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Amblyopia / Lazy Eye Research

Barrett BT, Bradley A, McGraw PV.
Understanding the neural basis of amblyopia.”
Neuroscientist. 2004 Apr;10(2):106-17.
Amblyopia is the condition in which reduced visual function exists despite full optical correction and an absence of observable ocular pathology. Investigation of the underlying neurology of this condition began in earnest around 40 years ago with the pioneering studies conducted by Hubel and Wiesel. Their early work on the impact of monocular deprivation and strabismus initiated what is now a rapidly developing field of cortical plasticity research. Although the monocular deprivation paradigm originated by Hubel and Wiesel remains a key experimental manipulation in studies of cortical plasticity, somewhat ironically, the neurology underlying the human conditions of strabismus and amblyopia that motivated this early work remains elusive. In this review, the authors combine contemporary research on plasticity and development with data from human and animal investigations of amblyopic populations to assess what is known and to reexamine some of the key assumptions about human amblyopia.

Barrett BT, Pacey IE, Bradley A, Thibos LN, Morrill P.,
Nonveridical visual perception in human amblyopia.”
Invest Ophthalmol Vis Sci 2003 Apr;44(4):1555-67
Purpose: Amblyopia is a developmental disorder of spatial vision. There is evidence to suggest that some amblyopes misperceive spatial structure when viewing with the affected eye. However, there are few examples of these perceptual errors in the literature. This study was an investigation of the prevalence and nature of misperceptions in human amblyopia.
Methods: Thirty amblyopes with strabismus and/or anisometropia participated in the study. Subjects viewed sinusoidal gratings of various spatial frequencies, orientations, and contrasts. After interocular comparison, subjects sketched the subjective appearance of those stimuli that had nonveridical appearances.
Results: Nonveridical visual perception was revealed in 20 amblyopes ( approximately 67%). In some subjects, misperceptions were present despite the absence of a deficit in contrast sensitivity. The presence of distortions was not simply linked to the depth of amblyopia, and anisometropes were affected as well as those with strabismus. In most cases, these spatial distortions arose at spatial frequencies far below the contrast detection acuity cutoff. Errors in perception became more severe at higher spatial frequencies, with low spatial frequencies being mostly perceived veridically. The prevalence and severity of misperceptions were frequently found to depend on the orientation of the grating used in the test, with horizontal orientations typically less affected than other orientations. Contrast had a much smaller e ffect on misperceptions, although there were cases in which severity was greater at higher contrasts.
Conclusions: Many types of misperceptions documented in the present study have appeared in previous investigations. This suggests that the wide range of distortions previously reported reflect genuine intersubject differences. It is proposed that nonveridical perception in human amblyopia has its origins in errors in the neural coding of orientation in primary visual cortex.

Birnbaum MH, Koslowe K, Sanet R.
Success in amblyopia therapy as a function of age: A literature survey.”
Am J Optom & Physiol Optics, 54(5): 269-275, 1977.
It is frequently stated that amblyopia is not corr ectable after the age of 6 years. However, many practitioners report marked success for older patients. To evaluate these conflicting reports, this study analyzed the results from 23 published amblyopia studies. The analysis indicates that substantial numbers of patients over age six were successfully treated. Success rates under age 6 were not significantly better than those in older patients when the criterion for success was achievement of 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.” Problems in Optometry, RP Rustein (ed), 3(2): 312, 1991. Conventional treatment of amblyopia 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 no evidence that treatment should be with held on the basis of age. Close follow-up is essential and maintenance therapy is oft en necessary.

Dobson V, Miller JM, Harvey EM, Mohan KM
Amblyopia in astigmatic preschool children.”
Vision Research, Volume 43, Issue 9, April 2003, 1081-1090
Best-corrected acuity was measured for vertical and horizontal gratings and for recognition acuity optotypes (Lea Symbols) in a group of three- to ve-year-old children with a high prevalence of astigmatism. Results showed meridional amblyopia (MA) among children with simple/compound myopic or mixed astigmatism, due to reduced acuity for horizontal gratings. Children with simple/compound hyperopic astigmatism showed no MA, but did show reduced acuity for both grating orientations. Reduced best-corrected recognition acuity was shown by both myopic/mixed and hyperopic astigmats. These results suggest that optical correction of astigmatism should be provided prior to age three to ve years, to prevent development of amblyopia.


