of Vision Therapy
by the American Optometric Association
Documentation on the
Clinical Research and Scientific Support Underlying Vision Therapy
There is a tremendous amount of literature available which documents the
effectiveness of vision therapy in treating binocular vision (eye coordination
and alignment), oculomotor (tracking and eye movements), and accommodative
(focusing) problems. The following is a copy of a report published by the
American Optometric Association entitled “The Efficacy of Vision Therapy.”
Please note over two hundred references listed at the end of the paper.
The clinical research, scientific studies, and professional articles
listed in the bibliography were first published in “refereed” scientific
journals, meaning each were examined by outside experts before publication to
validate their science, value, and research methodology.
refer to the Bibliography of
Research for a more complete list of studies and clinical reports
underlying the science supporting vision therapy.
Efficacy of Optometric Vision Therapy"
purpose of this paper is to offer supporting documentation for the efficacy
and validity of vision therapy for modifying and improving vision functioning.
is an independent primary health care profession. Its scope of practice
includes the prevention and remediation of disorders of the vision system
through the examination, diagnosis, treatment, and/or management of visual
efficiency and eye health as well as the recognition and diagnosis of related
systemic manifestations, all of which are designed to preserve and enhance the
quality of our lives and environment.
examine the eyes and related structures to determine the presence of vision
problems, eye disease, and other abnormalities. They gather information on the
vision system during the optometric examination, diagnose any conditions
discovered, and prescribe individual or combinations of interventions such as
corrective lenses, prescription drugs, contact lenses, and vision therapy.
American Optometric Association considers vision therapy an essential and
integral part of the practice of optometry (1). Forty-three states
specifically describe vision training, orthoptics, or some synonym in their
definitions of the profession of optometry .The Institute of Medicine of the
National Academy of Sciences (2), the Dictionary of Occupational Titles of the
Employment and Training Administration (3), the U .S. Public Health Service
(4), the U.S. Dept. of Labor, Employment and Training Administration (5), the
National Center for Health Statistics (6), the Bureau of Labor Statistics (7),
The Dept. of Health and Human Services (8) and the Association of Academic
Health Centers (9) all include vision therapy in their definitions of the
profession of optometry.
theory and procedures underlying the diagnosis and management of vision
disorders are taught in all the schools and colleges of optometry (9). In
addition, the National Board of Examiners in Optometry (10) and the majority
of the various state licensing agencies examine applicants for their
theoretical and clinical knowledge in vision therapy.
is vision therapy /
therapy (also called vision training, orthoptics, eye training, and eye
exercises) is a clinical approach for correcting and ameliorating the effects
of eye movement disorders, nonstrabismic binocular dysfunctions, focusing
disorders, strabismus, amblyopia, nystagmus, and certain visual perceptual
(information processing) disorders. The practice of vision therapy entails a
variety of non-surgical therapeutic procedures designed to modify different
aspects of visual function (11). Its purpose is to cure or ameliorate a
diagnosed neuromuscular, neurophysiological, or neurosensory visual
therapy typically involves a series of treatments during which carefully
planned activities are carried out by the patient under professional
supervision in order to relieve the visual problem. The specific procedures
and instrumentation utilized are determined by the nature and severity of the
diagnosed condition. Vision therapy is not instituted to simply strengthen eye
muscles, but rather is generally done to treat functional deficiencies in
order for the patient to achieve optimal efficiency and comfort.
treatment may appear to be relatively uncomplicated, such as patching an eye
as part of amblyopia therapy. Or, it may require complex infrared sensing
devices and computers, which monitor eye position and provide feedback to the
patient to reduce the uncontrolled jumping of an eye with nystagmus. Treatment
of strabismus, or turned eye, can involve complex optical and electronic
instruments or such simple devices as a penlight or a mirror. The particular
procedures and instruments are dependent on the nature of the visual
dysfunction and the doctor's clinical judgment.
therapy is utilized for conditions, which include oculomotor dysfunctions,
non-strabismus binocular coordination problems, accommodative disorders,
strabismus, amblyopia, and nystagmus.
disorders and dysfunctions have a prevalence rate second only to refractive
conditions, such as myopia and hyperopia, and are far greater than most ocular
diseases (12-16). Graham (17) reports overt strabismus in almost 4% of over
4,000 school children. Among clinical cases, Fletcher and Silverman (18) found
8% of 1,100 to be strabismic. Other studies have generally found rates between
these two levels (19).
reported prevalence of amblyopia varies somewhat depending upon the specific
criteria used, with low estimates at approximately 2% (20), and ranging up to
8.3% in the Rand HIE report (21), and also in the study by Ross, Murray and
Steed (22). The National Society to Prevent Blindness estimates 127,000 new
cases of amblyopia per year in the United States (23).
binocular coordination anomalies have an even higher incidence. Convergence
insufficiency is reported in 15% of adults by Duke-Elder (24). Graham (l5)
reports high heterophorias in over 13%, while Hokoda (25) found fusion or
accommodative problems in 21% of a non-presbyopic clinical population. The
recently developed New York State Vision Screening Battery probes oculomotor,
binocular, accommodative, and visual perceptual function. Testing of 1,634
children with this battery revealed a failure rate of 53% (27).
"special" populations are considered, the incidence of ocular
coordination and visual processing problems becomes very high. Among children
who are reading disabled, as many as 80% show deficiency in one or more basic
visual skills (26). Grisham (28) has recently reported that children with
reading problems showed greater than a 50% prevalence of visual deficiencies
in accommodation, fusional vergence or gross convergence, compared to their
normally achieving peers. Cerebral palsied patients show an incidence of
strabismus as high as 50%. (29,30)
hearing impaired (31.32), emotionally impaired (33), and developmentally
disabled (34,35) also demonstrate unusually high prevalence rates of visual
problems. This is of particular importance because almost 11% of the school
population has been identified as having one of the above handicapping
culture continues to foster higher educational standards and produces work
related tasks, which are increasingly visually demanding. This is evident in
the difficulties encountered by video display terminal (VDT) operators. A
majority of surveys have shown that more than 50% of VDT workers report they
experience some type of ocular discomfort or blurring (37,38). The National
Academy of Sciences (39) concluded that the oculomotor and binocular vision
changes noted at video display terminals are similar to those that occur
during standard nearpoint tasks.
are oculomotor skills and oculomotor dysfunctions?
and eye movements]
vision occurs when a precisely focused image of the object of regard is
centered on the fovea and when accurate eye movements maintain this
relationship. The components of the oculomotor or eye movement system include
fixations, vestibular and optokinetic movements, saccades, and pursuit
one of the components has its own distinct and different neuroanatomical
substrate and functional neurophysiology (41).
