Screening for amblyopia in preverbal children with photoscreening photographs: II. Sensitivity and specificity of the MTI photoscreener

Utilizing minicomputer technology for low-cost photorefraction: a feasibility study

Eccentric photorefraction is an objective technique to determine the refractive errors of the eye. To address the rise in prevalence of visual impairment, especially in rural areas, a minicomputer-based low-cost infrared photorefractor was developed using off-the-shelf hardware components. Clinical validation revealed that the developed infrared photorefractor demonstrated a linear working range between +4.0 D and -6.0 D at 50 cm. Further, measurement of astigmatism from human eye showed absolute error for cylinder of 0.3 D and high correlation for axis assessment. To conclude, feasibility was shown for a low-cost, portable and low-power driven stand-alone device to objectively determine refractive errors, showing potential for screening applications. The developed photorefractor creates a new avenue for telemedicine for ophthalmic measurements.

Photoleukocoria with smartphone photographs

A 3-year-old boy was referred with suspected leukocoria in the right eye, detected in all smartphone photographs taken by his parents. His medical and family history was unremarkable. The visual acuity was 20/20 in both eyes. Eye examination revealed full motility and normal pupils. The ocular fundi and ultrasonography appeared normal. The child was looking to the left side in his photographs, away from the camera, and illuminating the nasal retina. In this circumstance, the optic nerve head acts as a diffuse reflector, reflecting the light out of the eye through the pupil. In the case of normal clinical findings in a child presenting leukocoria in smartphone photographs (photoleukocoria), the ophthalmologist should suspect the possibility of the described phenomenon avoiding other studies.

[Possibilities and limitations of amblyopia screening with auto-refractometers]

Amblyopia is a frequent vision disorder with a prevalence of 3-6%, for which early treatment is more effective. More than half of the cases of amblyopia are due to refractive errors so that they are not obvious due to strabismus or other ocular abnormalities; therefore, examinations for early recognition are essential. Because no nationwide ophthalmological examination of infants with cycloplegia has been established in Germany, screening for refractive errors in the first 3 years of life could be very helpful. Only children with a very high risk of ametropia should be referred for a full ophthalmological and orthoptic assessment of cycloplegia in order to prevent excess prescription of eyeglasses. Mild amblyopia with a borderline refraction error can be more reliably detected with visual acuity tests at a later age of 3-4 years and still be treated successfully before entering school. Even with a good sensitivity and specificity of approximately 90%, refraction screening with handheld binocular video refractometers has a positive predictive value of 30%, which should be considered acceptable; however, screening with refractometers alone is insufficient to detect all types of amblyopia. Cataracts can easily be detected in >95% of patients but microstrabismus <6° cannot be detected with sufficient reliability. If other risk factors, such as a negative Lang stereopsis test, ptosis, other ocular abnormalities, developmental delay or a positive family history are present, a full ophthalmological evaluation with cycloplegic refraction is necessary.

Comparison of photorefraction, autorefractometry and retinoscopy in children

Photorefractive devices have been evaluated for their effectiveness in detecting anisometropia, hyperopia, myopia, and astigmatism. We investigated the reliability of Plusoptix S08, the newest photoscreener, and Topcon autorefractometer by comparing them with cycloplegic retinoscopy. Plusoptix S08, cycloplegic retinoscopy, and cycloplegic autorefractometer measurements for 235 eyes of 118 children (59 female, 59 male) with a mean age of 4.9 ± 2.6 and median age of 5 years (range 1-12) were conducted. The Plusoptix S08 produced the following mean (± SD) results--spherical 0.27 ± 1.64, cylindrical power -0.81 ± 0.71, axis 89.73 ± 61.18, and spherical equivalent -0.05 ± 1.61. The cycloplegic retinoscopy produced the following mean (± SD) results--spherical 0.12 ± 1.35, cylindrical power -0.89 ± 0.71, axis 92.18 ± 68.39, and spherical equivalent -0.15 ± 1.31. The cycloplegic autorefractometer produced the following mean (± SD) results--spherical 0.16 ± 1.44, cylindrical power -0.88 ± 0.72, axis 90.86 ± 68.21, and spherical equivalent -0.12 ± 1.41. This study has shown that cycloplegic autorefractometer and retinoscopy results are similar and Plusoptix S08 is a very safe, easy-to-use and reliable screening method of refraction, especially for ophthalmologists unskilled in retinoscopy. Plusoptix S08 is a useful tool for estimating refraction in patients for whom conventional autorefraction is not an option.

