July 2018
Volume 59, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2018
Evaluation of Evans Letter Contrast Test and Pelli-Robson chart in assessing threshold contrast sensitivity
Author Affiliations & Notes
  • Arsineh Annalya Amirkhanian
    Optometry , Western University of Health Sciences, Pomona, California, United States
  • Yliana Cetina
    Optometry , Western University of Health Sciences, Pomona, California, United States
  • Michelle M Hammond
    Optometry , Western University of Health Sciences, Pomona, California, United States
  • Bennett McAllister
    Optometry , Western University of Health Sciences, Pomona, California, United States
  • Pinakin Gunvant Davey
    Optometry , Western University of Health Sciences, Pomona, California, United States
  • Footnotes
    Commercial Relationships   Arsineh Amirkhanian, None; Yliana Cetina, None; Michelle Hammond, None; Bennett McAllister, None; Pinakin Davey, VectorVision (C)
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science July 2018, Vol.59, 1089. doi:
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    • Get Citation

      Arsineh Annalya Amirkhanian, Yliana Cetina, Michelle M Hammond, Bennett McAllister, Pinakin Gunvant Davey; Evaluation of Evans Letter Contrast Test and Pelli-Robson chart in assessing threshold contrast sensitivity. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1089.

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

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Abstract

Purpose : Contrast sensitivity can be an asset and “true” representation functional vision when compared to visual acuity measured using the high contrast Snellen or ETDRS acuity charts. The Pelli-Robson chart is utilized clinically worldwide and is a printed chart that requires external illumination. It has optotype of 20/700 when viewed at one meter, whereas, the Evans Letter Contrast Test (ELCT) is backlit chart and presents the ETDRS standard 20/630 at 1-meter. Given these differences we sought to evaluate and compare the threshold contrast as determined by the Evans Letter Contrast Test and Pelli-Robson chart in an ocular healthy population.

Methods : One hundred and forty eyes of 140 individuals (mean age 25.3 SD 3.02 years, range 21-44 years, 64 Males and 76 Females) were evaluated for the study purposes. All participants were free from any known ocular pathology and had best corrected visual acuity of 20/20 on a high contrast Snellen equivalent chart. All participants underwent testing using the Evans Letter Contrast Test and the Pelli-Robson chart by one of three trained observers (AAA, YC or MMH). The sequence of testing was randomized. The luminance of both these charts were set at 85 cd/m2. Both charts have three letters in each contrast sensitivity level and subjects had to read at least 2/3 letters correctly to be qualified for that contrast threshold. If they did not meet that criteria, the level above was recorded as the threshold.

Results : The mean contrast threshold for Evans Letter Contrast Test and the Pelli-Robson chart were 2.025 and 1.932 (SD 0.17 and 0.07 respectively) which was significantly different (paired t-test t=7.58, p= 4.53 E-12). The mean values of Evans Letter Contrast Test and the Pelli-Robson chart was not different in males versus females (p=1.0 and 0.94 respectively). The Altman and Bland analysis shows that the Pelli-Robson chart on average has lower contrast threshold when compared to Evans Letter Contrast Test (bias= -0.093) and upper limit of agreement was + 0.192 and lower limit of agreement was -0.379.

Conclusions : The measured mean contrast threshold is significantly different when measuring with the between the Evans and Pelli-Robson charts and should not be used interchangeably.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

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