There are times when several components interact. An example of this
occurs when the pursuit system interacts with other systems to create the
ocular stabilization or position maintenance system (42) to hold the eyes
a to-and-fro involuntary movement of the eyes, is caused by disturbances in
the mechanisms that hold images steady (position maintenance) and may be
exhibited in over a dozen different clinical patterns of movement (43). This
loss of ability to maintain central fixation and eye position with the foveal
area is one of the characteristics of pathological nystagmus.
with amblyopia represent another class of individuals with impaired central
fixational ability. Lack of ability to steadily fixate with the fovea is
accompanied by reduced visual acuity and is commonly observed in anisometropic
and especially strabismic amblyopes. Their characteristics have been described
extensively (44-46). Abnormal
saccadic and pursuit eye movements are exhibited in strabismic amblyopes and
appear to be related to dysfunctions in the monocular motor control center for
position maintenance (47-49).
nystagmus or nystagmoid movements are present, the clinical identification of
fixation pauses, regressions, and progressions during reading become
difficult. The erratic eye movements interfere with efficient visual
information processing (50,51).
reading, the function or behavior of the eye movement system involves more
than the physical movement of the eyes alone. This functional component
involves the integration of the eye movements with higher cognitive processes
including attention, memory, and the utilization of the perceived visual
and research evidence strongly suggest that many children and adults who have
difficulty with both reading and non-reading visual information processing
tasks exhibit abnormal eye movements (53-66).
studies (67-69) indicate that there is a distinct difference in the oculomotor
(eye movement) patterns between children with reflective strategies or styles
of processing visual information and those with impulsive styles. There is
evidence that children and adults with attentional difficulties and
hyperactivity exhibit inefficient eye movement patterns that interfere with
visual information processing (70-74).
summary, there are a variety of dysfunctions in the oculomotor system. Their
clinical manifestations are quite often related to problems with functional
visual performance and the efficient processing of information.
eye movement skills be modified?
in eye movement control and efficiency has been reported in individual case
studies following vision therapy (75-77).
et al (78) reported on 100 consecutive optometric vision therapy patients
whose eye movement skills were rated on the Heinsen-Schrock Performance Scale
(79). This is a 10-point observational scale for scoring saccadic and pursuit
eye movement performance. Only 6% of the children passed the eye movement
portion prior to therapy. Post-therapy
reevaluation revealed that 96% of the children were able to pass.
(80) discussed the influence of ocular-motor proficiency on reading. Sixty
third and fourth graders who scored below the 40th percentile on the
Metropolitan Reading Test and failed the ocular pursuit subtest of the Purdue
Perceptual Motor Survey were divided into control and experimental groups.
Results of the study showed significant improvement in ocular pursuit ability
for the experimental compared to the control group. In addition, those
children receiving therapy were found to score significantly better on a
post-test of the Metropolitan Reading Test.
et al (81) compared the use of various techniques for saccadic fixation
training. In this controlled clinical trial, both of the treated groups showed
a statistically significant improvement in speed and accuracy of eye movements
compared to an untreated control group.
controlled study of pursuit eye movements was conducted by Busby (82) in an
enhancement program for special education students. The subjects were rated on
their ability to maintain fixation on a moving target. The rating procedure
was shown to have a high interrater reliability. The results showed
statistically significant improvement by the experimental group in pursuit eye
movement and persistence of the therapeutic effect on retesting at a 3-month
interval after conclusion of the therapy.
and Steinhauer (83) conducted a controlled study investigating the effects of
eye movement training with and without feedback and reinforcement. There were
clear post-training differences between the eye movement skills of the control
and experimental group of reading disabled students. This demonstrated that
the use of reinforcement in training oculomotor facility could improve those
skills. There was an improvement in reading performance following the
oculomotor training as well. Similar results demonstrating the trainability of
eye movements have been obtained in studies employing behavior modification
and reinforcement (84,85).
and improving the oculomotor ability to maintain central fixation and eye
position in nystagmus patients has been reported over the years in various
use of after-images (86,87) and Emergent Textual Contour training to provide
visual biofeedback regarding eye position and stability has had some success
in improving fixational ability. Orthoptics, as well as verbal feedback
techniques, have helped some patients in reducing their nystagmus (88-90).
recently, the application of eye movement auditory biofeedback in the control
of nystagmus has shown positive results. Ciufredda et al (91) demonstrated a
significant reduction in the amplitude and velocity of eye movements in
congenital nystagmus patients. Vision was improved, and positive cosmetic and
psychological changes were reported as well. Abadi et al (92) reported
reduction in nystagmus and improvement of contrast sensitivity after auditory
biofeedback training. In addition to nystagmus, the use of auditory
biofeedback has been successfully used in expanding the range of eye movement
in gaze limitations (93).
is evidence (94) that large and unsteady eye movements occur in the eyes of
amblyopic patients during attempted monocular fixation. A number of studies
report the successful treatment of amblyopia resulting in improved vision and
oculomotor control (95-98). Occlusion therapy, a passive procedure, has been a
standard and relatively successful approach for many years (99-111).
However, there are individuals that either do not or cannot respond to
occlusion therapy. There is evidence that occlusion with active vision therapy
is more effective than occlusion alone (112).
Pleoptics (113,114) is an active vision therapy procedure in which
patients receive visual feedback about their position of fixation and
direction of gaze. These procedures are designed to correct the positional
fixation problem and thereby improve the vision of the patient. Pleoptics has
been used successfully in treating eccentric fixation in individuals not
responding to regular occlusion therapy (115-118).
therapy for amblyopia incorporates a broad spectrum of procedures, including
occlusion techniques, pleoptic techniques, and visual-motor spatial
localization feedback techniques using after-images and entoptic phenomena
(45,79) with a high success rate (119-124).
question of age and its influence on the efficacy of amblyopia therapy has
been addressed in a number of studies and reviews. These indicate that a
significant improvement in oculomotor and vision function can be achieved even
in adulthood (125). It is clear
from the evidence that amblyopia and its oculomotor components can be
successfully treated with occlusion and active vision therapy for a wide range
of patients of all ages.
have demonstrated that it is possible to change and improve inefficient and
inadequate visual information processing strategies and visual attention
patterns. Many of these changes have been accompanied by enhanced eye
number of techniques used to improve these poor visual scanning and attention
problems in children and adults, e.g., tachistoscopic procedures, pursuit and
fixation activities, and eye-hand coordination techniques have been described
and utilized professionally for many years (79,139-143).
are accommodative dysfunctions and their remediation?
(focusing) dysfunctions have been described in detail (144-146) in numerous
sources and are clinically classified as accommodative spasm, accommodative
infacility, accommodative insufficiency, and ill-sustained accommodation.
There are also clearly defined syndromes associated with accommodative
literature discusses many symptoms common to accommodative dysfunctions as a
group. These have been described as reduced nearpoint acuity, a general
inability to sustain nearpoint activity, asthenopia, excessive rubbing of the
eyes, headaches, periodic blurring of distance vision after prolonged near
activities, periodic double vision at near, and excessive fatigue at the end
of the day (152,154,156-160).
efficacy of applying vision therapy procedures in improving accommodative
functioning has considerable basic science and clinical research support.
Studies have shown that accommodative findings, although under
autonomic nervous system control, can respond to voluntary command (161-163)
and can be conditioned (164). These
studies demonstrate that voluntary control of accommodation can be controlled,
trained, and transferred.
pathological or iatrogenic causes have been eliminated, the treatment of
accommodative deficiencies includes plus lenses for near work and vision
therapy aimed at improving the functioning of the accommodative mechanism
(165-168). Levine et al (156) established baseline statistics for diagnostic
accommodation findings which differentiate symptomatic from asymptomatic
patients. Their findings were in close agreement with a similar study by
Zellers and Rouse (152). The significant element of these studies is the
relationship between symptoms and inadequate accommodative facility.
(78) reported on 100 children who had undergone accommodative vision therapy
procedures. These clinically selected cases showed an 80% rate of improvement
in accommodative amplitude and 76% in accommodative facility using a pre- and
post-treatment ordinal criterion referenced scaling method. These results are
similar to those reported by Hoffman and Cohen (168) a in which 70 patients
were successfully treated for accommodative insufficiency and infacility based
on clinical findings.
et al (169) investigated accommodative facility disorders by objective
laboratory methods using a dynamic optometer with an infrared photomultiplier.
