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The effectiveness of visual training in improving visual function


1 The effectiveness of visual training to improve visual function Documentation from the American Optometric Association (AOA) on clinical research and scientific results (German translation published in OPTOMETRIE). In the last year several reports were published, some of which dealt critically with functional optometry and visual training and questioned their effectiveness. For this reason, we would like to publish the following publication by the American Optometric Association in its entirety in German translation, even if we are aware that other legal bases apply in Germany. In the USA, optometric visual training is also used in the clinical area, so that diagnosis and medication are discussed. This is reserved for doctors in Germany. But optometric visual training is a part of optometry and this report shows very well the successes that can be achieved with it. So when you work through this report, please take the country-specific circumstances into account. (You can read the original article The Effectiveness of Vision Therapy in Improving Visual Function in English on the Internet at with further references.) This article is intended to demonstrably support the effectiveness and justification of visual training for changing and improving visual functions. Optometry is an independent profession primarily used in health care. Your treatment options include preventing and correcting disorders of the visual system by examining, diagnosing, treating and / or monitoring visual performance and eye health, as well as identifying and diagnosing associated systemic manifestations, all of which are aimed at maintaining and improving our lives. and serve environmental quality. Optometrists examine the eyes and the structures around them to determine if there are any visual problems, eye diseases, and other abnormalities. During the optometric examination, they collect information about the visual system, diagnose discovered ailments and prescribe remedies such as glasses, medication, contact lenses and visual training individually or in combination. The AOA regards visual training as an important and integrative part of optometry practice (1). 43 states describe visual training, orthoptics or similar terms for this as part of their profession in optometry. The Institute of the National Academy of Sciences (2), the Dictionary of Ocupational 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 visual training in their definition of the profession of optometrist. The theory and procedures underlying the diagnosis and treatment of visual disorders are taught in all schools and colleges of optometry (9). In addition, the National Board of Examiners in Optometry and the majority of the various state licensing agencies test their applicants for their theoretical and clinical knowledge of vision therapy. 1

2 What is visual therapy / vision training? Visual therapy (also called visual training, orthoptics, eye training and eye exercises) is a clinical approach to correcting and improving the effects of eye movement disorders, nonstrabismic binocular dysfunctions, focusing disorders, strabismus, amblyopia, nystagmus and certain visual perception disorders (information processing). Performing visual training involves various nonsurgical, therapeutic procedures designed to change various aspects of visual function (11). Its purpose is to cure or ameliorate a diagnosed neuromuscular, neurophysiological, or neurosensory visual dysfunction. Visual training typically involves a series of treatments during which patients perform carefully planned activities under professional supervision to alleviate the visual problem. The special procedures and the instrumentation used for this are determined according to the nature and degree of the diagnosed condition. Visual training is not only used to strengthen the eye muscles, but rather to treat functional defects so that the patient can achieve optimal performance and comfortable vision. Treatment may seem relatively straightforward, like covering an eye as part of amblyopia therapy. Or it requires complex infrared-sensitive devices and computers that monitor the position of the eyes and give the patient feedback in order to reduce uncontrolled jumping of an eye with nystagmus. Treatment of strabismus, or strabismus, can involve complex optical and electronic instruments as well as simple devices such as a light pen or a mirror. The specific procedures and instruments used depend on the nature of the visual dysfunction and the clinician's clinical judgment. Who can benefit from it? Visual therapy is used for conditions that include oculomotor dysfunction, nonstrabismic binocular coordination problems, accommodative disorders, strabismus, amblyopia, and nystagmus. The frequency of these disorders and dysfunctions is only in second place after refractive conditions such as myopia and hyperopia. They are far larger than most eye diseases (12-16). Graham (17) speaks of visible strabismus in almost 4% of over school children. Among clinical cases, Fletcher and Silverman (18) found 8% of those with strabismus. Other studies have generally found values ​​between these two percentages (19). The stated frequency of amblyopia varies slightly, depending on the specific criteria used, with low estimates of around 2% (20) 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 new cases of amblyopia each year in the United States (23). 2

3 Non-binocular coordination anomalies even have a higher rate. Duke Elder (24) reports a convergence failure in adults of 15%. Graham (15) assumes a high heterophoria of over 13%, while Hokoda (25) found fusion or accommodation problems in 21% of non-presbyopic, clinical patients. The recently developed New York State Vision Screening Battery examines oculomotor binoculars The study of children with this composition showed a failure rate of 53%. (27) When special populations are considered, the rate of problems with eye coordination and visual processing increases sharply. Of children who cannot read , had at least 80% deficits in one or more visual skills.26 Grisham (28) recently reported that children with reading difficulties were more than 50% more likely to have visual deficits in accommodation, fusional vergence, and gross convergence than their peers with normal performance In patients with cerebral palsy occurs in mi At least 50% of cases have strabismus (29, 30). The hard of hearing (31, 32), the emotionally impaired (33) and the developmentally retarded (34, 35) patients also show an unusually high frequency of visual problems. This is particularly important because almost 11% of all students have one of the above-mentioned handicaps (36). Our culture continues to promote higher and higher standards of upbringing and create work-related tasks with increasingly higher visual demands. This is evidenced by the difficulties encountered by people working on the PC. A majority of reviews showed that more than 50% of people at the PC complain of some kind of eye discomfort or blurry images (37,38). The National Academy of Sciences (39) concluded that changes in oculomotor and binocular vision exhibited by these people are similar to those that occur during normal close-up work. What are Oculomotor Skills and Oculomotor Dysfunction? (Follow-up and eye movements) Clear vision is created when the precisely focused image of a reference object hits the center of the fovea and when precise eye movements maintain this relationship. The components of the oculomotor or eye movement system include fixations, vestibular and optokinetic movements, saccades and subsequent movements (40). Each of these components has its own individual, different neuroanatomical basis and functional neurophysiology (41). Sometimes some components interact with each other. For example, when the system responsible for eye tracking interacts with other systems to establish ocular stabilization or the eye positioning system (42) to keep the eyes still. Nystagmus, an involuntary movement of the eyes to and fro, is caused by disturbances in the mechanisms that keep the images still (position maintenance) and 3

