Vision Therapy Research

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Vision and Dylsexia

Efficacy of Vision Therapy

Behavioral Vision

Scientific Basis for Vision Therapy

Vision Therapy Information

Convergence Insufficiency

Abstracts

Click on one of the following categories to view abstracts about that particular dysfunction or condition.

Accommodative Dysfunction

Vergence Anomalies

Amblyopia

Strabismus

Vision and Learning

Accommodative Dysfunctions - Abstracts

Bobier WR, Sivak JG. Orthoptic treatment of subjects showing slow accommodative responses. Am J Optom Physiol Opt, 60:678-87, 1983.

Abstract: five subjects showing slow accommodative responses were given orthoptic (vision therapy) treatment. Speed of accommodative response improved after 3 to 6 weeks. No regressions were evident 18 weeks after the cessation of training. The results of the study indicate that vision therapy is effective in improving slow accommodative responses. 

Cooper J, Fledman J, Selenow A, et al. Reduction of asthenopia after accommodative facility training. Am J Optom Physiol Opt, 64:430-6, 1987.

Abstract: Five patients reporting asthenopia secondary to accommodative deficiencies underwent automated monocular accommodative facility training. A matched-subjects, crossover design was used to control for placebo effects. All patients receiving automated accommodative training showed a marked increase in accommodative amplitude along with a concurrent reduction of asthenopia. Decreases of blur and increases of reading time were the most frequently reported changes by patients. This experiment shows the effectiveness of automated accommodative training in reducing asthenopia and improving accommodative facility.

Daum KM. Accommodative insufficiency. Am J Optom Physiol Opt, 60:352-9, 1983.

Abstract: A retrospective review of the records of 96 patients with accommodative insufficiency was conducted. The results of orthoptic exercises and/or a plus lens addition at near were examined. Most patients (90%) obtained some relief with treatment. About 53% had their objective and subjective problems totally solved during an average treatment period of 3.7 weeks.

Hung GK, Ciuffreda KJ, Semmlow JL. Static vergence and accommodation: population norms and orthoptics effects. Doc Opthalmologica 62:15-79, 1986.

Abstract: This study investigated the effect of orthoptic therapy lasting 8-16 weeks on the accommodative and vergence system function of 22 visually-normal asymptomatic individuals and 21 visually-abnormal symptomatic individuals. Following therapy, asymptomatic individuals experienced reduction of symptoms and improvement in visual parameters toward the normal mean function.

Hofman LG. The effect of accommodative deficiencies on the developmental level of perceptual skills. Am J Optom Physiol Opt, 59:254-62, 1982.

Abstract: The relation of accommodative to visual-motor perceptual abilities was investigated. Patients between 5 and 13 years of age manifesting both accommodative and visual-motor perceptual deficits were given accommodative therapy. The effect of this therapy was analyzed, and the results indicated that improvement in the visual and motor perceptual abilities occurred in the 5 to 7 years, 11 month age group.

Liu JS, Lee M, Jang J, et al. Objective assessment of accommodation orthoptics. 1. Dynamic Insufficiency. Am J Optom Physiol Opt, 56:285-94, 1979.

Abstract: Three young adult females with symptoms related to focusing difficulties at near were treated by standard orthoptic procedures. Home training was done 20 minutes each day for 4 1/2 - 7 weeks. Objective measures of dynamic accommodation were made each week. During treatment, the patients showed significant reductions in time constants and latencies that correlated well with elimination of subjective symptoms. Also, in all three patients, symptoms were either markedly diminished or no longer present at termination of therapy. These results clearly demonstrate that orthoptic treatment resulted in objective improvement of accommodation function.

Rouse MW. Management of binocular anomalies: Efficiency of vision therapy in the treatment of accommodative deficiencies. Am J Optom Physiol Opt, 64:415-20, 1987.

Abstract: This paper is a review of the literature supporting vision therapy as an effective treatment mode for accommodative deficiencies. Vision therapy procedures have been shown to improve accommodative function and eliminate or reduce associated symptoms. In addition, the actual physiological accommodative response variables modified by the therapy have been identified, eliminating the possibility of Hawthorne or placebo effects accounting for treatment success. The improved accommodative function appears to be fairly durable after treatment.

Suchoff IB, Petito GT. The efficiency of visual therapy: accommodative disorders and non-strabismic anomalies of binocular vision. J Am Optom Assoc, 57:119-25, 1986.

Abstract: This paper examines the available literature in order to answer the question, "Is there evidence that `orthoptics' or `vision therapy' causes changes in an individual's accommodative or vergence eye movement systems?' This review neither examines alternative methods of causing these changes nor provides information concerning which particular techniques are most effective although the literature does provide such information. The literature cited substantiates that visual therapy can modify visual functions and also points out the relationship of these changes to the relief of certain symptoms.

Weisz CL. Clinical therapy for accommodative responses: transfer effects upon performance. J Am Optom Assoc, 50:209-12, 1979.

Abstract: A clinical therapy program featuring accommodative training was administered to a group of children with diagnosed disorders of accommodative function. The children ranged in age from six to twelve years. A group of subjects representing the same clinical population, and not differing significantly in age or grade level, acted as a control group. The control subjects participated in a therapy program of a similar duration, wherein perceptual-motor training (unrelated to the training of accommodative skills) was administered. A nearpoint pencil-and-paper task was administered to all subjects before and after their training programs, to assess changes in performance as a criterion of learning transfer and behavioral generalization. A significantly greater decrease in errors occurred in the group receiving the accommodative training as contrasted to the control group. No significant differences were found in the time scores. The results suggest that accommodative training, for children with diagnosed accommodative disorders, had transfer effects upon nearpoint performance relating to improved accuracy.

Vergence Anomalies - Abstracts

Cohen AH, Soden R. Effectiveness of visual therapy for convergence insufficiencies for an adult population. J Am Optom Assoc, 55:491-4, 1984.

Abstract: Visual therapy is an effective treatment modality for convergence anomalies in both the adult and the geriatric populations. Complaints of blurred vision, diplopia, headaches, and asthenopia associated with convergence insufficiencies can be alleviated for most patients regardless of age. Once the basic reflexes of convergence are established there seems to be a high level of long-term success.

Cooper J, Duckman R. Convergence insufficiency: incidence, diagnosis, and treatment. J Am Optom Assoc, 49:673-8, 1978.

Abstract convergence insufficiency is one of the most common ocular problems. The paper carefully reviews the existing literature relating to etiology, diagnosis, sensory finding, treatment, and treatment results. Vision therapy for convergence insufficiency has been shown to be effective in reducing symptoms and improving vergence abilities.

Cooper J, Selenow A, et al. Reduction of asthenopia in patients with convergence insufficiency after fusional vergence training. Am J Optom Physiol Opt, 60:982-9, 1983.

