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Related Experiment Video

Updated: Jun 2, 2026

Binocular Dynamic Visual Acuity in Eyeglass-Corrected Myopic Patients
07:06

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Published on: March 29, 2022

Visual acuity with astigmatic blur.

David A Atchison1, Ankit Mathur

  • 1Visual and Ophthalmic Optics Laboratory, School of Optometry and Institute of Health & Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Queensland, Australia. d.atchison@qut.edu.au

Optometry and Vision Science : Official Publication of the American Academy of Optometry
|April 12, 2011
PubMed
Summary
This summary is machine-generated.

Small amounts of crossed cylinder blur significantly impact visual acuity, with effects varying by cylinder axis. This blur causes greater visual acuity loss than equivalent defocus, highlighting its unique impact on vision.

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Motion-Acuity Test for Visual Field Acuity Measurement with Motion-Defined Shapes
06:25

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Published on: February 23, 2024

Area of Science:

  • Ophthalmology
  • Optometry
  • Vision Science

Background:

  • Visual acuity is crucial for daily tasks.
  • Understanding factors affecting visual acuity, such as optical blur, is essential for vision correction.
  • Crossed cylinder lenses introduce specific types of blur that can impact visual performance.

Purpose of the Study:

  • To investigate the effects of varying levels of blur introduced by crossed cylinder lenses on both high- and low-contrast visual acuities.
  • To compare the impact of crossed cylinder blur on visual acuity with that of spherical defocus.

Main Methods:

  • Eight subjects had crossed cylinder lenses (0 to 0.75 diopters) placed over their correcting lenses.
  • Visual acuity was measured using single letter lines from the Bailey-Lovie chart at high (100%) and low (10%) contrast.
  • Pupil size was controlled between 4.5 to 6 mm under standard lighting conditions.

Main Results:

  • High-contrast visual acuity was superior to low-contrast acuity by 0.1 to 0.2 log units without added blur.
  • The rate of visual acuity loss per diopter of blur was similar for both high and low contrast.
  • Significant asymmetry was observed, with greater visual acuity loss at specific negative cylinder axes (e.g., 60° vs. 165°).

Conclusions:

  • Even small amounts of crossed cylinder blur (up to 0.75 D) reduce visual acuity, and the effect is dependent on the orientation of the cylinder axis.
  • Crossed cylinders of 0.75 D caused approximately double the visual acuity loss compared to spherical defocus of the same blur strength.