Assessing binocular interaction in amblyopia and its clinical feasibility

PURPOSE

To measure binocular interaction in amblyopes using a rapid and patient-friendly computer-based method, and to test the feasibility of the assessment in the clinic.

METHODS

Binocular interaction was assessed in subjects with strabismic amblyopia (n = 7), anisometropic amblyopia (n = 6), strabismus without amblyopia (n = 15) and normal vision (n = 40). Binocular interaction was measured with a dichoptic phase matching task in which subjects matched the position of a binocular probe to the cyclopean perceived phase of a dichoptic pair of gratings whose contrast ratios were systematically varied. The resulting effective contrast ratio of the weak eye was taken as an indicator of interocular imbalance. Testing was performed in an ophthalmology clinic under 8 mins. We examined the relationships between our binocular interaction measure and standard clinical measures indicating abnormal binocularity such as interocular acuity difference and stereoacuity. The test-retest reliability of the testing method was also evaluated.

RESULTS

Compared to normally-sighted controls, amblyopes exhibited significantly reduced effective contrast (∼20%) of the weak eye, suggesting a higher contrast requirement for the amblyopic eye compared to the fellow eye. We found that the effective contrast ratio of the weak eye covaried with standard clincal measures of binocular vision. Our results showed that there was a high correlation between the 1st and 2nd measurements (r = 0.94, p<0.001) but without any significant bias between the two.

CONCLUSIONS

Our findings demonstrate that abnormal binocular interaction can be reliably captured by measuring the effective contrast ratio of the weak eye and quantitative assessment of binocular interaction is a quick and simple test that can be performed in the clinic. We believe that reliable and timely assessment of deficits in a binocular interaction may improve detection and treatment of amblyopia.

New pediatric vision screener employing polarization-modulated, retinal-birefringence-scanning-based strabismus detection and bull's eye focus detection with an improved target system: opto-mechanical design and operation

Amblyopia ("lazy eye") is a major public health problem, caused by misalignment of the eyes (strabismus) or defocus. If detected early in childhood, there is an excellent response to therapy, yet most children are detected too late to be treated effectively. Commercially available vision screening devices that test for amblyopia's primary causes can detect strabismus only indirectly and inaccurately via assessment of the positions of external light reflections from the cornea, but they cannot detect the anatomical feature of the eyes where fixation actually occurs (the fovea). Our laboratory has been developing technology to detect true foveal fixation, by exploiting the birefringence of the uniquely arranged Henle fibers delineating the fovea using retinal birefringence scanning (RBS), and we recently described a polarization-modulated approach to RBS that enables entirely direct and reliable detection of true foveal fixation, with greatly enhanced signal-to-noise ratio and essentially independent of corneal birefringence (a confounding variable with all polarization-sensitive ophthalmic technology). Here, we describe the design and operation of a new pediatric vision screener that employs polarization-modulated, RBS-based strabismus detection and bull's eye focus detection with an improved target system, and demonstrate the feasibility of this new approach.

Performance of four new photoscreeners on pediatric patients with high risk amblyopia

PURPOSE

A new study by the American Academy of Pediatrics touts the benefits of photoscreening, especially in preverbal children who cannot yet perform monocular acuity screening. Emerging devices have not been compared in young and developmentally challenged children.

METHODS

Consecutive patients in a pediatric eye practice had a comprehensive eye examination and four photoscreens: PlusoptiX (PlusoptiX, Nuremburg, Germany), SPOT (PediaVision, Lake Mary, FL), iScreen (iScreen, Memphis, TN), and the GoCheckKids application (Gobiquity, Aliso Viejo, CA) for the iPhone 4s (Apple, Cupertino, CA) with Delta Center Crescent interpretation. They were validated according to the 2003 American Association for Pediatric Ophthalmology and Strabismus uniform guidelines.

RESULTS

One hundred eight children aged 1 to 12 years participated, with 56% having amblyopia risk factors and 10% having autism. For the four devices, sensitivity, specificity, and inconclusive results were as follows: PlusoptiX (83%, 86%, 23%), SPOT (80%, 85%, 4%), iScreen (75%, 88%, 13%) and iScreen (with Delta Center Crescent) (92%, 88%, 0%), and GoCheckKids (with Delta Center Crescent) (81%, 91%, 3%).

CONCLUSIONS

Even in high risk and young children, current instrument-based screeners can reliably screen for refractive and strabismic risk factors that lead to amblyopia. Some devices can reduce the proportion of inclusive results in challenging cases.

A descriptive study of ocular characteristics in Marfan syndrome

PURPOSE

To study the ocular characteristics in patients with Marfan syndrome (MFS).

METHODS

One hundred and two eyes of 51 participants with MFS were included in this descriptive study. Ocular characteristics, visual acuity (VA) and biometric values were studied.

RESULTS

The mean patient age was 39.0 years (range, 12.7-71.6). Seventy-seven eyes were phakic, five aphakic and 20 pseudophakic. Thirty-one eyes had ectopia lentis (EL), 12 eyes cataract, nine eyes strabismus, five eyes glaucoma and four eyes had undergone surgery for a retinal detachment (RD). Ninety-four eyes (92%) had a best spectacle-corrected VA of 0.3 logarithm of the minimum angle of resolution (logMAR) or better. In the 77 phakic eyes, myopia exceeding -3 D was seen in 12/31 eyes (39%) with EL, and in 12/46 eyes (26%) without EL. The mean axial length (AL) was 24.73 mm (range, 21.59-32.75); 39 eyes (51%) had abnormally increased AL (≥24.5 mm). The mean Kmed (mean value of Kmin and Kmax ) was 42.2 D (38.7-46.9 D). No significant difference was found in refraction, AL or corneal curvature between eyes with and without EL. Lens-related astigmatism was seen in 15 (48%) eyes with EL versus four (12%) eyes without EL. Seventeen of the pseudophakic eyes underwent surgery for EL, with history of postoperative RD in one eye.

CONCLUSION

Despite increased AL, high myopia is not as common in MFS as expected because of a flat cornea. Biometry should be considered in suspected cases of MFS when EL is not present.

Anterior visual pathways in amblyopia: quantitative assessment with diffusion tensor imaging

PURPOSE

To detect the abnormalities of the anterior visual pathways in children with amblyopia with diffusion tensor imaging.

METHODS

Ten children with unilateral amblyopia, 5 children with bilateral amblyopia, and 10 control children were treated using diffusion tensor imaging scanning in this institutional practice. Fractional anisotropy and mean diffusivity values were analyzed using diffusion tensor imaging in the prechiasmatic and chiasmatic regions. Fractional anisotropy and mean diffusivity values of the amblyopic groups were compared with the values of the control group using the Kruskal–Wallis test. The Mann–Whitney U test was used to evaluate pairwise differences between groups.

RESULTS

When compared with the control group, prechiasmatic fractional anisotropy values were significantly decreased in both affected and sound fellow eyes in the unilateral amblyopic group (P = .019 and .013), but not in the bilateral amblyopic group (P = .221). Mean diffusivity values were significantly greater in the sound fellow eye in the unilateral amblyopic group in the prechiasmatic region (P = .001 and .049).

CONCLUSION

Diffusion tensor imaging showed a significant decrease in fractional anisotropy and an increase in mean diffusivity values in the unilateral amblyopic group in both affected and sound fellow eyes. These findings may reflect axonal underdevelopment in anterior pathways, particularly in the unilateral amblyopic group.

Prevalence of the primary LHON mutations in Northern Finland associated with bilateral optic atrophy and tobacco-alcohol amblyopia

PURPOSE

Leber hereditary optic neuropathy (LHON) is regarded as the most common mitochondrial disease. We have previously reported comprehensive population-based epidemiological data on common mitochondrial DNA (mtDNA) mutations including m.3243A>G, m.8344A>G and large-scale mtDNA deletions in Northern Finland. Our aim was to investigate the prevalence of primary LHON mutations and mutations in the four mtDNA genes considered hot spots for LHON in the same population.

METHODS

The study population consisted of 42 adult patients with an aetiologically undefined bilateral optic atrophy. The major LHON mutations m.3460G>A, m.11778G>A and m.14484T>C were analysed by restriction fragment length polymorphism (RFLP), and MTND1, MTND6 and MTATP6 genes were sequenced. MTND5 gene was analysed by conformation-sensitive gel electrophoresis (CSGE).

RESULTS

No major LHON mutations were found in the population of the province of Northern Ostrobothnia giving the prevalence of these mutations 0-1.36:100 000 (95% CI). However, two main mutations were found elsewhere in Northern Finland, homoplasmic m.11778G>A from Kainuu and heteroplasmic m.3460G>A from Central Ostrobothnia. Furthermore, tobacco-alcohol amblyopia was diagnosed in five patients in the study population and one of them had m.11778G>A.

CONCLUSION

The prevalence of the three major LHON mutations is lower in Northern Finland than elsewhere in Finland or in Western Europe. As LHON and tobacco-alcohol amblyopia have a similar phenotype, we recommend analysing the known LHON-associated mutations before setting tobacco-alcohol amblyopia diagnosis.

Analysis of risk factors for consecutive exotropia and review of the literature

PURPOSE

To evaluate the possible risk factors in patients with consecutive exotropia following esotropia surgery.

METHODS

Medical records of patients who had comitant esotropia surgery between June 1999 and April 2011 were reviewed. Those who developed consecutive exotropia composed the exotropia group; patients matched for age and duration of follow-up who did not develop consecutive exotropia composed the no exotropia group. The charts of the patients were reviewed and possible risk factors for development of consecutive exotropia were investigated.

RESULTS

The average ages of 47 patients in the exotropia group and 54 patients in the no exotropia group were 10.8 ± 8.7 years (range: 1 to 41 years) and 8.5 ± 6.3 years (range: 1 to 30 years), respectively (P = .292). Amblyopia was detected in 31 (66%) and 12 (22.2%) patients in the exotropia and no exotropia groups, respectively (P = .004). Anisometropia was observed in 20 patients (42.6%) in the exotropia group and 5 patients (9.3%) in the no exotropia group (P = .003). Preoperative average esodeviation values were 42.5 ± 8.3 prism diopters (PD) (range: 25 to 60 PD) in the exotropia group and 42 ± 9.4 PD (range: 20 to 65 PD) in the no exotropia group (P = .673). Postoperative deviations were 32.8 ± 23 PD exotropia (range: 10 to 90 PD exotropia) in the exotropia group and 4.4 ± 4.2 PD esotropia (range: 0 to 10 PD esotropia) in the no exotropia group (P = .000). Asymmetric surgery had been performed in 61.7% of the exotropia group (n = 29) and 9.3% of the no exotropia group (n = 5) (P = .000). Limitation of adduction was detected in 14 patients (29.8%) in the exotropia group; none was noted in the no exotropia group (P = .000). The mean interval between the initial surgery and the onset of consecutive exotropia was 11.1 ± 15.1 months (range: 0 to 126 months).

CONCLUSIONS

Anisometropia, amblyopia, asymmetric surgery, and postoperative adduction deficit were associated with the development of consecutive exotropia. Long-term follow-up should be considered because consecutive exotropia can develop after months or years.

Echelette optical low-pass filter as a Bangerter filter for diagnosis and treatment of amblyopia and diplopia

This paper presents a new echelette optical low-pass filter that serves as a Bangerter filter (BF) for diagnosis and treatment of amblyopia and diplopia. Theoretical analysis and experimental measurements showed that echelette BFs have several advantages over the modern BFs used in medicine. Four echelette BFs with different grating periods and one BF were manufactured, and image blurring in an optical visual system with an echelette BF was experimentally investigated. The experimentally measured modulation transfer function and line spread function demonstrated definite image blurring (line expansion) that is inversely proportional to the width of the grating period. The results of measurements of the angular resolution of the optical system with an echelette BF coincide well with the results obtained by theory.

Epidemiological study of the development of visual acuity in preschoolers aged 3 to 6 in the Shenzhen area

PURPOSE

To investigate the visual acuity of preschoolers aged 3 to 6 years in Shenzhen of China.

METHODS

Visual acuity was measured in preschoolers from eight kindergartens in Shenzhen.

RESULTS

A total of 1147 children completed the visual acuity test.There were 77 boys and 62 girls aged 3 years, 259 and 216 aged 4, 193 and 160 aged 5 and 94 and 86 aged 6. The mean visual acuities of children aged 3, 4, 5, and 6 years were 0.51+/-0.10, 0.54+/-0.13, 0.65+/-0.14, and 0.71+/-0.17, respectively. The visual acuity was significantly improved with increasing age (P=0.000).

CONCLUSION

For preschoolers aged 3 to 6, the visual acuity continuously develops and improves. Therefore, age should be considered when diagnosing amblyopia in children.

Identification and treatment of amblyopia

Amblyopia is the leading cause of vision loss in children. It is treatable if diagnosed early, making identification of affected children critical. The American Association for Pediatric Ophthalmology and Strabismus and the American Academy of Pediatrics recommend that clinicians routinely perform age-appropriate vision chart testing, red reflex testing, and examination for signs of strabismus. The U.S. Preventive Services Task Force recommends vision screening for all children at least once between three and five years of age to detect the presence of amblyopia or its risk factors. Photoscreening may be a useful adjunct to traditional vision screening, but there is limited evidence that it improves visual outcomes. Treatments for amblyopia include patching, atropine eye drops, and optical penalization of the nonamblyopic eye. In children with moderate amblyopia, patching for two hours daily is as effective as patching for six hours daily, and daily atropine is as effective as daily patching. Children older than seven years may still benefit from patching or atropine, particularly if they have not previously received amblyopia treatment. Amblyopia recurs in 25 percent of children after patching is discontinued. Tapering the amount of time a patch is worn each day at the end of treatment reduces the risk of recurrence.

Screening for amblyopia among grade-1 students in primary school with uncorrected vision and stereopsis test in central China

BACKGROUND

Screening for amblyopia at earliest is important for early treatment and better prognosis. This study aimed to evaluate the validity of uncorrected distant and near visual acuity (VA) and stereoacuity for screening amblyopia in grade-1 students in primary school in central China.

METHODS

By stratified cluster sampling, 3112 grade-1 students from 11 Anyang primary schools were selected for the study. All the participants underwent uncorrected distant and near VA, stereopsis test, cycloplegic refraction, best corrected VA (BCVA), cover test, and ocular movement examination. VA was measured with a logarithm of the minimum angle of resolution (logMAR) chart. Stereoacuity was measured with the Lang II stereo card and TNO test. Amblyopia was defined as the BCVA less than or equal to 0.1 logMAR units of any eye in the absence of significant pathological abnormalities. The sensitivity, specificity, and positive and negative predictive value of uncorrected VA and stereoacuity for amblyopia were analyzed.

RESULTS

Out of the 3112 eligible students, 2893 (92.96%) completed the examinations. The average age of the students was (7.10 ± 0.41) years. Screened by distant VA with low cutoff (logMAR 0.1), high cutoff (logMAR 0.0), and near VA (logMAR 0.0), 31.64%, 73.18%, and 50.23% students were abnormal, respectively. Screened by stereopsis test, only 4.69% students were abnormal. Diagnosed by a senior pediatric ophthalmologist, 61 students had amblyopia. The sensitivities of distant VA with low/high cutoff and near VA were 92.31%, 100%, and 80.77%, respectively, whereas that of stereoacuity by TNO test was 15.38%. Simultaneous testing of either two of the three tests improved the sensitivity.

CONCLUSIONS

Distant VA test of high cutoff alone displays a high sensitivity but a low specificity. Simultaneous testing of distant VA of low cutoff and stereoacuity is a better choice to balance between sensitivity and specificity.

[Treating anisometric amblyopia with HTS Amblyopia iNet Software--preliminary results]

Amblyopia or "lazy eye" represents a disorder of the visual system characterized by poor vision in an eye that is otherwise physically normal. Anisometropia, the condition in which the two eyes have an unequal refractive error, is considered the second most common cause of amblyopia. The purpose of this study is to determine the efficiency of HTS Amblyopia iNet Software by studying the progress of visual acuity, contrast sensitivity and stereopsis vision in anisometropic amblyopic children. 5 patients (age: 5-13 years), treated with HTS Amblyopia iNet Software at OftaTotal Clinic from Sibiu, between 2010-2013, participated in this clinical trial. Initially, visual acuity ranged from 0.25 to 0.8, contrast sensitivity from 1.35 to 1.65 Log. Unit. and 1 patient presented stereoscopic vision. After treatment, visual acuity ranged from 0.8 to 1, contrast sensitivity from 1.35 to 1.95 Log. Unit., also all patients presented stereoscopic vision. HTS Amblyopia iNet Software represents an effective modern approach in the treatment of anisometropic amblyopia.

Pediatric photoscreeners in high risk patients 2012: a comparison study of Plusoptix, Iscreen and SPOT

BACKGROUND

New photoscreening models promise to detect amblyopia risk factors early in hopes of reducing permanent pediatric monocular and binocular vision impairment. The 3 commercially available interpreted photoscreeners had not yet been compared.

METHODS

This is a prospective, observational screening study following AAPOS guidelines on pediatric patients with and without developmental delays. 270 patients in a pediatric eye practice aged 4.7 +/- 4 years with 7% special needs. From December 2011 through March 2012, the Plusoptix, the iScreen, and the Pediavision SPOT were applied before confirmatory exam in a clinical pediatric eye practice.

RESULTS

The inconclusive rate ranged from 1-4% (iScreen) to 12% (Plusoptix). Sensitivity ranged from 72% (iScreen) to 84% (Plusoptix) and specificity ranged from 68% (SPOT) to 94% (Plusoptix). The iScreen can provide results in 99% of high risk patients.

CONCLUSIONS

In this cohort with high pre-screening prevalence, the 2011 photoscreeners had favorable validation that is expected to improve with further clinical study. Pediatricians have practical technology with a recognized procedure code to assist in amblyopia reduction.

[Assessment of macular and optic disc morphology in children with unilateral hypermmetropic amblyopia]

PURPOSE

To investigate macular thickness and retinal nerve fiber layer thickness of the optic disc using high resolution spectral optical coherence tomography.

MATERIAL AND METHODS

A study group consisted of 54 eyes of children aged from 5 to 13 years with unilateral hypermmetropic amblyopia. 25 children aged from 6 to 14 years with emmetropia or mild hyperopia (SE less than +1.0 D) were recruited as a reference group. All patients underwent a comprehensive ocular examination, including Scanning Laser Ophthalmoscope/Optical Coherence Tomography scans of the macula and the optic disc. The total macular volume, minimal central foveal thickness, parafoveal and perifoveal retinal thickness, global retinal nerve fiber layer thickness and in 4 quadrants were assessed using Statistica 10.0.

RESULTS

The total macular volume was significantly higher in amblyopic as compared to non-amblyopic eyes--8.9 (8.09-9.27) in the study group, 8.3 (7.17-9.32) in the reference group respectively. However, the retinal nerve fiber layer was significantly thinner in amblyopic eyes.

CONCLUSIONS

Amblyopia does not affect retinal thickness symmetry between the right and left eye. The analysis of Scanning Laser Ophthalmoscope/Optical Coherence Tomography morphometric parameters in amblyopic eyes is useful only when compared with the age-matched reference group. hypermmetropic amblyopia, macular retinal thickness, retinal nerve fiber layer thickness, spectral optical coherence tomography.

Flip chart Visual Acuity Screening for Amblyopia Risk Factors Compared to the PlusoptiX A09 Photoscreener,Tests Performed by a Lay Screener

IMPORTANCE

The gold standard of vision screening is considered acuity testing, this article will compare the gold standard against new technology to provide more choices for pediatric vision screening programs.

OBJECTIVE

To determine the reliability of recognition visual acuity screening performed by a lay screener compared to the plusoptiX A09 photoscreener for the detection of amblyopia risk factors.

DESIGN

One lay screener received basic training in how to test monocular visual acuity using the 10 foot Patti Pics single crowded chart and the plusoptiX A09 photoscreener. All children underwent a complete pediatric ophthalmology examination and cycloplegic refraction after screening and this examination was the standard against which the screening method was compared. Each patient received a pass or refer grade after either screening. For the Patti Pics screening, children were referred if they failed to reach threshold visual acuity of twenty forty in either eye; the plusoptiX determines if the child is a pass or refer based on pre-set referral criteria.

SETTING

Pediatric ophthalmology clinic.

PARTICIPANTS

Screening was performed on children ages 3 to 10 years.

RESULTS

Seventy-one children were screened. Flip chart-screening was found to have a sensitivity of 83%, specificity of 44%, false positive rate of 56% and false negative rate of 17%. Those same metrics for the plusoptiX A09 were 94%, 89%, 11% and 6%, respectively.

CONCLUSION

The plusoptiX photoscreener was more sensitive and specific in making appropriate referrals for further care than flip chart-screening in this cohort of children age 3-10. The plusoptiX A09 photoscreener operated by a lay screener is a reliable method to screen for amblyopia risk factors. These finding have important implications for community based vision screening, and screening in the medical home.

Retrospective cytological study of intraocular lymphoma using vitreous and intraocular perfusion fluid

Intraocular lymphoma (IOL) is an extremely rare tumor. We carried out a retrospective cytopathological study with vitreous and intraocular perfusion fluid obtained on conducting a pars plana vitrectomy in 18 cases of IOL. In the 18 cases, nine were patients of Kansai Medical University Takii Hospital from 1991 to 2007, and the other nine had already been reported by other hospitals. Most patients were male, and the average age at onset was 60.4-year-old. The main symptoms were vitreous opacity, amblyopia, and blurred vision. Cases of primary intraocular lymphoma numbered 8/15 (53%), while cases of infiltration of malignant lymphoma from the brain numbered 2/15 (13%). Although IOL contains various subtypes of lymphoma, the most frequent subtype is diffuse large B-cell type lymphoma. It has been reported that making a definite diagnosis of IOL is difficult because the clinical symptoms and examinations are similar to chronic uveitis, and so IOL is called "masquerade syndrome." Recently, serological and molecular pathological studies have been carried out in addition to morphological examination. However, a cytological diagnosis based on the clinical background and/or image findings is important for the diagnosis of IOL, because of the volume limit of the vitreous fluid and difficulty of obtaining specimens from the inside of the eyes.

The potential cost-effectiveness of amblyopia screening programs

PURPOSE

To estimate the incremental cost-effective-ness of amblyopia screening at preschool and kindergarten, the costs and benefits of three amblyopia screening scenarios were compared to no screening and to each other: (1) acuity/stereopsis (A/S) screening at kindergarten, (2) A/S screening at preschool and kindergarten, and (3) photoscreening at preschool and A/S screening at kindergarten.

METHODS

A probabilistic microsimulation model of amblyopia natural history and response to treatment with screening costs and outcomes estimated from two state programs was programmed. The probability was calculated that no screening and each of the three interventions were most cost-effective per incremental quality-adjusted life year (QALY) gained and case avoided.

RESULTS

Assuming a minimal 0.01 utility loss from monocular vision loss, no screening was most cost-effective with a willingness to pay (WTP) of less than $16,000 per QALY gained. A/S screening at kindergarten alone was most cost-effective at a WTP between $17,000 and $21,000. A/S screening at preschool and kindergarten was most cost-effective at a WTP between $22,000 and $75,000, and photoscreening at preschool and A/S screening at kindergarten was most cost-effective at a WTP greater than $75,000. Cost-effectiveness substantially improved when assuming a greater utility loss. All scenarios were cost-effective when assuming a WTP of $10,500 per case of amblyopia cured.

CONCLUSION

All three screening interventions evaluated are likely to be considered cost-effective relative to many other potential public health programs. The choice of screening option depends on budgetary resources and the value placed on monocular vision loss prevention by funding agencies.

[Mobius syndrome]

Mobius syndrom, an anomaly in cranial nerve developement, presents with a remarkable clinical polymorphism. The rare occurence of this pathology and the questions raised by the diagnosis and treatment determined us to make this presentation.

[Causes, diagnostics and therapy for paediatric ptosis]

BACKGROUND

The diagnosis of and therapy for paediatric ptosis present challenges because of difficulties in performing preoperative examinations and the inability of the patient to provide intraoperative cooperation for proper lid placement. The authors provide an overview of the different forms and findings in congenital ptosis patients and point out the difficulties of the surgical procedures.

DIAGNOSTICS AND THERAPY

The majority of paediatric ptosis cases is simple unilateral congenital ptosis with dysgenesis of the levator palpebrae superioris muscle. Other different forms exist due to neurological, neuro-myogenic, aponeurotic, sympathic, and mechanical reasons or syndromes. The relevant history is obtained, including birth history and family history, careful observation and full ophthalmological examination are necessary. Amblyopia because of ptosis, strabismus or anisometropia with corneal astigmatism should be recognised and treated early. The preoperative examination is vital for determining the appropriate diagnosis and is useful for selecting the appropriate procedure. Ptosis correction is based on ptosis severity, Bell phenomenon and levator function. The primary goal is symmetry of the upper lids. Most frequently a levator resection is performed between the 3rd and 5th year with a levator function of more than 3 mm. The most common complication is undercorrection, poor lid contour or amblyopia. Overcorrection may be associated with dry eye syndrome and keratopathy.

CONCLUSION

Levator resection is a useful procedure for the correction of mild to moderate ptosis. Frontalis suspension surgery is effective for congenital ptosis with poor levator function.

[Use of Plusoptix as a screening method for refractive ambliopia]

PURPOSE

Highlighting the differences in the objective refraction using the Plusoptix AO9 comparing them with the refraction performed with TOPCON KR-8900 autorefractor.

METHODS

Prospective study for 3 months held in the Ophthalmology Clinic in Iasi, Hospital Sf. Spiridon on a total of 39 children (21 girls and 18 boys) with mean age of 10.61 +/- 5.67 years. Clinical parameters: sex, age, objective refraction obtained with Plusoptix and with autorefractor corrected visual acuity (with different methods depending on each patient age), ortoptic examination (strabic deviation, binocular vision), the presence of symetry/asymetry while measuring with Plusoptix. The results were statistically processed by F-TEST calculating the correlation coefficient, standard deviation, significance level (using the spherical equivalent of the obtained values).

RESULTS

Age limits of the studied cases ranged between 2-23 years. Visual acuity of children who had cooperate was between 0.2-1 with correction, achieving best values on right eye than left eye. 8 cases (20.51%) had large differences between measurements made with Plusoptix and autorefractor, half of that (4 cases) had strabismus. Three of these cases were with small hypermetropia and one with small myopia (Plusoptix shows a lower value). In 2 cases occurred higher differences (about 2-2,5D) between the 2 measurements, in patients with average hypermetropia. Plusoptix refraction was not possible at high hypermetropia or high myopia.

CONCLUSIONS

This type of determining objective refraction using Plusoptix is a useful method of screening for discovery of refractive errors that can cause refractive amblyopia in young children and in those cases with a difficult collaboration. Because there are differences betweeti this 2 methods, for children with refractive errors are recommended further exploration to determine the appropriate optical correction. Plusoptix is a limited method because it cannot detect the exact values in those cases with high hypermetropia or high myopia.

Predictive value from pediatrician plusoptix screening: impact of refraction and binocular alignment

BACKGROUND

The positive predictive value (PPV) of conventional preschool acuity screening is about 50% whereas previous Polaroid photoscreening with experienced interpretation can achieve PPV greater than 85%. The Plusoptix photoscreener has immediate computer interpretation and a CPT code available to pediatricians.

METHODS

Two Plusoptix SO9 were used in two pediatric group practices with previously validated refractive criteria and new manufacturer's binocular alignment criteria. CPT billing was monitored. Referred patients had prior gold-standard AAPOS examinations.

RESULTS

12% of 675 photoscreened preschoolers were referred. Of the 39 with AAPOS gold-standard exams, the PPV from strabismus referrals was 17%, while 26 of 27 refractive referrals had true amblyopia risk factors (PPV 96%). Screening CPT code 99174 reimbursement rose from zero to half of insurers in 15 months.

CONCLUSION

Plusoptix photoscreening is valid after adjusting the binocular alignment criteria. Such photoscreening should be employed by pediatric practices to detect and ultimately to reduce amblyopia vision impairment in children.

[The estimation of higher order aberrations in children with anisometropic amblyopic]

Higher order aberrations (HOAs) were measured in 54 anisometropic amblyopic children using the ZY-WAVE II aberrometer. The results were compared in normal fellow and amblyoic eyes which were determined by the corrected visual acuity. Between the normal eyes and anisometropic amblyopic eyes, no statistically significant difference were found in mean root square of total HOAs, total coma (TC), total spherical aberration (TSA), and the 5th root mean square (RMS5). There was no correlation among best corrected visual acuity (BCVA), HOAs, TC, TSA, and RMS5. There was some positively correlation between the degree of anisometropia and TC. HOAs increase with the increasing of the degree of anisometropic amblyopia. Lower order aberrations are the main refractive factors leading to amblyopia, and HOAs is related to anisometropia amblyopia. The study helps us understand the mechanism of amblyopia and make the further study.

Validation of plusoptiX S04 photoscreener as a vision screening tool in children with intellectual disability

PURPOSE

Intellectual disability (ID) is a major public health issue, affecting more than 1% of children worldwide. Pediatric vision screening using standard eye charts may be challenging for children with ID, who may benefit from a quick noninvasive vision screening tool. This study evaluated the accuracy of plusoptiX S04 (Plusoptix Gmbh, Nuremberg, Germany) in detecting amblyopia risk factors in children with ID.

METHODS

Children diagnosed with ID according to age-appropriate psychological tests were examined consecutively. Vision screening was performed using the plusoptiX S04 prior to complete ophthalmological examination, including cycloplegic refraction. Pass/refer screening results was compared with findings of ophthalmological examination. Amblyogenic risk factors were defined according to American Association for Pediatric Ophthalmology and Strabismus referral criteria.

RESULTS

A total of 182 infants and children were examined. Only 3% of children were uncooperative for screening. Ophthalmological examination detected amblyogenic risk factors in 32% of patients. The sensitivity of plusoptiX S04 was 95% (95% CI, 85.6%-98.9%), and specificity was 50% (95% CI, 40.8%-59.1%). The positive predictive value was 47% (95% CI, 37.7%-56.4%) and the negative predictive value was 95.4% (95% CI, 87.1%-99.1%).

CONCLUSIONS

High sensitivity and negative predictive values suggest that the plusoptiX S04 will detect most children with ID who have amblyogenic risk factors, but one-half of all children referred will have no risk factors.

Comparison of the Retinomax and Palm-AR Auto-Refractors: a pilot study

PURPOSE

To compare the performance of two handheld auto-refractors, the Retinomax and the Palm-Automatic Refractometer (Palm-AR), for detecting significant vision disorders in pre-school children.

METHODS

Children attending Philadelphia PreKindergarten Head Start were screened with the Retinomax and Palm-AR and underwent a gold standard eye examination. The results of cycloplegic retinoscopy, cover testing, and visual acuity were used to classify children as having normal vision or one of four conditions: amblyopia, strabismus, significant refractive error, and reduced visual acuity. Pass/fail criteria for each instrument were selected to maximize overall sensitivity (with specificity set at 90% and at 94%) for detecting targeted disorders. Comparisons of sensitivities between the auto-refractors were performed using the exact McNemar test.

RESULTS

Testability was >99% for both instruments. Test time was similar for the two instruments (median 2 min; p=0.10). At 90% specificity, the sensitivity for detection of one or more targeted conditions was 74% for the Palm-AR and 78% for the Retinomax. At 94% specificity, the sensitivity for detection of one or more targeted conditions was 66% for both the Palm-AR and the Retinomax. At 90% specificity, the sensitivity for detecting significant refractive error was 84% for both auto-refractors, and at 94% specificity, the sensitivity was 76% for the Palm AR and 75% for the Retinomax. There were high correlations between the instruments for sphere (r=0.85) and cylinder (r=0.88) power. The mean difference between instruments was -0.13 diopters (D) (95% limit of agreement: -2.28 to 2.02) for sphere, and -0.15 D (95% limit of agreement: -0.89 to 0.59) for cylinder.

CONCLUSIONS

In this pilot study, the Retinomax and Palm-AR appear comparable with respect to testability, sensitivity, and specificity. There was strong agreement in readings of sphere and cylinder indicating that they may perform similarly in a screening setting.

[Amblyopia, a public health problem]

Amblyopia or the alteration of the visual function is a common and disabling condition which takes various forms. Screening is carried out during a baby's first week of life and then at regular intervals during early childhood. It is a public health issue insofar as the disorders are curable and treatment is effective when they are detected early.

[The lazy eye - contemporary strategies of amblyopia treatment]

Amblyopia is a condition of decreased monocular or binocular visual acuity caused by form deprivation or abnormal binocular interaction. Amblyopia is the most common cause of monocular vision loss in children with a prevalence of 2 to 5%. During the last decade, several prospective randomized studies have influenced our clinical management. Based on these studies, optimum refractive correction should be prescribed first. However, most patients will need additional occlusion therapy which is still considered the «gold standard» of amblyopia management. Now much lower doses have been shown to be effective. In moderate amblyopia, penalization with atropine is as effective as patching. New treatment modalities including perceptual learning, pharmacotherapy with levodopa and citicholine or transcranial magnetic stimulation have not yet been widely accepted.

A review: the determination of visual acuity in infants and preliterate children

In the field of pediatric ophthalmology, assessment of visual acuity is important and necessary in determining treatment plans for children with both functional as well as organic amblyopia, and also to monitor the effect and success of treatment.We shall review the qualitative/subjective tests, as well as the objective/quantitative tests described in the literature for assessing visual acuity, and we shall outline the complexity of vision and its impact on the objective tests.The main purpose of our paper is to present our own scheme of determining visual acuities in infants and pre-literate children, a scheme we believe is simple, effective, implies no extra costs, applicable to infants and young children, and almost infallible in detecting severe amblyopia.

[Brown syndrome. General considerations. Case report]

This is an overview of a few general aspects of Brown's syndrome followed by a case report of a three year old girl suffering from congenital Brown's syndrome, astigmatism and amblyopia, which was detected by an ophthalmological screening at her kindergarten. The main differential diagnosis is ipsilateral inferior oblique paresis/paralysis. Since this was a mild-degree syndrome, it didn't require surgery only optical treatement and follow-up.

Auto-objective accommodative measurements as a valid and reliable new method of pediatric, strabismus and amblyopia, vision screening

PURPOSE

Recent technological advances in photoscreening devices have improved their performance for pediatric vision screening. Monocular noncycloplegic autorefractors have also been used but cannot assure that accommodation is held constant between the two eyes. In this study we utilized a simple childrens near autorefraction without correction on the open field Grand Seiko autorefractor to determine if it alone could be a viable method of pediatric vision screening to detect amblyopia risk factors.

DESIGN

Retrospective chart review.

PARTICIPANTS

Fifty-two consecutive children with known amblyopia risk factors were enrolled into this study.

METHODS

Children had their accommodation measured at one third of a meter without glasses correction.

MAIN OUTCOME

In our study children with amblyopia or amblyopia risk factors were found to have abnormal readings indicating either poor ability to focus, or high refractive error. All children measuring minus 1.25 diopter of sphere or higher (less negative), or measuring plus 1.25 diopters of astigmatism or more without correction were found to have amblyogenic factors based on the standard, AAPOS referral criteria.

CONCLUSION

Children with amblyopia or amblyopia risk factors have classifiably abnormal autorefraction readings at near on the Grand Seiko binocular open field autorefractor. Measuring near autorefraction utilizing the Grand Seiko autorefractor may be a new and viable option for pediatric vision screening in the medical home (defined as the patients primary care doctor, which in this case could be a family doctor or a pediatrician).

Can a photoscreener help us remotely evaluate and manage amblyopia?

INTRODUCTION AND PURPOSE

To determine whether the plusoptiX® S04 photo-screener can assist in remotely managing amblyopia.

METHODS

A retrospective chart review was performed on 103 children with amblyopia. All patients had a plusoptiX® screening performed while wearing their optical correction during a comprehensive pediatric ophthalmology examination.

RESULTS

Children were classified as being fully treated in their glasses or needing further intervention to treat their amblyopia and / or strabismus. Further treatment was indicated if children were found to have abnormal alignment and / or best corrected visual acuity of 20 / 40 or worse in either eye with correction. Photoscreening results for these children demonstrated a sensitivity, specificity, false negative rate and false positive rate of 69%, 84%, 31%, and 16%, respectively. When visual acuity and photoscreening were combined for children who initially passed the plusoptiX® screen, these metrics improved to 97%, 89%, 2.7%, and 11%, respectively.

CONCLUSION

Photoscreening combined with simple measurements of visual acuity may be a viable option for following efficacy of treatment in amblyopes. In some parts of the United States and in many areas of the world where telemedicine plays an increasingly important role, the plusoptiX® photoscreener could enhance vision care and may enhance telemedicine and the treatment of amblyopia.

Detection and treatment of amblyopia in children

Refractive errors are a common cause of decreased visual acuity. They can be found in 2-4% of preschool children. If not discovered on time and not properly treated, they can lead to amblyopia and strabismus. The active participation of parents and paediatricians is of great importance in timely discovering and treatment of amblyopia. The most common causes of amblyopia are strabismus (50.1%) and refractive error (44.7%). The best treatment results are achieved in amblyopic children with strabismus. The cooperation of physicians of all specialties, above all paediatricians and ophthalmologists, as well as a good collaboration of parents based on their being well-informed, must exist in the process of timely diagnosing and treating of amblyopia.

[Visual evoked potentials in management of amblyopia in children]

GOAL

The authors want to point out the possibility of using the visual evoked potentials (VEP) in the diagnostic process of amblyopia, especially in preverbal children. We also researched the possibility of screening for amblyopia with VEP in young patients with anisometropia without strabismus being present, especially those who come from affected families. The authors followed changes in the course of an occlusion therapy and suggest that VEP could be used to predict a success of the amblyopia therapy.

MATERIAL AND METHODS

We analyzed group of 45 pediatric patients ages 2-10 years who were investigated in years 2006-2009 at Pediatric Ophthalmology Department of Children University Hospital in Bratislava with amblyopia. This group was compared with a control group of 25 healthy children. The cause of amblyopia in a majority of children (29 patients) was hyperopic anisometropia, 13 children had hyperopic isometropia, 3 patients had myopia over -3D. These causes in 22 children were combined with strabismus. The monocular pattern of VEP was evaluated in all patients. In cooperative children (25) we also evaluated binocular pattern of VEP. 18 patients with amblyopia had a second VEP evaluation done during the occlusion therapy, among those were 23 amblyopic eyes. The time frame from the first VEP evaluation to the second VEP evaluation was 1-11 months, average 5,1 months. The material was statistically evaluated.

RESULTS

Our study showed statistically significant prolongation of the latency of both P and N2 waves (p = 0.01) in children with amblyopia.This can be used in diagnostic process of amblyopia in preverbal children as well as in the screening for amblyopia. We also followed changes during the occlusion therapy and we discovered persistent prolongation of the latency of the P wave and also changes in the amplitudes (p = 0.05) During repeated measurements and with applied therapy one can follow the dynamics of amblyopia, course of therapy by VEP changes.

CONCLUSIONS

Results of our research suggest a great contribution of VEP especially in the diagnosis of anisometropic amblyopia, especially in preverbal children. The advantage of VEP is in the screening, prediction and dynamics of therapy too. The amblyopia management is a long lasting process requiring a thorough communication and cooperation among the patient, parent and a doctor.

Visual and systemic outcomes in pediatric ocular myasthenia gravis

PURPOSE

To evaluate visual and systemic outcomes in pediatric patients with purely ocular myasthenia gravis (OMG) treated at the Children's Hospital of Philadelphia.

DESIGN

Retrospective chart review.

METHODS

Pediatric patients with OMG seen at a single institution over a 16-year period with a minimum follow-up of 1 year were reviewed. Associations of demographic and clinical characteristics with disease resolution, amblyopia, and development of generalized symptoms of myasthenia gravis were analyzed.

RESULTS

Thirty-nine patients were identified, with a mean age of 5.4 ± 4.8 years and mean follow-up of 4.8 ± 4.3 years. Fifteen patients were treated with pyridostigmine only, 19 (49%) also received steroids, and 15 (38%) underwent thymectomy. Four patients (10%) received steroid-sparing immunosuppressive therapy. Resolution occurred in 10 patients, and generalized symptoms eventually occurred in 9 patients. Although 10 patients were treated for amblyopia, only 1 had amblyopia at the final visit. There was no correlation between sex or age with amblyopia or development of generalized symptoms. Thymectomy, when performed before the onset of generalized symptoms, showed a trend toward protection from the development of generalized symptoms (P = .07).

CONCLUSIONS

In our series, 24% of patients had disease resolution and 23% had generalized symptoms. Our larger cohort confirms previous findings that treated and untreated pediatric patients with OMG have a relatively low risk of developing generalized symptoms and that related amblyopia is readily reversible. Although our treatments were more aggressive than those previously reported, our rates of amblyopia and development of generalized symptoms are comparable.

[MR DTI and DTT study on the development of optic radiation in patients with anisometropia amblyopia]

OBJECTIVE

To evaluate the development of optic radiations (ORs) in patients with anisometropia amblyopia using magnetic resonance diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT), and to explore possible mechanism of pathogenesis of amblyopia.

METHODS

Brain scan was performed with 3.0 Tesla scanner on 8 patients with anisometropia amblyopia and 15 control subjects with normal sights. The fractional anisotropy (FA) values, the apparent diffusion coefficient (ADC) values, the numbers of neural fiber bundle of ORs, and the voxel numbers of ORs were compared between the patients with anisometropia amblyopia and those with normal sights and between the ipsilateral ORs and the contralateral ORs in the patients with amblyopia.

RESULTS

No differences in the FA values, the ADC values, the numbers of neural fiber bundle of ORs and the voxel numbers of ORs were found between the ipsilateral ORs and the contralateral ORs in the patients with amblyopia (P > 0.05). Significant decreases in the FA values and the voxel numbers of ORs were found in the patients with amblyopia compared with the controls (P < 0.05). No differences in the voxel numbers of both ORs in the anterior parts were found between the patients with amblyopia and the controls (P > 0.05). However, the patients with amblyopia had more voxel numbers of ORs in the posterior parts than the controls (P < 0.05). The differences in the ADC values and the numbers of neural fiber bundle of ORs between the patients with amblyopia and the controls were not significant (P > 0.05).

CONCLUSION

The compactability, integrity and directivity of ORs decrease in patients with anisometropia amblyopia. The projection of OR fibers is abnormal. The ORs are underdeveloped, especially in the posterior parts, although no abnormal morphologic changes occur. The DTI and DTT can detect the underdevelopment of optic radiations in patients with anisometropia amblyopia indirectly.

[Long-term functional effect of the photo screening in ocular diseases causing amblyopia]

Amblyopia represents the most common cause of insufficient monocular visual acuity in productive age.To begin the treatment in the early childhood is understood as the fundamental anticipation to achieve the optimal result. The research work concerns about the development of screening methods. Our retrospective study was not focused toward the efficacy of the screening itself, but it had to establish, how the participation of the suckling babies in the screening program influences the chance of good vision. The data analyzed in this study were obtained from retrospective review of medical records of two groups of patients of the Center for functional visual disorders. Four hundred and nineteen (419) patients with positive finding in the photo screening, selected by chance, were included into the study (SC group). In the second group, there were included 263 randomly selected patients who did not pass the photo screening procedure and to the first examination were referred by the pediatrician (PLDD group).The average age at the time of the first examination was 13 months in children from the SC group and 23 months in children from the PLDD group respectively.The difference was statistically highly significant. In both groups, the severity of the amblyopia related to the comparable degree of anisometropia and the degree of the involvement of binocular functions in strabismus related to the comparable degree of hypemetropia were compared. The data were evaluated according to the age of the child patients at the time of the examination used for the purpose of this study as well. The obtained data show, that the decrease of the visual acuity of the amblyopic eye in case of equal anisometropia is significantly higher in two to three years old children who were not screened. In older children, the results in the in the SC and PLDD groups did not significantly differ. The results of our study indicate that later (before the age of three years) beginning of systematic pleoptic treatment related to the absence in the screening program is not worsening the chance to good visual acuity at the age of six years in case of moderate to mid-severe amblyopia. The first examination indicated by the pediatrician later, at the time of evident signs of strabismus, may decrease the chance to the good functional results of the complex strabological treatment at the age of six years.

[Problems to be resolved urgently on amblyopia diagnosis and prevention in China]

For many years, the best corrected vision less than 0.9 was an unique amblyopia diagnostic criteria in the clinical practices in China. Because of no different visual acuity criteria for younger-aged children, the amblyopia prevalence was increased. In clinical practice, two phenomenons exist in the amblyopia diagnosis and prevention. One is that ignores the risk factors for amblyopia development and only considers the factor of visual acuity. The other is that only uses a corrected visual acuity of 0.9 as diagnostic criteria and ignores the visual development with ages. Therefore, it should be taken the different visual acuity criteria for amblyopia diagnosis in younger-aged children. And it should be emphasized on the co-existed risk factors in the amblyopia diagnosis.

Bilateral abnormalities of optic nerve size and eye shape in unilateral amblyopia

PURPOSE

To evaluate the optic nerve (ON) size and globe shape in amblyopic eyes using high-resolution magnetic resonance imaging (MRI) and to compare these values with those of the sound fellow eye and of normal control eyes.

DESIGN

Prospective case-control study.

METHODS

Thirty-four amblyopic patients and 60 normal control patients were evaluated using surface coil MRI. Retrobulbar ON cross-section, maximum globe cross-section, globe noncircularity (globe major axis/minor axis), axial length (AL), and the ratio of AL to ON (AL/ON) were measured.

RESULTS

Corrected logarithm of the minimum angle of resolution acuity of all 34 amblyopic eyes averaged 0.43 +/- 0.30. The mean retrobulbar ON cross-section was 9.7 +/- 2.4 mm(2), 9.5 +/- 2.3 mm(2), and 10.7 +/- 2.6 mm(2) for amblyopic, fellow, and normal ONs, respectively. Although amblyopic and fellow ONs had similar cross-sections, both were significantly (P = .02) subnormal. AL/ON was 2.7 +/- 1.2 mm(-1), 2.7 +/- 1.0 mm(-1), and 2.3 +/- 0.5 mm(-1), respectively. Although AL/ON significantly exceeded normal in amblyopic eyes (P = .01), there was no significant difference between amblyopic and fellow eyes. Globe noncircularity of amblyopic eyes (1.17 +/- 0.07; P = .002) and fellow eyes (1.15 +/- 0.04; P < .001) was significantly greater than that of control eyes (1.11 +/- 0.04), but amblyopic and fellow eyes did not differ significantly.

CONCLUSIONS

Unilateral amblyopia is associated with bilaterally, but also with subclinically hypoplastic ONs, greater than normal AL/ON, and abnormally noncircular globe cross-section. These factors evidently do not determine which of the 2 eyes will become amblyopic. Reduced circularity of amblyopic and fellow eyes may reflect optical causes of amblyopia or bilateral dysregulation of globe shape secondary to amblyopia.

Defining Amblyopia: The Need for a Joint Classification

Recent years have shown an impressive rise in high quality research on amblyopia. Unfortunately, the condition is not sufficiently defined, and consequently different studies have been used different definitions of amblyopia. Aspects in need of consideration include the degree of visual acuity reduction, magnitude of interocular difference in acuity, method of visual acuity testing used, the effect of refractive adaption, the presence of amblyogenic factors, the absence of organic cause and the treat ability of the deficit. Vision scientists worldwide are encouraged to jointly decide on what is, and what is not, amblyopia.

Effectiveness of screening preschool children for amblyopia: a systematic review

BACKGROUND

Amblyopia and amblyogenic factors like strabismus and refractive errors are the most common vision disorders in children. Although different studies suggest that preschool vision screening is associated with a reduced prevalence rate of amblyopia, the value of these programmes is the subject of a continuing scientific and health policy discussion. Therefore, this systematic review focuses on the question of whether screening for amblyopia in children up to the age of six years leads to better vision outcomes.

METHODS

Ten bibliographic databases were searched for randomised controlled trials, non-randomised controlled trials and cohort studies with no limitations to a specific year of publication and language. The searches were supplemented by handsearching the bibliographies of included studies and reviews to identify articles not captured through our main search strategy.

RESULTS

Five studies met the inclusion criteria. Of these, three studies suggested that screening is associated with an absolute reduction in the prevalence of amblyopia between 0.9% and 1.6% (relative reduction: between 45% and 62%). However, the studies showed weaknesses, limiting the validity and reliability of their findings. The main limitation was that studies with significant results considered only a proportion of the originally recruited children in their analysis. On the other hand, retrospective sample size calculation indicated that the power based on the cohort size was not sufficient to detect small changes between the groups. Outcome parameters such as quality of life or adverse effects of screening have not been adequately investigated in the literature currently available.

CONCLUSION

Population based preschool vision screening programmes cannot be sufficiently assessed by the literature currently available. However, it is most likely that the present systematic review contains the most detailed description of the main limitations in current available literature evaluating these programmes. Therefore, future research work should be guided by the findings of this publication.

Neuroimaging in Human Amblyopia

Functional magnetic resonance imaging (fMRI), positron emission tomography (PET) and magnetoencephalography (MEG) have been the principal neuroimaging tools used to assess the site and nature of cortical deficits in human amblyopia. A review of this growing body of work is presented here with particular reference to various controversial issues, including whether or not the primary visual cortex is dysfunctional, the involvement of higher-order visual areas, neural differences between strabismic and anisometropic amblyopes, and the effects of modern-day drug treatments. We also present our own recent MEG work in which we used the analysis technique of synthetic aperture magnetometry (SAM) to examine the effects of strabismic amblyopia on cortical function. Our results provide evidence that the neuronal assembly associated with form perception in the extrastriate cortex may be dysfunctional in amblyopia, and that the nature of this dysfunction may relate to a change in the normal temporal pattern of neuronal discharges. Based on these results and existing literature, we conclude that a number of cortical areas show reduced levels of activation in amblyopia, including primary and secondary visual areas and regions within the parieto-occipital cortex and ventral temporal cortex.

An Automated Method for Creating Simulated Distorted Images in Amblyopic Vision

Spatial distortions in amblyopic vision can be captured by subjective reports or by a point-by-point mapping of the central part of the visual field. In this study, we developed a series of algorithms that provide a fine-grain mapping of the amblyopic percept. These algorithms can be applied to any real-world image. The images created based on these algorithms can be compared with the subjective percept of each amblyope.