Abstract: Seven patients with convergence insufficiency and related asthenopia underwent automate fusional convergence training. A matched-subjects control group crossover design was used to reduce placebo effects. All patients showed significant increases in vergence ranges with concurrent marked reduction of symptoms after training. All patients showed a flattening of and a increase in the base-out portion of their fixation disparity curve. Results demonstrated the effectiveness of fusional vergence training in reducing asthenopia in these patients. Subsequent accommodation and vergence training using traditional orthoptic procedures yielded further reduction of asthenopia, as well as an increase I the base-out fusional range.

Cooper J. Review of computerized orthoptics with specific regard to convergence insufficiency. Am J Optom Physiol Opt, 65:448-54, 1988.

Abstract: Traditional vision training or orthoptics has used line or contour targets to eliminate suppression and improve vergence performance. Manipulation of these stimuli is slow and arduous. Line stimuli require an experienced doctor/technician to interpret responses. Recently, automated vision training using microprocessor anaglyph stimuli, i.e., random dot stereograms (RDS), has been used in an operant conditioning paradigm. This technique had improved motivation of the patient, improved reliability, and provided standardization of therapy. In addition, the utilization of RDS associated with operant conditioning has been shown to improve vergence performance and to reduce asthenopia in the convergence insufficiency patient.

Dalziel CC. Effect of vision training on Patients who fail Sheard's criterion. Am J Optom Physiol Opt, 58:21-3, 1981.

Abstract: One hundred convergence insufficiency patients who did not meet Sheard's criterion at near were given a program of in-office and at-home training. The objective was to see if they would meet Sheard's criterion after training. Results were analyzed in terms of the numbers successfully meeting this criterion as well as other criteria, i.e., Percival's elimination of symptoms, improvement of stereopsis, and elimination of fixation disparity. Of the 100 patients, 84 successfully met Sheard's criterion correlated well with having subjective symptoms.

Daum KM. Characteristics of exodeviations: II. Changes with treatment with orthoptics. Am J Optom Physiol Opt, 63:244-51, 1986.

Abstract: This study examines retrospectively the records of 179 patients who had binocular visual dysfunction as a result of an exodeviation (either at distance or neat or both). The patients were classified as having convergence insufficiency (N=110), equal exodeviations (N=49), or divergence excess (N=18). The diagnostic groups and the different frequencies of deviation reacted differently to treatment with a standard orthoptic regimen. Nearly al the patients (97%) achieved some improvement in either objective or subjective areas or both. However, fewer were able to satisfy the criteria set for total success. Factors correlated with the success of the treatment were the initial angle of deviation at distance and the initial level of stereopsis. The results and implications of this study are discussed.

Daum KM. Convergence insufficiency. Am J Optom Physiol Opt, 61:16-22, 1984.

Abstract: A retrospective study of 110 subjects with convergence insufficiency was completed. Their mean age was 19.9 years. There were 72 females and 38 males in the group. The clinical profiles of these subjects were examined before and after a standard orthoptic treatment regimen. Over the course of treatment, the near angle of deviation, the AC/A ratio, a portion of the negative vergence values, the nearpoint of convergence, and the amplitude of accommodation were found to have changed in a statistically significant manner.

Daum KM. The course and effect of visual training on the vergence system. Am J Optom Physiol Opt, 59:223-7, 1982.

Abstract: The effect of a variety of vergence training procedures on the visual system of 35 asymptomatic young adults with normal binocularity was evaluated. Vergence ranges were measured before the study began and at the end of the 3-week period. Sub-populations were evaluated at one week and at 6 months to document further the course of the effects. Positive fusional vergence training significantly increased the vergence ranges after 1 week of training; a greater effect was measured after 3 weeks. The vergence capability was found to have decreased 6 months later, but the effects of the training were still apparent. Negative fusional vergence training was less effective; however, significant increases were demonstrable after 3 weeks of training. The phorias and accommodative amplitude were not affected by the orthoptics. Relatively short periods of training can provide long-lasting increases in the vergence ability of a group of binocular normals.

Daum K. Double-blind placebo-controlled examination of timing effects in the training of positive vergences. Am J Optom Physiol Opt, 63:807-12, 1986.

Abstract: The purpose of this study was to document the effects of positive fusional vergence therapy and to determine the most effective timing of such training. Four experimental protocols were selected and five subjects were assigned randomly to each of the four experimental groups. Each subject in each group spent 120 min (total) over a period of 3 weeks doing positive fusional vergence training. Group A trained in twelve 10-min sessions; group B in six 20-min sessions; and group C in three 40min sessions. Group D was a control group. All the training was in-office and consisted of positive fusional vergence training on the synoptophore. Each of the test groups showed increases in their positive fusional vergence ability at both distance and near. Group A (shorter sessions) demonstrated the largest increases overall. In addition, the group that trained in short 10-min session (group A) was the only one that showed significant increases in the negative fusional vergences and the positive blur finding. It is best to use short, frequent training sessions to increase the amplitude of positive fusional vergence.

Daum KM, Rutstein RP, Eskridge JB. Efficacy of computerized vergence therapy. Am J Optom Physiol Opt, 64:83-9, 1987.

Abstract: The purpose of this study was to determine the efficacy of computerized fusional vergence therapy and the effect of two different vergence-training velocities. Six subjects received positive vergence training using a slow vergence training rate (0.75/s) and six subjects received positive vergence training using a fast vergence-training rate (5.00/s). Six subjects served as controls and did not receive therapy. The duration of therapy was 80 min over a period of 4 weeks. All training activities were monitored. All vergence evaluations were double masked. Subjects using a slow training rate showed significant increases in positive vergence ranges as measured with the major amblyoscope, whereas subjects training with fast rates did not. Vergence therapy using computerized video display is an effective technique for increasing the amplitudes of positive fusional vergence and slower rates are more productive than faster rates.

Daum KM, Rutstein RP, et al. Horizon and vertical vergence training and its effect on vergences and fixation disparity curves: I. Horizontal data. Am J Optom Physiol Opt, 65:1-7, 1988.

Abstract: The purpose of this study was to assess the effects of horizontal and vertical vergence training on fusional vergencies and the fixation disparity (FD) curve. Thirty-four subjects were divided into three groups. One-third served as controls and the other two-thirds underwent 5 hours of supervised horizontal and vertical vergence training, respectively. Before and after the 4-week training period, vergences and FD curves were measured by a single individual who was intentionally uniformed of each subject's group. Analysis revealed that the positive vergences increased significantly for those in the horizontal group. No evidence was found to suggest changes in any variable related to the FD curve.

Daum KM. Negative vergence training in humans. Am J Optom Physiol Opt, 63:487-96, 1986.