They objectively identified the dynamic aspects of the accommodative response
that were improved by vision therapy. Young adults with symptoms related to
focusing difficulties were treated by procedures commonly used in orthoptic or
vision therapy practice. Significant improvement in their focus flexibility
occurred and these changes correlated with marked reduction or elimination of
symptoms. Standard clinical measures of accommodative facility were found to
correlate well with the more objective measures.
and Sivak (l70) replicated the work of Liu et al (169) using a greater degree
of recording precision with a dynamic photorefractor (television camera and
monitor with light-emitting diodes}. They found no evidence of regression in
improved focusing flexibility during an l8-week interval after cessation of
training. The subjects' symptoms also abated as accommodative function
normalized. Hung et al (l71) demonstrated the efficacy of accommodation,
vergence, and accommodative vergence orthoptic therapy using a dynamic
binocular simulator. This experiment objectively validated optometric vision
therapy procedures through use of photoelectric eye movement recording systems
and an optometer.
is a higher prevalence of accommodative insufficiencies and infacilities in
persons with cerebral palsy (172). Duckman demonstrated that accommodative
abilities can be modified and improved in a cerebral palsy population using
vision therapy techniques (173,174).
accommodative changes take place when looking from near to far and back to
near, Haynes and McWilliams (175) investigated the effects of training this
near-far response on school age and college students. Their results indicate
that this near-far response ability is trainable and can be improved with
(l76) has shown that improvement in accommodative ability transfers to
improvement in near point task performance. In a double blind clinical study
following vision therapy, her experimental group was found to improve
significantly in accuracy of performance on a Landolt-C resolution task as
compared with the controls.
(160) investigated the impact of accommodative deficiencies on visual
information processing tasks. He compared the results of vision therapy for
the accommodative problems in an experimental and control group of school age
children. This study indicated that by improving accommodative skills, there
was a concomitant improvement in his subject's visual perceptual skills.
in a detailed series of analyses involving retrospective studies, Daum
(177-180) investigated the full range of accommodative disorders. He used a
stepwise discriminant analysis of regression variables in patient care
records, to establish a model to determine the length of treatment necessary,
and to predict the success of treatment for accommodative disorders.
conclusion, these studies demonstrate that accommodative disorders can cause
significant discomfort, inefficiency or avoidance of nearpoint tasks. They
further demonstrate that when diagnosed and treated appropriately, these
dysfunctions may be ameliorated or eliminated through vision therapy.
are binocular vision disorders and their remediation?
coordination and alignment]
and efficient binocular vision is based on the presence of motor alignment and
coordination of the two eyes and sensory fusion. The range of binocular
disorders extends from constant strabismus with no binocular vision present to
non-strabismic binocular dysfunctions, e.g., convergence insufficiency (146).
first category is non-strabismic binocular disorders. Standard techniques and
diagnostic criteria in the assessment of the vergence system and binocular
sensory fusion ability have been described in detail elsewhere (181-185).
exhibiting non-strabismic anomalies of binocular vision quite often report
feeling ocular discomfort and asthenopia (186).
Some of the patient complaints include eyestrain, soreness of the eyes,
frontal and occipital headaches, and ocular fatigue which result in an
aversion to reading and studying (187,187a).
therapy has long been advocated as a primary intervention technique for the
amelioration of non-strabismic anomalies of binocular vision (188-194).
Suchoff and Petito (l46) have concluded that vision therapy for these
conditions is directed toward several therapeutic goals: First, to increase
the efficiency of the accommodative system so as to facilitate a more
effective interaction between this system and the vergence system. Second, to
maximize the functioning of the fusional vergence system (i.e., divergence and
convergence) and the binocular sensory system. Since the training of
accommodation has been covered in the previous section, the remainder of this
section will be devoted to the evidence of the modifiability of the vergence
vision therapy procedures are intended to improve the patient's ability to
compensate for fusional stress which may result in asthenopia, headache,
and/or diplopia. A number of studies will be reviewed showing that
improvements can be made in fusional vergence skills by vision therapy
clinical assumption that fusional vergences can be trained is not a new one.
Over 50 years ago, Berens et al advocated the use of this aspect of orthoptics
for all non-strabismic anomalies of binocular vision (195). Within the past
several years a number of investigators have sought to determine
experimentally whether the clinical assumption of the trainability of the
vergence system was a valid one.
(196) prospectively studied a group of 35 young adults. The results of daily
vision therapy showed statistically significant improvement in convergence
ranges. The gains persisted on post-testing 24 weeks after completion of the
therapy program. The conclusion was that relatively short periods of training
can provide long-lasting increases in vergence ability.
(l97) conducted a retrospective study of 110 patients who received treatment
for convergence insufficiency. The patients were classified according to the
effectiveness of the treatment program into total success, partial success or
no success categories. Post training diagnostic findings and changes in
patient symptomatology were used to define the classification categories. A
comparison of pre- and post-training findings revealed statistically
significant improvement. In a companion report, (198) a portion of the above
data (l97) was used to investigate and identify which of 14 common diagnostic
measures best predicted the success of the vision training program. These
measures were 75% accurate in predicting efficacy of the vision therapy
study (l99) utilized tonic and phasic vergence training and demonstrated
impressive changes in convergence and divergence abilities. The 34 subjects
were randomly assigned in a double crossover design, wherein subjects served
as their own controls, and learning effects were controlled.
another study, Veagan used a motor-driven prism stereoscope (ophthalmic
ergograph) to train divergence and convergence (200). Forty- seven adults were
divided into convergence and divergence experimental and control groups. The
findings led Veagan to conclude that sustained divergence and convergence
training showed large and significant immediate and stable improvement in the
trained vergence ranges of the experimental groups.
and McMonnies (201) utilized a recording device that measured eye movements
during vergence activity. They were able to objectively demonstrate that
convergence training with prism-induced changes resulted in sustained
improvement of convergence ability. In a companion study, Vaegan (202)
demonstrated substantial long-lasting gains in convergence and divergence
ability from both tonic and phasic vergence training.
(203) studied over 200 subjects with convergence insufficiency who underwent
vision therapy and evaluated them 2 years later. The majority remained
asymptomatic with normal clinical findings. Those subjects who had learned to
control convergence and accommodation together had the best success.
(204, 205) used vergence latencies, velocity, and step vergence tracking rate
by measuring them objectively with infra-red eye monitor recordings; He
reported improved step vergence tracking after vision therapy of 4 to 8 weeks.
and Duckman, in their extensive review of convergence insufficiency, stated
that 95% of the patients reported in these studies responded favorably to
vision therapy for this binocular disorder (206).
and Feldman (207) investigated the role and clinical use of operant
conditioning in vision therapy based on random dot stereograms (RDS). They
demonstrated that response-contingent positive reinforcement, immediate
feedback, and preprogrammed systematic changes during discrimination learning
improves convergence ability. Control and experimental groups were formed with
subjects matched in baseline convergence ability and randomly assigned to each
group. The convergence ranges of the experimental group improved significantly
while there were little or no increases for the control group.
et a1 (208) conducted a controlled study of vision therapy and its
relationship to symptomatology for a group of patients with convergence
insufficiency. A vision therapy program of fusional vergence activities was
administered in a matched-subjects control group crossover design to reduce
placebo effects. They used a written assessment scale for rating asthenopia in
terms of discomfort and/or fatigue, and conclusively demonstrated that the
symptoms were eliminated or relieved. Clinical findings also improved,
corroborating the subjective assessments.
(209) reported on 100 convergence insufficiency patients who did not meet
Sheard's criterion, and were given a program of vision therapy. After vision
therapy, clinical findings were again assessed and 84% of the patients
successfully met Sheard's criterion. Eighty-three percent of the patients
reported they had symptoms of discomfort or loss of efficiency prior to
treatment. Only 7% reported these symptoms after therapy. The post-training
group who failed to meet Sheard's criterion correlated well with those still
reporting subjective symptoms.
(78) reported on the results of 100 patients who underwent vision therapy.