4 shows up in over a dozen different clinical movement patterns (43). This loss of maintenance of central fixation and eye positioning of the foveal area is one of the pathological features of nystagmus. Patients with amblyopia represent a different group of people with inadequate fixation ability. The inability to constantly fixate with the fovea is associated with decreased visual acuity and is generally observed in anisometropic and especially strabismic amblyopes. Their characteristics have been described in detail (44-46). Abnormal saccadic and eye following movements are seen in strabismic amblyopes and appear to be related to dysfunction of the monocular motor control center for position maintenance (47-49). In the presence of nystagmatic or nystagmoid movements, it becomes difficult to clinically identify the pauses in fixation, regressions, and progressions during reading. The fluctuating eye movements disrupt the efficient visual information processing (50,51). During reading, the function or behavior of the eye movement system involves more than just moving the eyes. This functional component also includes the integration of eye movements with higher cognitive processes. This includes attention, memory, and the use of perceived visual information (52). The clinical evidence and research strongly suggest that many children and adults who have difficulty with visual information processing tasks, whether reading or not, have abnormal eye movements (53-66). Many studies (67-69) show that there is an individual difference in oculomotor patterns (eye movements) between children with reflective strategies or their type of visual information processing and those with impulsive ones. There is evidence that children and adults with attention difficulties and hyperactivity have inefficient patterns of eye movement that interfere with visual information processing (70-74). In summary, there are a number of different dysfunctions in the oculomotor system. Quite often, their clinical manifestations are related to problems in functional visual performance and efficient information processing. Can eye movement skills be changed? There have been reports of improvements in eye movement control and efficiency in individual studies using visual training (75-77). Wold et al (78) reported on 100 consecutive optometric vision training patients whose eye movement abilities were rated on the Heinsen-Schrock performance table (79). There is a 10-point observation scale for grading the performance of saccadic and eye following movements. Only 6% of the children passed the eye movement 4

5 part before therapy. After the therapy, the reassessment showed that 96% of the children could pass. Heath (80) discussed the influence of ocular motor performance in reading. Graduates 63 and 64 who were below the 40% mark on the Metropolitan Reading Test and failed the Purdue Perceptual Motor Survey sub-test for eye tracking were divided into control groups and experimental groups. The results of the study showed significant improvement in eye following in the experimental group compared to the control group. In addition, the children who received therapy performed significantly better in the Metropolitan Reading preliminary test. Fujimoto et al (81) compared the use of different techniques for saccadic fixation training. In this controlled clinical trial, both treated groups showed a statistically significant improvement in terms of speed and accuracy of eye movements compared to the untreated control group. Busby (82) conducted a controlled study of eye movements in an improvement program for special school children. The subjects were rated according to their ability to maintain their fixation on a moving target. The classification procedure had a high interrater reliability. The test group was tested again 3 months after the end of therapy. The results of the experimental group showed statistically significant improvements in eye tracking and maintenance of therapeutic effect. Punnett and Steinhauer (83) conducted a controlled study and examined the effectiveness of eye movement training with and without feedback and reinforcement (84, 85). Before the training, there were very clear differences between the eye movement skills of the control and experimental group of reading-poor students. This indicated that augmenting ocular motor skills training could improve those skills. There was an improvement in reading aloud, which also followed oculomotor training. Similar results, which show the trainability of the eyes, were obtained in studies in which behavior modification and reinforcement were used (84, 85). Changes and improvements in the oculomotor abilities to maintain the central fixation and position of the agent in nystagmus patients have been reported for years in various studies. The use of afterimages (86, 87) and emergent textual contour training to provide visual biofeedback regarding eye positioning and stability has had some success in improving fixation skills. Orthoptics and verbal feedback techniques have helped some patients reduce their nystagmus (88-90). Only recently, eye movement biofeedback through the ear has been used to control nystagmus and positive results have been achieved. Ciufredda (91) et al demonstrated a significant reduction in amplitude and speed in 5