Garzia RP.
Efficacy of vision therapy in amblyopia: A literature review.”
Am J Optom & Physiol, 64(6): 393-404, 1987
In this paper the major optometric, ophthalmologic, and orthoptic literature on the efficacy of vision therapy for amblyopia was surveyed. 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 has been applied 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 for active vision therapy as an integral part of the clinical treatment of amblyopia.

Goodwin RT, Romano PE
“Stereoacuity degradation by experimental and real monocular and binocular amblyopia.”
Invest. Ophthalmol. Vis. Sci. 1985 26: 917-923.
Fourteen normal adult volunteers with normal binocular single vision and normal stereoacuity submitted to monocular and binocular degradation of their stereoacuity by cycloplegia and fogging with spherical lenses. Stereoacuity (SA) was reduced as soon as visual acuity (VA), both monocular and binocular, was reduced. There was a marked similarity in the degree of SA reduction produced by monocular and binocular amblyopia. The degree of SA reduction was slightly more marked with monocular decrements than with binocular at VAs between 20/25 and 20/50. Significant intersubject variation was noted. The majority of subjects maintained gross SA at 20/200 monocular or binocular. One subject was reduced to gross stereopsis at 20/30 monocular and 20/50 binocular VAs. Two subjects were able to retain 40 sec of SA until vision was degraded to 20/50. Conversely, 40 sec of SA was not achieved by any subject at monocular or binocular vision less than 20/40 (test for malingering). Thirteen patients with real monocular and binocular organic or functional amblyopia were then compared with the experimental group. On the whole, patients scored somewhat better than normals but their scores fell within the range of responses found in the normal group.

Hess RF, Mansouri B, Thompson B. A binocular approach to treating amblyopia: antisuppression therapy. Optom Vis Sci. 2010 Sep;87(9):697-704.

Purpose: We developed a binocular treatment for amblyopia based on antisuppression therapy.

Methods: A novel procedure is outlined for measuring the extent to which the fixing eye suppresses the fellow amblyopic eye. We hypothesize that suppression renders a structurally binocular system, functionally monocular.

Results: We demonstrate using three strabismic amblyopes that information can be combined normally between their eyes under viewing conditions where suppression is reduced. Also, we show that prolonged periods of viewing (under the artificial conditions of stimuli of different contrast in each eye) during which information from the two eyes is combined leads to a strengthening of binocular vision in such cases and eventual combination of binocular information under natural viewing conditions (stimuli of the same contrast in each eye). Concomitant improvement in monocular acuity of the amblyopic eye occurs with this reduction in suppression and strengthening of binocular fusion. Furthermore, in each of the three cases, stereoscopic function is established.

Conclusions: This provides the basis for a new treatment of amblyopia, one that is purely binocular and aimed at reducing suppression as a first step.

Hokoda SC, Ciuffreda KJ.
“Different rates and amounts of vision function recovery during orthoptic therapy in an older strabismic amblyope.”
Ophthal & Physiol Opt, 6(2): 213-220, 1986.
Orthoptic therapy was instituted in an 11-year-old patient having deep amblyopia, a constant small-angle esotropia with anomalous retinal correspondence, and a 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 patient with amblyopia.

Koskela PU, Mikkola T, Laatikainen L.
“Permanent results of pleoptic treatment.”
ACTA Ophthalmologica, 69: 39-44, 1991.
The value of pleoptic treatment was assessed by long-term follow-up of patients treated 15-22 years ago, employing a questionnaire sent of 232 patients and a clinical examination of a sample of 44 of these. Answers were received from 157 persons with different occupations and educational levels. The poorest results were found in the combined strabismic and anisometropic amblyopia group. The final VA correlated positively with the initial VA and negatively with age at the time of treatment. Binocular single vision improved the prognosis. Altogether ¼ of the patients achieved a VA of 1.0 or better, about one half experienced no permanent increase in VA and the remainder were distributed evenly between these two extremes.