Abstract: Two healthy subjects (male and female, ages 22 and 25 years) spent 50 hours over a period of 7 consecutive weeks training the negative vergence system. The training was performed in two 45-min daily sessions, usually immediately before and after the workday. The training was exclusively negative vergence training using a device such as variable vectograms, the aperture rule, the synoptophore, and loose or bar prisms. An extensive examination of the visual systems before after, and periodically during the training demonstrated that the negative vergences increased at distance by 5.0* and at near by 9.1* (using hand-held prisms, bar prisms and the synoptophore). The phorias of both subjects became more exophoric or less esophoric at both distance and near by 3.6*. A haploscope equipped with a coincidence optometer showed only small increases in vergence amplitude but confirmed that the lag of accommodation became more stable after the training than it was before. Other testing suggested that the negative relative accommodation, the angle of deviation at both distance and near, positive vergences, the associated phoria, and the slope of the fixation disparity curve changed significantly over the period of training. Negative vergence training can increase the negative vergence capabilities and also affect the phoria position of the eyes via feedback into the slow vergence system.

Ficarra AP, Berman J, et al. Vision training: predictive factors for success in visual therapy for patients with convergence excess. J Optom Vision Dev, 27:213-9, 1996.

Abstract: A retrospective study was conducted to analyze predictive factors for success of visual therapy (VT) in patients with convergence excess. The records of 31 patients (mean age = 15.9 years) were reviewed. Each had received at least four VT sessions and full pre and post-training evaluation. The mean number of VT sessions was 19.4. VT produced a significant reduction in symptoms of both distance blur and headaches. Additionally, significant post-therapy changes occurred in distance base-in recovery, near base-in break and recovery, near phoria, and positive relative accommodation. The relative exohoric shift in near phoria was significantly correlated with pre-therapy refractive error, near phoria, and the magnitude of the prescribed near addition. Furthermore, a non-significant reduction in the stimulus accommodative convergence-accommodation ratio was found. Significant changes in quantifiable optometric parameters were observed after VT. The post-therapy change in near phoria was best predicted by the magnitude of the pre-VT near phoria.

Gallaway M, Scheiman M. The efficacy of vision therapy for convergence excess. J Am Optom Assoc, 68:81-6, 1997.

Abstract: The records of 83 consecutive patients with convergence excess who were treated with vision therapy were reviewed to assess the impact of treatment on clinical findings and patient symptoms. Statistically and clinically significant changes in direct and indirect measures of negative fusional vergence were seen, with 84% of patients reporting a total elimination of initial symptoms. Larger increases in negative fusional vergence were found than those previously reported. This may be a result of the more extensive and better-controlled in-office treatment used in this study. Vision therapy was successful in enhancing negative fusional vergence and eliminating symptoms in the vast majority of patients with convergence excess and should be considered an effective treatment for this condition.

Grisham JD, Bowman MC, et al. Vergence orthoptics: validity and persistence of the training effect. Optom Vis Sci, 68:441-51, 1991.

Abstract: This study investigated the validity and permanence of orthoptic treatment for vergence deficiencies. The relation between Risley prism vergences, a subjective measure, and vergence-tracking rate, an objective index, was investigated. The course of orthoptics progress was compared in cases of clinical vergence dysfunction. Vergence-deficient control subjects showed no significant change in either index. However, trained subjects demonstrated rapid increases in both indices. The persistence of the training effect was monitored for up to 9 months. No regression was observed in subjects who met all release criteria, but one subject who chose to terminate therapy early showed a slow regression in tracking rate and recurrence of symptoms. These data support the validity of vergence training and increase the plausibility of previous clinical reports of orthoptics success.

Hung GK, Ciuffreda KJ, Semmlow JL. Static vergence and accommodation: population norms and orthoptic effects. Doc Opthalmologica, 2:165-79, 1986.

Abstract: This study investigated the effect of orthoptic therapy lasting 8-16 weeks on the accommodative and vergence system function of 22 visually-normal asymptomatic individuals and 21 visually-abnormal symptomatic individuals. Following therapy, asymptomatic individuals experienced reduction of symptoms and improvement in visual parameters toward the normal mean function.

Mazow ML, France TD, et al. Acute accommodative and convergence insufficiency. Tr Am Opthmalmol Soc, 87:158-68, 1989.

Abstract: The facility of accommodation and convergence allows persons to read at close range. When these mechanisms fail, reading becomes tiring, frequently producing headaches and even diplopia. This study reviewed the treatment of 26 young patients with asthenopic symptoms who had a combination of profoundly decreased accommodation and convergence in the absence of any other neurologic symptoms or signs. Twenty-two of 26 (84.6%) patients were treated with orthoptic exercises to improve convergence. Twenty-one of 26 (81%) were given plus lenses to aid in accommodation. Patients were seen for mean f 3.3 visits over an average of 11.8 months. Seventeen of 26 patients (65.3%) showed definite improvement after treatment and were completely asymptomatic. Seven of 26 patients (26.9%) reported some improvement of symptoms. Two of 26 patients (7.6%) reported no improvement of symptoms. However, both of these patients had been treated for less than 2 months. Of the 24 patients whom experienced improvement in symptoms, their headaches decreased and their school performance improved dramatically.

North RV, Henson DB. The effect of orthoptic treatment upon the vergence adaptation mechanism. Optom Vis Sci, 69:294-9, 1992.

Abstract: Visual training has an effect on the vertical vergence amplitudes. Three mature symptomatic patients exhibited a significant increase in the vertical vergence that compensates for the vertical heterophoria. Subjects with normal binocularity and have no vertical heterophoria did not exhibit increased vertical vergence amplitudes after training.

Shorter AD, Hatch SW. Vision therapy for convergence excess. N Engl J Optom, 45:51-3, 1993.

Abstract: This report presents a retrospective study of symptomatic patients with diagnosis of convergence excess (CE) that received vision therapy (VT). In a sample of 12 nonpresbyopic subjects, 8 (66%0 reported significant improvements in symptoms. Of 8 records where pre and post-treatment base in vergence ranges were available, 5 (63%) showed improvement, but this improvement was not statistically significant. We conclude that VT is an acceptable option for treatment of CE, but more research is indicated for conclusive evidence.

Vaegen. Convergence and divergence show large and sustained improvement after short isometric exercise. Am J Optom Physiol opt, 56:22-33, 199.

Abstract: There are conflicting reports on the effect of vergence training. In two studies using push up and prism vergence exercises the conflict is shown to result from differences in the constancy of effort. Improvement only occurs in exercises involving sustained effort in the direction being trained. The effect of alternating movements in both directions is small and inconsistent. Substantial long lasting gains in either convergence or divergence prism vergence scores can result from just 5 min. of sustained effort at an angle halfway between the break and recovery points. Results for adults and children on motor-driven instruments are comparable and the scores obtained discriminate better than those from hand-turned instruments. The most likely physiological model involves potentiating processes that are specifically maximized by isometric exercise. Potentiation results in a positive feedback process, the effects of which are strong enough to precipitate strabismus and which might be deliberately manipulated in therapy of poor vergence control, if responses in the required direction can be induced.