6 Eye movements in patients with congenital nystagmus. Eyesight improved and positive cosmetic and psychological changes were also reported. Abadi et al (92) reported a reduction in nystagmus and an improvement in contrast sensitivity after training in hearing biofeedback. In addition to nystagmus, hearing biofeedback is successfully used to expand the range of eye movements when the viewing width is restricted (93). It has been proven that large and restless eye movements occur in the eyes of amblyopic patients when attempting monocular fixation. A number of studies report successful treatment of amblyopia with improved visual performance and oculomotor control (95 98). Occlusion therapy, a passive approach, has been a common and relatively successful approach for many years (99-111). However, there are people who either do not respond or are unable to respond to occlusion therapy. It has been proven that occlusion with active visual training is more effective than just occlusion (112). Pleoptics (113, 114) is an active visual training procedure in which patients receive visual feedback about their fixation point and direction of gaze. These procedures are designed to correct the fixation point problem while improving the patient's visual performance. Pleoptics have been used successfully in the treatment of eccentric fixation in people who did not respond to regular occlusion therapy (). The visual training for amblyopes contains a wide range of procedures, including occlusion techniques, pleoptic techniques and visual-motor feedback techniques for spatial localization, in which one uses afterimages and entoptic phenomena (45,79) with a higher success rate (). The question of age and its influence on the effectiveness of amblyopia training has been raised in many studies and reviews. These indicate that a noticeable improvement in oculomotor and visual function can be achieved even in an adult (125). It is clearly proven that amblyopia and its oculomotor components can be successfully treated with occlusion and active visual training in a large number of people of all ages. Studies have shown that it is possible to change and improve inefficient and inadequate visual information processing strategies and visual attention patterns.Many of these changes were accompanied by improved eye movements (). A number of techniques such as Tachistoscopic procedures, follow-up and fixation exercises, and one-handed coordination techniques, which have been used to improve these poor visual scanning and attention problems in children and adults, have been described and used professionally for years (79,). What are accommodative dysfunctions and their healing methods? (Focus) 6

7 Accommodation (focusing) dysfunctions are described in detail in many sources () and are clinically classified into accommodative spasms, inability to accommodate, accommodative insufficiency and disease-related accommodation. There are also well-defined syndromes associated with accommodative dysfunction (). In the literature, many symptoms similar to accommodative dysfunction are discussed as a group. These are described as decreased near-point visual acuity (a general inability to maintain near-point activity), asthenopia, excessive eye rubbing, headache, intermittent blurring of distant images after prolonged close work, intermittent double vision at close range, and excessive fatigue in the evening (152,154,). The effectiveness of using visual training exercises to improve accommodative function has considerable support from basic science and clinical research. Studies have shown that accommodative findings, even if they are subject to the autonomic nervous system, can react to arbitrary command () and can be conditioned (164). These studies show that voluntary control over accommodation can be controlled, trained, and transferred. In the past, pathological or iatrogenic causes were corrected, the treatment of accommodative defects included plus lenses for close work, and visual training aimed at improving the function of the accommodative mechanism (). Levine et al (156) compiled basic statistics for diagnostic accommodation findings that differentiate symptomatic from asymptomatic patients. Their findings largely agreed with a similar study by Zellers and Rouse (152). The significant part of these studies is the relationship between symptoms and inadequate opportunity for accommodation. Wold (78) reported on 100 children who had undergone accommodative visual training. These clinically selected cases showed an 80% improvement rate in the accommodative amplitude and a 76% improvement rate in the ability to accommodate, using a measurement method that related to the order criterion of the pre- and post-treatment. The results are similar to those of Hoffman and Cohen (168) in whom 70 patients were successfully treated for accommodative insufficiency and inability to accommodate based on clinical findings. Liu et al (169) investigated disturbances of accommodative abilities through objective laboratory methods using a dynamic optometer with an infrared photomultiplier. They objectively identified the dynamic aspects of the accommodative response that were enhanced by the visual training. Young adults with symptoms of difficulty focusing were treated with procedures commonly practiced in vision schools and visual training practices. There were significant improvements in their focus flexibility, and these changes were related to the marked decrease or elimination of symptoms. It has been found that standard clinical measurements of accommodation ability are related to more objective measurements. 7th

8 Bobier and Sivak (170) replicated the work of Liu et al (169) and used the higher recording precision of a dynamic photorefractor (television camera and monitor with light-emitting diodes). They found no evidence of the decrease in focus flexibility during an 18-day break after training ended. The subjects' symptoms also subsided as accommodative function normalized. Hung et al (171) showed the effect of accommodation, vergence and accommodative vergence orthoptic therapy using a dynamic binocular simulator. This experiment objectively validated the optometric vision therapy exercises through the use of a photoelectric eye movement pickup system and an optometer. Inadequate and inadequate accommodation ability occurs more frequently in people with cerebral palsy (172). Duckman demonstrated that accommodation skills in people with cerebral palsy can be changed and improved through the use of visual training techniques (173, 174). Since changes in accommodation occur when looking up into distance and back up close, Haynes and McWilliams (175) investigated the effects of training this near / far response in high school and university students. Their results indicate that the ability to this near / far reaction can be trained and can be improved with visual training. Weisz (176) shows that the improvement in the ability to accommodate leads to an improvement in the ability to work at close quarters. In a double-blind clinical study after visual training, it was found that their experimental group was significantly more accurate in performing Landolt C problem solving than the control group. Hoffman (160) investigated the effect of accommodative defects on the tasks of visual information processing. He compared the results of visual training for accommodation problems in an experimental group and a control group of school-age children. This study showed that the improvement in accommodative skills also improved the visual perception skills of his subjects. Recently, Daum () examined the entire spectrum of accommodative disorders in an extensive series of analyzes including retrospective studies. He used a stepwise discriminant analysis of regression variables from patient records to build a model for determining the duration of necessary treatment and to predict the success of treatment for accommodation disorders. In conclusion, all of these studies show that accommodation disorders can lead to significant malaise, inability to perform and the avoidance of close work tasks. Furthermore, they show that with appropriate diagnosis and treatment, these disorders can be improved or completely eliminated through visual training. 8th