Krumholtz I, FitzGerald D.
“Efficacy of treatment modalities in refractive amblyopia.”
J am Optom Assoc, 70(6):399-404, 1999.
A retrospective review was performed of 78 patients diagnosed with refractive amblyopia. Each patient’s progress was tracked for a period of 6 months. Treatment alternatives were optical correction alone, optical correction in conjunction with patching, and optical correction and patching with vision therapy. The groups that patched with correction and those that received vision therapy had similar visual activity improvements; however, the latter group had a significantly greater improvement in stereopsis. Though patching alone may be sufficient for improvement of visual activity, binocular performance is significantly better when vision therapy is included in the treatment regimen.

Mintz-Hittner HA, Fernandez KM.
“Successful amblyopia therapy initiated after age 7 years.”
Arch Ophthalmol 118(11):1535-41, 2000.
This article reports successful therapy for anisometropic and strabismic amblyopia initiated after age 7 years. A consecutive series of 36 compliant children older than 7 years (range, 7.0 to 10.3 years; mean, 8.2 years) at initiation of amblyopia therapy for anisometropic (19 patients; mean age, 8.3 years), strabismic (9 patients; mean age, 8.0 years), or anisometropic and strabismic (8 patients; mean age, 8.0 years) amblyopia was studied. Initial (worst) visual acuities were between 20/50 and 20/400 (log geometric mean, -0.83 [antilog, 20/134] for all patients; -0.88 [antilog, 20/151] for anisometropic patients; -0.70 [antilog, 20/100] for strabismic patients; and -0.88 [antilog, 20/151] for anisometropic and strabismic patients). Initial (worst) binocularity was absent or reduced in all cases. Therapy consisted of (1) full-time standard occlusion (21 patients; mean age, 8.0 years), (2) total penalization (7 patients; mean age, 7.8 years), or (3) full-time occlusive contact lenses (8 patients; mean age, 8.8 years). Final (best) visual acuities were between 20/20 and 20/30 for all 36 patients. Final (best) binocularity was maintained or improved for 22 (61 percent) of 36 patients, including 16 anisometropic patients (84 percent), 2 strabismic patients (22 percent), and 4 anisometropic and strabismic patients (50 percent). Given compliance, therapy for anisometropic and strabismic amblyopia can be successful even if initiated after age 7 years.


Mitchell DE, Howell ER and Keith CG.
“The effect of minimal occlusion therapy on binocular visual functions in amblyopia.”
Invest. Ophthalmol. Vis. Sci. 1983 24: 778-781.
The binocular visual functions of amblyopic children were studied during treatment involving brief weekly periods of occlusion of the unaffected eye while the child performed demanding visuomotor tasks against either a background of rotating gratings or a stationary uniform gray stimulus. The gains in stereoacuity were quite significant and in most cases more obvious than the rather small gains in letter visual acuity. On initial presentation only 21 of the 60 patients showed evidence of stereopsis and of these only seven possessed a stereoacuity of 100 secs or better. Following six treatment sessions the number of patients that demonstrated stereopsis increased to 36 of whom 17 possessed reasonably good stereoacuity (100 secs or better). However, there was no difference in the degree of improvement exhibited by those patients that viewed rotating grating patterns during treatment and others from the control group that viewed the uniform gray stimulus. Thus, there was no evidence that any of the visual gains were enhanced or promoted by active visual stimulation of the amblyopic eye with rotating gratings during the brief periods of occlusion of the unaffected eye. Finally, a comparison of the scores of the children on various stereo-tests suggest that tests comprised of small figure elements that are present in high density may be best for screening purposes. On the other hand, for quantifying the stereoacuity of children known to possess abnormal binocular vision it may be more appropriate to employ tests that use large figure elements that provide strong fusion cues.

