September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Performance, usability and comparison of three and four alternate forced choice versions of the handheld Radial Shape Discrimination test
Author Affiliations & Notes
  • Jae Ku
    Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, United Kingdom
  • Ashli Milling
    Directorate of Orthoptics and Vision Science, University of Liverpool, United Kingdom
  • Paul Knox
    Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, United Kingdom
  • Footnotes
    Commercial Relationships   Jae Ku, None; Ashli Milling, None; Paul Knox, Vital Art & Science Inc (F)
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 206. doi:
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      Jae Ku, Ashli Milling, Paul Knox; Performance, usability and comparison of three and four alternate forced choice versions of the handheld Radial Shape Discrimination test. Invest. Ophthalmol. Vis. Sci. 2016;57(12):206.

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

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Abstract

Purpose : The handheld Radial Shape Discrimination (hRSD) test (Wang et al, IOVS, 2013;54:5497) is now widely used to detect macular pathologies, and is being used for self-monitoring by patients. Recently a 4 alternate forced choice (4AFC) version was introduced in addition to the 3 alternate forced choice (3AFC) version used in previous studies. We investigated the performance of both versions of the test.

Methods : We recruited 98 healthy participants (59 F; median age: 33y; range 18-72y); 6 eyes with ocular pathologies were excluded. Tests (near and distance visual acuity, VA; Pelli Robson Contrast Sensitivity, CS; Amsler grid, AG) were conducted with participants’ habitual visual correction. Slit lamp biomicroscopy and undilated fundoscopy examinations were performed. Threshold results for the 3- and 4AFC hRSD tests, presented on an Apple Ipod Touch, were recorded as a logMAR value with the time taken for each test. The test order (3AFCvs4AFC) was counterbalanced across participants and they also completed a 5 question usability survey.

Results : For all eyes with a normal undilated fundoscopy examination, median (IQR) distance VA was -0.08 (0.18) logMAR, near VA was -0.08 (0.16 logMAR and CS 1.65 (0.0). The 3AFC and 4AFC hRSD median (IQR) thresholds were -0.84 (0.15) and -0.82 (0.13) respectively (Wilcoxon signed ranks paired test; Z=1.923, p=0.054; NS); across participants the thresholds were significantly correlated (Spearman’s rho= 0.468, p<0.001). There was no significant difference in test time (median (IQR); 3AFC: 172.5s (56s); 4AFC: 184.5s (56s); Z=1.229, p=0.22). Age was weakly correlated with the 3AFC thresholds (rho=0.181; p=0.01) but not with 4AFC thresholds (rho=0.121; p=0.10). 187/190 eyes reported a normal AG. From the survey, the majority of participants understood how to use the test, found it easy to use, felt it did not take too long and was confident using it. While 41% of participants expressed no preference between versions of the hRSD test, 34% found the 3AFC version easier to use, 25% found the 4AFC hRSD easier to use.

Conclusions : The 3 and 4AFC versions of the hRSD test had comparable performance; there were no statistically significant differences in threshold or test time. Across the participants neither version was clearly preferred. Given the underlying psychometric advantages of a 4AFC task, this version should be used as standard.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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