Based on standard clinical tests, only 25% of the children had adequate
binocular sensory fusion prior to vision therapy and 9% had adequate binocular
fusional vergence. Post-training evaluation showed 96% had achieved
appropriate sensory fusion findings and 75% demonstrated adequate fusional
et al (210), along with Saladin and Rick (211), used slightly different
techniques and demonstrated that stereopsis thresholds could be improved in
normal subjects. In Dalziel's (212) study there was a statistically
significant improvement in stereopsis after vision therapy.
category of binocular vision disorders is strabismus. Strabismus may be
described as a misalignment of the eyes (referred to as crossed-eyes, eye
turn, weak eye muscle, etc.). Many forms and variations of strabismus exist,
depending upon direction and amount of the eye turn, the number of affected
nerves or muscles, and the degree to which it is associated with reduced
vision. The clinical characteristics and diagnostic criteria have been
described in detail (212-215).
comprehensive reviews and studies relating to the success of vision therapy
for strabismus exist. Flom (216) reviewed studies and used detailed
multifactorial analysis. This revealed an overall functional cure rate for
strabismics receiving vision therapy of 50%, with esotropia less responsive
than exotropia. Ludlam (217) evaluated a sample of 149 unselected strabismics
who received vision therapy and determined a 73% overall success rate
utilizing the rigorous criteria established by Flom.
a longitudinal follow-up study of this population, Ludlam and Kleinman (218)
found 89% of these patients had retained their functional cure (binocular
vision present). The long-term overall success rate of vision therapy was
calculated at 65%. If one adopts a less stringent definition of "success,
" such as the cosmetic criterion of "straight-looking eyes"
employed in some less precise studies, the success rate increases to 96% of
the re-analyzed population, or a 71% long- term success rate.
and Duckman, (219) in their literature review of treatment for strabismus,
found strong support for the efficacy of vision therapy for strabismus. They
gathered data from numerous studies, each of which met rigorous criteria for
success, and reported an overall success rate of 86%.
a controlled study of 100 cases (220) Gillan reported that 76% of strabismic
patients attained a cosmetic cure with orthoptics. None of those in the
control group, treated with glasses alone, showed a spontaneous cure.
a series of controlled studies conducted by Guibor (221-223), 50% of the
experimental group achieved alignment of the eyes with glasses and vision
therapy (orthoptics) as compared with only 12.5% of the control group who
received glasses without vision therapy.
recently, Ziegler et al (224) conducted a literature review of the efficacy of
vision therapy for strabismus. An important contribution is their comparative
analysis of published papers using the functional cure criteria defined by
Flom. They noted the study conducted by Etting (225) in which he reported a
65% overall success rate in patients with constant strabismus (57% of
esotropes and 82% of exotropes), 89% success rate with intermittent strabismus
(100% of esotropes and 85% of exotropes), and a 91% success rate when retinal
correspondence was normal.
a study designed to investigate the effectiveness of vision therapy utilizing
computer generated stereo graphics for subjects with strabismus, Kertesz and
Kertesz (226) reported a 74% success rate in 57 strabismics. They combined
traditional vision therapy techniques with computer generated stimuli as
successfully applied by CooperO7 to the remediation of non-strabismic
binocular vision anomalies. The functional cures obtained persisted on
long-term follow-up visits for a period of up to 5 years.
and Clahane (227) designed a prospective study of the results of orthoptic
therapy for divergent strabismus (exotropia). Of the patients who completed
the study, 64.5% attained a functional cure upon completion, and 51.7%
retained this status on an average follow-up interval of 5 years and 4 months.
two studies on the effectiveness of orthoptics (vision therapy) for
intermittent and constant exotropes, Altizer (228) and Chryssanthou (229)
found the majority of their patients had significant improvement in clinical
findings as well as relief of symptoms.
(230) reviewed records of patients completing a vision therapy program for
exotropia of the divergence excess type. Of the patients reviewed, 71.4%
attained a functional cure following approximately 5 months of standardized
sequential therapy procedures used in-office as well as at home.
studies have applied biofeedback in vision therapy to assist in training
patients to align their eyes (231-236). The use of biofeedback to enhance
traditional vision therapy, provide reinforcement, and increase motivation was
supported in these studies.
patients exhibiting esotropia with anomalous correspondence tend to be the
most difficult to successfully treat. The use of more aggressive and
sophisticated techniques for vision therapy has been reported with a better
success rate for anomalous correspondence and esotropia than earlier studies
(237,238). In general, the treatment period tends to be longer for
anomalous correspondence and esotropia than other types of strabismus.
is not simply the ability to read a certain size letter at a distance of 20
feet. Vision is a complex and adaptable information gathering and processing
system which collects, groups, analyzes, accumulates, equates, and remembers
this review, some of the essential components of the visual system and their
disorders which can be physiologically and clinically identified. i.e., the
oculomotor, the accommodative, and the fusional vergence systems have been
discussed. Any dysfunctions in these systems, can lessen the quality and
quantity of the initial input of information into the visual system.
in one or more of these visual subsystems have been shown to result in
symptoms, such as blurred or uncomfortable vision or headaches, or behavioral
signs such as rubbing of the eyes, eyes turning inward or outward, reduced job
efficiency or reading performance, or simply the avoidance of near point
tasks. In addition, these signs/symptoms may contribute to reducing a person's
attention and interest in near tasks. The goal of vision therapy is to
eliminate visual problems, thereby reducing the frequency and severity of the
patient's signs and symptoms. Vision therapy should only be expected to be of
clinical benefit to patients who have detectable visual deficiencies.
response to the question, "How effective is vision therapy in remediating
visual deficiencies?," it is evident from the research presented that there
is sufficient scientific support for the efficacy of vision therapy in
modifying and improving oculomotor, accommodative, and binocular system
disorders, as measured by standardized clinical and laboratory testing
methods, in the majority of patients of all ages for whom it is properly
undertaken and employed.
American Optometric Association reaffirms its long-standing position that
vision therapy is an effective therapeutic modality in the treatment of many
physiological and information processing dysfunctions of the vision system. It
continues to support quality optometric care, education, and research and will
cooperate with all professions dedicated to providing the highest quality of
life in which vision plays such an important role (1).
author: Allen H. Cohen, O.D. SUNY State College of Optometry 100 E. 24th St.,
New York. NY 10010
Task Force would like to acknowledge Jack E. Richman, O.D., Nathan Flax, O.D.,
and Leonard Press, O.D. for their major contributions to the research and
preparation of this document. A number of editorial revisions were based on
the recommendations of the following individuals and organizations: Arol
Augsburger, O.D., Louis G. Hoffman, O.D., Mike Rouse, O.D., Ralph T. Garzia,
O.D., the College of Optometrists in Vision Development, and the Optometric
Extension Program Foundation. The members of the 1985-86 Task Force also
contributed to the initial development of this document: Donald J. Getz, O.D.,
chairman; Paul A. Harris, O.D.; Paul J. Lederer, O.D.; Ronald L. Bateman. O.D.;
and D. Gary Thomas. O.D.
of the task force
H. Cohen, O.D., chairman; Sue E. Lowe, O.D.; Glen T. Steele, O.D.; Irwin B.
Suchoff, O.D.; Daniel D. Gottlieb, O.D., consultant; Torrance L. Trevorrow,
Special report: Position
statement on vision therapy. J Am Optom Assoc 1985;56:782-83.
Costs of education in the health professions--1974. Institute of
Medicine of the National Academy of Sciences.
Dictionary of occupational titles, 1977. 4th ed. GPO No.
029-013-0079-9, Employment and Training Administration.
Facts about medical and dental practitioners 1975-76. US Department
of Health, Education and Welfare Public Health Service Health Resources
Administration, Bureau of Health Resources Development.
