June 2020
Volume 61, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2020
Lags and leads of accommodation are smaller than previously thought
Author Affiliations & Notes
  • Vivek Labhishetty
    School of Optometry and Vision Science, University of California Berkeley, Berkeley, California, United States
  • Steven A Cholewiak
    School of Optometry and Vision Science, University of California Berkeley, Berkeley, California, United States
  • Martin S Banks
    School of Optometry and Vision Science, University of California Berkeley, Berkeley, California, United States
  • Footnotes
    Commercial Relationships   Vivek Labhishetty, None; Steven Cholewiak, None; Martin Banks, None
  • Footnotes
    Support  NSF, Intel, Huawei, Applied Materials, and CIVO
Investigative Ophthalmology & Visual Science June 2020, Vol.61, 1717. doi:
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      Vivek Labhishetty, Steven A Cholewiak, Martin S Banks; Lags and leads of accommodation are smaller than previously thought. Invest. Ophthalmol. Vis. Sci. 2020;61(7):1717.

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

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Abstract

Purpose : Typically, objective measurement of accommodation using autorefractors, photorefractors or aberrometers reveals response lags and leads implying that the eye does not focus precisely at the distance of the object of regard. These errors are thought to be due to the eye’s depth of focus. Because of the depth of focus an out-of-focus image is perceived as acceptably sharp. We examined these response errors by comparing objective and subjective measures of best focus.

Methods : Accommodative stimuli were presented to six healthy adults (20-35 years) using a varifocal display system. Changes in accommodation and pupil size were recorded using a wavefront sensor. On each trial, subjects first fixated a Maltese cross at a distance of 0, 2, 4 or 6D and were told to try to maintain image sharpness. After the 3-sec presentation of the cross, we measured visual acuity with a briefly presented tumbling E stimuli (100msec) presented at different distances (between -1.50D to +1.50D). The tumbling E was followed by a brief noise mask. The E was presented too briefly to affect accommodation. Subjects indicated the direction of the E at the end of each presentation. Trials were run in blocks with one accommodative stimulus distance and seven tumbling E distances presented in random order. Objective (defocus term from wavefront sensor) and subjective (acuity performance) measurements were made with 4 accommodative stimulus distances, 9 tumbling E distances, and 50 repetitions for a total of 1800 trials per subject.

Results : The objective measurements revealed typical lags and leads of accommodation. The subjective measurements revealed much smaller lags and leads. Thus, by subjective measurement, the eye appeared to be focused rather accurately at the distance of the fixation stimulus.

Conclusions : We conclude that accommodative response curves reported previously have overestimated the actual error of accommodation. In other words, the eye is better focused at the stimulus distance than previously thought. Image quality metrics such as Strehl or Visual Strehl Ratio provide a higher correlation with the subjective measure of accommodation. Our observations have important implications for the understanding of accommodation, the development of myopia, and next-generation head-mounted displays.

This is a 2020 ARVO Annual Meeting abstract.

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