Amblyopic children read more slowly than controls under natural, binocular reading conditions

doi:10.1016/j.jaapos.2015.09.002

Journal of American Association for Pediatric Ophthalmology and Strabismus

Volume 19, Issue 6, December 2015, Pages 515-520

Presented at the 41st Annual Meeting of the American Association for Pediatric Ophthalmology and Strabismus, New Orleans, Louisiana, March 25-29, 2015.

https://doi.org/10.1016/j.jaapos.2015.09.002 Get rights and content

Background

Recent evidence suggests that amblyopia results in fixation instability and atypical saccades. Reading is a vision-reliant ability that requires sequential eye movements, including forward and regressive saccades. This study investigated reading and associated eye movements in school-age amblyopic children.

Methods

Amblyopic children with strabismus and/or anisometropia (n = 29) were compared to nonamblyopic children treated for strabismus (n = 23) and normal control children (n = 21). While fitted with the ReadAlyzer, an eye movement recording system, children silently read a grade-level paragraph of text during binocular viewing. Reading rate, number of forward and regressive saccades per 100 words, and fixation duration were determined. Comprehension was evaluated with a 10-item quiz; only data from children with at least 80% correct responses were included.

Results

Amblyopic children read more slowly and had more saccades compared with nonamblyopic children with treated strabismus and normal controls. Fixation duration did not differ significantly for amblyopic children versus normal controls. Treated strabismic children without amblyopia did not differ significantly from normal controls on any reading measure. Amblyopic eye visual acuity was not correlated with any reading measure.

Conclusions

Amblyopia was associated with slower reading speed in school-age children. Treatment for monocular amblyopia visual acuity impairment could improve reading speed and efficiency.

Section snippets

Methods

The research protocol was approved by the Institutional Review Board of the University of Texas Southwestern Medical Center and conformed to the requirements of the US Health Insurance Portability and Privacy Act of 1996. Informed consent was obtained from a parent or legal guardian prior to testing and after explanation of the nature and possible consequences of the study.

Nonamblyopic and amblyopic school-age children treated for strabismus and/or anisometropia were diagnosed and referred to

Results

A total of 73 children met the comprehension and tracking reliability criteria; 29 amblyopia (15 males; mean age with standard deviation [SD], 9.4 ± 1.2 years; age range, 8.0-12.4 years), 23 treated strabismus without amblyopia (7 males; mean age, 9.8 ± 1.4 years; range, 8.2-12.3 years), and 21 normal controls (11 males; mean age, 10.1 ± 1.4 years; range, 8.1-12.5 years). Four children (1 normal control, 2 with amblyopia, 1 with treated strabismus without amblyopia) were excluded in the

Discussion

We report for the first time that amblyopia, not strabismus, is the key factor in poorer reading in school-age children with amblyopia. The amblyopic children in our study were slower at binocular silent reading compared with treated strabismic children without amblyopia and normal control children, consistent with previous studies that reported slower reading in children and adults with strabismic amblyopia.9, 10, 11 However, previous studies did not emulate natural reading conditions that the

Acknowledgments

The authors thank Faye C. Briggs for generously donating funds to purchase the ReadAlyzer, Kenneth Ciuffreda and Preethi Thiagarajan for loaning a ReadAlyzer to us for training and pilot work, and Kirby Mateja and John F Gilmore III for collecting pilot data as ExxonMobil Community Summer Jobs Program interns.

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Citation Excerpt :
This allows for the decoding of phonemes. Prior studies have reported reading difficulties in amblyopic patients with and without strabismus and strabismus patients without amblyopia with some abnormalities noted in previously treated patients under monocular and binocular viewing conditions [35–37,54–58]. In agreement with previous studies, we found that silent reading speeds are affected under fellow eye, amblyopic eye and both eye viewing conditions in anisometropic, strabismic and mixed amblyopia patients.
Reading is a vision-reliant task, requiring sequential eye movements. Binocularly discordant input results in visual sensory and oculomotor dysfunction in amblyopia, which may contribute to reading difficulties. This study aims to determine the contributions of fixation eye movement (FEM) abnormalities, clinical type and severity of amblyopia to reading performance under binocular and monocular viewing conditions.
Twenty-three amblyopic patients and nine healthy controls were recruited. Eye movements elicited during fixation and reading of preselected passages were collected for each subject using infrared video-oculography. Subjects were classified as having no nystagmus (n = 9), fusion maldevelopment nystagmus (FMN, n = 5), or nystagmus without structural anomalies that does not meet criteria for FMN or infantile nystagmus (n = 9). Reading rate (words/min), the number of forward and regressive saccades (per 100 words) and fixation duration (s) were computed.
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The presence of oculomotor dysfunction and the extent of visual acuity and stereoacuity deficits contribute to reading difficulties in patients with amblyopia, with and without nystagmus. The understanding of reading difficulties is essential to devise accommodations to limit long-term academic and vocational consequences of amblyopia.
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Amblyopia is a neurodevelopmental disorder caused by abnormal visual experience in early life that affects 3–5% of the population. Amblyopia results in a host of monocular and binocular visual afferent function deficits including reduced visual acuity, contrast sensitivity, depth perception, interocular suppression, and efferent function abnormalities such as unstable and inaccurate fixation. Conventional treatments such as patching therapy and newer dichoptic treatments are not always successful as 30–40% of patients experience recurrence/regression of amblyopia. There are numerous review articles focused on visual afferent function deficits and treatment modalities and outcomes in amblyopia. Recently, the advent of high spatial and temporal resolution eye trackers has spurred studies on fixation eye movements (FEMs) in healthy controls and neurologic and ophthalmic disorders. In this focused review, we will summarize studies evaluating FEM abnormalities in amblyopia. We will first describe the common devices and techniques used to quantify fixation abnormalities, and then highlight the importance of systematically evaluating the eye movements under different viewing conditions and describe the parameters crucial in assessing FEM abnormalities in amblyopia. We will summarize the evidence suggesting that FEM abnormalities are not limited to the amblyopic eye only but also affects the fellow eye and that FEM abnormalities can serve as biomarkers to predict the impact of amblyopia on visual functions. Beyond diagnosis, we will discuss the treatment and prognostic implications of the evaluation of FEM abnormalities in clinical practice.

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: Supported by the Knights Templar Eye Foundation (16-2015-CS), Fight for Sight (PD15002), the National Eye Institute (EY02313), the ExxonMobil Community Summer Jobs Program.

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Major ArticleAmblyopic children read more slowly than controls under natural, binocular reading conditions

Background

Methods

Results

Conclusions

Section snippets

Methods

Results

Discussion

Acknowledgments

J AAPOS

Vision Res

Am J Ophthalmol

Am J Ophthalmol

Vision Res

J AAPOS

Eye position stability in amblyopia and in normal binocular vision

Invest Ophthalmol Vis Sci

A quantitative study of fixation stability in amblyopia

Invest Ophthalmol Vis Sci

Effects of strabismic amblyopia and strabismus without amblyopia on visuomotor behavior, I: saccadic eye movements

Invest Ophthalmol Vis Sci

Effects of anisometropic amblyopia on visuomotor behavior, I: saccadic eye movements

Invest Ophthalmol Vis Sci

Major Article
Amblyopic children read more slowly than controls under natural, binocular reading conditions