Mohan K, Saroha V, Sharma, A.
“Successful Occlusion Therapy for Amblyopia in 11 to 15 Year Old Children.”
Journal of Pediatric Ophthalmology and Strabismus 41:#2 p. 89-95 March/April 2004
Purpose: To investigate the effectiveness of fulltime occlusion therapy in treating amblyopia in 11- to 15-year-old children and to determine its lasting results.
Patients & Methods: Fifty-five compliant children 11 to 15 years old who had amblyopia were treated with full-time (during all waking hours) occlusion of their good eye until no further improvement in the visual acuity of their amblyopic eye was observed on 3 consecutive monthly follow-up examinations. After this, part-time (4 hours per day) occlusion therapy was used randomly in 24 of 55 patients for 3 to 6 months for maintenance of the final visual acuity. Snellen visual acuity and its logMAR equivalent were recorded before treatment, at the cessation of full-time occlusion therapy, and on the most recent examination.
Results: All 55 of the patients had improved visual acuity after treatment. The mean improvement was 0.46 logMAR unit (4.6 Snellen lines). Thirty-two of the patients had a mean follow-up of 17.6 months after the cessation of full-time and maintenance occlusion therapy. Twentynine (91%) of the 32 patients maintained improved visual acuity, whereas 3 (9%) exhibited a regression in visual acuity. Maintenance occlusion therapy did not have a significant stabilizing effect on the improved visual acuity.
Conclusion: Compliant, full-time occlusion effectively improves acuity in children 11 to 15 years old who have amblyopia due to strabismus, anisometropia, or both. Most older patients have lasting improvement with or without maintenance patching.

Pediatric Eye Disease Investigator Group,
“A randomized trial of patching regimens for treatment of moderate amblyopia in children.”
Arch Ophthalmol 121:603-611, 2003. In a randomized multicenter (35 sites) clinical trial, 189 children younger than 7 years with amblyopia in the range of 20/40 to 20/80 were assigned to receive either 2 hours or 6 hours of daily patching combined with at least 1 hour of near visual activities during patching. When combined with prescribing 1 hour near visual activities, 2 hours of patching produces an improvement in visual acuity that is of similar magnitude to the improvement produced by 6 hours of daily patching in treating moderate amblyopia in children aged 3 to 7 years.
Pediatric Eye Disease Investigator Group,
“A randomized trial of atropine vs patching for treatment of moderate amblyopia in children.”
Arch Ophthalmol 120:268-278, 2002.
Amblyopia is the most common cause of monocular visual impairment in both children and young and middle-age adults. In a randomized clinical trial, 419 children younger that 7 years with amblyopia and visual acuity in the range of 20/40 to 20/00 were assisted to receive with patching or atropine eye drops at 47 clinical centers. Atropine and patching produce improvement of similar magnitude, and both are appropriate modalities for the initial treatment of moderate amblyopia in children aged 3 to less than 7 years.


Pediatric Eye Disease Investigator Group
“A randomized trial of atropine vs patching for treatment of moderate amblyopia in children – follow-up at age 10 years.”
Arch Ophthalmol. 2008;126(8):1039-1044.
Objective: To determine the visual acuity outcome at age 10 years for children younger than 7 years when enrolled in a treatment trial for moderate amblyopia.
Methods: In a multicenter clinical trial, 419 children with amblyopia (visual acuity, 20/40-20/100) were randomized to patching or atropine eyedrops for 6 months. Two years after enrollment, a subgroup of 188 children entered long-term follow-up. Treatment after 6 months was at the discretion of the investigator; 89% of children were treated.
Main Outcome Measure: Visual acuity at age 10 years with the electronic Early Treatment Diabetic Retinopathy Study test.
Application to Clinical Practice: Patching and atropine eyedrops produce comparable improvement in visual acuity that is maintained through age 10 years.
Results: The mean amblyopic eye acuity, measured in 169 patients, at age 10 years was 0.17 logMAR (logarithm of the minimum angle of resolution) (approximately 20/32), and 46% of amblyopic eyes had an acuity of 20/25 or better. Age younger than 5 years at entry into the randomized trial was associated with a better visual acuity outcome (P.001). Mean amblyopic and sound eye visual acuities at age 10 years were similar in the original treatment groups (P=.56 and P=.80, respectively).
Conclusions: At age 10 years, the improvement of the amblyopic eye is maintained, although residual amblyopia is common after treatment initiated at age 3 years to younger than 7 years. The outcome is similar regardless of initial treatment with atropine or patching.