9 What are binocular vision disorders and their healing methods? (Eye coordination and alignment) Normal and powerful 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 without binocular visual performance to non-strabismic binocular dysfunctions, e.g. Convergence insufficiency (146). The first category is non-strabismic, binocular disorders. Standard techniques and diagnostic criteria for assessing the vergence system and the ability for binocular sensory fusion have been described in detail elsewhere (). Patients with non-strabismic anomalies of binocular vision report quite often eye discomfort and asthenopia (186). Some of the patient's complaints include eye strain, eye soreness, headache in the forehead or back of the head, eye fatigue leading to an aversion to reading and studying (187, 187a). Visual training has long been advocated as the main intervention technique for improving non-strabismic anomalies in binocular vision (). Suchoff and Petito (146) conclude that visual training for this condition is directed towards several therapeutic goals: First, to improve the performance of the accommodative System to enable a more effective interaction between this system and the Vergence System. Second, to maximize the function of the fusional vergence system (i.e. divergence and convergence) and the binocular sensory system. Since accommodation training was covered in the previous section, the remainder of this section is devoted to demonstrating the possibility of change in the vergence system. Clinical vision training aims to improve the patient's ability to compensate for fusional stress. This stress can result in asthenopia, headache, and / or diplopia. A number of studies will be reviewed and show that visual training can improve fusional vergence skills. The clinical assumption that fusional vergences can be trained is not new. Over 50 years ago, Berens et al advocated the use of this aspect of orthoptics for all non-strabismic anomalies of binocular vision (195). Over the past few years, some of those who have investigated this have tried experimentally 9

10 determine whether the clinical assumption that the vergence system can be trained was justified. Daum (196) looked ahead to a group of 35 young adults. The result of daily visual training showed statistically significant improvements in the area of ​​convergence, and these lasted until the retest 24 weeks after the end of the therapy program. The conclusion from this was that relatively short training periods can provide long-lasting increases in vergence ability. Daum (197) conducted a retrospective study of 110 patients treated for convergence insufficiency. The patients were categorized according to the effectiveness of the treatment program: total success, partial success, or no success. Post-exercise diagnostic findings and changes in patient symptoms were used to define the classification categories. A comparison between the pre- and post-exercise findings revealed statistically significant improvement. In a companion report (198), some of the above data (197) was used to investigate and identify which of 14 common diagnostic measures best predicted the success of the visual training program. These measures had an accuracy of 75% in predicting the effectiveness of the visual training program. Another study (199) used tonic and phasic vergence training and showed impressive changes in convergence and divergence skills. The 34 subjects were randomly assigned to a double crossover model in which subjects served themselves as controls, and the learning effects were controlled. In another study, Vaegan used a motorized prism stereoscope (ophthalmic ergograph) to train divergence and convergence (200). 47 adults were divided into convergence / divergence groups and experimental / control groups. The findings led Veagan to conclude that sustained divergence and convergence training showed large and meaningful immediate and consistent improvements in the trained vergence areas of the experimental groups. Vaegan and McMonnies (201) used a recorder that measures eye movements during vergence activity. They were able to objectively demonstrate that convergence training with prism-related changes led to a permanent improvement in the ability to converge. In a companion study, Vaegan (202) demonstrated significant, sustained gains in convergence and divergence ability through both tonic and phasic vergence training. 10

11 Pantano (203) examined over 200 test persons with convergence insufficiency who underwent visual training and evaluated them 2 years later. The majority remained asymptomatic with normal clinical findings. Those subjects who had learned to control convergence and accommodation with one another were the most successful. Grisham (204,205) used latent vergence, speed and frequency of gradual vergence tracking by measuring them objectively with images from the infrared eye monitor; He reported improved gradual vergence tracking after four to eight weeks of visa training. Cooper and Duckman found in their extensive review of convergence insufficiency that 95% of the patients in these studies respond primarily to visual training with regard to their binocular disorder (206). Cooper and Feldman (207) investigated the role and clinical use of operant conditioning in visual training based on arbitrary point stereograms (RDS). They demonstrated that responsive, positive reinforcement, immediate feedback, and preprogrammed, systematic changes in learning discrimination improve the ability to converge. Control groups and experimental groups were formed from test persons with basically the same ability to converge, who were then randomly assigned to the corresponding group. The convergence margin of the experimental group improved significantly, while there was little or no increase in the control group. Cooper et al (208) conducted a control study of visual training and its relationship to symptoms in a group of patients with convergence insufficiency. In a crossover model, a visual training program with fusional vergence exercises was created with a control group of suitable test persons in order to reduce placebo effects. A written rating scale for malaise and / or fatigue was used to assess asthenopia and it was clearly demonstrated that the symptoms disappeared or were reduced. Clinical findings also improved, which in turn supported the subjective assessments. Dalziel (209) reported 100 patients with vergence insufficiency who did not meet Sheard's standard and put them on a visual training program. After the visual training, clinical findings were restored and 84% of the patients successfully achieved Sheard's standard. 83% of patients reported having symptoms of malaise or deterioration in performance prior to treatment. Only 7% reported these symptoms after therapy. The group that after therapy 11