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.

Uncorrected visual acuity and noncycloplegic autorefraction predict significant refractive errors in Taiwanese preschool children

PURPOSE

To investigate the accuracy of uncorrected visual acuity (UCVA), stereopsis, and noncycloplegic autorefraction (NCAR) tests performed by vision-screening technicians and to determine the best referral criteria when using these methods to screen for significant refractive errors in preschool children.

DESIGN

Retrospective, case-control, and cross-sectional study.

PARTICIPANTS

We reviewed 1000 records for a population-based preschool vision-screening program. The target conditions were defined as myopia ≤-3.0 diopters (D), hyperopia ≥ 4.5 D, astigmatism ≥ 2.0 D, and anisometropia ≥ 2.0 D.

METHODS

Receiver operating characteristic (ROC) curve was used to calculate optimal referral cutoff values. The examination results obtained by the vision-screening technicians were compared with those obtained by a pediatric ophthalmologist, which were considered the gold standard.

MAIN OUTCOME MEASURES

The efficacies (sensitivity, specificity, positive predictive value, and negative predictive value) of different tests were evaluated.

RESULTS

In 7.0% (95% confidence interval [CI], 5.3-8.7) of the children, at least 1 eye showed 1 of the target conditions. If only the right eyes were considered, the prevalence of target conditions was 4.2% (95% CI, 2.9-5.5). The ROC curve analysis indicated that the NCAR cylinder test (cutoff value ≥ 0.875 D) was the best test for screening target conditions. With regard to age groups, UCVA ≤ 0.75 (Snellen equivalent) and ≤ 0.85 were the best referral criteria for ages ≤ 4 years and ≥ 5 years, respectively. Combining the UCVA test with the NCAR test (the child was referred after failing both tests) increased specificity without significantly decreasing sensitivity.

CONCLUSIONS

The UCVA and NCAR tests performed by vision-screening technicians are adequately sensitive and specific for preschool vision screening. The ROC curve analysis was used for determining the appropriate screening criteria for these tests, and combining the tests increased their accuracy. The screening criteria should be age dependent. When analyzing the test accuracy in ophthalmic problems, if the disease of interest does not symmetrically (in terms of disease severity and prevalence) involve both eyes, the prevalence based on only 1 eye should be interpreted with caution.

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.

Performance of the plusoptiX S04 photoscreener for the detection of amblyopia risk factors in children aged 3 to 5

PURPOSE

Our previous study of the plusoptiX S04 photoscreener included children ages 6 months to 16 years and allowed us to modify the referral criteria retrospectively to improve specificity and sensitivity. In this study we used the new referral criteria and tested children ages 3 to 5 years, a more appropriate range for a pediatric vision screening program.

METHODS

A total of 153 children were examined consecutively. Each patient was screened with the plusoptiX S04 photoscreener on the same day as part of a comprehensive pediatric ophthalmology examination.

RESULTS

Fifty-three percent of the patients were found to have amblyopia or amblyopia risk factors during the pediatric ophthalmology examination. By using these results as our standard, we calculated that the plusoptiX S04 photoscreener offered a sensitivity of 99%, specificity of 82%, false-positive rate of 18%, and false-negative rate of 1.2%. These findings were similar to the results we achieved in our previous study with a broader age range.

CONCLUSIONS

The plusoptiX S04 is an automated photoscreening device that takes multiple images in less than 30 seconds, determining a noncycloplegic refraction. Sensitivity and specificity suggests that testing the plusoptiX S04 for applications in a general screening environment should be considered.

A comparison of photorefraction and retinoscopy in children

PURPOSE

To compare the results of photorefraction measurement obtained with a Plusoptix CR03 to those of cycloplegic retinoscopy as a standard refraction method in children.

METHODS

We assessed the refractive status of 204 eyes in 204 healthy children. The values acquired via photorefraction (noncycloplegic refraction) with a Plusoptix CR03 device were compared with those obtained via cycloplegic retinoscopy. Both methods were used in the same eyes and in all children. The paired tt-test and Pearson's correlation analysis were used for statistical analysis.

