June 2021
Volume 62, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2021
Quantification of near word acuity thresholds with and without flankers for individuals with keratoconus
Author Affiliations & Notes
  • Sujata Rijal
    Optometry, University of Houston, Houston, Texas, United States
  • Daniel R Coates
    Optometry, University of Houston, Houston, Texas, United States
  • Jason D Marsack
    Optometry, University of Houston, Houston, Texas, United States
  • Footnotes
    Commercial Relationships   Sujata Rijal, None; Daniel Coates, None; Jason Marsack, None
  • Footnotes
    Support  NIH/NEI P30EY07551(Core Grant to UHCO), UH sVRSG to SR
Investigative Ophthalmology & Visual Science June 2021, Vol.62, 505. doi:
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    • Get Citation

      Sujata Rijal, Daniel R Coates, Jason D Marsack; Quantification of near word acuity thresholds with and without flankers for individuals with keratoconus. Invest. Ophthalmol. Vis. Sci. 2021;62(8):505.

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

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Purpose : Residual aberrations are present in the eyes of individuals with keratoconus, even when the eyes are “well corrected” by today’s clinical standards. High contrast visual acuity (VA), the most common method to assess visual performance, does not reflect the full spectrum of challenges that accompany real-world visual tasks. This study aims to move beyond VA and quantify threshold word acuity for “well corrected” individuals with keratoconus.

Methods : To date, 2 typically-sighted individuals (28 and 34 years old) and 1 individual with keratoconus (45 years old) have been recruited. VA was measured at distance with logMAR charts. Residual aberrations were quantified at distance with a wavefront sensor. In addition, subjects were asked to monocularly read words (with and without 4 flanking words) aloud at a 40cm test distance. Ten trials of each condition (5 font sizes and 5 durations at 100% contrast) were randomly presented using Arial font, for a total of 500 trials/eye. Psychometric functions were fitted and thresholds were defined as 80% correct for each font size and duration.

Results : Higher-order root mean square (HORMS) for a 3mm pupil was within normal limits (mean ± SD = 0.04 ± 0.02 μm) for both eyes of the typically-sighted individuals, and elevated for the individual with keratoconus (OD: 0.21 μm and OS: 0.14 μm). All individuals were able to achieve the common clinical standard of 0.00 logMAR (20/20) in both eyes. As the word presentation duration was increased to a maximum of 1 second, threshold word acuity decreased with an average slope of -0.17 ± 0.05 (logMAR/log(msec)). There was a moderate correlation between threshold word acuity and HORMS (r2= 0.43). There was no systematic difference between threshold word acuity with and without flankers for typically-sighted individuals. For the one individual with keratoconus, there was a trend of threshold word acuity being worse in the presence of flankers than without flankers, as HORMS increased.

Conclusions : As stimulus duration is increased, threshold word acuity decreases. In the two eyes with elevated HORMS, threshold word acuity was reduced compared to typical. Flankers impacted threshold levels for the 2 eyes with elevated HORMS. The study is ongoing, and will include more highly aberrated eyes, a range of disease severity and low contrast words.

This is a 2021 ARVO Annual Meeting abstract.


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