Amblyopia - Abstracts

Birnbaum MH, Koslowe K, Sanet R. Success in amblyopia therapy as a function of age: a literature survey. Am J Optom Physiol Opt, 54:269-75, 1977.

Abstract: It is frequently stated that amblyopia is not correctable after the age of 6 years. Many practitioners report marked success for older patients. To evaluate these conflicting reports, the results from 23 published amblyopia studies were analyzed. The analysis indicates that substantial numbers of patients over age 6 were successfully treated. Success rates under age 6 were not significantly better than those in older patients when the criterion for success was achievement o 20/30 acuity or better. When a criterion of 4 lines improvement was used, success rates at all ages under 16 were quite similar; in patients 16 and over, success by this criterion was significantly less frequent but even in this group success was achieved by 42% of the patients.

Cotter SA. Conventional therapy for amblyopia. In: Problems in Optometry, RP Rutstein (ed), 3(2): 312, 1991.

Abstract: Amblyopia is an important socioeconomic problem because the amblyopic patient's risk of becoming blind is markedly higher than that of the general population. Conventional treatment involves appropriate refractive correction, occlusion of the dominant eye, and active vision therapy. The specific occlusion regimen is determined based on the patient's age, binocular status, acuity level, and performance needs. Successful amblyopia treatment is dependent on several factors, of which patient compliance is the most important. There is not evidence that treatment should be withheld on the basis of age. Close follow-up is essential and maintenance therapy is often necessary.

Garzia RP. Efficacy of vision therapy in amblyopia: a literature review. Am J Optom Physiol Opt, 64:393-404, 1987.

Abstract: This paper surveyed the major optometric, opthalmologic, and orthoptic literature on the efficacy of vision therapy for amblyopia. Over the past four decades there are many examples of the successful treatment of amblyopia in the form of well documented individual case reports or large sample studies. Although occlusion of the dominant eye had been applies universally, there are some instances of the successful use of minimal occlusion combined with extensive visual-motor therapy. Overall, the results of the literature review strongly support the use of active vision therapy as an integral part of the clinical treatment of amblyopia.

Hokoda SC, Ciuffreda KJ. Different rates and amounts of vision function recovery during orthoptic therapy in an older strabismic amblyope. Ophthal Physiol Opt, 6:213-20, 1986.

Abstract: Orthoptic therapy was instituted in an 11-year-old patient having deep amblyopia, constant small-angle esotropia with anomalous retinal correspondence, and past history of minimal success with such therapy. This combination of factors pointed toward a poor prognosis for substantial recovery of vision functions. Rate of recovery of several monocular and binocular vision functions was monitored during the course of 18 months of intensive orthoptic therapy. Results showed marked improvement in several monocular vision functions, suggesting presence of considerable residual neural plasticity of multiple sites in the visual pathways of this older amblyope.

Rustein RP. Alternative treatment for amblyopia. In: Problems in Optometry, RP Rustein (ed), 3(2): 331, 1991.

Abstract: Although constant occlusion of the nonamblyopic eye is regarded as the most effective method for treating amblyopia, there are difficulties and risks associated with its use. Accordingly, other treatment modalities have been developed. This chapter reviews the more recent alternative forms of amblyopia treatment. Included are minimal occlusion, penalization, orthoptic training, partial and sector occlusion, and the experimental pharmacologic agents. The basis and efficacy of each procedure are discussed.

Rustein RP, Fuhr PS. Efficacy and stability of amblyopia therapy. Optom Vis Sci, 69:747-54, 1992.

Abstract: To determine the efficacy and stability of therapy, we reviewed the charts of 4 amblyopes with strabismic and/or anisometropia who had been treated by direct occlusion. For patients aged 7 years or less (N=39), 90% 935/39) showed some acuity gain, with 69% (27/39) achieving at least a doubling of acuity (0.3 log units). Fifty-four percent obtained 20/40 (6/12) or better after an average treatment period of 3.8 months. Some reduction in visual acuity (VA) subsequently occurred for 75% (24/32) of those patients followed. For patients aged 8 years or more (N=26), 77% (20/26) showed some acuity gain with 31% (8/26) improving at leas 0.3 log units. Twenty-seven percent (7/26) obtained 0/40 (6/12) or better after an average treatment period of 4.2 months, although no patients older than 10 years (N=13) achieved 20/40 (6/12). Loss of some of the acuity gain subsequently occurred for 67% (12/18) of those followed. These findings indicate that VA can be improved by patching therapy in most patients older than 7 years, but the acuity improvement is somewhat less than in younger patients. At least 67% of all amblyopes followed for 1 year lost some of the acuity gain after cessation of therapy, regardless of the age when treated. As a reduction of the acuity gain is likely to occur within the first year after cessation of therapy, it is recommended that amblyopic patients of all ages be followed at regular intervals.

Saulles H. Treatment of refractive amblyopia in adults. J Amer Optom Assoc, 58:959-60, 1987.

Abstract: Treatment of amblyopia had been relatively ignored in the adult population. In a retrospective study at the University of Michigan Health Service, 10 patients with refractive amblyopia showed visual acuity improvement in their amblyopic eye after completing simple vision therapies.

Selenow A, Ciuffreda KJ. Vision function recovery during orthoptic therapy in an adult exotropic amblyope. J Amer Optom Assoc, 57:132-40, 1986.

Abstract: Orthoptic therapy was instituted in a 29-year-old patient having moderate amblyopia, constant small-angle esotropia, and large and steady eccentric fixation. This combination of factors, especially the age, pointed toward a poor prognosis for attainment of markedly improved vision function. Rate of recovery of several monocular vision functions was monitored during one year of orthoptic therapy. Results showed substantial improvement in most areas, thus providing evidence of neural plasticity at multiple sites in the visual pathways of this adult amblyope.

Selenow A, Ciuffreda KJ. Vision function recovery during orthoptic therapy in an exotropic amblyope with high unilateral myopia. Am J Optom Physiol Opt, 60:659-66, 1983.

Abstract: Orthoptic therapy was instituted in a 6 1/2-year-old patient having deep amblyopia, constant exotropia, and high unilateral myopia. The combination of these factors pointed toward a poor prognosis for attainment of normal monocular and binocular vision function. Rates of recovery of several vision functions were monitored during orthoptic therapy. Results showed marked improvement in most areas, thus providing evidence of neural plasticity at multiple sites in the visual pathways.

Wick B, Wingard M, et al. Anisometropic amblyopia: is the patient ever too old to treat? Optom Vis Sci, 69:866-78, 1992.