12 did not meet Sheard's standard, correlated well with those patients still reporting subjective symptoms. Wold (78) reported the results of 100 patients who underwent visual training. Based on standard clinical tests, only 25% of children had adequate binocular sensory fusion and 9% had adequate binocular fusion vergence prior to vision therapy. The post-training evaluation showed that 96% had achieved adequate fusion results and that 75% had sufficient fusional vergence width. Wittenberg et al (210) together with Saladin and Rick (211) used slightly different techniques and demonstrated that stereopsis thresholds can be improved in normal subjects. In Daziel's (212) study there was a statistically significant improvement in stereopsis after visual training. Another category of binocular vision disorder is strabismus. Strabismus can be described as a misalignment of the eyes (meaning strabismus, twisting of the eye, weak eye muscles, etc.). Strabismus come in many forms and varieties, depending on the direction and severity of the eye rotation, the number of nerves or muscles affected, and the degree to which it is associated with decreased vision. The clinical features and diagnostic criteria have been described in detail (). There are numerous comprehensive reviews and studies relating to the success of visual training in strabismus. Flom (216) reviewed studies and applied extensive multifactorial analysis. This revealed an overall functional cure rate for strabismus patients who received 50% visual training, with esotropia being less responsive than exotropia. Ludlam (217) evaluated a random group of 149 strabismus patients who received visual training and determined a 73% overall success rate using the strict criteria established by Flom. In a subsequent long-term study of this population, Ludlam and Kleinman (218) found that 89% of these patients had regained their functional healing (existing binocular vision). The overall long-term success rate of the visual training was estimated at 65%. If someone defines the term success less strictly, such as the cosmetic aspect of straight eyes, which is used in less precise studies, the success rate rises to 96% of the re-analyzed population, or a 71% long-term success rate. In their review of the strabismus treatment literature, Flax and Duckman (219) found great support for the effectiveness of visual training in 12

13 strabismus. They collected data from numerous studies, all of which had strict success criteria, and reported an overall success rate of 86%. In a control study of 100 cases (220), Gillan reported that 76% of strabismus patients were cured cosmetically by orthoptics. None of the control group who were treated with glasses alone showed spontaneous healing. In a series of control studies carried out by Guibor (), 50% of the experimental group achieved straightening of the eyes with glasses and visual training (orthoptics) compared to only 12.5% ​​of the control group who received glasses but no vision training. Recently, Ziegler et al (224) chaired a literature review on the effectiveness of visual training in strabismus. An important contribution is their comparative analysis of published records using Flom's functional healing criteria. They named the study led by Etting (225).In this he named a 65% overall success rate in patients with constant strabismus (57% esotropes and 8% exotropes), an 89% success rate with intermittent strabismus (100% esotropes and 85% exotropes) and a 91% success rate if the retinal correspondence was normal. In a study that was carried out to investigate the effectiveness of visual training using computer-generated stereographics for test subjects with strabismus, Kertesz and Kertesz (226) reported a 74% success rate in 57 cases of strabismus. They combined traditional visual training techniques with computer-generated stimuli that Cooper successfully used to heal non-strabismic binocular visual anomalies. The functional cures that were achieved were persistent on follow-up visits for a long period of up to 5 years. Sanfilippo and Clahane (227) designed a future study of the results of orthoptic therapy for divergent strabismus (exotropia). Of the patients who completed the study, 64.5% achieved a complete functional cure at the end and 51.7% maintained this status over an average follow-up interval of 5 years and 4 months. In two studies of the effectiveness of orthoptics (visual therapy) for intermittent and constant exotropes, Altizer (228) and Chryssanthou (229) found that the majority of their patients showed significant improvements in both clinical findings and symptom relief. Goldrich (230) reviewed records of patients who had a visual training program for exotropia with excessive divergence 13

14 performed. 71.4% of the patients examined achieved a functional cure after approximately five months of standardized therapy procedures carried out in sequence, which were carried out in the practice as well as at home. Several studies have used biofeedback in visual training to help patients train eye alignment (). The use of biofeedback to improve traditional visual therapy contributes to reinforcement, and the motivation for improvement was supported in these studies. Strabismic patients suffering from esotropia with abnormal eye coordination tend to be the most difficult to treat successfully. It is said that the use of more aggressive and more sophisticated visual therapy techniques for abnormal eye coordination and esotropia would have a higher success rate compared to previous studies (237, 238). In general, the duration of treatment for abnormal eye coordination and esotropia tends to be longer than for other forms of strabismus. Summary and Conclusion Eyesight is not simply the ability to read letters of a certain size at a distance of 6 meters. Eyesight is a complex and adaptable system that collects and processes information. It collects, groups, analyzes, accumulates, identifies and remembers information. In this revision, some of the essential components of the visual system and their disorders that can be physiologically and clinically determined (e.g. the oculomotor, accommodative and fusional vergence systems) have been discussed. Any dysfunction in these systems can degrade the quality and quantity of the original information input into the visual system. It was made clear that defects in one or more of these visual subsystems lead to symptoms such as blurred or uncomfortable vision, headaches, behavioral problems such as rubbing eyes, squinting outwards or inwards, decreased performance at work or reading, or simply avoiding close work. In addition, these signs / symptoms can contribute to a person's decrease in attention and interest in local work. The goal of visual training is to solve visual problems, thereby reducing the frequency and intensity of the patient's signs and symptoms. One should expect clinical benefit from visual training only for those patients who have noticeable visual defects. 14th