Pediatric Eye Disease Investigator Group,
Patching vs atropine to treat amblyopia in children aged 7 to 12 years.
Arch Ophthalmol. 2008;126(12):1634-1642.
Objective: To compare patching with atropine eyedrops in the treatment of moderate amblyopia (visual acuity, 20/40-20/100) in children aged 7 to 12 years.
Methods: In a randomized, multicenter clinical trial, 193 children with amblyopia were assigned to receive weekend atropine or patching of the sound eye 2 hours perday.
Main Outcome Measure: Masked assessment of visual acuity in the amblyopic eye using the electronic Early Treatment Diabetic Retinopathy Study testing protocol at 17 weeks.Results: At 17 weeks, visual acuity had improved from baseline by an average of 7.6 letters in the atropine group and 8.6 letters in the patching group. The mean difference between groups (patching  atropine) adjusted for baseline acuity was 1.2 letters (ends of complementary 1-sided 95% confidence intervals for noninferiority, 0.7, 3.1 letters). This difference met the prespecified definition for equivalence (confidence interval 5 letters). Visual acuity in the amblyopic eye was 20/25 or better in 15 participants in the atropine group (17%) and 20 in the patching group (24%; difference, 7%; 95% confidence interval,3% to 17%).
Conclusions: Treatment with atropine or patching led to similar degrees of improvement among 7- to 12-year-olds with moderate amblyopia. About 1 in 5 achieved visual acuity of 20/25 or better in the amblyopic eye.
Clinical Relevance: Atropine and patching achieve similar results among older children with unilateral amblyopia.

Pediatric Eye Disease Investigator Group,
Randomized trial of treatment of amblyopia in children aged 7 to 17 years.
Arch Opthalmol, 2005.
Objective: To evaluate the effectiveness of treatment of amblyopia in children aged 7 to 17 years.
At 49 clinical sites, 507 patients with amblyopic eye visual acuity ranging from 20/40 to 20/400 were provided with optimal optical correction and then randomized to a treatment group (2-6 hours per day of prescribed patching combined with near visual activities for all patients plus atropine sulfate for children aged 7 to 12 years) or an optical correction group (optical correction alone). Patients whose amblyopic eye acuity improved 10 or more letters (2 lines) by 24 weeks were considered responders.
Results: In the 7- to 12-year-olds (n=404), 53% of the treatment group were responders compared with 25% of the optical correction group (P.001). In the 13- to 17- year-olds (n=103), the responder rates were 25% and 23%, respectively, overall (adjusted P=.22) but 47% and 20%, respectively, among patients not previously treated with patching and/or atropine for amblyopia (adjusted P=.03). Most patients, including responders, were left with a residual visual acuity deficit.
Conclusions: Amblyopia improves with optical correction alone in about one fourth of patients aged 7 to 17 years, although most patients who are initially treated with optical correction alone will require additional treatment for amblyopia. For patients aged 7 to 12 years, prescribing 2 to 6 hours per day of patching with near visual activities and atropine can improve visual acuity even if the amblyopia has been previously treated. For patients 13 to 17 years, prescribing patching 2 to 6 hours per day with near visual activities may improve visual acuity when amblyopia has not been previously treated but appears to be of little benefit if amblyopia was previously treated with patching.Wedo not yet know whether visual acuity improvement will be sustained once treatment is discontinued; therefore, conclusions regarding the long-term benefit of treatment and the development of treatment recommendations for amblyopia in children 7 years and older await the results of a follow-up study we are conducting on the patients who respondedto treatment.

