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John Hayes, Yu-Chi Tai, Sung Ouk Jang, James Sheedy; Visual acuity with a motion detection target compared to Landolt Rings. Journal of Vision 2011;11(11):748. doi: 10.1167/11.11.748.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of this study was to compare visual acuity measurements with a new visual target compared to Landolt Ring visual acuity measurements. The new target, named “Dyops™” (short for Dynamic Optotypes™), is a circular ring comprised of 8 black-and-white equally sized segments. The ring spins at 40 rotations/minute and is reduced in angular size until the subject can no longer detect the rotation. The width of the ring and the size of the gaps were 1/5 the total diameter – similar to LR dimensions. Methods: Visual acuity was assessed using both methods on 34 young adult subjects screened for 20/20 vision. The 4-position LR acuity was measured by showing 5 targets at each 0.1 logMAR step to include lines that gave 100% correct and also 20% or less correct. Dyops were likewise presented in 0.1 logMAR steps. For each presentation the subject was shown 5 Dyops™ and required to identify which one was spinning. Five such presentations were made at each logMAR step. Measurements using both methods were made with no lenses, and through +1.00 and +2.00 D lenses to create blur levels. Results: For each condition the probability of correct identification as function of logMAR size was determined with logistic regression. The mean slopes of Dyops and LRs were 34.9 (21.8 SD) and 15.7 (8.7 SD) respectively, indicating greater precision for Dyops. With no lenses, +1.00, and +2.00 D lenses, Dyops™ must be enlarged 0.39, 0.24, and 0.09 logMAR units respectively to provide the same measurements as LRs. Considering both the precision (slope) and the logMAR difference induced by plus lenses, Dyops™ was 1.5 times as sensitive to blur changes as LRs. Conclusions: Compared to LRs, Dyops were more precise in detecting threshold acuity and more sensitive to blur, although size adjustment is needed for proper calibration.
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