Early screening for amblyogenic risk factors lowers the prevalence and severity of amblyopia

Impaired Activation of Visual Attention Network for Motion Salience Is Accompanied by Reduced Functional Connectivity between Frontal Eye Fields and Visual Cortex in Strabismic Amblyopia

Strabismic amblyopia is now acknowledged to be more than a simple loss of acuity and to involve alterations in visually driven attention, though whether this applies to both stimulus-driven and goal-directed attention has not been explored. Hence we investigated monocular threshold performance during a motion salience-driven attention task involving detection of a coherent dot motion target in one of four quadrants in adult controls and those with strabismic amblyopia. Psychophysical motion thresholds were impaired for the strabismic amblyopic eye, requiring longer inspection time and consequently slower target speed for detection compared to the fellow eye or control eyes. We compared fMRI activation and functional connectivity between four ROIs of the occipital-parieto-frontal visual attention network [primary visual cortex (V1), motion sensitive area V5, intraparietal sulcus (IPS) and frontal eye fields (FEF)], during a suprathreshold version of the motion-driven attention task, and also a simple goal-directed task, requiring voluntary saccades to targets randomly appearing along a horizontal line. Activation was compared when viewed monocularly by controls and the amblyopic and its fellow eye in strabismics. BOLD activation was weaker in IPS, FEF and V5 for both tasks when viewing through the amblyopic eye compared to viewing through the fellow eye or control participants' non-dominant eye. No difference in V1 activation was seen between the amblyopic and fellow eye, nor between the two eyes of control participants during the motion salience task, though V1 activation was significantly less through the amblyopic eye than through the fellow eye and control group non-dominant eye viewing during the voluntary saccade task. Functional correlations of ROIs within the attention network were impaired through the amblyopic eye during the motion salience task, whereas this was not the case during the voluntary saccade task. Specifically, FEF showed reduced functional connectivity with visual cortical nodes during the motion salience task through the amblyopic eye, despite suprathreshold detection performance. This suggests that the reduced ability of the amblyopic eye to activate the frontal components of the attention networks may help explain the aberrant control of visual attention and eye movements in amblyopes.

Zagreb Amblyopia Preschool Screening Study: near and distance visual acuity testing increase the diagnostic accuracy of screening for amblyopia

AIM

To present and evaluate a new screening protocol for amblyopia in preschool children.

METHODS

Zagreb Amblyopia Preschool Screening (ZAPS) study protocol performed screening for amblyopia by near and distance visual acuity (VA) testing of 15 648 children aged 48-54 months attending kindergartens in the City of Zagreb County between September 2011 and June 2014 using Lea Symbols in lines test. If VA in either eye was >0.1 logMAR, the child was re-tested, if failed at re-test, the child was referred to comprehensive eye examination at the Eye Clinic.

RESULTS

78.04% of children passed the screening test. Estimated prevalence of amblyopia was 8.08%. Testability, sensitivity, and specificity of the ZAPS study protocol were 99.19%, 100.00%, and 96.68% respectively.

CONCLUSION

The ZAPS study used the most discriminative VA test with optotypes in line as they do not underestimate amblyopia. The estimated prevalence of amblyopia was considerably higher than reported elsewhere. To the best of our knowledge, the ZAPS study protocol reached the highest sensitivity and specificity when evaluating diagnostic accuracy of VA tests for screening. The pass level defined at ≤0.1 logMAR for 4-year-old children, using Lea Symbols in lines missed no amblyopia cases, advocating that both near and distance VA testing should be performed when screening for amblyopia.

Prevalence of Amblyopia and Refractive Errors Among Primary School Children

Purpose:

To determine the prevalence of amblyopia and refractive errors among 7 to 12-year-old primary school children in Tehran, Iran.

Methods:

This population-based cross-sectional study included 2,410 randomly selected students. Visual acuity was tested using an E-chart on Yang vision tester. Refractive errors were measured by photorefractometry and cycloautorefraction. Strabismus was checked using cover test. Direct ophthalmoscopy was used to assess the anterior segment, lens opacities, red reflex and fundus. Functional amblyopia was defined as best corrected visual acuity ≤20/40 in one or both eyes with no anatomical problems.

Results:

Amblyopia was present in 2.3% (95% CI: 1.8% to 2.9%) of participants with no difference between the genders. Amblyopic subjects were significantly younger than non-amblyopic children (P=0.004). Overall, 15.9% of hyperopic and 5.9% of myopic cases had amblyopia. The prevalence of hyperopia ≥+2.00D, myopia ≤-0.50D, astigmatism ≥0.75D, and anisometropia (≥1.00D) was 3.5%, 4.9%, 22.6%, and 3.9%, respectively. With increasing age, the prevalence of myopia increased (P<0.001), that of hyperopia decreased (P=0.007), but astigmatism showed no change. Strabismus was found in 2.3% of cases. Strabismus (OR=17.9) and refractive errors, especially anisometropia (OR=12.87) and hyperopia (OR=11.87), were important amblyogenic risk factors.

Conclusion:

The high prevalence of amblyopia in our subjects in comparison to developed countries reveals the necessity of timely and sensitive screening methods. Due to the high prevalence of amblyopia among children with refractive errors, particularly high hyperopia and anisometropia, provision of glasses should be specifically attended by parents and supported by the Ministry of Health and insurance organizations.

Amblyaudia: Review of Pathophysiology, Clinical Presentation, and Treatment of a New Diagnosis

OBJECTIVE

Similar to amblyopia in the visual system, "amblyaudia" is a term used to describe persistent hearing difficulty experienced by individuals with a history of asymmetric hearing loss (AHL) during a critical window of brain development. Few clinical reports have described this phenomenon and its consequent effects on central auditory processing. We aim to (1) define the concept of amblyaudia and (2) review contemporary research on its pathophysiology and emerging clinical relevance.

DATA SOURCES

PubMed, Embase, and Cochrane databases.

REVIEW METHODS

A systematic literature search was performed with combinations of search terms: "amblyaudia," "conductive hearing loss," "sensorineural hearing loss," "asymmetric," "pediatric," "auditory deprivation," and "auditory development." Relevant articles were considered for inclusion, including basic and clinical studies, case series, and major reviews.

CONCLUSIONS

During critical periods of infant brain development, imbalanced auditory input associated with AHL may lead to abnormalities in binaural processing. Patients with amblyaudia can demonstrate long-term deficits in auditory perception even with correction or resolution of AHL. The greatest impact is in sound localization and hearing in noisy environments, both of which rely on bilateral auditory cues. Diagnosis and quantification of amblyaudia remain controversial and poorly defined. Prevention of amblyaudia may be possible through early identification and timely management of reversible causes of AHL.

IMPLICATIONS FOR PRACTICE

Otolaryngologists, audiologists, and pediatricians should be aware of emerging data supporting amblyaudia as a diagnostic entity and be cognizant of the potential for lasting consequences of AHL. Prevention of long-term auditory deficits may be possible through rapid identification and correction.

Results of CAM therapy in amblyopic patients

AIM

to evaluate changes in visual acuity and compliance after CAM therapy in patients that initially failed to respond to occlusion or were non-compliant.

MATERIAL AND METHODS

Twenty nine patients aged 4-10 years that failed to improve under occlusion therapy were included in this prospective study. Patients were divided into two groups according to the age (16 patients of 4-7 years of age and 13 patients of 8-10 years of age) and two other groups according to the type of amblyopia (15 anisometropic and 14 strabismic cases). CAM stimulation was prescribed to all patients for six days. Occlusion therapy was then recommenced. Best corrected visual acuity was measured before the CAM course, immediately after, at 3- and 6-month follow-ups, and on the last visit.

RESULTS

Visual acuities in all study groups increased significantly immediately after the CAM therapy with further improvement during the follow-up period.

CONCLUSION

CAM therapy for amblyopia is helpful in improving visual acuity as well as patients' compliance to subsequent occlusion therapy.

Discriminating anisometropic amblyopia from myopia based on interocular inhibition

Amblyopia screening during childhood is critical for early detection and successful treatment. In the current study, we develop and evaluate a screening method that exploits the imbalanced interocular inhibition between amblyopic and fellow eyes. In nineteen subjects with anisometropic amblyopia and twenty-two age-matched subjects with myopia, we measured the area under the contrast sensitivity functions (AUCSFs) in eight monocular conditions defined by the tested eye (left, right), patching of the untested eye (translucent, opaque), and refractive status (corrected, uncorrected). For each tested eye, we defined the inhibition index as the ratio between the AUCSF values obtained in the translucent and opaque patching conditions of the untested eye. To evaluate the screening potential of the inhibition index, we compared results from patients with amblyopia and myopia. With and without optical correction, the index was significantly lower in the amblyopic eye than in the fellow eye of the amblyopic subjects and both eyes of the myopic subjects. No significant difference was found among the two eyes of the myopic subjects and the fellow eyes of the amblyopic subjects. With the inhibition index as the predictor, a logistic regression model successfully discriminated amblyopic eyes from myopic eyes with 100% accuracy in the uncorrected condition. In the corrected condition, with the inhibition index and interocular visual acuity difference as predictors, amblyopic eyes were likewise discriminated from myopic eyes with 100% accuracy. This pattern of CSF changes, caused by the different patching modes of the untested eye, provides a potential CSF signature to discriminate anisometropic amblyopia from myopia.

Binocular versus standard occlusion or blurring treatment for unilateral amblyopia in children aged three to eight years

BACKGROUND

Current treatments for amblyopia in children, occlusion and pharmacological blurring, have had limited success, with less than two-thirds of children achieving good visual acuity of at least 0.20 logMAR in the amblyopic eye, limited improvement of stereopsis, and poor compliance. A new treatment approach, based on the dichoptic presentation of movies or computer games (images presented separately to each eye), may yield better results, as it aims to balance the input of visual information from each eye to the brain. Compliance may also improve with these more child-friendly treatment procedures.

OBJECTIVES

To determine whether binocular treatments in children aged three to eight years with unilateral amblyopia result in better visual outcomes than conventional occlusion or pharmacological blurring treatment.

SEARCH METHODS

We searched the Cochrane Eyes and Vision Group Trials Register (last date of searches: 14 April 2015), the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 3), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to April 2015), EMBASE (January 1980 to April 2015), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov), and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials.

SELECTION CRITERIA

Two review authors independently screened the results of the search in order to identify studies that met the inclusion criteria of the review: randomised controlled trials (RCTs) that enrolled participants between the ages of three and eight years old with unilateral amblyopia, defined as best-corrected visual acuity (BCVA) worse than 0.200 logMAR in the amblyopic eye, and BCVA 0.200 logMAR or better in the fellow eye, in the presence of an amblyogenic risk factor such as anisometropia, strabismus, or both. Prior to enrolment, participants were to have undergone a cycloplegic refraction and comprehensive ophthalmic examination including fundal examination. In addition, participants had to have completed a period of optical treatment, if indicated, and BCVA in the amblyopic eye had to remain unchanged on two consecutive assessments despite reportedly good compliance with glasses wearing. Participants were not to have received any treatment other than optical treatment prior to enrolment. We planned to include any type of binocular viewing intervention; these could be delivered on different devices including computer monitors viewed with LCD shutter glasses or hand-held screens including mobile phone screens with lenticular prism overlay. Control groups were to have received standard amblyopia treatment; this could include occlusion or pharmacological blurring of the better-seeing eye. We planned to include full-time (all waking hours) and part-time (between 1 and 12 hours a day) occlusion regimens.

DATA COLLECTION AND ANALYSIS

We planned to use standard methodological procedures expected by The Cochrane Collaboration. We had planned to meta-analyse the primary outcome, that is mean distance BCVA in the amblyopic eye at 12 months after the cessation of treatment.

MAIN RESULTS

We could identify no RCTs in this subject area.

AUTHORS' CONCLUSIONS

Further research is required to allow decisions about implementation of binocular treatments for amblyopia in clinical practice. Currently there are no clinical trials offering standardised evidence of the safety and effectiveness of binocular treatments, but results from non-controlled cohort studies are encouraging. Future research should be conducted in the form of RCTs, using acknowledged methods of visual acuity and stereoacuity assessment with known reproducibility. Other important outcome measures include outcomes reported by users, compliance with treatment, and recurrence of amblyopia after cessation of treatment.

Danish Rural Eye Study: the association of preschool vision screening with the prevalence of amblyopia

PURPOSE

To determine the prevalence of amblyopia in Denmark before and after the initiation of the Danish national preschool vision screening programme.

METHODS

In a population-based cross-sectional study, 3826 participants of the Danish General Suburban Population Study (GESUS) aged 20 years and older from a Danish rural municipality received a complete general health examination and an ophthalmological interview and examination. This study included a comprehensive ophthalmologic interview, measurement of best corrected visual acuity (BCVA) in each eye, Hirschberg's test for strabismus and two 45-degree retinal fundus photographs of each eye. A complete ophthalmologic examination was performed when indicated.

RESULTS

The prevalence of monocular visual impairment (MVI) was 4.26% (95% CI, 3.66-4.95, n = 163). Amblyopia was the most common cause, accounting for 33%. The prevalence of amblyopia was 1.44% (95% CI, 1.01-1.81, n = 55), being higher among non-preschool vision screened persons compared to those who were offered (estimated 95% attendance) preschool vision screening (1.78%, n = 41, 95% CI 1.24-2.33 versus 0.44%, n = 2, 95% CI, 0.12-1.60, p = 0.024). The leading cause of amblyopia was anisometropia (45.5%, 25/55).

CONCLUSIONS

Amblyopia was the most common cause of MVI. Following the initiation of the Danish national preschool vision screening programme, which has an approximate attendance rate of 95%, the prevalence of amblyopia decreased by fourfold.

Performance of the Plusoptix A09 photoscreener in detecting amblyopia risk factors in Chinese children attending an eye clinic

Purpose

To assess the accuracy of the Plusoptix A09 photoscreener in detecting amblyopia risk factors in children and determine referral criteria when using Plusoptix A09 for a large-scale vision screening.

Methods

Pediatric patients attending our eye clinic underwent a comprehensive ophthalmic examination that included photorefraction, orthoptic examination, anterior segment assessment, fundus examination and cycloplegic retinoscopy. The measurements were collected for statistical analyses.

Results

One hundred and seventy-eight children (mean age ± SD: 6.2±2.4 years, range: 2.2 to 14.1 years) were included in the study. The mean spherical equivalent (SE) obtained using Plusoptix A09 (P_SE) was 0.57 D lower than that obtained from cycloplegic retinoscopy (CR_SE) (P = 0.00). However, there was no statistically significant difference of Jackson cross cylinder J₀ and J₄₅ between Plusoptix A09 (P_J) and cycloplegic retinoscopy (CR_J) (P = 0.14, P = 0.26). The relationship of SE obtained from Plusoptix A09 and SE obtained from cycloplegic retinoscopy was presented as the equation: CR_SE = 0.358 + 0.776 P_SE + 0.064 P_SE² + 0.011 P_SE³. Based on the Receiver Operating Characteristic (ROC) curve, the Plusoptix A09 had an overall sensitivity of 94.9% and specificity of 67.5% for detecting refractive amblyopia risk factors. The sensitivity and specificity of the Plusoptix A09 for detection of strabismus were 40.7% and 98.3%, respectively; detection of amblyopia and/or strabismus was 84.7% and 63.2%, respectively.

Conclusions

The Plusoptix A09 photoscreener underestimated hyperopia and overestimated myopia according to SE when compared with cycloplegic retinoscopy. The accuracy of the Plusoptix A09 in detecting amblyopia risk factors in children could be improved by the regression equation and optimized criteria for refractive amblyopia risk factors developed in the present study. Moreover, the Plusoptix A09 photoscreener is not suitable for a large-scale strabismus screening when it is applied solely.

Prevalence of amblyopia in primary school children in Qassim province, Kingdom of Saudi Arabia

PURPOSE

To determine the prevalence and causes of amblyopia in primary school children in Qassim province, Kingdom of Saudi Arabia (KSA).

MATERIALS AND METHODS

In this cross sectional study, 5176 children, aged 6 to 13 years (mean - 9.53 ± 1.88 years) were evaluated. There were 2573 (49.71%) males and 2603 (50.29%) females. Distance visual acuity (V/A) was tested monocularly using a logMAR chart with and without correction. Cycloplegic refraction was performed in children with reduced vision. To determine the etiology of amblyopia, children were enrolled if there was a difference in V/A of two or more lines between eyes or an absolute reduction in acuity <20/30 in either eye, that could not be corrected by refraction. P ≤ 0.05 was considered statistically significant.

RESULTS

There 202 out of 5176 (3.90%) with ambylopia. There are 98 (1.88%) amblyopic females. There was no statistical difference in gender for amblyopes (P > 0.05). The prevalence of amblyopia was statistically significant higher in the older age group (10-13 year) compared to younger age group (6 to 9 years) (P < 0.05). Unilateral amblyopia (3.24%) was more frequent than bilateral amblyopia (0.66%). The most frequent causes of amblyopia were refractive error (94.56%), of which anisometropic amblyopia was present in 77.72%, isoametropic amblyopia in 16.84% and strabismus in 5.44%.

CONCLUSION

The prevalence of amblyopia in Qassim province, KSA, is 3.9% which is similar or higher than other published studies on amblyopia. Anisometropic refractive errors are the most common underlying cause for this population. We recommend implementation of visual screening programs for children with appropriate clinical and social settings for early detection and proper management of amblyopia.

Increased prevalence of ametropia in children with neurofibromatosis type 1 disease

Neurofibromatosis type 1 disease is an autosomal dominant disorder associated with numerous ophthalmic and systemic manifestations. Organic causes of visual loss include optic pathway gliomas, orbital plexiform neurofibroma, and glaucoma. In this study, the authors analyzed the prevalence of ametropia as a cause for visual loss in children with neurofibromatosis type 1 disease younger than age 12 years compared to matched controls. Only children with normal neuroimaging were evaluated. Myopia, hyperopia, astigmatism, and anisometropia were all more common in children with neurofibromatosis type 1 disease; however, statistically significant differences were observed in mild myopia and astigmatism alone. A higher need for optical correction was found in children with neurofibromatosis type 1 disease (33.3% vs 17.1% of controls, P = .049). In conclusion, children with neurofibromatosis type 1 disease have a higher prevalence of ametropia, especially mild myopia and astigmatism, often requiring optical correction. Routine refraction screening is recommended for limiting preventable visual loss.

Prevalence and etiology of amblyopia in Southern India: results from screening of school children aged 5-15 years

PURPOSE

To determine the prevalence and etiology of amblyopia in school children.

METHODS

A total of 4020 school children aged between 5 and 15 years were screened in a population-based, cross-sectional study. Best corrected visual acuity and detailed ophthalmic evaluation were performed in all participants. Amblyopia associated with degraded visual input due to high refractive error was labeled ametropic amblyopia. Anisometropic amblyopia was diagnosed in participants with interocular refractive error difference ≥1 diopter. Strabismic amblyopia included that due to conflicting visual inputs between the eyes due to squint. Stimulus deprivation amblyopia was defined as amblyopia due to obstruction of the visual axis.

RESULTS

Prevalence of amblyopia was 1.1% (n = 44). The number of boys with amblyopia (n = 25, 57%) was slightly higher than the number of girls with amblyopia (n = 19, 43%; p = 0.6). A total of 28 (63.7%) children had mild to moderate amblyopia, whereas 16 (36.3%) had severe amblyopia. Underlying amblyogenic causes were ametropia (50%), anisometropia (40.9%), strabismus (6.8%), visual deprivation (4.5%) and combined causes (2.2%). No statistically significant difference was noted in the prevalence of amblyopia between rural (1.2%) and urban (0.9%) children (p = 0.5).

CONCLUSION

In this study, the prevalence of amblyopia was 1.1% of the school children. Ametropia and anisometropia were the most common causes of amblyopia. We did not find any significant difference in amblyopia prevalence between rural and urban school children.

The relationship between anisometropia and amblyopia

This review aims to disentangle cause and effect in the relationship between anisometropia and amblyopia. Specifically, we examine the literature for evidence to support different possible developmental sequences that could ultimately lead to the presentation of both conditions. The prevalence of anisometropia is around 20% for an inter-ocular difference of 0.5D or greater in spherical equivalent refraction, falling to 2-3%, for an inter-ocular difference of 3D or above. Anisometropia prevalence is relatively high in the weeks following birth, in the teenage years coinciding with the onset of myopia and, most notably, in older adults starting after the onset of presbyopia. It has about one-third the prevalence of bilateral refractive errors of the same magnitude. Importantly, the prevalence of anisometropia is higher in highly ametropic groups, suggesting that emmetropization failures underlying ametropia and anisometropia may be similar. Amblyopia is present in 1-3% of humans and around one-half to two-thirds of amblyopes have anisometropia either alone or in combination with strabismus. The frequent co-existence of amblyopia and anisometropia at a child's first clinical examination promotes the belief that the anisometropia has caused the amblyopia, as has been demonstrated in animal models of the condition. In reviewing the human and monkey literature however it is clear that there are additional paths beyond this classic hypothesis to the co-occurrence of anisometropia and amblyopia. For example, after the emergence of amblyopia secondary to either deprivation or strabismus, anisometropia often follows. In cases of anisometropia with no apparent deprivation or strabismus, questions remain about the failure of the emmetropization mechanism that routinely eliminates infantile anisometropia. Also, the chronology of amblyopia development is poorly documented in cases of 'pure' anisometropic amblyopia. Although indirect, the therapeutic impact of refractive correction on anisometropic amblyopia provides strong support for the hypothesis that the anisometropia caused the amblyopia. Direct evidence for the aetiology of anisometropic amblyopia will require longitudinal tracking of at-risk infants, which poses numerous methodological and ethical challenges. However, if we are to prevent this condition, we must understand the factors that cause it to develop.

The accuracy of the plusoptiX A08 photoscreener in detecting risk factors for amblyopia in central Iowa

PURPOSE

To evaluate the accuracy of the plusoptiX A08 photoscreener in detecting risk factors for amblyopia in children aged 0-5 years in central Iowa.

METHODS

The medical records of consecutive patients seen at 1 practice during a 2-month period were retrospectively reviewed. All patients were screened with the plusoptiX A08 photoscreener and received a comprehensive pediatric ophthalmology examination. Photoscreening results, according to our age-based criteria, were compared with the comprehensive examination findings. Patients were considered to have amblyopia or amblyogenic risk factors in the comprehensive examination based on the American Association for Pediatric Ophthalmology and Strabismus referral criteria guidelines.

RESULTS

A total of 290 children were examined during the study period. Of these, 190 (66%) patients were found to have amblyopia or amblyogenic risk factors during the pediatric ophthalmology examination on the basis of American Association for Pediatric Ophthalmology and Strabismus guidelines. The plusoptiX A08 offered an overall testability rate of 98%, sensitivity of 87%, specificity of 88%, positive predictive value of 93%, and negative predictive value of 78%. The sensitivity for detection of strabismus ≤20(Δ) was 52%.

CONCLUSIONS

The plusoptiX showed a high sensitivity for the detection of refractive amblyogenic risk factors and had a high successful testability rate in infants; however, it had low sensitivity for detecting strabismus ≤20(Δ). We postulate that sensitivity for detecting amblyogenic risk factors can be improved by combining the use of this instrument with a cover or stereo test.

Practical community photoscreening in very young children

OBJECTIVE

Recent US Preventive Services Task Force recommendations on vision screening reported insufficient data to recommend vision screening in children <3 years of age. The Iowa photoscreening program, KidSight, has screened children from 6 months of age and older since 2000. We report our experience with vision screening in these children and compare the results of the photoscreens in children younger than 3 years with those of children of preschool age and older.

METHODS

A retrospective review of results from the Iowa KidSight database using the MTI PhotoScreener containing results of children screened between May 1, 2000, and April 30, 2011.

RESULTS

During the 11 years of the study, 210 695 photoscreens on children were performed at 13 750 sites. In the <3-year age group, the unreadable rate was 13.0%, the referral rate was 3.3%, and the overall positive-predictive value was 86.6%. In the 3- to 6-year-old children, the unreadable rate was 4.1%, the referral rate was 4.7%, and the overall positive-predictive value was 89.4%.

CONCLUSIONS

No statistically significant difference was found in screening children from 1 to 3 years old compared with screening children >3 years old. These results confirm that early screening, before amblyopia is more pronounced, can reliably detect amblyogenic risk factors in children younger than 3 years of age, and we recommend initiation of photoscreening in children aged 1 year and older.

Amblyopia and refractive errors among school-aged children with low socioeconomic status in southeastern Turkey

PURPOSE

To investigate the prevalence of refractive errors and other eye diseases, incidence and types of amblyopia in school-aged children, and their relation to gender, age, parental education, and socioeconomic factors.

METHODS

A total of 21,062 children 6 to 14 years old were screened. The examination included visual acuity measurements and ocular motility evaluation. Autorefraction under cycloplegia and examination of the external eye, anterior segment, media, and fundus were performed.

RESULTS

There were 11,118 females and 9,944 males. The average age was 10.56 ± 3.59 years. When all of the children were evaluated, 3.2% had myopia and 5.9% had hyperopia. Astigmatism 0.50 D or greater was present in 14.3% of children. Myopia was associated with older age, female gender, and higher parental education. Hyperopia was inversely proportional with older age. Spectacles were needed in 4,476 (22.7%) children with refractive errors, and 10.6% of children were unaware of their spectacle needs. Amblyopia was detected in 2.6% of all children. The most common causes of amblyopia were anisometropia (1.2%) and strabismus (0.9%).

CONCLUSION

Visual impairment is a common disorder in school-aged children. Eye health screening programs are beneficial in early detection and proper treatment of refractive errors.

Visual acuity testability and comparability in Australian preschool children: the Sydney Paediatric Eye Disease Study

PURPOSE

To establish standardised protocols for vision screening, testability and comparability of three different vision tests were examined in a population-based, cross-sectional sample of preschool children (Sydney Paediatric Eye Disease Study).

METHODS

Measurement of presenting monocular distance visual acuity (VA) using the Amblyopia Treatment Study (ATS) HOTV protocol, was attempted by all (1774) children aged≥24 months. In addition, in children aged≥60 months (576), VA was also tested using the logMAR retro-illuminated HOTV or Early Treatment Diabetic Retinopathy Study (ETDRS) linear charts (CSV 1000). Children able to have both eyes tested monocularly were considered.

RESULTS

Testability significantly increased with age for all VA tests. The ATS HOTV with an overall testability of 80% (females: 82%, males: 78%) was the most testable of the VA tests (P<0.0001). In children aged <3 years testability was low (≤47%) rising to≥80% in children aged≥3. In children≥60 months, testability was higher for the HOTV (94%) than the ETDRS (59%) chart. In those that did two VA tests, mean difference of the ATS HOTV compared with the HOTV(CSV) was -0.1, and compared with ETDRS was -0.12 (P<0.0001).

CONCLUSIONS

Children aged <3 years had poor VA testability, whereas those 3 years and above were highly testable using the ATS HOTV. The HOTV (CSV) retro-illuminated test was appropriate for children aged >5 years, and may be possible in younger children with early educational exposure. When comparing VA measures using these tests, the higher VA attained using the ATS HOTV, needs to be taken into account.

Childhood vision screening in Canada: public health evidence and practice

OBJECTIVES

Best practice guidelines recommend vision testing in children 3 to 5 years of age for the prevention of amblyopia; however, universal vision screening is controversial. In Canada, amblyopia screening can be the responsibility of physicians, optometrists, and/or Public Health. We review the evidence underlying preschool vision screening for amblyopia using an Evidence-based Public Health (EBPH) approach, and consider implications for the Public Health provision of universal screening programs for amblyopia in Canadian jurisdictions in light of present practices.

METHODS

We searched the literature to address each major screening criterion (disease, test, treatment, program requirements) necessary to support preschool vision screening for amblyopia. We also reappraised papers cited in two systematic reviews related to the impact of vision screening. The Chief Medical Officer of Health of each province/territory was sent a short survey asking whether there currently was a Public Health preschool vision screening program in place and if so, for specifics about the program.

RESULTS

An EBPH approach to the literature with respect to the criteria for screening and available intervention studies support amblyopia screening by Public Health. There is a public health divide in amblyopia screening practice in Canada; while some provinces maintain organized programs, others have chosen to delegate the task to other professionals, without a concurrent surveillance function to monitor disparities in uptake.

CONCLUSIONS

Amblyopia deserves attention from Public Health. Efforts should be made to maintain existing programs, and provinces without organized screening programs should reconsider their role in the prevention of inequities with regard to preventable blindness in Canadian children.

Validation and cost-effectiveness of a home-based screening system for amblyopia

PURPOSE

To investigate the cost-effectiveness of a novel home-based screening system for amblyopia and amblyogenic risk factors.

DESIGN

Evaluation of diagnostic test or technology.

PARTICIPANTS

Two thousand four hundred forty-two preschoolers 3 to 6 years of age from 10 kindergartens randomly selected from Guangzhou participated in the study in 2009.

METHODS

Preschoolers were assessed for amblyopia and amblyogenic risk factors by their parents using the home-based screening system and were re-evaluated by professionals who conducted a comprehensive eye examination.

MAIN OUTCOME MEASURES

Sensitivity, specificity, positive predictive value, negative predictive value, and the cost-benefit of the home-based screening system were calculated by comparing the results from the home-assessed model and those from the professional evaluation.

RESULTS

Three thousand three hundred children were invited to participate in the study, and 2308 (1216 boys and 1092 girls) completed all of the procedures. Twenty-four amblyopes were found by professional examinations. Fifteen of these amblyopes had not been diagnosed previously, and 12 of them were detected by the home-assessment model. The sensitivity, specificity, positive predictive value, and negative predictive value were 80.0%, 94.1%, 8.2%, and 99.9%, respectively. Professional examinations cost an average of US $1131.00 per case of amblyopia detected, whereas the cost was only US $266.00 per case for the home-based method. For amblyogenic factors, 50, 87, and 96 children were classified into grade I, II, or III according to the professional examinations. The corresponding numbers in the home-based system were 23, 29, and 15, respectively. Accordingly, the true positive rates were 46.0%, 33.3%, and 15.6% for each grade.

CONCLUSIONS

The home-based amblyopia screening system was found to be a simple, effective, and cost-beneficial method for amblyopia screening and amblyogenic risk factors. The approach offers a practical option for developing areas with large populations.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Accuracy of referrals from an orthoptic vision screening program for 3- to 4-year-old preschool children

PURPOSE

To determine the accuracy of orthoptist referrals from a preschool-based vision screening program for children 3-4 years of age and to report the outcomes of referred children.

METHODS

This was a retrospective review of records of participants in the preschool vision screening program in the Walsall, United Kingdom, area for the 2006-2007 school year. Screening examinations were performed by orthoptists and included assessment of visual acuity, ocular alignment, ocular motility, and stereoacuity.

RESULTS

For the 2006-2007 school year, 2,830 of 3,623 children (78%) were screened, Of these, 413 were referred to the Hospital Eye Service. Comparison of the screening results and the Hospital Eye Service examination revealed that recorded visual acuities were similar in 81% of subjects and ocular alignment in 94%. Visual acuity was 6/9 or better at the hospital examination in 87% of referred children, with 46% requiring spectacle use only; 17% of referrals were diagnosed with amblyopia.

CONCLUSIONS

Although the Walsall vision screening program diverged from UK national guidelines by testing at an earlier age, there was no evidence that earlier screening led to a large number of incorrect referrals, and early screening may allow for better outcomes. Sensitivity of screening was not tested, and orthoptist screening in the United Kingdom is likely to be more accurate in this age group than nonspecialist or lay screening that is performed in many other areas.

Laser refractive correction of myopia in visually impaired patients improves visual acuity

PURPOSE

To retrospectively evaluate the visual and refractive outcome of visually impaired adults treated with refractive surgery (photorefractive keratectomy or laser-assisted in situ keratomileusis).

METHODS

We searched a refractive surgery database comprising 1716 mildly visually impaired patients [best spectacle-corrected visual acuity (BSCVA) on a logMAR scale ≤ -0.1 (Snellen ≤ 0.8)] who had undergone either PRK or LASIK (n = 96). PRK patients who had visits at 5-7, 8-13 and 14-24 months postoperatively were selected. Eleven patients and nine PRK control myopic patients were found (cohort 1). From the same database, 41 visually impaired patients and 54 controls who had a postoperative control at 14-24 months postoperatively were chosen. These patients formed cohort 2.

RESULTS

Preoperatively, in cohort 1, the mean BSCVA on a logMAR scale was -0.15 ± 0.13 (Snellen 0.73 ± 0.16) in visually impaired patients and 0.04 ± 0.02 (Snellen 1.11 ± 0.17) in myopic controls. At 14-24 months postoperatively, the mean BSCVA improved to 0.05 ± 0.04 (Snellen 1.13 ± 0.10) in visually impaired patients and 0.05 ± 0.08 (Snellen 1.13 ± 0.21) in control patients. In cohort 2, preoperatively the mean BSCVA on a logMAR scale was -0.15 ± 0.12 (Snellen 0.74 ± 0.14) in visually impaired patients and 0.01 ± 0.03 (Snellen 1.04 ± 0.10) in myopic controls. At 14-24 months postoperatively, the mean BSCVA improved to 0.02 ± 0.07 (Snellen 1.06 ± 0.16) in visually impaired patients and 0.06 ± 0.06 (Snellen 1.15 ± 0.16) in control patients.

CONCLUSION

Refractive surgery improves BSCVA in visually impaired patients, possibly through plastic changes in the visual cortex. Consequently, refractive surgery may be used successfully for the treatment of visually impaired adults to enhance their visual acuity.

Assessment of a modification of Brückner's test as a screening modality for anisometropia and strabismus

BACKGROUND

Current amblyopia screening methods are not cost effective.

AIM

To evaluate the diagnostic capability of a modified Brückner test (MBT) for amblyopiogenic risk factors.

MATERIALS AND METHODS

We applied the MBT using the streak retinoscope to identify anisometropia and strabismus by noting an inter-ocular difference in movement and glow, from children who failed 6/9 Snellen on community vision screening, followed by comprehensive eye examination. STATISITICS: Data were analyzed by 2 × 2 tables for diagnostic test parameters (95% CI).

RESULTS

From 7998 children vision-screened, 392 failed 6/9 VA and were referred. Since 34 failed to reach the centers, and 15 were excluded due to poor/ no glow, data from 343 was analyzed. The prevalence of anisometropia of 0.5D was 17%, of 1D was 11% and of strabismus 5%. For the MBT the accuracy was ≥ 90% (95%CI 89% to 97%) over the three outcomes. The sensitivity, specificity, NPV and +LR for anisometropia of 0.5D were: 0.57 (0.48, 0.64), 0.97 (0.95, 0.98), 0.92 (0.90, 0.93) and 18 (9.7, 35); for 1D: 0.74(0.60, 0.82), 0.95 (0.94, 0.97), 0.97 (0.95, 0.98) and 16 (9.3, 28); and for strabismus: 0.5 (0.32, 0.66), 0.98 (0.97, 0.98), 0.97 (0.96, 0.98) and 20 (9.1, 42).

CONCLUSION

Our data suggests that the MBT is highly accurate and useful for ruling in anisometropia and strabismus in children who fail 6/9 Snellen. The MBT needs further validation, both by different care givers and on differing populations. It offers an affordable, portable, and clinically useful tool to detect anisometropia and strabismus. We suggest that performing an MBT prior to uniocular retinosocpy should be a routine practice.

Visual development in infants: physiological and pathological mechanisms

PURPOSE OF REVIEW

This review summarizes current knowledge on ocular conditions related to abnormal visual development in infants, including prevalence, risk factors, causes, and mechanisms involved. We discuss the role of eyeball growth with pathologic mechanism of visual deprivation and development of amblyopia in infants, particular developmental issues in preterm neonates, methods of visual assessment and screening, diagnosis, treatment, and nutritional issues.

RECENT FINDINGS

Visual development is incomplete at birth, particularly in premature infants; maturation of the visual system--including neurological and ocular components--is influenced by many factors including prenatal and postnatal nutrition and postnatal visual stimulation. In early life, particularly during sensitive periods of development, abnormal visual input, for example caused by visual deprivation mechanism, amblyopia, or ocular misalignment, leads to abnormalities in visual development, including abnormal eyeball growth and neurological changes. Untreated anomalies or abnormal visual development can result in long-term or even permanent visual impairment. Nutrition plays a key role in visual development: infant formulas containing nutrients essential for normal visual development (specifically omega-3 fatty acid docosahexaenoic acid and omega-6 fatty acid arachidonic acid) may protect nonbreast-fed infants against visual development abnormalities.

SUMMARY

Problems related to visual anomalies are common among young children, particularly in preterm neonates. Screening to enable early diagnosis and correction of visual deficiency is important as abnormal visual input can lead to abnormalities in visual development, which can become permanent visual impairment if left untreated. Optimized nutrition can help to reduce the risk of abnormal visual development and prevent long-term or permanent visual deficits.

Amblyopia: a mini review of the literature

Amblyopia is a form of cerebral visual impairment in the absence of an organic cause. It is considered to derive from the degradation of the retinal image associated with abnormal visual experience during the developmental period of the visual system in infancy and early childhood. Amblyopia is a significant cause of unilateral visual deficit in childhood and is still considered as one of the most common causes of persistent unilateral visual impairment in adulthood. The following review aims at presenting the contemporary literature regarding the prevalence, the aetiology, the neural correlates, the period of critical development, the treatment, the prognosis and the disability associated with this visual deficit.

Screening for visual impairment in children ages 1-5 years: update for the USPSTF

CONTEXT

Screening could identify preschool-aged children with vision problems at a critical period of visual development and lead to treatments that could improve vision.

OBJECTIVE

To determine the effectiveness of screening preschool-aged children for impaired visual acuity on health outcomes.

METHODS

We searched Medline from 1950 to July 2009 and the Cochrane Library through the third quarter of 2009, reviewed reference lists, and consulted experts. We selected randomized trials and controlled observational studies on preschool vision screening and treatments, and studies of diagnostic accuracy of screening tests. One investigator abstracted relevant data, and a second investigator checked data abstraction and quality assessments.

RESULTS

Direct evidence on the effectiveness of preschool vision screening for improving visual acuity or other clinical outcomes remains limited and does not adequately address whether screening is more effective than no screening. Regarding indirect evidence, a number of screening tests have utility for identification of preschool-aged children with vision problems. Diagnostic accuracy did not clearly differ for children stratified according to age, although testability rates were generally lower in children 1 to 3 years of age. Treatments for amblyopia or unilateral refractive error were associated with mild improvements in visual acuity compared with no treatment. No study has evaluated school performance or other functional outcomes.

CONCLUSIONS

Although treatments for amblyopia or unilateral refractive error can improve vision in preschool-aged children and screening tests have utility for identifying vision problems, additional studies are needed to better understand the effects of screening compared with no screening.

Screening for refractive errors in children: the plusoptiX S08 and the Retinomax K-plus2 performed by a lay screener compared to cycloplegic retinoscopy

PURPOSE

To evaluate the performance of the autorefractor Retinomax K-plus2 and the photoscreener plusoptiX S08 in measuring refractive errors by comparing them with cycloplegic retinoscopy (CR) and to assess limitations associated with their use.

METHODS

Cross-sectional study to compare data from CR, performed by an orthoptist, to data from Retinomax K-plus2 and plusoptiX S08 performed by a lay screener. Sensitivity and specificity for the detection of significant refractive errors were determined according to American Academy of Pediatric Ophthalmology and Strabismus criteria.

RESULTS

Two hundred children were included, with a mean age of 5.2 ± 2.6 years (3 months to 11 years). Compared to CR, the plusoptiX S08 showed a mean difference of -1.13 ± 1.25 D (95% limits of agreement [LOA], -3.59 to +1.32) for spherical equivalent (SE) and -0.23 ± 0.53 D (LOA, -1.28 to +0.81) for the cylinder. Mean difference for the Retinomax K-plus2 before cycloplegia was -0.08 ± 0.58 D (LOA, -1.23 to +1.06) for SE and 0.03 ± 0.38 D (LOA, -0.72 to +0.78) for the cylinder; after cycloplegia -2.11 ± 1.64 D (LOA, -5.33 to +1.10) for SE and -0.06 ± 0.47 D (LOA, -0.98 to +0.86) for the cylinder. Sensitivity for detecting hyperopia >3.5 D with the plusoptiX S08 was 33.3%, the Retinomax before cycloplegia 31.0% and after cycloplegia 84.6% and high for detecting myopia, astigmatism, and anisometropia.

CONCLUSIONS

Retinomax K-plus2 and plusoptiX S08 have high sensitivity for the detection of myopia, astigmatism, and anisometropia compared to cycloplegic retinoscopy; however, when used without cycloplegia, hyperopia is underestimated.

Comparing a traditional single optotype visual acuity test with a computer-based visual acuity test for childhood amblyopia vision screening: a pilot study

OBJECTIVE

To investigate the effectiveness of a traditional flip-chart optotype test, the Sheridan Gardiner test (SGT), in measuring visual acuity and detecting amblyopia, compared with a free, computer-based test (CBT), LazyeyeTest.org.

DESIGN

Prospective, masked, cross-over study.

PARTICIPANTS

Seventy kindergarten-aged children from a downtown Toronto elementary school enrolled in the Kids2See vision screening program.

METHODS

Visual acuity in the children was measured monocularly using both tests. The visual acuity results, number of referrals, and outcomes of referrals were compared, as was the usability from the perspective of the child and the vision screener.

RESULTS

The children were more likely to score low visual acuity values with the CBT, a result predicted by the existence of crowding bars on the CBT's optotypes. The CBT referred an extra 5 children than the SGT, and of the 4 who saw an ophthalmologist 2 had amblyopia. The SGT referred one child not referred by the CBT. The Cohen's kappa coefficient was 0.67 and the difference in referral rates was not significant (p = 0.13). Relative to the SGT, the sensitivity of the CBT was 88%, specificity was 92%, positive predictive value was 58%, and negative predictive value was 98%. The CBT appeared to be easier and more efficient to administer, more stimulating, and was preferred by the children.

CONCLUSIONS

Replacing the SGT with LazyeyeTest.org would increase the efficiency and likely the sensitivity of amblyopia screening. Further research is warranted to confirm the outcomes and to determine if the CBT can be administered accurately by lay screeners.

A review of the evidence on the effectiveness of children's vision screening

Screening programmes enable health conditions to be identified so that effective interventions can be offered. The aim of this review was to determine: (1) the effectiveness of children's vision screening programmes; (2) at what age children should attend vision screening; and (3) what form vision screening programmes should take to be most effective. A literature review on the effectiveness of vision screening programmes in children aged 0-16 years was undertaken. Eligible studies/reviews were identified through clinical databases, hand searches and consultation with expert reviewers. The methodological quality of papers was rated using National Health and Medical Research Council (NHMRC) guidelines. Screening of children 18 months to 5 years, and subsequent early treatment, led to improved visual outcomes. The benefit was primarily through treatment of amblyopia, with improved visual acuity of the amblyopic eye. However, the overall quality of the evidence was low. The implication of improved visual acuity (e.g. any potential impact on quality of life) was not considered. Without consideration of 'quality of life' values, such as loss of vision in one eye or possibility of future bilateral vision loss, the cost-effectiveness of screening is questionable. Screening and treating children with uncorrected refractive error can improve educational outcomes. Evidence suggested that screening occur in the preschool years. Orthoptists were favoured as screening personnel; however, nurses could achieve high sensitivity and specificity with appropriate training. Further research is required to assess the effectiveness of neonatal screening. Most studies suggested that children's vision screening was beneficial, although programme components varied widely (e.g. tests used, screening personnel and age at testing). Research is required to clearly define any improvements to quality of life and any related economic benefits resulting from childhood vision screening. The evidence could be used to guide optimization of existing programmes.

Design of a randomized clinical trial to improve rates of amblyopia detection in preschool aged children in primary care settings

PURPOSE

To present the design of a cluster randomized controlled trial (cRCT) to evaluate the effectiveness of a web-based intervention for improving provider knowledge about strabismus and amblyopia (S/A) and preschool vision screening (PVS), increase PVS rates, and improve rates of S/A diagnoses made by eye specialists. This is the first cRCT targeting amblyopia prevention.

METHODS

Participants were Medicaid providers in AL, SC, or IL who had Internet access and had filed at least 8 claims for well child visits (WCV) for children ages 3 or 4 years old during a 12-month period before enrollment. Randomization to the Intervention (vision) or Control (blood pressure) arm occurred at the cluster level, defined as the provider (or group of providers) and his/her patients seen for WCVs.

RESULTS

65 Intervention providers (IPs) with 3547 children aged 3 or 4 years, and 71 Control providers (CPs) with 5053 children enrolled. The study will report measures of knowledge and self-reported vision screening behaviors from web-based data. The primary outcomes will be rates of PVS among PCPs, and rates of diagnosis of S/A by eye specialists among the children belonging to Control and Intervention practices.

CONCLUSIONS

We had the same difficulty recruiting PCPs as reported by others. Baseline rates of PVS were low (14.1%), as were rates that S/A were diagnosed by eye providers (1.4%). Our data show a need to improve both primary outcome measures.

Vision screening in preschool children: do the data support universal screening?

BACKGROUND

Comprehensive, systematic reviews on the benefit of vision screening in preschool children were published in 2008 by major national organizations in both Germany and the United Kingdom. These reviews raised public interest in the topic.

METHODS

This article contains a discussion of the sensitivity, specificity, efficacy, and cost-effectiveness of preschool vision screening, on the basis of the two national reports mentioned above as well as relevant literature retrieved by a selective PubMed search.

RESULTS

All studies that have been published to date on the efficacy of preschool visual screening suffer from methodological flaws. The available data suggest a benefit from screening, though this has not been proven. Model calculations reveal that the positive predictive value of screening tests performed in isolation is inadequate. The authors of the two national reports applied different methods and arrived at similar, but not identical conclusions. Preschool vision screening may also be cost-effective; whether this is the case or not depends on the probability of a long-term benefit--specifically, on the probability of preventing bilateral loss of vision in adulthood. To prevent one such case, it is estimated that 13 cases of childhood amblyopia must be identified and successfully treated (number needed to treat [NNT] = 13).

CONCLUSION

The available data do not allow any firm conclusion about the efficacy and cost-effectiveness of preschool vision screening. Further clinical studies are needed to answer these questions.

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.

Photo screening around the world: Lions Club International Foundation experience

PURPOSE

To describe the use of photoscreening for preschool vision screening in several diverse locations throughout the world.

METHODS

The MTI photo screener was used to screen pre-verbal children; photographs were interpreted using standard criteria.

RESULTS

The Tennessee vision screening program remains successful, screening over 200,000 children during the past 8 years. Similar programs modeled across the United States have screened an additional 500,000 children. A pilot demonstration project in Hong Kong, Beijing, and Brazil screened over 5000 additional children with good success and appropriately low referral rates.

CONCLUSION

Photoscreening can be an appropriate technique for widespread vision screening of preschool children throughout the world.

Infant hyperopia: detection, distribution, changes and correlates-outcomes from the cambridge infant screening programs

PURPOSE

To report on two population screening programs designed to detect significant refractive errors in 8308 8- to 9-month-old infants, examine the sequelae of infant hyperopia, and test whether early partial spectacle correction improved visual outcome (strabismus and acuity). The second program also examined whether infant hyperopia was associated with developmental differences across various domains such as language, cognition, attention, and visuomotor competences up to age 7 years. Linked programs in six European countries assessed costs of infant refractive screening.

METHOD

In the first program, screening included an orthoptic examination and isotropic photorefraction, with cycloplegia. In the second program we carried out the same screening procedure without cycloplegia. Hyperopic infants (> or = +4 D) were followed up alongside an emmetropic control group, with visual and developmental measures up to age 7 years, and entered a controlled trial of partial spectacle correction.

RESULTS

The second program showed that accommodative lag during photorefraction with a target at 75 cm (focus > or = +1.5 D) was a marker for significant hyperopia. In each program, prevalence of significant hyperopia at 9 to 11 months was around 5%; manifest strabismus was 0.3% at 9 months and 1.5 to 2.0% by school age. Infant hyperopia was associated with increased strabismus and poor acuity at 4 years. Spectacle wear by infant hyperopes produced better visual outcome than in uncorrected infants, although an improvement in strabismus was found in the first program only. The corrections did not affect emmetropization to 3.5 years; however, both corrected and uncorrected groups remained more hyperopic than controls in the preschool years. The hyperopic group showed poorer overall performance than controls between 1 and 7 years on visuoperceptual, cognitive, motor, and attention tests, but showed no consistent differences in early language or phonological awareness. Relative cost estimates suggest that refractive screening programs can detect visual problems in infancy at lower overall cost than surveillance in primary care.

CONCLUSIONS

Photo/videorefraction can successfully screen infants for refractive errors, with visual outcomes improved through early refractive correction. Infant hyperopia is associated with mild delays across many aspects of visuocognitive and visuomotor development. These studies raise the possibility that infant refractive screening can identify not only visual problems, but also potential developmental and learning difficulties.

Impact of amblyopia on vision at age 12 years: findings from a population-based study

AIMS

To report prevalence of amblyopia and long-term impact of its treatment on vision in a population-based sample of 12-year-old Australian children.

METHODS

Logarithm of minimum angle of resolution (logMAR) visual acuity (VA) was measured in 2353 children (response rate 75.3%); visual impairment was defined as VA<6/12. Amblyopia was defined using various criteria of best-corrected VA, together with an amblyogenic factor and absence of significant organic pathology. Corroborative historical data on previous diagnosis and treatment were obtained from parental questionnaires.

RESULTS

Forty-four children (1.9%) were diagnosed with amblyopia, unilateral in 40 and bilateral in four. Isolated anisometropia was the most frequent cause (41%), followed by strabismus (25%), combined anisometropia and strabismus (23%), and high ametropia (9%). Myopia, hyperopia, and astigmatism were present in 28, 51, and 44% of amblyopic children, respectively, compared to 12, 4, and 9% of non-amblyopic children. Mean best-corrected VA in amblyopic eyes was 44.5 logMAR letters (Snellen equivalent 6/9), range: 11-60 letters. Most children with amblyopia (84%) had been treated. Only 27% were visually impaired in their amblyopic eye.

CONCLUSIONS

This report documents a low amblyopia prevalence in a population of 12-year-old Australian children. Amblyopic visual impairment was infrequent in this sample despite absence of mandatory vision screening.