Abstract: Amblyopia is an example of abnormal visual development that is clinically defined as a reduction of best corrected Snellen acuity to less than 6/9(20/30) in one eye or a two-line difference between the two eyes, with no visible signs of eye disease. We describe a sequential management program for anisometropic amblyopia that consists of four steps: (1) the full refractive correction, (2) added lenses or prism when needed to improve alignment of the visual axes, (3) 2 to 5 hours/day of direct occlusion, and (4) active vision therapy to develop monocular acuity and improve binocular visual function. We examined records of 19 patients over six years of age who had been treated using this sequential management philosophy. After 15.2 (+/-7.7) weeks of treatment the Amblyopia Success Index (ASI) documented an average improvement in visual acuity of 92.1% +/- 8.1 with a range from a low of 75% by a 49-year-old patient to a maximum of 100% achieved by 42.1% of the patients (8-19). Patients who had completed therapy 1 or more years ago (N=4) maintained their acuity improvement. From these results we conclude that following a sequential management plan for treatment of anisometropic amblyopia can yield substantial long-lasting improvement in visual acuity and binocular function for patients of any age.

Strabismus - Abstracts

Caloroso EE. A sequential strategy for achieving functional binocularity in strabismus. J Amer Optom Assoc, 59:378, 1988.

Abstract: The clinical approach to achieving functional binocularity for constant strabismus includes a series of sequential steps utilizing several therapy options. Passive therapy included lenses, prisms, filters, occlusion, medications, and strabismus surgery. Active therapy adds visual exercises and/or self-monitoring systems such as biofeedback. Consideration of commonly used options and an overall sequential strategy is presented as a practical guide to the successful management of strabismic patients.

Coffey B, Wick B, et al. Treatment options in intermittent exotropia: a critical appraisal. Optom Vis Sci, 69:386-1404, 1992.

Abstract: This paper reviews the clinical literature related to five different treatment modalities used for IXT: overminus lens therapy, prism therapy, occlusion therapy, extra-ocular muscle surgery, and orthoptic vision therapy. Based upon review of 59 studies of treatment of IXT, and using each author's stated criteria for success, the following pooled success rates were revealed: overminus lens therapy (N=215), 28%; prism therapy (N=201), 28%; occlusion therapy (N=170), 37%; extra-ocular muscle surgery (N=2530), 46%; and orthoptic vision therapy (N=740), 59%. Success rates for IXT surgery differed depending upon whether a functional (43%) or cosmetic (61%) criterion was used to evaluate treatment success. These pooled success rates must be viewed carefully because nearly all the studies suffer from serious scientific flaws such as small sample sizes, selection bias, inadequately defined treatment and success criteria, absence of statistical analysis, and results reported in a manner that makes interpretation difficult.

Cooper J, Medow N. Intermittent exotropia basic and divergence excess type. Binocular Vis & Eye Muscle Surg, 8:185-216, 1993.

Abstract: Intermittent exotropia is a unique strabismus with a specific set of sensory motor findings. This paper provides a comprehensive review of nomenclature, epidemiology, sensory motor findings, theories of etiology, and treatment of intermittent exotropia, of both basic and divergence excess types.

Cooper J. Orthoptic treatment of vertical deviations. J Amer Optom Assoc, 59:463-8, 1988.

Abstract: Four patients with large vertical deviations were treated with a combination of prismatic glasses and orthoptics. The lease amount of prism which eliminated diplopia, followed by horizontal fusional range extension, was prescribed. After vergences were normalized, the prism was further reduced by two prism diopters and horizontal fusional range extension was repeated. This process was repeated until either a plateau was achieved or the prism was eliminated. All four patients completed therapy with almost total alleviation of symptoms and elimination of full-time prismatic correction.

Duckman RH. Management of binocular anomalies: efficacy of vision therapy, exotropia. Am J Optom Physiol Opt, 64:421-9, 1987.

Abstract: This paper presents a survey of the literature on management of the various forms of exotropia. Criteria for success of treatment are examined. A table summarizing the results of 11 studies is given. The data support the premise that vision therapy is successful in the treatment of exotropia. Over 61% of patients achieved a status of good or better.

Flax, N. A comparison of functional results in intermittent divergent strabismus treated surgically and optometrically. J Opt Vis Devel, 17:18-9, 1986.

Abstract: The literature was reviewed to determine functional outcomes when intermittent exotropia is treated surgically. Twenty-two credible papers were located and these were analyzed in terms of binocular function. The results achieved surgically are compared and contrasted with published results when strabismus

Flax N, Duckman RH. Orthoptic treatment of strabismus. J Amer Optom Assoc, 49:1353-61, 1978.

Abstract: This paper examined the effectiveness of orthoptics as a viable treatment modality for strabismus. A review of pertinent literature and an analysis of the data was presented. The results of several studies show a combined functional cure rate of 72.4%.

Gallaway M, Vaxmonsky T, Scheiman M. Management of intermittent exotropia using a combination of vision therapy and surgery. J Amer Optom Assoc, 60:428, 1989.

Abstract: Vision therapy has been shown to provide higher success rates than surgery in the treatment of intermittent exotropia, but vision therapy is not successful in all cases. A case of intermittent exotropia is presented that illustrates the use of vision therapy in combination with surgery. Issues that should be considered when selecting this treatment option are discussed.

Goldrich SG. Optometric therapy of divergence excess strabismus. Am J Optom Physiol Opt, 57:7-14, 1980.

Abstract: A review and analysis of the vision training procedures were carried out over a period of 2 years at State University of New York (SUNY), University Optometric Center. Training included motility, accommodative rock, fusion, anti-suppression, and stereoscopic skills by a variety of techniques and devices. Patients who exhibited smaller pre-training angles of deviation, increased maturity, and greater motivation responded most successfully to treatment. The results achieved in this study compare favorably with those obtained by traditional orthoptic procedures.

Kran BS, Duckman R. Divergence excess exotropia. J Amer Optom Assoc, 58:921-30, 1987.

Abstract: This paper presents a summary of information regarding divergence excess exotropia. The first portion of the paper deals with the description (i.e., definition, onset, natural history, prevalence, sexual distribution, symptomatology, and the differential diagnosis of the two (subtypes) of this entity. The second portion of the paper reviews the various treatment options (surgery, lens therapy, prism therapy, and vision training) currently available with emphasis on vision training/orthoptics. It was concluded that divergence excess exotropia is effectively managed at least as well as by vision training/orthoptics as it is by surgery.

Wick B. Accommodative esotropia: efficacy of therapy. J Amer Optom Assoc, 58:562-6, 1987.

Abstract: Retrospective examination was performed on the records of 54 patients who had undergone treatment of accommodative esotropia. The patients were classified based on the Duane classification as having either convergence excess (n=11) or equal esodeviations (n=43). Over 90% of the patients achieved total restoration of normal binocular function with treatment. The results and implications of this study are discussed.

Wick B, Cook. Management of anomalous correspondence: efficacy of therapy. Am J Optom Physiol Opt, 64:405-10, 1987.

