society Annual Meeting Abstract  |   September 2021
Simplifying the repeated crowding-distance test for normal and amblyopic children.
Author Affiliations
  • Louisa Haine
    Anglia Ruskin University, Cambridge, U.K.
  • Sarah Waugh
    Anglia Ruskin University, Cambridge, U.K.
  • Monika Formankiewicz
    Anglia Ruskin University, Cambridge, U.K.
  • Denis Pelli
    New York University
Journal of Vision September 2021, Vol.21, 1982. doi:
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      Louisa Haine, Sarah Waugh, Monika Formankiewicz, Denis Pelli; Simplifying the repeated crowding-distance test for normal and amblyopic children.. Journal of Vision 2021;21(9):1982.

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

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Crowding distance can be measured clinically with skinny Pelli optotypes that enable closer horizontal spacing. Crowding distance develops more steeply with age than visual acuity and is more pronounced in amblyopia. Adult amblyopes have unsteady fixation and spatially-repeated optotype tests minimize the effect of inaccurate eye positioning on measured crowding distance. However, young children are reluctant to engage in the full-screen repeated test due to its visual complexity, which could reduce participation rates. We sought to simplify the repeated crowding distance test to enhance engagement by young children, while retaining its insensitivity to eye movements. Crowding distance with Pelli optotypes was measured for trigrams and three repeated arrangements (single-line, single-line-with-bars, full-screen) in 28 normal healthy children (3 to 11 years) and 6 adults. The spacing to width ratio was 1.4x, so size covaried with spacing. Visual acuity was measured using isolated Sloan letters. A 9AFC paradigm with QUEST procedure estimated threshold centre-to-centre letter spacing and size. Crowding distance was also measured with trigram and single-line-repeated arrangements in over 40 amblyopic children and normal controls. Crowding distance decreases with age in normal children (p < 0.05), but no significant differences were found among the 4 different crowding distance tests (p > 0.05). Children found the single-line repeat test easier to perform than the full-screen repeat test, but crowding distances were not different (0.16±0.03 deg vs. 0.16±0.03 deg). Crowding distance was 3.4x larger in amblyopic children at 0.32±0.10 deg vs. 0.09±0.02 deg in normal healthy children. Acuity letter size was only 2.8x larger in amblyopic vs. normal children. Crowding distance was successfully measured using trigrams and a single-line repeat arrangement in young normal, and amblyopic children. Amblyopia increases crowding distance in children. Future work will test sensitivity of measures to changes with treatment, development, and amblyopia type.


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