Orthoptic are exercises designed to improve the
function of the eye muscles. These exercises are considered particularly useful
in the treatment of strabismus (cross-eyes). Pleoptic are exercises designed to
improve impaired vision when there is no evidence of organic eye diseases.
While there is some evidence
that vision therapy may provide some benefit in patients with neurological
impairment, there has been little critical evaluation of these techniques.
There is also difficulty in assessing the literature because of variation
in definitions and methods. A remote
near point of convergence is generally considered diagnostic of convergence
insufficiency, but there is little consensus on what constitutes a normal near
point. Symptoms thought to be caused
by convergence insufficiency (headache, eye strain) are subjective and difficult
In 2010, the American
Optometric Association revised a guideline (originally produced in 1998) on
accommodative and Vergence dysfunction.
This guideline recommends vision therapy for various dysfunctions of
Vergence, and states that such treatment is beneficial for Asthenopia (eye
strain). However, the guideline does
not detail its sources of evidence, its rating of evidence, or other attributes
expected in an evidence-based guideline.
Further, this document only speaks of improving Vergence, without
addressing clinically important outcomes.
The American Academy of
Pediatrics in 1998 stated: “Learning disabilities are common conditions in
pediatric patients. The etiology of these difficulties is multifactorial,
reflecting genetic influences and abnormalities of brain structure and function.
Early recognition and referral to qualified educational professionals is
critical for the best possible outcome. Visual problems are rarely responsible
for learning difficulties. No scientific evidence exists for the efficacy of eye
exercises (“vision therapy”) or the use of special tinted lenses in the
remediation of these complex pediatric developmental and neurologic conditions.”
Scheiman et al, in a pilot
study reported in 2005, concluded vision therapy/Orthoptic was more effective
than pencil push-ups or placebo vision therapy/Orthoptic in reducing symptoms
and improving signs of convergence insufficiency in children 9-18 yrs of age.
This study enrolled only 47 children in three treatment groups but only 38 were
included in the final analysis. This study was designed as a pilot study to
prepare the CITT Study Group for a large scale randomized clinical trial.
“Based on an assessment of
claims and a study of published data, the consensus of ophthalmologists
regarding visual training is that, except for near point of convergence
exercises, visual training lacks documented evidence of effectiveness."
The widely reported
Convergence Insufficiency Treatment Trial randomized 221 children aged 9-17 to
four treatment groups: home based
pencil push-ups, home-based computer therapy and pencil push-ups, office based
therapy with home reinforcement, or office based placebo therapy with home
reinforcement. The office based
therapy group showed improved near point of convergence and reduced symptoms
compared to the other groups at 12 weeks, and this improvement was sustained for
one year. However, the office based
therapy group may well have benefited from specific home reinforcement not
provided to the other groups, and the intensity of the office based program far
surpassed that of the home based Orthoptic program.
The Convergence Insufficiency
Treatment Study (NCT01515943) was reported in 2016.
Due to difficulty with recruitment and retention, the study investigators
concluded “estimates of success are not precise and comparisons across groups
are difficult to interpret.”
Dusek evaluated base prism
reading glasses or computer training compared to placebo in 134 children, and
found the best results to be from prismatic correction.
In this group, there was sustained improvement in reading time even when
not wearing corrective lenses, suggesting that use of appropriate spectacles
results in longer term improvement.
This is also one of the few studies to use patient oriented objective outcomes