Abstract: Recently reported success rates for treatment of anomalous correspondence were reviewed and an estimate of the prognosis for successful binocular re-education of patients with esotropia and anomalous correspondence was presented. Based on current therapy techniques reported in the literature, with careful aggressive therapy, 50% of esotropic patients with anomalous correspondence should be expected to achieve binocular vision provided sufficient time (up to 12 months) can be devoted to binocular re-education.

Vision and Learning - Abstracts

Atzmon D, Nemet P, et al. A randomized prospective masked and matched comparative study of orthoptic treatment versus conventional reading tutoring treatment for reading disabilities in 62 children. Binocular Vis & Eye Muscle Surgery Qtrly, 8(2): 91-106, 1993.

Abstract: Controversies remain whether orthoptics and/or "visual training" can remedy reading disabilities. Therefore, and to extend our prior studies, we under took a comparative and controlled study. One hundred and twenty children with reading disability were tested extensively, matched and randomly divided into three groups: orthoptic conventional (reading tutoring) and no-treatment control. Unfortunately, participants in the control group were unable to adhere to no-treatment and were deleted. Each of the 40 children in the first two groups had 40 sessions, 20 minutes daily.

Orthoptic treatment was directed to markedly increasing fusional convergence amplitudes for both neat and distance to 60*. The two treatments were also carefully matched in time and effort. Sixty-two children in 31 matched pairs completed the course of treatment and testing. The results were equal and statistically significant (P< .05) marked improvement in reading performance in both treatment groups on essentially all tests.

Orthoptic treatment, to increase convergence amplitudes to 60*, is as effective as conventional in-school reading tutoring treatment of reading disabilities. An advantage of orthoptic treatment was that subjective reading and asthenopic symptoms virtually disappeared after orthoptics. We recommend orthoptic treatment as: 1) an effective alternate primary treatment; 2) adjunctive treatment for those who do not respond well to standard treatment; and 3) as primary treatment in any case with asthenopic symptoms of /or convergence inadequacy.

Borsting E. Measures of visual attention in children with and without visual efficiency problems. J Behavioral Optom, 2:151-6, 1991.

Abstract: Research has shown a relationship between improvements in accommodative functioning and certain visual perceptual skills. One explanation for these results is that accommodative dysfunction interferes with the development of visual attention. This study compared three components of attentional ability: coming to attention, decision making, and sustaining attention in children with and without non-strabismic dysfunctions of accommodation and/or vergence. Twenty children, ages 8-11 years (10 boys and 10 girls) of normal intelligence participated in the study. The group with inefficient visual skills performed significantly poorer compared to the visually normal functioning group on coming to attention and sustaining attention but not on decision making. This implies that a relationship exists between dysfunctions in accommodation and/or vergence and dysfunctions of certain attentional skills.

Buzzelli AR. Stereopsis, accommodative and vergence facility: do they relate to dyslexia? Optom Vis Sci, 68:842-6, 1991.

Abstract: The relation between visual functions and reading performance has been the subjet of conflicting opinion over the years. The purpose of this study is 2-fold: first, to examine factors other than visual acuity, i.e., stereopsis, accommodative facility and vergence facility, which might show a greater impact on reading achievement; and second, to utilize well defined dyslexic and normal controls to ensure that the reading deficits were not caused by overt neurological, psychological, educational, or environmental factors. Thirteen normal readers and 13 dyslexics were carefully matched by rigorous quantitative criteria. The performance of both groups on tests of visual acuity and stereopsis was similar. The dyslexic readers tended to show better accommodative facility. Dyslexics performed significantly worse than the matched normal readers on a test of vergence facility. These results, in agreement with those reported by other studies, indicate that less efficient dynamic vergence facility may contribute to reading impairment, unlike other static functions such as visual acuity and stereopsis. It may be that the vergence problems of the dyslexics are related to sequential oculo-motor abnormalities. The dyslexics' vergence problems may also be partly responsible for their large number of small eye movements.

Christenson GN, Griffin JR, Wesson MD. Optometry's role in reading disabilities: resolving the controversy. J Amer Optom Assoc, 61:33-72, 1990.

Abstract: Optometry's involvement in the management of reading disabilities is often misunderstood. This paper clarifies the confusion surrounding specific reading disabilities and optometric vision therapy in the management of them. Topics include a historical review of dyslexia, theories of brain function, and a neuroanatomical model, as well as operational definitions and behavioral characteristics of the types of dyslexia. Methods for direct diagnosis of coding deficits in specific reading disability (dyslexia) are discussed. This approach explains the beneficial role of optometric vision therapy in the management of patients with reading problems.

Eden GF, Stein JF, Wood MH, et al. Verbal and visual problems in reading disability. J Learning Disabilities, 28:272-90, 1995.

Abstract: This study investigated whether visuospatial and oculomotor tests can be used to differentiate children with reading disabilities from non-disabled children. Using 93 children from the Bowman Gray Learning Disability Project (mean age=11.3 years; 54 boys, 39 girls), the phonological and visuospatial abilities of non-disabled children (children whose reading at fifth grade rated a Woodcock-Johnson reading standardized score between 85 and 15) and children with reading disability (whose reading standardized score was below 85 on the Woodcock-Johnson) were compared. In addition to performing poorly on verbal tests, the children with reading disability were significantly worse than non-disabled children at many visual and eye-movement tasks. A high proportion of the variance (68%) in reading ability of both the non-disabled children and those with reading disability could be predicted by combining visual and phonological scores in a multiple regression. These results provide further support for the hypothesis that reading disability may, to some extent, result from dysfunction of the visual and oculomotor systems.

Garzia RP, Nicholson SB. Visual function and reading disability: an optometric viewpoint. J Amer Optom Assoc, 6:88-97, 1990.

Abstract: Recent research has identified a low-level transient visual system deficit in patients with reading disability. This deficit has been shown to have consequences on higher level perceptual and cognitive functions, including reading. This new information provides optometrists with a theoretical framework to expand the understanding of the relationship between vision and reading. In this paper, traditional concepts are described and an extensive literature review is provided. The impact of these processing deficits on reading performance is discussed based on metacontrast masking and foveal-parafoveal sequential attention models of reading. Clinical implications of transient system function in other clinical entities are also provided.

Griffen JR, et al. Dyslexia and visual perception: is there a relation? Optom Vis Sci, 70:374-9, 1993.