15 In response to the question How effective is visual training at removing visual defects? one can see from the research presented here that there is sufficient scientific support for the effectiveness of visual training in changing and improving oculomotor, accommodative and binocular system disorders. This has been measured using standardized clinical and laboratory test methods on the majority of patients of all ages on whom it has been performed and applied. The AOA reaffirms its longstanding position that visual training is an effective therapeutic modality in the treatment of many physiological and information processing disorders of the visual system. She continues to support qualitative optometric care, education and research and will cooperate with all professions dedicated to the highest quality of life, in which eyesight plays a major role (1). Note: There is a plethora of literature that demonstrates the effectiveness of visual training through binocular treatment (eye coordination and alignment), oculomotor (following and eye movement), and accommodative (focusing) problems. The following text is a copy of a report published by the AOA entitled The Effectiveness of Visual Training. Please note the list of over two hundred references at the end of the report. The clinical research, scientific studies and specialist articles listed in the bibliography were initially published in neutral science magazines. This means that each text has been examined by an outside expert before publication to validate its scientific nature, value and research methodology. For the more complete list of studies and clinical reports on which research into vision training is based, please refer to the Bibliography of Research. REFERENCES 1. Special report: Position statement on vision therapy. J Am Optom Assoc 1985; 56: Costs of education in the health professions Institute of Medicine of the National Academy of Sciences. 3. Dictionary of occupational titles, th ed. GPO No, Employment and page 15 of 26 Training Administration. 4. Facts about medical and dental practitioners US Department of Health, Education and Welfare Public Health Service Health Resources Administration, Bureau of Health Resources Development. 5. Health careers guidebook th ed. GPO No, Department of Labor, Employment and Training Administration and US Department of Health and Human Services, Health Resources Administration. 15th

16 6. National Center for Health Statistics US Department of Health, Education, and Welfare, Health Manpower and Health Facilities, Health Resources Statistics. 7. Occupational outlook handbook, April US Department of Labor Bureau of Labor Statistics, Bulletin Third report to the president and congress on the status of health professions personnel in the United States. Publication No. (HRS) January 1982, Department of Health and Human Services. 9. 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, Special Committee Report, Association of Schools and Colleges of Optometry. Curriculum model for oculomotor, binocular and visual perception dysfunctions. Washington, DC, Flax N, ed. Vision therapy and insurance: A position statement. New York: State University of New York, State College of Optometry, National Center for Health Statistics. Eye examination findings among children, United States. DHEW Publication No, Series 11, No 115. Rockville, Md: Department of Health, Education, and Welfare, National Center for Health Statistics. Refraction status and motility defects of persons 4-74 years, United States DHEW Publication No, Series 11, No 206. Hyattsville, Md: Department of Health, Education and Welfare, National Center for Health Statistics. Refraction status of youths years, United States. DREW Publications No, Series 11, No.148, Rockville, Md: Department of Health, Education and Welfare, Bennett GR, Blondin M, Ruskiewicz J. Incidence and prevalence of selected visual conditions. J Optom Assoc 1982; 53: Blum HL, Peters HB, Bettman JW. Vision screening for elementary schools: the Orinda study. Berkeley: University of California Press, Graham PA. Epidemiology of strabismus. Br J Ophthalmol 1974; 58: Fletcher CF, Silverman SJ. Strabismus. Part I. A summary of 1110 consecutive cases. Am J Ophthalmol 1966; 61: Frendsen AD. The occurrence of squint. Acta Ophthalmol (Suppl) 1960; Flom MC, Neumaier RW. Prevalence of amblyopia. Am J Optom Arch Am Acad Optom 1966; 73: Rubenstein RS, Lohr KN, Brook RH, et al. Measurement of the physiological health of children. Vol 4, Vision Impairments. Santa Monica: Rand Corp, Ross E, Murray AL, Stead S. Prevalence of amblyopia in grade 1 school children in Saskatoon. Can J Public Health 1977; 68: Operational Research Department of the National Society to Prevent Blindness. Vision problems in the United States. A statistical analysis. New York: National Society to Prevent Blindness, Duke-Elder S. The physiology of the eye and of vision. In: Duke-Elder S, ed. System of ophthalmology, vol IV: St. Louis: Mosby, Hokoda SC. General binocular dysfunctions in an urban optometry clinic. J Am Optom Assoc 1985; 56: Hoffman LH. Incidence of vision difficulties in children with learning disabilities. J Am Optom Assoc 1980; 51:

17 27. Lieberman S, Cohen A, Stolzberg M, et al. Validation study of the New York State Optometric Association (NY-SOA) vision 28. Grisham JD. Computerized visual therapy-year 1 report. Palo Alto: American Institutes for Research, LoCascio GP. A study of vision in cerebral palsy. Am J Optom Physiol Opt 1977; 54: Scheiman MN. Optometric findings in children with cerebral palsy. Am J Optom Physiol Opt 1984; 61: Gottlieb DD, Allen W. Incidence of visual disorders in a selected population of hearing impaired students. J Am Optom Assoc 1985; 56: Mohindra I. Vision profile of deaf children. Am J Optom Physiol Opt 1976; 53: Lieberman S. The prevalence of visual disorders in a school for emotionally disturbed children. J Am Optom Assoc 1985; 56: Levy B. Incidence of oculo-visual anomalies in an adult population of mentally retarded persons. Am J Optom Physiol Opt 1984; 61: Woodruff ME, Cleary E, Bader D. The prevalence of refractive and ocular anomalies among 1242 institutionalized mentally retarded persons. Am J Optom Physiol Opt 1980; 57: Plisko VW, Stern JD, eds. The condition of education, Washington: United States Department of Education, Smith MJ, Cohen BGF, Stammerjohn LW; Jr, et al. An investigation of health complaints and job stress in video display operation. Hum Factors 1981; 23: National Institute of Occupational Safety and Health. Potential health hazards of video display terminals. DHHS (NIOSH) Publication No Cincinnati: National Institute for Occupational Safety and Health, Panel on Impact of Video Viewing on Vision of Workers. Video displays, work, and vision. Washington: National Academy Press, Leigh JR, Zee DS. The diagnostic value of abnormal eye movements. A pathophysiological approach. Johns Hopkins Med J 1982; 151: Leigh JR, Zee DS. The neurology of eye movements. Philadelphia: FA Davis, 1984: Leigh JR, Zee SD. The neurology of eye movements. Philadelphia: FA Davis, 1984: Leigh JR, Zee DS. The neurology of eye movements. Philadelphia: FA Davis, 1984: Schor C. A directional impairment of eye movement control in strabismus amblyopia. Invest Ophthalmol Vis Sci 1975; 15: Schapero M. Amblyopia. Philadelphia: Chilton, Von Noorden GK. Burian-Von Noorden's binocular vision and ocular motility. 2nd ed. St. Louis: Mosby, 1980: 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: Ciufredda KJ, Kenyon RV; Stark L. Abnormal saccadic substitution during small amplitude pursuit tracking in amblyopic eyes. Invest Ophthalmol Vis Sci 1979; 18: Ciufredda KJ, Kenyon RV, Stark L. Saccadic intrusions in strabismus. Arch Ophthalmol 1979; 97: Metz HS, Jampolsky A, O'Meara DM. Congenital ocular nystagmus and nystagmoid head movements. Am J Ophthalmol 1974; 6:

18 51. Ciufredda KJ, Bahill AT, Kenyon RV, et al. Eye movements during reading: case reports. Am J Optom Physiol Opt 1976; 53: Senders JW, Fisher DF, Monty RA, eds. Eye movements and higher psychological functions. Hillsdale, NJ: Lawrence Erlbaum Assoc, 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: Senders JW, Fisher DF, Monty RA, eds. Eye movements: cognition and visual perception. Hillsdale, NJ: Lawrence Erlbaum Assoc, Leigh. JR, Zee DS. The neurology of eye movements. Philadelphia: FA Davis, 1984: Fisk JD, Goodale MA, Burkart G, et al. Progressive supernuclear palsy: The relationship between ocular motor dysfunction and psychological test performance. Neurology 1982; 32: Pavlidis GT. Eye movements in dyslexia: Their diagnostic significance. J Learn Disabil 1985; 18: Pirozzolo FJ. Eye movements and reading disability. In: Rayner K, ed. Eye movements in reading: perceptual and language processes. New York: Academic Press, 1983: Rayner K Eye movements in reading and information processing. Psychol Bull 1978: 85: Poynter HL, Schor C, Haynes HM, et al. Oculomotor functions in reading disability. Am J Optom Physiol Opt 1982; 59: 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: Senders JW, Monty RA, eds. Eye movements and psychological processes. Hillsdale, NJ: Lawrence Erlbaum Assoc, Kundel 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: Locher 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: Locher PJ, Worms PF. Visual scanning strategies of perceptually impaired and normal children viewing the motor-free visual perception test. J Learn Disabil 1981; 14: Tinker MA. Bases for effective reading. Minneapolis, MN: University of Minneapolis Press, 1966: Ault RL, Crawford DE, Jeffrey WE. Visual scanning strategies of reflective, impulsive, fastaccurate, and slow-inaccurate children on the Matching Familiar Figures Test. Child Dev 1972; 43: Sato K. An investigation of visual scanning strategies of reflective and impulsive children and adults. Jap Educ Psych: Drake DM. Perceptual correlates of impulsive and reflective behavior. Dev Psycho1 1970; 2: Cohen B, Bala S, Morris AG. Do hyperactive children have manifestations of hyperactivity in their eye movements? ERIC Document ED,