Health careers guidebook 1979. 4th ed. GPO No. 029-000- 00343-2,
Department of Labor, Employment and Training Administration and US Department
of Health and Human Services, Health Resources Administration.
National Center for Health Statistics 1976-77. US Department of Health,
Education, and Welfare, Health Manpower and Health Facilities, Health
Occupational outlook handbook, April 1982. US Department of Labor
Bureau of Labor Statistics, Bulletin 2200.
Third report to the president and congress on the status of health
professions personnel in the United States. Publication
No. (HRS) 82-2. January 1982, Department of Health and Human Services.
National Board of Examiners in Optometry. New content outline.
Implementation plans for the new entry-level examinations. Washington, DC:
National Board of Examiners in Optometry, 1986.
Special Committee Report, Association of Schools and Colleges of
Optometry. Curriculum model for oculomotor, binocular and visual perception
dysfunctions. Washington, DC, 1987.
Flax N, ed. Vision therapy and insurance: A position statement. New
York: State University of New York, State College of Optometry, 1986.
National Center for Health Statistics. Eye examination findings
among children, United States. DHEW Publication No. 72-1057, Series 11, No
115. Rockville, Md: Department of Health, Education, and Welfare, 1972.
National Center for Health Statistics. Refraction status and motility
defects of persons 4-74 years, United States DHEW Publication No.78-1654,
Series 11, No 206. Hyattsville, Md: Department of Health, Education and
National Center for Health Statistics. Refraction status of youths
12-17 years, United States. DREW Publications No. 75-1630, Series 11, No.148,
Rockville, Md: Department of Health, Education and Welfare, 1974.
Bennett GR, Blondin M, Ruskiewicz J. Incidence and prevalence of
selected visual conditions. J Optom Assoc 1982; 53:647-56.
Blum HL, Peters HB, Bettman JW. Vision screening for elementary
schools: the Orinda study. Berkeley: University of California Press, 1959.
Graham PA. Epidemiology of strabismus. Br J Ophthalmol
Fletcher CF, Silverman SJ. Strabismus. Part I. A summary of 1110
consecutive cases. Am J Ophthalmol 1966;61:86-94.
Frendsen AD. The occurrence of squint. Acta Ophthalmol (Suppl)
Flom MC, Neumaier RW. Prevalence of amblyopia. Am J Optom Arch Am
Acad Optom 1966;73:732-51.
Rubenstein RS, Lohr KN, Brook RH, et al. Measurement of the
physiological health of children. Vol 4, Vision Impairments. Santa Monica:
Rand Corp, 1985.
Ross E, Murray AL, Stead S. Prevalence of amblyopia in grade 1
school children in Saskatoon. Can J Public Health 1977; 68:491-3.
Department of the National Society to Prevent Blindness. Vision problems in
the United States. A statistical analysis. New York:
National Society to Prevent Blindness, 1980.
Duke-Elder S. The physiology
of the eye and of vision. In: Duke-Elder S, ed. System of ophthalmology, vol
IV: St. Louis: Mosby, 1968.
Hokoda SC. General binocular dysfunctions in an urban optometry clinic.
J Am Optom Assoc 1985;56:560-3.
Hoffman LH. Incidence of vision difficulties in children with learning
disabilities. J Am Optom Assoc 1980;51:447-51.
Lieberman S, Cohen A, Stolzberg M, et al. Validation study of the New
York State Optometric Association (NY-SOA) vision
Grisham JD. Computerized visual therapy-year 1 report. Palo Alto:
American Institutes for Research, 1986.
LoCascio GP. A study of vision in cerebral palsy. Am J Optom Physiol
Scheiman MN. Optometric
findings in children with cerebral palsy. Am J Optom Physiol Opt
Gottlieb DD, Allen W.
Incidence of visual disorders in a selected population of hearing impaired
students. J Am Optom Assoc 1985;56:292-6.
Mohindra I. Vision profile of deaf children. Am J Optom Physiol Opt
Lieberman S. The prevalence
of visual disorders in a school for emotionally disturbed children. J Am Optom
Levy B. Incidence of oculo-visual
anomalies in an adult population of mentally retarded persons. Am J Optom
Physiol Opt 1984;61:324-6.
Woodruff ME, Cleary
E, Bader D. The prevalence of refractive and ocular anomalies among 1242
institutionalized mentally retarded persons. Am J Optom Physiol Opt
Plisko VW, Stern JD, eds. The condition of education, 1985. Washington:
United States Department of Education, 1985.
Smith MJ, Cohen BGF, Stammerjohn LW; Jr, et al. An investigation of
health complaints and job stress in video display operation. Hum Factors
National Institute of Occupational Safety and Health. Potential health
hazards of video display terminals. DHHS (NIOSH) Publication No. 81-129.
Cincinnati: National Institute for Occupational Safety and Health, 1981.
Panel on Impact of Video
Viewing on Vision of Workers. Video displays, work, and vision. Washington:
National Academy Press, 1983.
Leigh JR, Zee DS. The
diagnostic value of abnormal eye movements. A pathophysiological approach.
Johns Hopkins Med J 1982;151:122-35.
Leigh JR, Zee DS. The
neurology of eye movements. Philadelphia: FA Davis, 1984:11-89.
Leigh JR, Zee SD. The neurology of eye movements. Philadelphia: FA
Leigh JR, Zee DS. The neurology of eye movements. Philadelphia: FA
Schor C. A directional impairment of eye movement control in strabismus
amblyopia. Invest Ophthalmol Vis Sci 1975; 15:692-7.
Schapero M. Amblyopia.
Philadelphia: Chilton, 1971.
Von Noorden GK. Burian-Von
Noorden's binocular vision and ocular motility. 2nd ed. St. Louis: Mosby,
Von Noorden GK. Mackensen G.
Pursuit movements of normal and amblyoptic eyes - an electromyographic study.
II. Pursuit movements of amblyopic patients. Am J Ophthalmol 1962;53:477-87.
Ciufredda KJ, Kenyon RV;
Stark L. Abnormal saccadic substitution during small amplitude pursuit
tracking in amblyopic eyes. Invest Ophthalmol Vis Sci 1979;18:506-16.
Ciufredda KJ, Kenyon
RV, Stark L. Saccadic intrusions in strabismus. Arch Ophthalmol
Metz HS, Jampolsky A, O'Meara DM. Congenital ocular nystagmus and
nystagmoid head movements. Am J Ophthalmol 1974;6:1131-3.
Ciufredda KJ, Bahill AT,
Kenyon RV, et al. Eye movements during reading: case reports. Am J Optom
Physiol Opt 1976; 53:389-95.
Senders JW, Fisher
DF, Monty RA, eds. Eye movements and higher psychological functions.
Hillsdale, NJ: Lawrence Erlbaum Assoc, 1978.
Lefton LA. Eye movements in reading disabled children. In: Senders JW;
Fisher DF, Monty RA, eds. Eye movements and higher psychological functions.
Hillsdale NJ: Lawrence Erlbaum Assoc, 1978:225-37.
Senders JW, Fisher DF, Monty RA, eds. Eye movements: cognition
and visual perception. Hillsdale, NJ: Lawrence Erlbaum Assoc, 1981.
Leigh. JR, Zee DS. The neurology of eye movements. Philadelphia: FA
Fisk JD, Goodale MA, Burkart G, et al. Progressive supernuclear palsy:
The relationship between ocular motor dysfunction and psychological test
performance. Neurology 1982; 32:698-705.
Pavlidis GT. Eye movements in
dyslexia: Their diagnostic significance.
J Learn Disabil 1985;18:42-50.
Pirozzolo FJ. Eye movements and reading disability. In: Rayner K,
ed. Eye movements in reading: perceptual and
language processes. New York: Academic Press, 1983:499-509.
