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The amblyopic eye in subjects with anisometropia show increased saccadic latency in the delayed saccade task.

Perdziak M, Witkowska D, Gryncewicz W, Przekoracka-Krawczyk A, Ober J - Front Integr Neurosci (2014)

Bottom Line: The term amblyopia is used to describe reduced visual function in one eye (or both eyes, though not so often) which cannot be fully improved by refractive correction and explained by the organic cause observed during regular eye examination.Amblyopia is associated with abnormal visual experience (e.g., anisometropia) during infancy or early childhood.By the use of LATER (Linear Approach to the Threshold with Ergodic Rate) decision model we interpret our findings as a decrease in accumulation of visual information acquired by means of central retina in subjects with anisometropic amblyopia.

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Oculomotor Research, Department for Biophysical Measurements and Imaging, Nałęcz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences Warsaw, Poland.

ABSTRACT
The term amblyopia is used to describe reduced visual function in one eye (or both eyes, though not so often) which cannot be fully improved by refractive correction and explained by the organic cause observed during regular eye examination. Amblyopia is associated with abnormal visual experience (e.g., anisometropia) during infancy or early childhood. Several studies have shown prolongation of saccadic latency time in amblyopic eye. In our opinion, study of saccadic latency in the context of central vision deficits assessment, should be based on central retina stimulation. For this reason, we proposed saccade delayed task. It requires inhibitory processing for maintaining fixation on the central target until it disappears-what constitutes the GO signal for saccade. The experiment consisted of 100 trials for each eye and was performed under two viewing conditions: monocular amblyopic/non-dominant eye and monocular dominant eye. We examined saccadic latency in 16 subjects (mean age 30 ± 11 years) with anisometropic amblyopia (two subjects had also microtropia) and in 17 control subjects (mean age 28 ± 8 years). Participants were instructed to look at central (fixation) target and when it disappears, to make the saccade toward the periphery (10°) as fast as possible, either left or the right target. The study results have proved the significant difference in saccadic latency between the amblyopic (mean 262 ± 48 ms) and dominant (mean 237 ± 45 ms) eye, in anisometropic group. In the control group, the saccadic latency for dominant (mean 226 ± 32 ms) and non-dominant (mean 230 ± 29 ms) eye was not significantly different. By the use of LATER (Linear Approach to the Threshold with Ergodic Rate) decision model we interpret our findings as a decrease in accumulation of visual information acquired by means of central retina in subjects with anisometropic amblyopia.

No MeSH data available.


Related in: MedlinePlus

Experimental procedure. Participant fixates at central target (a); after 200 ms either left or right peripheral (10°) stimuli is displayed (b); the GO signal for saccadic refixation is the disappearance of the central target, which is randomized in time: 1500–2500 ms (c); after the saccade lands on the peripheral target it stays on for another 200 ms, after that it is switched off and this completes the single stimuli exposure (d). It is followed by the pause of 1000 ms after which the stimulation procedure is repeated again starting from (a).
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Figure 3: Experimental procedure. Participant fixates at central target (a); after 200 ms either left or right peripheral (10°) stimuli is displayed (b); the GO signal for saccadic refixation is the disappearance of the central target, which is randomized in time: 1500–2500 ms (c); after the saccade lands on the peripheral target it stays on for another 200 ms, after that it is switched off and this completes the single stimuli exposure (d). It is followed by the pause of 1000 ms after which the stimulation procedure is repeated again starting from (a).

Mentions: The subjects were seated in front of the white, uniform wall at the distance of 3 m. The overall room illumination was medium. The visual stimuli for horizontal saccade subtended ~4.5 arcminute. Before the experiment, participants performed the practice trials, consisted with 10 saccades either to the left or right. The experiment consisted of 100 trials for each eye. The experiment was performed under two viewing conditions: monocular amblyopic/non-dominant eye and monocular dominant eye. There was one minute break between trials. The order of viewing conditions was randomized across the subjects, starting either with the dominant or non-dominant eye. The experiment was performed in silence and all subjects have used their optimal refractive correction. In the course of the experiment, the central fixation stimuli (red laser spot) were generated at the beginning, and after 200 ms the peripheral (10°) either left or right stimuli for saccadic refixation response is displayed. The signal for saccadic refixation is given by the disappearance (randomized in time) of central stimuli (GO signal for saccade). Participants were instructed to look at central (fixation) target and when it disappears to make as quickly as possible the saccade toward the peripheral target. The graphical representation of experimental procedure is presented in Figure 3.