Abstract: Opinions differ concerning the relation between dyslexia and visual perception. In this pilot study we addressed this question by analyzing the results of visual perceptual testing on 19 elementary grade subjects diagnosed as having dyseidesia, one type of dyslexia that manifests as problems with sight-word recognition. The subjects, who have different degrees of severity of dyseidesia, were compared with 11 subjects tested as nondyslexic, but with reading problems. The Dyslexia Determination Test (DDT) and the Test of Visual Perceptual Skills (TVPS) were given to all subjects. Both multivariate analysis of variance (MANOVA) and univariate one-way analysis of variance (ANOVA) to test for differences in performance among four test groups (ranging from nondyslexic to increasing levels of severity of dyseidesia) showed no trends of either statistical or clinical importance. An individual with reading problems may by nondyslexic but have poor visual perceptual skills. These results are consistent with the contention that reading problems caused by dyseidesia (as defined by the DDT) and those caused by visual perceptual deficiencies (as defined by the TVPS) are different. Although dyseidetic dyslexia results in characteristic coding patterns producing specific reading problems, it is probable that visual perceptual deficiencies contribute to learning problems that include general reading problems. Each condition would, therefore, require different forms of therapy. Limitations of this study and recommendations for future research are discussed.

Grisham JD, Sheppard MM, Tran WU. Visual symptoms and reading performance. Optom Vis Sci, 70:384-91, 1993.

Abstract: Clinical observation indicates that visual asthenopic symptoms are frequently associated with reading for long periods of time. We investigated the relation between visual symptoms and standard measures of reading performance in 78 university students. The number of asthenopic complaints increased during the reading phase of the experiment and decreased during the relaxation phase. Overall, a weak but significant negative correlation was found between number of symptoms and reading rate on the Nelson-Denny reading test. The most symptomatic subjects scored lower on vocabulary and comprehension than the least asthenopic subjects. A limited retrospective analysis revealed no reading performance differences between subjects having normal binocular vision and those showing a minimum visual symptoms. This study suggests that visual symptoms are a factor in reducing reading performance, particularly in very symptomatic individuals.

Grisham JD, Simons HD. Refractive error and the reading process: a literature analysis. J Amer Optom Assoc, 57:44-55, 1986.

Abstract: The literature analysis of refractive error and reading performance includes only those studies which adhere to the rudiments of scientific investigation. The relative strengths and weaknesses of each study are described and conclusions are drawn where possible. Hyperopia and anisometropia appear to be related to poor reading progress and their correction seems to result in improved performance. Reduced distance visual acuity and myopia are not generally associated with reading difficulties. There is little evidence relating astigmatism and reading, but studies have not been adequately designed to draw conclusions. Implications for school vision screening are discussed.

Kulp MT, Schimdt PP. Visual predictors of reading performance in kindergarten and first grade children. Optom Vis Sci, 73:255-62, 1996.

Abstract: A masked investigation of the relation between performance on various vision tests and reading was conducted with 90 kindergartners (mean age of 5.73 years) and 91 first graders (mean age of 6.76 years) from a middle class, suburban, elementary school near Cleveland, Ohio. Vision testing included the Modified Clinical Technique (MCT), +2.00 D flipper lenses with red/green suppression check for accommodative facility and Randot for stereoacuity. Reading performance was independently evaluated with the Metropolitan Achievement Test 6 reading Test and teachers' assessments.

The results revealed that accommodative facility was predictive of successful reading performance in 7-year-olds (p=0.0431), first graders (p=0.0125), and in the entire subject group when age (p=0.0254) or grade (p=0.0224) was controlled. Failure on the MCT was significantly associated with decreased reading skill in 5-year-olds (p=0.0431). In addition, stereoacuity worse than 50 sec arc (p=0.0316), and accommodative facility (p=0.0155) were predictive of whether children of average intelligence would show successful or unsuccessful reading ability.

Visual performance was significantly related to reading performance even in children of average intelligence when IQ was partially controlled. Also, the predictive value of the MCT for reading achievement could be improved by the addition of a referral criterion for stereoacuity. This would make the results of MCT screening more readily applicable to educators.

Lehmkuhle S, Garzia RP, Turner L, et al. A defective visual pathway in children with reading disability. New Eng J Medicine, 328-989-96, 1993.

Abstract: The possibility that reading disability in children is associated with visual problems is in dispute. We sought to test the existence of this association by using electrophysiologic techniques to measure the processing of visual information in the magnicellular and parvicellular visual pathways of the brain.

Visual evoked potential were measured with scalp electrodes in children 8 to 11 years old who were normal readers and in those with reading disability. With a steady background, the latencies of the early components of the visual evoked potentials were longer in the reading-disabled children than in the normal readers when a low-spatial-frequency target was used. In normal readers, the flickering background increased the latency and reduced the amplitude of the early components, whereas in the reading-disabled children only the amplitude was affected. No differences were observed in either group with the high-spatial-frequency target.

The pattern of results suggests that the response of the magnicellular visual pathway is slowed in reading-disabled children, who do not, however, have a general slowing of the visual response. The possibility that there is a cause-and-effect relation between these findings and reading disability will require further study.

Lovegrove WJ, Garzia RP, Nicholson SB. Experimental evidence of a transient system deficit in specific reading disability. J Am Optom Assoc, 61:137-46, 1990.

Abstract: This paper summarizes the experimental evidence for a transient system deficit in specific reading disability. Differences have been found between controlled readers and specifically disabled readers in measurements of visible persistence, pattern contrast sensitivity and temporal or flicker contrast sensitivity. This transient system deficit was found in approximately 75% of the specifically reading disabled subjects tested. A further series of experiments failed to demonstrate differences in sustained system function between the two groups. Evidence is also presented which suggests that the visual system deficit precedes the reading disability. Possible mechanisms of the impact of a transient system deficit on reading are discussed.

O'Grady J. The relationship between vision and educational performance: a study of year 2 children in Tasmania. Aust J Optom, 67:126-40, 1984.

Abstract: This paper reports on a joint research study carried out by Tasmanian optometrists and the Education Department of Tasmania. The main purpose of the study was to determine if a relationship existed between vision factors and educational performance. A random sample of Year 2 children from Tasmanian government schools was given a comprehensive series of vision tests by optometrists throughout the State. School guidance officers also gave the children a series of broadly based educational tests. The two testing programs were totally independent of each other. Comparison of the results of the two forms of testing indicated a statistically significant relationship between vision defects and educational performance.

Rosner J, Rosner J. Comparison of visual characteristics in children with and without learning difficulties. Am J Optom Physiol Opt, 64:531-3, 1987.

Abstract: This report compares the refractive status, visual acuity, binocular status, vergence/accommodation facility, perceptual skills, and ocular health of 261 children, all between the ages of 6 and 12 years. Data reveal that among conditions diagnosed routinely by optometrists, hyperopia and perceptual skills dysfunction were more prevalent in LD children and myopia in non-LD children. No other significant between-group differences were found.

Rounds BB, Manley CW, and Norris RH. The effect of oculomotor training on reading efficiency. J Amer Optom Assoc, 62:92-7, 1991.

