A number of studies have looked at the impact of binocular vision problems on reading and school performance. They have found a significant link between academic and reading problems and treatable binocular vision problems. Binocular vision refers to the way they eyes move and work together as a team.
These studies, some of which are discussed below, demonstrate that children with reading or other academic problems need to be evaluated by a developmental optometrist and treated if a problem is found. Too often, parents waste thousands of dollars on extra tutoring and think that a child is lazy and needs to work harder. The reality often is that the child’s visual system is not functioning properly because of a binocular vision problem that can be treated with vision therapy.
A 2010 study published in the journal BMC Ophthalmology by Dusek at al. examined the visual functioning of two groups of school children in Austria. One group had reading and writing difficulties and the other was an age matched normal groups of kids.
The study found that the group of children with reading difficulties was statistically more likely to have visual problems such as poorer distance visual acuity, an binocular problems such as exophoric deviation at near, a lower amplitude of accommodation, reduced accommodative facility, reduced vergence facility, a reduced near point of convergence, a lower AC/A ratio and a slower reading speed.
The study confirmed the importance of a full assessment of binocular visual status in order to detect and remedy these deficits in order to prevent the visual problems continuing to impact upon educational development.
A study , entitled “Association between reading speed, cycloplegic refractive error, and oculomotor function in reading disabled children versus controls” was published in the May 2012 issue of the journal Graefes Archives of Clinical Experimental Ophthalmology. The study was prompted by the fact that one in ten students aged 6 to 16 in Ontario have an individual education plan (IEP) in place because of various learning disabilities. May of those learning problems were specific to reading. They wanted to investigate the relationship between reading, vision and binocular vision disorders.
Here is the study’s conclusion:
This research indicates there are significant associations between reading speed, refractive error, and in particular vergence facility. It appears sensible that students being considered for reading specific IEP status should have a full eye examination (including cycloplegia), in addition to a comprehensive binocular vision evaluation.
Similar results come from a 2007 American study published in the Journal, Optometry that measured visual skills and visual acuity in 461 students with an average age of 15.4 years in four California high schools within the same school district.
Participating students had been identified by their schools as poor readers. In the studied sample, 80% of the students were found to be inadequate or weak in one or more of the following binocular visual skills: binocular fusion ranges at near, accommodative facility, and convergence near point. In contrast, only 17% had deficient visual acuity—20/40 or worse in one eye— which is the standard model of deficiency for school vision screenings.
This demonstrates not only the inadequacy of school vision screenings but also that academic deficits are correlated much more strongly with binocular vision problems (which can’t be fixed with corrective lenses) rather than with acuity (which can be fixed with corrective lenses).
How prevalent is binocular dysfunction among students?
Research shows that binocular vision problems are a big problem among students. A 1997 study by Porcar and Martinez-Polomero published in the journal Optometry and Vision Science concluded that acommodative and nonstrabismic binocular vision problems are prevalent in the university population. Accommodative excess is the most common condition. Because these dysfunctions have a negative effect on performance, appropriate vision evaluation for this population is important.
The researchers concluded that among university students, 32.3% showed general binocular dysfunctions. In 10.8% of the cases, accommodative excess was present. 7.7% had convergence insufficiency with accommodative excess. 6.2% showed accommodative insufficiency. 3.1% had basic exophoria.
More recently, a longitudinal study was published by Jorge et al. in 2008 in Optometry and Vision Science the purpose of which was to investigate the changes in accommodation and binocular vision parameters during a 3-year period. The research team found significant changes in near heterophoria, fusional vergences, and positive relative accommodation.
These two studies indicate that binocular dysfunction is not rare in university students and that the demands of university appear to worsen binocular vision over time.
The most effective treatment for binocular vision problems is vision therapy.