June 2022
Volume 63, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2022
Fixation Stability for Emmetropic and Myopic Patients as a Function of the Target's Frequency Content
Author Affiliations & Notes
  • Pablo De Gracia
    Chicago College of Optometry, Midwestern University - Downers Grove Campus, Downers Grove, Illinois, United States
  • Azra Wazir
    Midwestern University Chicago College of Osteopathic Medicine, Downers Grove, Illinois, United States
  • Zachary Goodman
    Midwestern University Chicago College of Osteopathic Medicine, Downers Grove, Illinois, United States
  • Emily Ong
    Midwestern University Chicago College of Osteopathic Medicine, Downers Grove, Illinois, United States
  • Footnotes
    Commercial Relationships   Pablo De Gracia Lentechs, Code C (Consultant/Contractor), CooperVision, Code F (Financial Support), MarkEnnovy, Code F (Financial Support); Azra Wazir None; Zachary Goodman None; Emily Ong None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science June 2022, Vol.63, 882. doi:
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      Pablo De Gracia, Azra Wazir, Zachary Goodman, Emily Ong; Fixation Stability for Emmetropic and Myopic Patients as a Function of the Target's Frequency Content. Invest. Ophthalmol. Vis. Sci. 2022;63(7):882.

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

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Abstract

Purpose : To describe fixation stability in emmetropic and myopic subjects through focus as a function of the frequency content of targets.

Methods : In order to identify the patterns of FEMs (microsaccades) of emmetropic, myopic, and hyperopic subjects, we measured the binocular fixational eye movements of 35 subjects (7 emmetropic or low hyperopes, 28 myopic) with an eye tracker (EyeLink 1000). We did this for three targets: natural image (NI), Maltese cross (MC), and 20/40 letter E (LE). And 11 levels of blur (+5D and -5D in 1 D steps). A total of 33 trials were recorded per subject. Each complete session of measurements for one subject lasted between two and three hours. The order of the conditions was randomized across subjects.
The optical system is formed by an Eye Tracker attached to an optical system that allows representing different vergence levels (without introducing magnification) through two motorized Badal systems with a precision of 0.01D. Also, this optical system also allows to precisely control pupil sizes. Pupil sizes were set to 4 mm by controlling a physical aperture placed in a conjugated plane to the eye’s pupil plane: this allowed for constant retinal illumination across subjects. For each trial, the EyeLink recorded binocular eye movements during two minutes at a rate of 1,000 measurements per second. If needed, subjects were corrected for their natural refractive error using contact lenses to standardize the baseline level of blur at 0 D.

Results : Microsaccades were identified and analyzed following the Engbert and Kliegl model (2003). More than 150,239 binocular microsaccades were recorded. Emmetropes modulate peak velocity and magnitude as a function of the level of blur imposed, obtaining larger peak velocities and magnitudes than myopes when experiencing both myopic and accommodation inducing blur. This was seen across all three target stimuli, each stimulus possessing different ranges of spatial frequency content. Natural image and Letter E targets shown larger differences between emmetropes and myopes than the Maltesse Cross target. Microsaccade frequency was a 20% higher on average in myopes than emmetropes (23.15 % LE, 21.74% MC, and 15.83% NI) .

Conclusions : Through the presented data, we provide initial evidence on the characteristics of microsaccades in myopes and emmetropic/hyperopic subjects for different levels of blur and frequency contents in the target.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

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