Rayner K Eye movements in reading and information processing.
Psychol Bull 1978:85:618-60.
Poynter HL, Schor C, Haynes HM, et al. Oculomotor functions in reading
disability. Am J Optom Physiol Opt 1982; 59:116-27.
Pollatsek A. What can eye movements tell us about dyslexia? In:
Rayner K, ed. Eye movements in reading: perceptual and language processes. New
York: Academic Press, 1983:511-21.
Senders JW, Monty RA, eds. Eye movements and psychological
processes. Hillsdale, NJ: Lawrence Erlbaum Assoc, 1976.
HL, Nodine CF. Studies of eye movements and visual search in radiology. In:
Senders JW, Fisher DF, Monty RA, eds. Eye movements and higher psychological
functions. Hillsdale, NJ: Lawrence Erlbaum Assoc, 1978:317 -28.
PJ, Worms PP. Visual scanning strategies of neurologically impaired,
perceptually impaired, and normal children viewing the Bender-Gestalt
drawings. Psychol in the Schools 1977;14:147-57.
Locher PJ, Worms PF. Visual scanning strategies of perceptually
impaired and normal children viewing the motor-free visual perception test. J
Tinker MA. Bases for effective reading. Minneapolis, MN: University
of Minneapolis Press, 1966:81-94.
RL, Crawford DE, Jeffrey WE. Visual scanning strategies of reflective,
impulsive, fast-accurate, and slow-inaccurate children on the Matching
Familiar Figures Test. Child Dev 1972; 43:1412-7.
Sato K. An investigation of visual scanning strategies of reflective
and impulsive children and adults. Jap Educ Psych 1976 24:224-34.
Drake DM. Perceptual correlates of impulsive and reflective
behavior. Dev Psycho1 1970; 2:202-14.
Cohen B, Bala S, Morris AG. Do hyperactive children have
manifestations of hyperactivity in their eye movements? ERIC Document ED
Cohen B, Morris AG, et al. Saccades of hyperactive and normal boys during
ocular pursuits. Dev Med Chill Neurol 1981;23:323-36.
Richman JE. Use of a sustained visual attention task to determine
children at risk for learning problems. J Am Optom Assoc 1986;57:20-6.
Simon MJ. Use of a vigilance task to determine school readiness of
preschool children. Percept Mot Skills 1982; 54:1020-2.
Berch DB, Kanter DR. Individual differences. In: Warm JS, ed.
Sustained attention in human performance. New York: John Wiley and Sons,
Ludlam WM. Visual training, the alpha activation cycle and reading.
J Am Optom Assoc 1979;50: 111-5.
Ludlam WM. Optometric visual training for reading disability--a case
report. Am J Optom Physiol Opt 197: 50:58-66.
Camuccio D, Griffin JR. Visual skills therapy--a case report. Optom Mon
Wold RM, Pierce JR, Keddington J. Effectiveness of optometric
vision therapy. J Am Optom Assoc 1978;49:1047-59.
Griffin JR. Binocular anomalies-procedures for vision therapy. Chicago:
Professional Press, 1982:349-65.
Heath, EJ, et al. Eye exercises and reading efficiency. Academic
Fujimoto DH, Christensen EA, Griffin JR. An investigation in use of
videocassette techniques for enhancement of saccadic eye movements. J Am Optom
Busby RA. Vision development in the classroom. J Learn Disabil
Punnett AF, Steinhauer GD. Relationship between reinforcement and eye
movements during ocular motor training with learning disabled children. J
Learn Disabil 1984; 17: 16-9.
Punnett AF. Relationship between reinforcement and eye movements during
vision therapy with dyslexic children. PhD thesis. Ann Arbor: University of
Feldman J. Behavior modification in vision training: facilitating
prerequisite behaviors and visual skills. J Am Optom Assoc 1981;52:329-40.
Stohler T. Afterimage treatment of nystagmus. Am Orthopt J
Goldrich SG. Emergent textual contours: A new technique for visual
monitoring in nystagmus, oculomotor dysfunction, and accommodative disorders.
Am J Optom Physiol Opt 1981 ; 58:451-9.
Healy E. Nystagmus treated by orthoptics. Am Orthopt J 1952;2:53-5.
Stegall FW: Orthoptic aspects of nystagmus. Am Orthopt J
Ciufredda KJ, Kenyon RV; Stark L. Suppression of fixational saccades in
strabismic and anisometropic amblyopia. Ophthalmic Res 1979;11:31-9.
Ciufredda KJ, Goldrich SG, Neary C. Use of eye movement auditory
feedback in the control of nystagmus. Am J Optom Physiol Opt 1982;59:396-409.
Abadi RV; Carden D, Simpson J. A new treatment for congenital
nystagmus. Br J Ophthalmol 1980;64:2-4.
Letourneau JE. Biofeedback reinforcement in the training of
limitation of gaze: A case report. Am J Optom Physiol Opt 1976;53:672-6.
Schor CM, Flom MC. Eye position control and visual acuity in
strabismus amblyopia. In: Lennerstrand G, Bach-y-Rita P, Collins CC, et al,
eds. Basic mechanisms of ocular motility and their clinical manifestations.
New York: Pergamon Press, 1975.
Ciufredda KJ. Visual system plasticity in human amblyopia. In:
Hilfer RS, Sheffield JB, eds. Development of order in the visual system. New
York: Springer-Verlag, 1986:212-44.
Burian HM, Von Noorden GK. Binocular vision and ocular motility. 3rd
ed. St. Louis: Mosby, 1985.
Schapero M. Amblyopia. New York: Chilton Book Co, 1971.
Duke-Elder S, ed. System of ophthalmology, vol VI. Ocular motility
and strabismus. St. Louis: Mosby, 1973:424-56.
Gortz H. The corrective treatment of amblyopia with eccentric fixation.
Am J Ophthalmol 1960;49:1315-21.
Gregersen E. Occlusion treatment of squint amblyopia in young
adults. Acta Ophthalmol 1966;44:166-8.
Brown MH, Edleman PM. Conventional occlusion in the older amblyope.
Am Orthopt J 1976;26:34-6.
Eibschitz N, Friedman Z, Neuman E. Comparative results of amblyopia
treatment. Metab Ophthalmol 1978;2:111-2.
Garzia, RP. The efficacy
of visual training in amblyopia: A literature review. Am J Optom Physiol Opt
Nawratzki I. Treatment of amblyopia. Ir J Med Sci 1972; 8:1475-9.
Massie H. Fixing eye occlusion: Survey of approximately 1000 case
histories of patients who received occlusion of the fixing eye. Trans
Ophthalmol Soc Aust 1965;24:39-46.
Kupfer C. Treatment of amblyopia ex anopsia in adults. Am J Ophthalmol
Gregersen E, Rindziunski E. Conventional occlusion in the treatment of
squint amblyopia. Acta Ophthalmol 1965;43:462- 74.
Scott WE, Stratton VB, Fabre J. Fulltime occlusion therapy for
amblyopia. Am Orthopt J 1980;30:125-30.
Haldi B, Mitchelson JE. Amblyopia therapy: Expected results from
standard techniques. Am Orthopt J 1981;31:19-28.
Ingram RM, Rogers S, Walker C. Occlusion and amblyopia. Br Orthopt
HM. Some results of conventional occlusion. Br Orthopt J 1974;31:55-8.
Francois J, James M. Comparative study of amblyopic treatment. Am
Orthopt J 1955;5:61-4.
Bangerter A. Amblyopienhandling. Aufl 2. Basel: Karger, 1955.
Bangerter A. Die occlusion in der pleoptik and orthoptic. Klin
Monatsbl Augenheilkd 1960;136:305-31.