Pediatric Eye Disease Investigator Group,
“Two-year follow-up of a 6-month randomized trial of atropine vs patching for treatment of moderate amblyopia in children.”
Arch Ophthalmol. 2005;123:149-157.
Objective: To compare patching and atropine sulfate as treatments for moderate amblyopia in children 18 months after completion of a 6-month randomized trial.
Methods: In a randomized, multicenter (47 sites) clinical trial, 419 children younger than 7 years with amblyopia (20/40 to 20/100 in the affected eye) were assigned to receive either patching or atropine eye drops for 6 months. Between 6 months and 2 years, treatment was at the discretion of the investigator.
Main Outcome Measure: Visual acuity in the amblyopic eye and sound eye after 2 years. Results: At 2 years, visual acuity in the amblyopic eye improved from baseline a mean of 3.7 lines in the patching group and 3.6 lines in the atropine group. The difference in visual acuity between treatment groups was small: 0.01 logMAR (95% confidence interval, 0.02 to 0.04). In both treatment groups, the mean amblyopic eye acuity was approximately 20/32, 1.8 lines worse than the mean sound eye acuity, which was approximately 20/20.
Conclusions: Atropine or patching for 6 months followed by best clinical care until 2 years produced similar improvement of moderate amblyopia in children between 3 and 7 years of age at enrollment. However, on average the amblyopic eye acuity was still approximately 2 lines worse than the sound eye.

Polat U, Ma-Naim T. Melking M, Sagi D.,
“Improving Vision in Adult Amblyopia by Perceptual Learning.”
PNAS (Proceeding of National Academy of Sciences) 101:6692-7, 2004
Practicing certain visual tasks leads, as a result of a process termed perceptual learning, to a significant improvement in performance. Learning is specific for basic stimulus features such as local orientation, retinal location, and eye of presentation, suggesting modification of neuronal processes at the primary visual cortex in adults. It is not known, however, whether such low-level learning affects higher-level visual tasks such as recognition. By systematic low-level training of an adult visual system malfunctioning as a result of abnormal development (leading to amblyopia) of the primary visual cortex during the critical period, we show here that induction of low-level changes might yield significant perceptual benefits that transfer to higher visual tasks. The training procedure resulted in a 2-fold improvement in contrast sensitivity.

Rutstein, R,
“Contemporary Issues in Amblyopia Treatment.”
Optometry 76: 570-78, 2005.
Purpose: The aim of this report is to review the contemporary research in amblyopia treatment and how it will affect clinical practice patterns.
Method: Topics addressed include prescribing the optimal refractive correction, the most effective treatment, duration and intensity of treatment, regression after treatment, the upper age for treatment, and the chance of the amblyope losing his or her sound eye.
Results and Conclusions: The optimal refractive correction is best determined with cycloplegic retinoscopy; pharmacologic penalization can be as effective as patching in children with moderate amblyopia; less-intense treatment regimens have been found to be as effective as more-intense treatment regimens; regression can occur in as many as 25% of all treated patients; some older amblyopes can be treated successfully; and the amblyope has a higher chance of becoming blind than the nonamblyope.