Abstract: The purpose of this study was to record and measure, by means of a microcomputer, the reading eye movements and reading efficiency of a sample of "poor readers" from an adult, professional school population. A program of oculomotor sill enhancement training was given to 10 students who failed an academically appropriate reading test. Their pre- and post- training reading performance was compared to that of a group of students who also failed the reading test but received no such training. All subjects' eye movements were monitored and recorded individually while reading, using a Visagraph Eye-Movement Recording System. The subjects were split into an experimental group (receiving training) and a control group (receiving no training). Following a 12-hour program of in-office" and "home" training, the group receiving oculomotor training showed trends toward improved reading eye movement efficiency (number of regressions, number of fixations and span of recognition), compared to that of the untrained group.

Seiderman AS. Optometric vision therapy - results of a demonstration project with a learning disabled population. J Amer Optom Assoc, 51:489-93, 1980.

Abstract: Thirty-six children attending a private school for learning disabled children were diagnosed as having visual and/or perceptual disorders. The experimental group received individual programming in visual and perceptual development at their appropriate developmental levels. The control group received instruction in physical education, art or music classes. Both groups received individualized reading assistance. Statistical analysis of the two year demonstration project, which included nine months of actual training, indicated that the experimental group made significant gains in reading as compared to the control group. The improvement in basic instructional level of The Informal Reading Inventory (Temple University), and the Word Reading and Paragraph Meaning sub-tests of the Stanford Achievement Tests, and the actual classroom reading levels were all statistically significant. The Informal Word Recognition Inventory (Daniels) and the Spelling sub-test of the Stanford Achievement Tests showed a definite trend approaching statistical significance.

Simons HD. An analysis of the role of vision anomalies in reading interference. Optom Vis Sci, 70:369-73, 1993.

Abstract: Several reviews of the literature have shown a relation between vision anomalies and reading problems. The studies have been correlational - comparative in nature and thus have not established causal relations. This paper suggests that before experimental studies are conducted to establish causation, studies of the process by which vision anomalies produce reading interference need to be conducted. The paper discusses the factors to consider in studying vision and reading interference. The factors are: nature of the vision anomaly, type and severity of symptoms produced, type of reading interference (perceptual or functional deficiency), amount and type of near task demands, reading skill, and reading development stage.

Simons HD, Gassler Pa. Vision anomalies and reading skill: a meta-analysis of the literature. Am J Optom Physiol Opt, 65:893-904, 1988.

Abstract: We report a meta-analysis of studies of the relation of vision anomalies to reading skill. Meta-analysis is a quantitative technique for combining the results of multiple studies that reduces the subjectivity of literature reviews. The results of the analysis of 34 studies of vision anomalies and reading skill that met the criteria for inclusion in the meta-analysis showed that hyperopia, exophoria at near, vertical phoria, anisometropia, and aniseikonia are associated with below average performance. Myopia and esophoria and esophoria at far are associated with average and above average reading performance. Reduced visual acuity, astigmatism esophoria at near, fusional convergence and divergence, strabismus, near point of convergence, and stereopsis were not found to be associated with reading performance.

Simons HD, Grisham JD. Binocular anomalies and reading problems. J Amer Optom Assoc, 58:578-87, 1987.

Abstract: This paper reviews and evaluates the research literature on the relationship of binocular anomalies to reading problems. The weight of the evidence supports a positive relationship between certain binocular anomalies and reading problems. The evidence is positive for exophoria at near, fusional vergence reserves, aniseikonia, anisometropia, convergence insufficiency, and fixation disparity. There is some weak positive evidence for esophoria at near and mixed evidence for stereopsis. The evidence on lateral phorias at distance is negative.

Solan HA. Transient & sustained processing: a dual subsystem theory of reading disability. J Behavioral Optom, 5:149-54, 1994.

Abstract: This article reviews the concept of interactive processing that involves two parallel, segregated visual pathways, the transient and sustained processing systems. Evidence that deficits in the transient, but not the sustained system, interfere with the reading process is examined. After tracing these pathways from the retina to the visual cortex, and beyond, special attention is given to the mechanism of the dual processing system in reading, the synchronization of these two systems, and the effects of poor timing on visual processing and reading. Two successful treatment procedures for reading-disabled are described. The importance of integrating these concepts into optometric therapeutic procedures is discussed.

Solan HA Ciner EB. Visual perception and learning: issues and answers. J Amer Optom Assoc, 60:457-60, 1989.

Abstract: The role of the optometrist in treating children who are identified as learning disabled is not always understood by members of an interdisciplinary team. Correlational studies are cited to establish a basic relationship between perceptual dysfunctions and learning readiness in normal children. After establishing that perceptual training does indeed improve perceptual skills, a number of investigations where intervention enabled children who had been classified as learning disabled to respond more effectively to school learning are cited. The role of the optometrist as a member of an interdisciplinary team is addressed.

Spafford C, Grosser GS. Retinal differences in light sensitivity between dyslexic and proficient reading children: new prospects for optometric input in diagnosing dyslexia. J Amer Optom Assoc, 62:610-5, 1991.

Abstract: The role of visual processes in dyslexia has been overlooked in the recent past as linguistic explanations for this problem dominated educational thought. It is the intent of this paper to relate new information about visual functions with dyslexia. Static perimetry was used to assess brightness thresholds of dyslexic and proficient-reading children. The dyslexic subjects obtained significantly lower sensitivity scores (higher thresholds) than proficient readers for the upper hemifields. Visual field screening tests may be useful in the differential diagnosis of dyslexia.

Streff JW, Poynter HL, et al. Changes in achievement scores as a result of a joint optometry and education intervention program. J Amer Optom Assoc, 61:475-81, 1990.

Abstract: This study tested the effect of a visually directed intervention program on changes in standardized test results of intelligence quotient and achievement during kindergarten. Two groups of 19 kindergarten children from equivalent schools were matched for intelligence quotient, age, and sex. Fall and spring measurements were made in the following areas: intelligence quotient, academic achievement tests, and paper and pencil perceptual tests. A visually based intervention program involving both optometry and education was provided for the experimental group. Kindergarten children n the experimental group who received the visually directed optometry and education intervention program showed significant differences in the rate of change in four of the eight tested areas when matched to the control group.

Young Bs, Collier-Gary K, Schwing S. Visual factors: a primary cause of failure in beginning reading. J Optom Vis Dev, 25:276-88, 1994.

Abstract: In a longitudinal study of 144 beginning readers in public school, data on 25 measures of visual efficiency were subjected to two- and three-way Analyses of Variance. Binocular function, visual acuity, discrepancies in acuity, and color deficiencies were all found to be statistically significant in impending beginning reading. Significant differences were also found in the sequencing of visual development between sexes, between eye dominance for different tasks, between specific factors for 6-, 7-, and 8-year-olds and first and second grades. It was concluded that visual factors are a primary cause of beginning reading failure and that most current school screenings are inadequate in scope and rigor.

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