Girard LJ, Fletcher MC, Tomlinson E, et al. Results of pleoptic
treatment of suppression amblyopia. Am Orthopt J 1962;12:12-31.
Jablonski M, Tomlinson E. A new look at pleoptics. Ophthalmology
Mayweg S, Massie HH. A preliminary report of the more recent methods of
treatment of amblyopia, especially when associated with eccentric fixation in
cases of strabismus. Br. J Ophthalmol 1958;42:257-69.
Deller M, Streiff EB. Apropos de l'amblyopie a fixation excentrique.
Ophthalmologica 1965; 150:76-82.
Selenow A, Ciufredda KJ. Vision function recovery during orthoptic
therapy in an adult esotropic amblyope. J Am Optom Assoc 1986;57:132-40.
Ciuffreda KJ, Kenyon RV; Stark L. Different rates of functional
recovery of eye movements during orthoptics treatment in an adult amblyope.
Invest Ophthalmol Vis Sci 1979; 18:213-9.
Hoffman L, Cohen AH, Feuer G, et al. Effectiveness of optometric
therapy for strabismus in a private practice. Am J Optom Arch Am Acad Optom
Shippman S. Video games and amblyopia treatment. Am Orthopt J
Porter EE. Treatment of amblyopia. Am Orthopt J 1962; 12:157.61.
Cohen AH. Monocular fixation in a binocular field. J Am Optom Assoc
Birnbaum MH, Koslowe K, Sanet R. Success in amblyopia therapy as a
function of age: A literature survey. Am J Optom Physiol Opt 1977;54:269-75.
Blackman S, Goldstein KM. Cognitive styles and learning
disabilities. J Learn Disabil1982;15:106-15.
Messer SB. Reflection-impulsivity: a review. Psychol Bull
Abikoff H. Cognitive training interventions in children: Review of a
new approach. J Learn Disabil1979;12:123-35.
Meichenbaum DH, Goodman J. Training impulsive children to talk to
themselves: A means of developing self-control. J Abnorm Psychol
Egeland B. Training impulsive children in the use of more efficient
scanning techniques. Child Dev 1974;45:165-71.
Zelniker, Oppenheimer L. Modification of information processing of
impulsive children. Child Dev 1973;44:445-50.
Orbach I. Impulsive cognitive style: Three modification techniques,
Psychol in the Schools 1977;14:353-9.
McKinney JD, Haskins R. Cognitive training and the development of
problem-solving strategies. Except Educ Q 1980;1.41-51.
Douglas VI, Parry P, Marton P, et al. Assessment of a cognitive training
program for hyperactive children. J Abnorm Child Psychol 1976; 4:389-410.
Brown RT, Wynne ME. Correlates of teacher ratings, sustained attention,
and impulsivity in hyperactive and normal boys. J Clin Child Psycho1
Brown RT, Conrad KJ. Impulse control or selective attention. Remedial
programs for hyperactivity. Psychol in the Schools 1982;19:92-7.
Brown RT, Alford N. Amelioration attentional deficits and concomitant
academic deficiencies in learning disabled children through cognitive
training. J Learn Disabil 1984;17:20-6.
Sherman CF, Anderson RP. Modification of attending behavior in
hyperactive children. Psychol in the Schools 1980;17:372-9.
Schrock RE. Introduction to vision training. Series 1-2, 1965- 67, OEP
Foundation, Santa Ana, CA.
MacDonald LW. Visual training.
Series 1-2. 1978-79, OEP Foundation, Santa Ana, CA.
Forrest EB. Visual imagery: An optometric approach. OEP Foundation,
Santa Ana, CA, 1981.
Richman JE, Cron MT, Cohen E. Basic vision therapy: a clinical
handbook. Big Rapids, Mich: Ferris State College Press, 1983.
Smith W. Clinical orthoptic
procedure: A reference book on clinical methods of orthoptics. St. Louis:
Borish IM. Clinical refraction. 3rd ed. Chicago: Professional Press,
Griffin JR. Binocular anomalies: Procedures for vision therapy, 2nd ed.
Chicago: Professional Press, 1982:377-93.
Suchoff IB, Petito TG. The efficacy of visual therapy:
accommodative disorders and non-strabismic anomalies of binocular vision.
Duane A. Anomalies of the
accommodation, clinically considered. Trans Am Ophthalmol Soc 1915;1:386-402.
Duane A. Anomalies of the
accommodation, clinically considered. Arch Ophthalmol 1916;45:124-36.
Pierce J, Greenspan S. Accommodative rock procedures in vision
training, a clinical guide. Optom Wkly 1971;62(33):754-7.
Pierce J, Greenspan S. Accommodative rock procedures in vision
training, a clinical guide. Optom Wkly 1971; 62(34):776-80.
Weisz CL. How to find and treat accommodative disorders. Rev. Optom
Zellers JA, Alpert TL, Rouse
MW. A review of the literature and a normative study of accommodative
facility. J Am Optom Assoc 1984;55:31-7.
Richman J. Accommodative facility: A study of young adults. J Am Optom Assoc
Why nearpoint retinoscopy with children? Optom Wkly 1974;65(3):54-7.
Apell R. Clinical application of bell retinoscopy. J Am Optom Assoc
Levine S, Ciuffreda KJ , Selenow A, et al. Clinical assessment o accommodative
facility in symptomatic and asymptomatic individuals. J Am Optom Assoc
LG, Rouse, MW. Referral recommendations for binocular function and/or
developmental perceptual deficiencies. J Am Optom Assoc 1980;51:119-26.
D, Iosue R, Rouse M. Relation of symptoms t, accommodative infacility of
school-aged children. Am J Optom Physiol Opt 1984;61:177.
Accommodative dysfunction. Doc Ophthalmol 1983; 55:177-98.
L. The effect of accommodative deficiencies on the development level of
perceptual skills. Am J Optom Physiol Opt 1982:59:254-62.
An investigation of voluntary as distinguished from reflex accommodation. Am J
Optom Arch Am Acad of Optom 1951;28:347-56.
R. Volitional control of visual accommodation. In: Conf Proceedings, Advisory
Group for Aerospace Research and Development, 1970;82:15-7.
R, Enoch J. On voluntary ocular accommodation. Percept Psychophys
TN, Crane H. Training the visual accommodative system. Vision Res
A. Subnormal accommodation. Arch Ophthalmol 1931;6:906-18.
Anomalies of accommodation clinically considered. Arch Ophthalmol (Old Series)
P, Agarwal L, Nag S. Accommodational weakness and convergence insufficiency.
Orient Arch Ophthalmol 1972; 10:261-4.
Noorden G, Brown D, Parks M. Associated convergence and accommodative
insufficiency. Doc Ophthalmol 1973; 4:393-403.
L, Cohen AH. Effectiveness of non strabismic optometric vision training in a
private practice. Am J Optom Arch Am Acad Optom 1973;50:813-6.
Lee M, Jang J, et al. Objective assessment of accommodation orthoptics: 1.
dynamic insufficiency. Am J Optom Physiol Opt 1979;56:285-91.
Sivak JG. Orthoptic treatment of subjects showing slow accommodative
responses. Am J Optom Physiol Opt 1983;60:678-87.
Ciuffreda KJ, Semmlow JL. Static vergence and accommodation: population norms
and orthoptic effects. Doc Ophthalmol1986;62:165-79.
RH. The incidence of visual anomalies in a population of cerebral palsy
children. J Am Optom Assoc 1979; 50:1013-6.
RH. Effectiveness of visual training on a population of cerebral palsied
children. J Am Optom Assoc 1980;51:607-14.
RH. Accommodation in cerebral palsy: Function and remediation. J Am Optom
HM, McWilliams LG. Effects of training on near-far response time as measured
by the distance rock test. J Am Optom Assoc 1979;50:715-8.
Clinical therapy for accommodative responses: Transfer effects upon
performance. J Am Optom Assoc 1979; 50:209-21.
Accommodative dysfunction. Doc Ophthalmol1983 55:177-98.
Accommodative insufficiency. Am J Optom Physiol Opt 1983;60:352-9.
Orthoptic treatment in patients with inertia of accommodation. Aust J Optom
Predicting results in the orthoptic treatment o accommodative dysfunction. Am
J Optom Physiol Opt 1984;61:184-9.
IM. Clinical refraction. 3rd ed. Chicago: Professional Press,1970:859-937.
S. System of ophthalmology, vol VI. Ocular motility and strabismus. St. Louis:
JR. Binocular anomalies: procedures for vision therapy 2nd ed. Chicago:
Professional Press, 1982: 126-30.
Ciuffreda KJ, eds. Vergence eye movements: basic and clinical aspects. Boston:
von Noorden GK. Binocular vision and ocular motility. 2nd ed. St. Louis: Mosby,
IM. Clinical refraction. 3rd ed. Chicago: Professional Press, 1970:327.
von Noorden K Binocular vision and ocular motility. 2nd ed. St. Louis: Mosby,
Saladin JJ. Association of symptoms with measures of oculomotor deficiencies.
Am J Otpom Physiol Opt 1978;55:670-6.
The oculorotary muscles. 2nd ed. St. Louis: Mosby, 1952:160-8.
S. System of ophthalmology, vol v: Ophthalmic optics and refraction, St.
Louis: Mosby, 1970:479-87.
JE. A manual of orthoptics. Springfield, IL: CC Thomas, 1951.
Shaterian ET. Practical ocular motility. Springfield, IL: CC Thomas, 1967.
R, Hugonnier Sc. Strabismus, heterophoria, ocular motor paralysis: clinical
ocular muscle imbalance. St. Louis: Mosby, 1969.
Textbook of orthoptics. London: Hanon Press Ltd, 1955.
Rasicovici A, Windsor CE. Comprehensive review of orthoptics and ocular
motility. St. Louis: Mosby, 1972.
Connolly P, Kern D. Certain motor anomalies of the eye in relation to
prescribing lenses. Am J Ophthalmol 1933; 5:199-213.
The course and effect of visual training on the vergence system. Am J Optom
Physiol Opt 1982;59: 223-7.
Convergence insufficiency. Am J Optom Physiol Opt 1984;61:16-22.
Classification criterion for success in the treatment of convergence
insufficiency. Am J Optom Physiol Opt 1984; 61: 10- 5.
A comparison of the results of tonic and phasic training on the vergence
system. Am J Optom Physiol Opt 1983;60:769-75.
Convergence and divergence show longer and sustained improvement after short
isometric exercise. Am J Optom Physiol Opt 1979;56:23-33.
McMonnies C. Clinical vergence training. Aust J Optom 1979;62:28-36.
Convergence and divergence show large and sustained improvement after short
isometric exercise. Am J Optom Physiol Opt 1979;56:23-33.
R. Orthoptic treatment of convergence insufficiency: A two year follow-up
rep9rt. Am Orthopt J 1982;32:73-80.
J. The dynamics of fusional vergence eye movements in binocular dysfunction.
Am J Optom Physiol Opt 1980; 57:645-55.
J. Treatment of binocular dysfunction. In: Schor C, Ciuffreda KJ, eds.
Vergence eye movements. Boston: Butterworths, 1983:605-46.
Duckman R. Convergence insufficiency: incidence, diagnosis and treatment. J Am
Optom Assoc 1918;49:673-80.
Feldman J. Operant conditioning of fusional convergence ranges using random
dot stereograms. Am J Optom Physiol Opt 1980;57:205-13.
Selenow A, Ciuffreda KJ, et al. Reduction of asthenopia in patients with
convergence insufficiency after fusional vergence training. Am J Optom Physiol
Opt 1983; 60:982-9.
CC. Effect of vision training on patients who fail Sheard's criterion. Am J
Optom Physiol Opt 1981;58:21-3.
S, Brock FW; Folsom WC. Effect of training on stereoscopic acuity. Am J Optom
Arch Am Acad Optom 1969; 46:645-53.
JJ, Rick JO. Effect of orthoptic procedures on stereoscopic acuities. Am J
Optom Physiol Opt 1982;59:718-25.
S. System of ophthalmology, Vol VI. Ocular motility and strabismus. St. Louis:
von Noorden GK, Binocular vision and ocular motility. 2nd ed. St. Louis: CV
Oculomotility and strabismus. In: Duane TD, ed. Clinical ophthalmology.
Hagerstown, MD: Harper & Row, 1979:1.
Strabismus diagnosis and prognosis. In: Schor C, Ciuffreda KF, eds. Vergence
eye movements: basic and clinical aspects. Boston: Butterworths, 1983:579-95.
Treatment of binocular anomalies of vision. In: Hirsch MJ, Wick RE, eds.
Vision of children. Philadelphia: Clinton, 1963:197-228.
WM. Orthoptic treatment of strabismus. Am J Optom Arch Am Acad Optom
WM, Kleinman BI. The long range results of orthoptic treatment of strabismus.
Am J Optom Arch Am Acad Optom 1965;42:647-84.
Duckman RH. Orthoptic treatment of strabismus. J Am Optom Assoc
RU. An analysis of one hundred cases of strabismus treated orthoptically. Br J
GP. Practical details in the orthoptic treatment of strabismus. Arch
GP. Some possibilities of orthoptic training. Arch Ophthalmol 1934;11:433-61.
GP. The possibilities of orthoptic training-a further report. Am J Ophthalmol
D, Huff D, Rouse MW. Success in strabismus therapy: a literature review. J Am
Optom Assoc 1982;53:979-83.
Strabismus therapy in private practice: Cure rates after three months of
therapy. J Am Optom Assoc 1978; 49:1367-73.
AE, Kertesz J. Wide-field stimulation in strabismus. Am J Optom Physiol Opt
S, Clahane AC. The effectiveness of orthoptics alone in selected cases of
exodeviation: the immediate results and several years later. Am Orthopt J
LB. The non-surgical treatment of exotropia. Am Orthopt J 1972;22:71-6.
G. Orthoptic management of intermittent exotropia. Am Orthopt J 1974;24:69-72.
SG. Optometric therapy of divergence excess strabismus. Am J Optom Physiol Opt
Brocklin MD, Vasche TR, Hirons RR, et al. Biofeedback enhanced strabismus
therapy. J Am Optom Assoc 1981; 52:731-6.
RR, Yolton RL. Biofeedback treatment of strabismus: Case studies. J Am Optom
AJ. Auditory biofeedback and intermittent exotropia. J Am Optom Assoc
SG. Oculomotor biofeedback therapy for esotropia. Am J Optom Physiol Opt
Kirschen DG, Bedell HE. Control of unsteady, eccentric fixation in amblyopic
eyes by auditory feedback of eye position. Invest Ophthalmol Vis Sci
MM, Peli E, Libassi D. Auditory biofeedback used to enhance convergence
insufficiency therapy. J Am Optom Assoc 1983;54:1001-3.
R. Use of prism in pre-operative and post-operative treatment. In: Fells P,
ed. The First Congress of the International Strabismus Assoc. St. Louis: Mosby,
1971 :242- 75.
PV: Constant wearing of prisms in treatment of concomitant strabismus. In:
Ferrer OM, ed. Int Ophthalmol Clin, Ocular Motility. Boston: Little, Brown
& Co, 1971:283-91.