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Pablo De Gracia, Brian Helmetag, Ashley Coots, Sara Javidinejad; Microsaccades: A Biomarker for Preventing the Development of Myopia. Invest. Ophthalmol. Vis. Sci. 2020;61(7):1921.
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© ARVO (1962-2015); The Authors (2016-present)
To identify the patterns of FEMs (microsaccades) of myopic, hyperopic, and emmetropic subjects. Also, to measure how the use of Biofinity multifocal contact lenses affects microsaccade size and frequency.
We measured binocularly the fixational eye movements on 20 subjects with an Eye Link 1000 eye tracker. The Eyelink 1000 was attached to an optical system that allows correcting the refractive error of the patients with two motorized Badal systems. Each Badal system allows correcting the monocular refractive error of the subject from +5D to -10D without introducing magnification on the viewed target. Constant retinal illumination for all subjects was achieved by artificially setting the pupil size to 4 mm by using a diaphragm placed on the optical system conjugated with the pupil plane of the eye. During the measurements, we used three targets: a natural image, a Maltese cross, and a letter E (20/40) when measuring differences between the microsaccades of myopic, hyperopic, and emmetropic patients. Only the Maltese cross was used when evaluating Biofinity Multifocal "D" with a +1.50D add power, and the Biofinity Multifocal "D" with a +2.50D. For all conditions, subjects were asked to fixate on the center of the image. The field of view through the system was 1.25 degrees. Badal positions were chosen to measure a wide range of through focus positions between +5D and -5D in one diopters steps. At each position, the Eyelink recorded eye movements during 2 minutes. Subjects were given breaks as necessary. A complete session of measurements lasted approximately 4 hours.
The amplitude of the microsaccades was correlated with the amount of spherical equivalent of the subjects across all stimuli. Amongst targets, the Maltese cross produced the largest microsaccade’s size. When subjects were accommodating microsaccade’s size increased by a 20%. Biofinity Multifocal “D” lenses modified microsaccade’s size by a +9.1% and -4.3% for the +1.50 and +2.50 levels of addition respectively.
The correlation found between the amplitudes of the microsaccades and the level of refractive error of the patients opens the door to explore whether the neural computations occurring in the anatomical circuits of the retina could be affected by this altered input. Biofinity Multifocal “D” lenses used of label to reduce myopia progression do alter the size of the fixational eye movements of the subjects in our study.
This is a 2020 ARVO Annual Meeting abstract.
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