The heterophoria of 3–5 year old children as a function of viewing distance and target type

Troyer, Mary E.; Sreenivasan, Vidhyapriya; Peper, T. J.; Candy, T. Rowan

doi:10.1111/opo.12342

Cited by 9 publications

(11 citation statements)

References 35 publications

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“…One, we did not find difference in the drifts, if the vergence angle was responsible then we would find differences in both drifts and saccades. Two, previous studies have reported similar amounts of vergence at the viewing distance used in the current study[ 63 – 65 ].…”

Section: Discussionsupporting

confidence: 69%

Fixational saccades are more disconjugate in adults than in children

Shaikh

Ghasia

2017

PLoS ONE

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PurposeFixational eye movements are of particular interest for three reasons. They are critical for preventing visual fading and enhancing visual perception; their disconjugacy allows scanning in three dimensions, and their neural correlates span through the cortico-striatal, striato-collicular and brainstem networks. Fixational eye movements are altered in various pediatric ophthalmologic and neurologic disorders. The goal of this study was to compare the dynamics of fixational eye movements in normal children and adults.MethodsWe measured the fixational saccades and inter-saccadic drifts in eye positions using infrared video-oculography in children and adults. We assessed the frequency, amplitude, main-sequence, and disconjugacy of fixational saccades as well as the intra-saccadic drift velocity and variance between these two groups.ResultsWe found a similar frequency but an increase in the amplitude of fixational saccades in children compared to adults. We also found that the fixational saccades were more conjugate in children than in adults. The inter-saccadic drifts were comparable between the two groups.DiscussionThis study provides normative values of dynamics of fixational eye movement in children and adults. The greater disconjugacy of fixational saccades in adults suggests the existence of neural mechanisms that can independently regulate the movements of two eyes. The differences between adult and pediatric populations could be due to completion of the development of binocularly independent regulation of fixational saccades nearing adulthood. The alternate possibility is that the increased disconjugacy between the two eyes may represent a deficiency in the eye movement performance as a function of increasing age.

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Section: Discussionsupporting

confidence: 69%

Fixational saccades are more disconjugate in adults than in children

Shaikh

Ghasia

2017

PLoS ONE

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“…The 95% limits of agreement obtained in the current study were comparable with the ones obtained by Babinsky et al on a sample of young children [ 16 ]. Recently, Troyer et al obtained slightly better agreement than Babinsky yet still comparable values between cover test and objective measurements in both children and adults [ 35 ].…”

Section: Discussionmentioning

confidence: 99%

An automated and objective cover test to measure heterophoria

et al. 2018

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Heterophoria is the relative deviation of the eyes in absence of fusional vergence. Fusional vergence can be deprived by, for example, occluding one eye while the other fixates a visual target. Then, the occluded eye will presumably deviate from its initial position by an amount that corresponds to the heterophoria. Its assessment in clinical practice is crucial for the diagnosis of non-strabismic binocular dysfunctions such as convergence insufficiency. Traditional clinical methods, like the cover test or the modified Thorington test, suffer from practitioner’s subjectivity, impossibility to observe the occluding eye or unusual viewing conditions. These limitations could be overcome by using eye tracking systems to measure objectively the heterophoria. The main purpose of this study was to compare the performance of an automated and objective method to measure near heterophoria using an eye-tracker with two conventional methods: the cover-uncover test and the modified Thorington test. The eye tracking method gave us the possibility to measure the heterophoria as the deviation of the occluded eye (mimicking the cover test) or as the deviations of the occluded and fixating eyes (adhering to the theoretical definition of heterophoria). The latter method provided smaller results than the former, although on average the differences might not be clinically relevant. The proposed objective method exhibited considerably better repeatability than the two conventional clinical methods. It showed better agreement with the modified Thorington test than with the cover-uncover test, and a similar level of agreement was obtained between the two clinical methods. To conclude, the use of eye-trackers to measure heterophoria provides objective and more repeatable measures. As eye-trackers become common tools in clinical settings, their use to measure heterophoria should be the new gold standard.

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“… 40 Similarly, standard heterophoria testing and power refractor objective testing of heterophoria with movies vs. a standard clinical target did not result in significant differences. 24 As such, we can assume that the use of a penlight for our cover testing and ET protocol yield similar results to accommodative targets, but future investigations should include a systematic comparison of target type and its effect on subjective and objective heterophoria testing.…”

Section: Discussionmentioning

confidence: 92%

“…Babinsky et al 2 reported the normative values of heterophoria using an IR-filter as a cover over the right eye and a 25-Hz PowerRefractor recording of the eye position. The PowerRefractor has also been used by others to objectively assess heterophoria in children 24 and adults. 3 Recently, an automated system of eye tracking at 60 Hz with a synchronous controlled sliding occluder for cover testing has been reported.…”

Section: Introductionmentioning

confidence: 99%

Synchronization of a Removable Optical Element with an Eye Tracker: Test Case for Heterophoria Measurement

Gantz

Caspi

2020

Trans. Vis. Sci. Tech.

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Heterophoria describes the deviation of the optical axes in the absence of binocular fusion. Eye trackers (ET) can provide an objective assessment but are not broadly used clinically. We examined the feasibility of combining an infrared (IR) passfilter, IR detector, and an off-the-shelf ET. The proposed setup was validated against the broadly used cover test (CT). Furthermore, the setup was used to examine whether testing conditions can affect the measurements. Methods: An IR detector was attached to a handheld IR-pass filter that blocks visible light to provide occlusion while passing IR light for eye tracking. The detector senses the IR illumination of the eye tracker, creating a recordable signal of the occluder position synchronized with eye positions acquired by the SMI Red250 tracker. The mean of three measurements of each condition, three versus ten seconds occlusion, the occluded eye, and ET versus CT results were compared using the Wilcoxon test, correlation and Bland and Altman plots. Differences between measurements that were within 2 were considered clinically insignificant. Results: Thirty normally-sighted subjects (mean age 24.50 ± 2.20, range 20-28) with heterophoria ranging between 14 exophoria and 4 esophoria were recruited. There was no significant difference between the occluded eyes. However, there was a difference between 3 and 10 seconds' cover duration. The CT data were more similar to the 10 seconds cover duration, although differences were less than the clinical resolution of 2. Conclusions: An inexpensive off-the-shelf ET can be used to measure heterophoria with controlled testing parameters. Translational Relevance: Our study demonstrated a robust technique for synchronization of an optical element such as an IR cover, with an off-the-shelf commercial eye tracker. The synchronization of optical elements with eye tracking, which has been described here for heterophoria, can be adapted for other clinical measurements.

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The heterophoria of 3–5 year old children as a function of viewing distance and target type

Cited by 9 publications

References 35 publications

Fixational saccades are more disconjugate in adults than in children

Fixational saccades are more disconjugate in adults than in children

An automated and objective cover test to measure heterophoria

Synchronization of a Removable Optical Element with an Eye Tracker: Test Case for Heterophoria Measurement

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