The amblyopic eye in subjects with anisometropia show increased saccadic latency in the delayed saccade task.

Perdziak M, Witkowska D, Gryncewicz W, Przekoracka-Krawczyk A, Ober J - Front Integr Neurosci (2014)

Experimental procedure. Participant fixates at central target (a); after 200 ms either left or right peripheral (10°) stimuli is displayed (b); the GO signal for saccadic refixation is the disappearance of the central target, which is randomized in time: 1500–2500 ms (c); after the saccade lands on the peripheral target it stays on for another 200 ms, after that it is switched off and this completes the single stimuli exposure (d). It is followed by the pause of 1000 ms after which the stimulation procedure is repeated again starting from (a).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4196517&req=5

Figure 3: Experimental procedure. Participant fixates at central target (a); after 200 ms either left or right peripheral (10°) stimuli is displayed (b); the GO signal for saccadic refixation is the disappearance of the central target, which is randomized in time: 1500–2500 ms (c); after the saccade lands on the peripheral target it stays on for another 200 ms, after that it is switched off and this completes the single stimuli exposure (d). It is followed by the pause of 1000 ms after which the stimulation procedure is repeated again starting from (a).
Mentions: The subjects were seated in front of the white, uniform wall at the distance of 3 m. The overall room illumination was medium. The visual stimuli for horizontal saccade subtended ~4.5 arcminute. Before the experiment, participants performed the practice trials, consisted with 10 saccades either to the left or right. The experiment consisted of 100 trials for each eye. The experiment was performed under two viewing conditions: monocular amblyopic/non-dominant eye and monocular dominant eye. There was one minute break between trials. The order of viewing conditions was randomized across the subjects, starting either with the dominant or non-dominant eye. The experiment was performed in silence and all subjects have used their optimal refractive correction. In the course of the experiment, the central fixation stimuli (red laser spot) were generated at the beginning, and after 200 ms the peripheral (10°) either left or right stimuli for saccadic refixation response is displayed. The signal for saccadic refixation is given by the disappearance (randomized in time) of central stimuli (GO signal for saccade). Participants were instructed to look at central (fixation) target and when it disappears to make as quickly as possible the saccade toward the peripheral target. The graphical representation of experimental procedure is presented in Figure 3.

Bottom Line: The term amblyopia is used to describe reduced visual function in one eye (or both eyes, though not so often) which cannot be fully improved by refractive correction and explained by the organic cause observed during regular eye examination.Amblyopia is associated with abnormal visual experience (e.g., anisometropia) during infancy or early childhood.By the use of LATER (Linear Approach to the Threshold with Ergodic Rate) decision model we interpret our findings as a decrease in accumulation of visual information acquired by means of central retina in subjects with anisometropic amblyopia.

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Oculomotor Research, Department for Biophysical Measurements and Imaging, Nałęcz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences Warsaw, Poland.

ABSTRACT
The term amblyopia is used to describe reduced visual function in one eye (or both eyes, though not so often) which cannot be fully improved by refractive correction and explained by the organic cause observed during regular eye examination. Amblyopia is associated with abnormal visual experience (e.g., anisometropia) during infancy or early childhood. Several studies have shown prolongation of saccadic latency time in amblyopic eye. In our opinion, study of saccadic latency in the context of central vision deficits assessment, should be based on central retina stimulation. For this reason, we proposed saccade delayed task. It requires inhibitory processing for maintaining fixation on the central target until it disappears-what constitutes the GO signal for saccade. The experiment consisted of 100 trials for each eye and was performed under two viewing conditions: monocular amblyopic/non-dominant eye and monocular dominant eye. We examined saccadic latency in 16 subjects (mean age 30 ± 11 years) with anisometropic amblyopia (two subjects had also microtropia) and in 17 control subjects (mean age 28 ± 8 years). Participants were instructed to look at central (fixation) target and when it disappears, to make the saccade toward the periphery (10°) as fast as possible, either left or the right target. The study results have proved the significant difference in saccadic latency between the amblyopic (mean 262 ± 48 ms) and dominant (mean 237 ± 45 ms) eye, in anisometropic group. In the control group, the saccadic latency for dominant (mean 226 ± 32 ms) and non-dominant (mean 230 ± 29 ms) eye was not significantly different. By the use of LATER (Linear Approach to the Threshold with Ergodic Rate) decision model we interpret our findings as a decrease in accumulation of visual information acquired by means of central retina in subjects with anisometropic amblyopia.

No MeSH data available.


Related in: MedlinePlus