19 71. Bala SP, Cohen B, Morris AG, et al. Saccades of hyperactive and normal boys during ocular pursuits. Dev Med Chill Neurol 1981; 23: Richman JE. Use of a sustained visual attention task to determine children at risk for learning problems. J Am Optom Assoc 1986; 57: Simon MJ. Use of a vigilance task to determine school readiness of preschool children. Percept Mot Skills 1982; 54: Berch DB, Kanter DR. Individual differences. In: Warm JS, ed. Sustained attention in human performance. New York: John Wiley and Sons, 1984: Ludlam WM. Visual training, the alpha activation cycle and reading. J Am Optom Assoc 1979; 50: Ludlam WM. Optometric visual training for reading disability - a case report. Am J Optom Physiol Opt 197:50: Camuccio D, Griffin JR. Visual skills therapy - a case report. Optom Mon 1982; 73: Wold RM, Pierce JR, Keddington J. Effectiveness of optometric vision therapy. J Am Optom Assoc 1978; 49: Griffin JR. Binocular anomalies-procedures for vision therapy. Chicago: Professional Press, 1982: Heath, EJ, et al. Eye exercises and reading efficiency. Academic Therapy 1976; 11: Fujimoto DH, Christensen EA, Griffin JR. An investigation in the use of videocassette techniques for enhancement of saccadic eye movements. J Am Optom Assoc 1985; 56: Busby RA. Vision development in the classroom. J Learn Disabil 1985; 18: Punnett AF, Steinhauer GD. Relationship between reinforcement and eye movements during ocular motor training with learning disabled children. J Learn Disabil 1984; 17: Punnett AF. Relationship between reinforcement and eye movements during vision therapy with dyslexic children. PhD thesis. Ann Arbor: University of Microfilms, 1981: Feldman J. Behavior modification in vision training: facilitating prerequisite behaviors and visual skills. J Am Optom Assoc 1981; 52: Stohler T. Afterimage treatment of nystagmus. Am Orthopt J 1973; 23: 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: Healy E. Nystagmus treated by orthoptics. Am Orthopt J 1952; 2: Stegall FW: Orthoptic aspects of nystagmus. Am Orthopt J 1973; 23: Ciufredda KJ, Kenyon RV; Stark L. Suppression of fixational saccades in strabismic and anisometropic amblyopia. Ophthalmic Res 1979; 11: Ciufredda KJ, Goldrich SG, Neary C. Use of eye movement auditory feedback in the control of nystagmus. Am J Optom Physiol Opt 1982; 59: Abadi RV; Carden D, Simpson J. A new treatment for congenital nystagmus. Br J Ophthalmol 1980; 64: Letourneau JE. Biofeedback reinforcement in the training of limitation of gaze: A case report. Am J Optom Physiol Opt 1976; 53: 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,

20 95. 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: Burian HM, Von Noorden GK. Binocular vision and ocular motility. 3rd ed. St. Louis: Mosby, Schapero M. Amblyopia. New York: Chilton Book Co, Duke-Elder S, ed.System of ophthalmology, vol VI. Ocular motility and strabismus. St. Louis: Mosby, 1973: Gortz H. The corrective treatment of amblyopia with eccentric fixation. Am J Ophthalmol 1960; 49: Gregersen E. Occlusion treatment of squint amblyopia in young adults. Acta Ophthalmol 1966; 44: Brown MH, Edleman PM. Conventional occlusion in the older amblyope. Am Orthopt J 1976; 26: Eibschitz N, Friedman Z, Neuman E. Comparative results of amblyopia treatment. Metab Ophthalmol 1978; 2: Garzia, RP. The efficacy of visual training in amblyopia: A literature review. Am J Optom Physiol Opt 1987; 64: Nawratzki I. Treatment of amblyopia. Ir J Med Sci 1972; 8: 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: Kupfer C. Treatment of amblyopia ex anopsia in adults. Am J Ophthalmol 1957; 43: Gregersen E, Rindziunski E. Conventional occlusion in the treatment of squint amblyopia. Acta Ophthalmol 1965; 43: Scott WE, Stratton VB, Fabre J. Fulltime occlusion therapy for amblyopia. Am Orthopt J 1980; 30: Haldi B, Mitchelson JE. Amblyopia therapy: Expected results from standard techniques. Am Orthopt J 1981; 31: Ingram RM, Rogers S, Walker C. Occlusion and amblyopia. Br Orthopt J 1977; 34: Goodier HM. Some results of conventional occlusion. Br Orthopt J 1974; 31: Francois J, James M. Comparative study of amblyopic treatment. Am Orthopt J 1955; 5: Bangerter A. Amblyopia handling. 2nd edition Basel: Karger, Bangerter A. Die occlusion in der pleoptik and orthoptic. Klinmonthsbl Augenheilkd 1960; 136: Girard LJ, Fletcher MC, Tomlinson E, et al. Results of pleoptic treatment of suppression amblyopia. Am Orthopt J 1962; 12: Jablonski M, Tomlinson E. A new look at pleoptics. Ophthalmology 1979; 86: 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: Deller M, Streiff EB. Apropos de l'amblyopie a fixation excentrique. Ophthalmologica 1965; 150: