Sensitivity of the MTI photoscreener for amblyogenic factors in infancy and early childhood

Tests for detecting strabismus in children aged 1 to 6 years in the community

BACKGROUND

Strabismus (misalignment of the eyes) is a risk factor for impaired visual development both of visual acuity and of stereopsis. Detection of strabismus in the community by non-expert examiners may be performed using a number of different index tests that include direct measures of misalignment (corneal or fundus reflex tests), or indirect measures such as stereopsis and visual acuity. The reference test to detect strabismus by trained professionals is the cover‒uncover test.

OBJECTIVES

To assess and compare the accuracy of tests, alone or in combination, for detection of strabismus in children aged 1 to 6 years, in a community setting by non-expert screeners or primary care professionals to inform healthcare commissioners setting up childhood screening programmes.Secondary objectives were to investigate sources of heterogeneity of diagnostic accuracy.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 12) (which contains the Cochrane Eyes and Vision Trials Register) in the Cochrane Library, the Health Technology Assessment Database (HTAD) in the Cochrane Library (2016, Issue 4), MEDLINE Ovid (1946 to 5 January 2017), Embase Ovid (1947 to 5 January 2017), CINAHL (January 1937 to 5 January 2017), Web of Science Conference Proceedings Citation Index-Science (CPCI-S) (January 1990 to 5 January 2017), BIOSIS Previews (January 1969 to 5 January 2017), MEDION (to 18 August 2014), the Aggressive Research Intelligence Facility database (ARIF) (to 5 January 2017), the ISRCTN registry (www.isrctn.com/editAdvancedSearch); searched 5 January 2017, ClinicalTrials.gov (www.clinicaltrials.gov); searched 5 January 2017 and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 5 January 2017. We did not use any date or language restrictions in the electronic searches for trials. In addition, orthoptic journals and conference proceedings without electronic listings were searched.

SELECTION CRITERIA

All prospective or retrospective population-based test accuracy studies of consecutive participants were included. Studies compared a single or combination of index tests with the reference test. Only those studies with sufficient data for analysis were included specifically to calculate sensitivity and specificity and determine diagnostic accuracy.Participants were aged 1 to 6 years. Studies reporting participants outside this range were included if subgroup data were available.Permitted settings included population-based vision screening programmes or opportunistic screening programmes, such as those performed in schools.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. In brief, two review authors independently assessed titles and abstracts for eligibility and extracted the data, with a third senior author resolving any disagreement. We analysed data primarily for specificity and sensitivity.

MAIN RESULTS

One study from a total of 1236 papers, abstracts and trials was eligible for inclusion with a total number of participants of 335 of which 271 completed both the screening test and the gold standard test. The screening test using an automated photoscreener had a sensitivity of 0.46 (95% confidence interval (CI) 0.19 to 0.75) and specificity of 0.97 (CI 0.94 to 0.99). The overall number affected by strabismus was low at 13 (4.8%).

AUTHORS' CONCLUSIONS

There is very limited data in the literature to ascertain the accuracy of tests for detecting strabismus in the community as performed by non-expert screeners. A large prospective study to compare methods would be required to determine which tests have the greatest accuracy.

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.

Wave-front analysis as screening technique for amblyogenic ametropia with and without cycloplegia

INTRODUCTION

For many years, attempts have been made to find an easy, efficient and inexpensive method to screen children for amblyogenic ametropia. Wave-front analysis is a new way to determine the refractive state of the eye from a distance. This technique could be a useful tool for infant screening.

PURPOSE

The purpose of the study was the evaluation of the efficacy of a commercially available wave-front analyzing autorefractometer (SureSight, software version 2.0, Welch Allyn, Skaneateles Falls, NY 13153, U.S.A.) in detecting amblyogenic ametropia in patients with and without cycloplegia.

METHODS

256 eyes (-28.25 D to +7.88 D spherical equivalent) of 128 patients (1-81 years) were examined with the wave-front autorefractometer under cycloplegia. Prior to this investigation, 108 eyes (-21.38 D to 75 D) of 54 of these patients (1-76 years) were refracted without cycloplegia. The readings of the wave-front autorefractometer were compared with the results of retinoscopy under cycloplegia.

RESULTS

Without cycloplegia, the sensitivity in detecting any amblyogenic ametropia such as anisometropia, astigmatism, myopia or hyperopia was 94%, while the specificity was 63%. Following cycloplegia, the sensitivity decreased to 87% and the specificity increased to 80%.

CONCLUSION

Wave-front analyzing refractometry is highly applicable for infant screening. At the present state of development, the efficacy in detecting amblyogenic ametropia is similar to that of other screening techniques and instruments that operate from distance. Cycloplegia enhances the sensitivity in detecting hyperopia and decreases the sensitivity in detecting astigmatism.

A new visual evoked potential system for vision screening in infants and young children

INTRODUCTION

With a prevalence of 3-5%, amblyopia represents a major public health problem. Effective treatment depends on early detection, and a broad consensus of professional opinion supports vision screening of infants and young children. No single method of screening has been demonstrated to be superior in detecting amblyopia and all methods have significant limitations.

METHODS

We assessed a new, "child-friendly" visual evoked potential (VEP) system (ENFANTtrade mark II, Diopsys Corp., Metuchen, NJ) for use in screening. We studied 122 children, aged 6 months to 5 years, comparing test results in a masked fashion to results of standard ophthalmologic examinations. A statistical program analyzed VEP differences between fellow eyes to determine a "pass" or "fail" for each child. For verbal patients, clinical amblyopia was defined as an interocular difference of two or more lines in best-corrected visual acuity. For preverbal patients, clinical amblyopia was defined by the clinician's decision to treat with occlusion or atropine penalization. Preverbal children with significant refractive errors or structural eye pathology were also considered clinically abnormal.

RESULTS

The test was completed by 94% of the study group, each child requiring an average of 10 minutes to complete testing of both eyes. The sensitivity was 0.973, the specificity 0.808, the positive predictive value 0.706, and the negative predictive value 0.984.

CONCLUSION

With its easy electrode placement and rapid, attractive stimulus, the new system overcomes technical difficulties which were associated with older VEP techniques. The test shows promise as a screening tool for detecting amblyopia and other visual deficits in young children.

A cost-benefit analysis of vision screening methods for preschoolers and school-age children

INTRODUCTION

The purpose of this study was to determine costs and benefits of visual acuity screening (VAS) or photoscreening (PS) in children.

METHODS

A societal-perspective, decision-analytic model compared VAS and PS conducted in three age groups: children 6 to 18 months, 3 to 4 years, and 7 to 8 years old. Literature estimates of sensitivity, specificity, and prevalence were used. Cost estimates and referral rates for surgical treatment were derived from a managed care database and the United States Social Security Administration.

RESULTS

All the benefit-to-cost ratios exceeded 1.0, meaning that all screening programs studied had benefits that exceeded the cost of screening. The total net benefit was highest for PS in children of 3 to 4 years of age (19,412 US dollars) and the least for VAS in children 7 to 8 years of age (15,179 US dollars). The benefit-to-cost ratio was highest for the VAS in children 3 to 4 years of age (162 US dollars) and least for PS in infants 6 to 18 month old (140 US dollars). Sensitivity of the PS instrument and VAS charts were the most influential variables in determining the most cost-beneficial program.

CONCLUSIONS

Based on the best available data, the net benefit of PS in 3 to 4 year old preschool children is greater than VAS in children 7 to 8 years of age, PS in toddlers, and VAS in children 3 to 4 years of age.

Sensitivity of photoscreening to detect high-magnitude amblyogenic factors

PURPOSE

To determine the sensitivity of a unique pupil-size based set of referral criteria of the MTI PhotoScreener(Medical Technology and Innovations, Inc, Cedar Falls, Iowa) to detect high magnitude refractive error.

METHODS

The photoscreening photographs of 949 preschool children previously analyzed were reevaluated with the new referral criteria. The original photographs had been obtained from pediatricians' offices and public health and Women, Infants, and Children's (WIC) clinics. The results of this analysis were compared with the gold standard clinical examination and cycloplegic refraction. Sensitivities were calculated for amblyogenic factors based on the magnitude of the refractive error.

RESULTS

For 26 patients with anisometropia, the sensitivity to detect anisometropia increased from 46% for +1.25 or greater spherical interocular difference to 100% for +2.50 spherical intraocular difference. For 36 patients with hypermetropia in at least 1 meridian ranging from +3.75 to +7.50 D, sensitivity increased from 53% to detect +3.75 D or greater to 70% for +5.00 D or greater. The sensitivity to detect hypermetropia of +5.75 D or greater was 100%. These criteria detected 82% of patients with astigmatism greater than or equal to +3.00 D, and 100% of patients with astigmatism greater than +3.50 D.

CONCLUSION

It is crucial that screening programs avoid over-referrals caused by high false-positive screening rates. The sensitivity of our new criteria increases with higher magnitude refractive error; patients with moderate and severe amblyogenic factors are almost never missed. While the sensitivity to detect lower magnitude refractive error is poor, the amblyogenic impact of such errors remains to be determined.

Screening for amblyogenic factors using a volunteer lay network and the MTI photoscreener. Initial results from 15,000 preschool children in a statewide effort

PURPOSE

To describe the results from a statewide preschool vision screening program using the MTI PhotoScreener (Medical Technology and Innovations, Inc., Cedar Falls, IA).

DESIGN

Cross-sectional study.

PARTICIPANTS

A total of 15,059 children aged 6 to 47 months enrolled in childcare and preschool settings throughout the state of Tennessee.

METHODS

Volunteers from local Lions Clubs took photoscreening photographs of children in a statewide effort. Photographs were interpreted at the Vanderbilt Ophthalmic Photography Reading Center using predetermined criteria. Children who failed the screening were referred to community ophthalmologists or optometrists who performed a comprehensive evaluation and forwarded the results to the authors.

MAIN OUTCOME MEASURES

Referral rate, unreadable rate, and predictive value positive (PVP).

RESULTS

During the 2 years of the screening program, 15,059 children were screened in 850 screenings. The screening referred 1013 children (6.7%), and 704 photographs (4.7%) were unreadable. Children who failed the screening had a significant abnormality (strabismus, anisometropia, high hypermetropia, high astigmatism, or high myopia) in 320 of the 531 cases where adequate follow-up results were reported. The PVP ranged from 84% when a diagnosis of strabismus was suggested by the photoscreen reading to 41% for astigmatism. Despite intense attention to follow-up, many children who failed the screening never received a formal eye examination.

CONCLUSIONS

The MTI PhotoScreener can be used by volunteers to screen preschool children and can have a high PVP in organized settings, provided that meticulous attention is paid to photograph interpretation and quality control. The PVP of the MTI PhotoScreener depends on the diagnosis suggested when the photograph is read. Significant obstacles exist in obtaining care for those who fail screening.

Evaluating photoscreeners II: MTI and fortune videorefractor

BACKGROUND

Amblyopia is a public health problem, usually amenable to treatment if detected early. Photoscreeners are camera-based instruments which can detect risk factors for amblyopia such as squint, refractive errors and media opacities.

OBJECTIVE

To evaluate two commercially available photoscreeners, namely the MTI photoscreener (Medical Technology, Iowa City, IA, USA) and the Fortune Optical VRB-100 (Fortune Optical, Padova, Italy) videophotorefractor, in a selected childhood population, having a high prevalence of amblyopia, before undertaking a full-scale trial in the general population.

SUBJECTS AND METHODS

The study design was a double-masked study. One-hundred and five children aged between 12 and 44 months with either normal vision or known visual disorders were photoscreened without cycloplegia using the Fortune and the MTI photoscreeners. Each child had a full ophthalmic examination either on the day of screening or in the preceding 6 months. Risk factors were: any manifest strabismus (squint), hypermetropia >3.5 D, anisometropia > or =1 D sphere, myopia > or =2 D sphere, astigmatism > or =2 D, media opacity or fundus abnormality affecting vision. The prevalence of risk factors for amblyopia was 60%. Photoscreen images were reviewed by two independent masked observers for indicators of amblyopiogenic risk factors and compared to the full ophthalmological examination to determine sensitivity and specificity for each instrument.

RESULTS

Sensitivities and specificities for the detection of risk factors for amblyopia were as follows. Fortune photoscreener: reader 1, sensitivity 60%, specificity 75%; reader 2, sensitivity 68% specificity 86%. MTI photoscreener: reader 1, sensitivity 56%, specificity 79%; reader 2, sensitivity 61%, sensitivity 86%. The results for reader 1 and 2 showed no significant differences for either instrument.

CONCLUSION

Both instruments performed unsatisfactorily in a study population aged 1-4 years with a high prevalence of amblyopiogenic risk factors. Accordingly, we do not believe that either instrument can be recommended to screen for eye disorders in children between the ages of 1 and 4 years because the low prevalence of amblyopia in this population demands very high sensitivity and specificity in order to avoid inappropriate over- or under-referral.

Development of refraction and strabismus

In the past year, as in recent years, most of the research on the development of refraction has focused on the following: 1) mechanisms whereby the eye can maintain coordinated growth to achieve emmetropia and 2) disruptions of emmetropization resulting in myopia or hyperopia. Preterm children and those with Down syndrome have higher refractive errors than other children, suggesting a failure of emmetropization. One of the most intriguing studies of the past year and one certain to lead to follow-up studies reported that ambient room illumination at night in a child's first two years is associated with a higher prevalence of myopia than sleeping in darkness. Reports on the development of hyperopia showed that it is axial in nature, similar to myopia. The effects of spectacle interventions to correct refractive errors are still being debated, with recent evidence from children suggesting that lenses do not exacerbate myopia. Analyses of risk factors and numerous new screening procedures detect patients with strabismus for referral at a variety of sensitivity and specificity levels. Hyperopia and high AC/A ratios are most clearly associated as causal agents for esotropia and intermittent exotropia. However, the action of even these simple mechanisms is confounded by abnormal binocular fusion mechanisms and the inability of optical correction to align the eyes of many patients. Asymmetric optokinetic nystagmus, latent nystagmus, and dissociated vertical deviation appear to be linked to infantile esotropia from before its onset. But the way the mechanisms underlying these oculomotor anomalies are causally related to the onset of infantile esotropia remains a mystery.