Rutstein RP, Fuhr PS.
“Efficacy and stability of amblyopia therapy.”
Optom & Vis Sci, 69(1): 747-754, 1992.
To determine the efficacy and stability of therapy, the charts for 64 amblyopes with strabismus and /or anisometropia who had been treated by direct occlusion were reviewed. For patients aged 7 years or less (N=39), 90% showed some acuity gain, with 69% achieving at least a doubling of acuity. Fifty-four percent obtained 20/40 or better after an average treatment period of 3.8 months. Some reduction in visual acuity (VA) subsequently occurred for 75% of those patients followed. For patients aged eight years or more (N=26), 77% showed some acuity gain with 31% (8/260 improving at least 0.3 log units. Twenty-seven percent obtained 20/40 (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 . Loss of some of the acuity gain subsequently occurred for 67% 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 one 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(12): 959-960, 1987.
Treatment of amblyopia has 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, Mozlin R, and Rumpf D.
“Prognostic value of laser interferometric visual acuity in amblyopia therapy.”
Invest. Ophthalmol. Vis. Sci. 1986 27: 273-277.
There has been no simple clinical test which accurately predicts post- therapy visual acuity in amblyopic eyes. Since grating test patterns generally yield optimal visual acuity in amblyopic eyes, the authors sought to determine if pre-therapy laser interferometric grating visual acuity would predict conventional post-therapy visual acuity in functional amblyopia. In 90% of the patients who completed therapy, the pre-therapy laser visual acuity was within two lines of the post- therapy Snellen visual acuity. Thus, pre-therapy laser visual acuity is a good prognostic indicator of conventional post-therapy visual acuity in amblyopic eyes.

Selenow A, Ciuffreda KJ.
“Vision function recovery during orthoptic therapy in an adult esotropic amblyope.”
J Amer Optom Assoc, 57(2); 132-140, 1986.
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 orthopic therapy. Results showed substantial improvement in most areas, thus providing evidence of neural plasticity at multiple sites in the visual pathways in 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 Optics, 60(8): 659-666, 1983.
Orthoptic therapy was instituted in a 6 ½-year-old patient having deep amblyopia, constant exotropia, and high unilateral myopia. The combination of these factors pointed toward 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.

Webber, A.L.,1 Wood, J.M.,1 Gole, G.A.,2 and Brown, B.1 (1From the School of Optometry and Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Queensland, Australia; and the 2Department of Paediatrics and Child Health, University of Queensland, Herston, Queensland, Australia)
“The Effect of Amblyopia on Fine Motor Skills in Children.”
Investigative Ophthalmology and Visual Science
. 49:594-603, 2008.
Purpose: In an investigation of the functional impact of amblyopia in children, the fine motor skills of amblyopes and age-matched control subjects were compared. The influence of visual factors that might predict any decrement in fine motor skills was also explored. Methods: Vision and fine motor skills were tested in a group of children (n = 82; mean age, 8.2 ± 1.7 [SD] years) with amblyopia of different causes (infantile esotropia, n = 17; acquired strabismus, n = 28; anisometropia, n = 15; mixed, n = 13; and deprivation n = 9), and age-matched control children (n = 37; age 8.3 ± 1.3 years). Visual motor control (VMC) and upper limb speed and dexterity (ULSD) items of the Bruininks-Oseretsky Test of Motor Proficiency were assessed, and logMAR visual acuity (VA) and Randot stereopsis were measured. Multiple regression models were used to identify the visual determinants of fine motor skills performance.
Results: Amblyopes performed significantly poorer than control subjects on 9 of 16 fine motor skills subitems and for the overall age-standardized scores for both VMC and ULSD items (P < 0.05). The effects were most evident on timed tasks. The etiology of amblyopia and level of binocular function significantly affected fine motor skill performance on both items; however, when examined in a multiple regression model that took into account the intercorrelation between visual characteristics, poorer fine motor skills performance was associated with strabismus (F1,75 = 5.428; P = 0.022), but not with the level of binocular function, refractive error, or visual acuity in either eye.
Conclusions: Fine motor skills were reduced in children with amblyopia, particularly those with strabismus, compared with control subjects. The deficits in motor performance were greatest on manual dexterity tasks requiring speed and accuracy.

Wick B, Wingard Ml
“Anisometropic amblyopia: Is the patient ever too old to treat?”
Optom & Vis Sci, 69(11): 866-878, 1992.
This report describes 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 hour/day of direct occlusion and (4) active vision therapy to develop monocular acuity and improve binocular visual function. The records of 19 patients over six years of age who had been treated using this sequential management philosophy were evaluated. After 15.2 weeks of treatment the Amblyopia Success Index (ASI) documented an average improvement in visual acuity of 92.1% 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 of 19). Patients who had completed therapy one 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.