RESULTS

The mean age was 7.1 +/- 2.4 years (range, 9 months to 14 years). The average spherical refractive error was +0.05 +/- 0.65 D for photorefraction versus +0.75 +/- 0.77 D for cycloplegic retinoscopy (average difference, -0.70 D; p < 0.001), with moderate correlation between measures (r = 0.63). The average cylinder power was +0.43 +/- 0.38 D for photorefraction versus +0.29 +/- 0.38 D for cycloplegic retinoscopy (average difference, +0.14 D; p < 0.001), with moderate correlation between measures (r = 0.70). The average spherical equivalent was +0.26 +/- 0.63 D for photorefraction versus +0.90 +/- 0.76 D for cycloplegic retinoscopy (average difference, -0.64 D; p < 0.001), with moderate correlation between measures (r = 0.63).

CONCLUSIONS

The Plusoptix CR03 device tends toward minus overcorrection in children, resulting in overdiagnosis of myopia. Studies of a population of subjects with a larger range of ametropia will be required to validate this instrument as a screening tool.

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.

Pediatric Amblyopia Risk Investigation Study (PARIS)

PURPOSE

To assess the learning curve, testability, and reliability of vision screening modalities administered by pediatric health extenders.

DESIGN

Prospective masked clinical trial.

METHODS

Two hundred subjects aged 3 to 6 underwent timed screening for amblyopia by physician extenders, including LEA visual acuity (LEA), stereopsis (RDE), and noncycloplegic autorefraction (NCAR). Patients returned for a comprehensive diagnostic eye examination performed by an ophthalmologist or optometrist.

RESULTS

Average screening time was 5.4 +/- 1.6 minutes (LEA), 1.9 +/- 0.9 minutes (RDE), and 1.7 +/- 1.0 minutes (NCAR). Test time for NCAR and RDE fell by 40% during the study period. Overall testability was 92% (LEA), 96% (RDE), and 94% (NCAR). Testability among 3-year-olds was 73% (LEA), 96% (RDE), and 89% (NCAR). Reliability of LEA was moderate (r = .59). Reliability of NCAR was high for astigmatism (Cyl) (r = .89), moderate for spherical equivalent (SE) (r = .66), and low for anisometropia (ANISO) (r = .38). Correlation of cycloplegic autorefraction (CAR) with gold standard cycloplegic retinoscopic refraction (CRR) was very high for SE (.85), CYL (.77), and moderate for ANISO (.48).

CONCLUSIONS

With NCAR, physician extenders can quickly and reliably detect astigmatism and spherical refractive error in one-third the time it takes to obtain visual acuity. LEA has a lower initial cost, but is time consuming, moderately reliable, and more difficult for 3-year-olds. Shorter examination time and higher reliability may make NCAR a more efficient screening tool for refractive amblyopia in younger children. Future study is needed to determine the sensitivity and specificity of NCAR and other screening methods in detecting amblyopia and amblyopia risk factors.

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.

Evaluation of the measurement of refractive error by the PowerRefractor: a remote, continuous and binocular measurement system of oculomotor function

BACKGROUND/AIM

The technique of photoretinoscopy is unique in being able to measure the dynamics of the oculomotor system (ocular accommodation, vergence, and pupil size) remotely (working distance typically 1 metre) and objectively in both eyes simultaneously. The aim of this study was to evaluate clinically the measurement of refractive error by a recent commercial photoretinoscopic device, the PowerRefractor (PlusOptiX, Germany).

METHOD

The validity and repeatability of the PowerRefractor was compared to: subjective (non-cycloplegic) refraction on 100 adult subjects (mean age 23.8 (SD 5.7) years) and objective autorefraction (Shin-Nippon SRW-5000, Japan) on 150 subjects (20.1 (4.2) years). Repeatability was assessed by examining the differences between autorefractor readings taken from each eye and by re-measuring the objective prescription of 100 eyes at a subsequent session.

RESULTS

On average the PowerRefractor prescription was not significantly different from the subjective refraction, although quite variable (difference +0.05 (0.63) D, p=0.41) and more negative than the SRW-5000 prescription (by -0.20 (0.72) D, p<0.001). There was no significant bias in the accuracy of the instrument with regard to the type or magnitude of refractive error. The PowerRefractor was found to be repeatable over the prescription range of -8.75D to +4.00D (mean spherical equivalent) examined.

CONCLUSION

The PowerRefractor is a useful objective screening instrument and because of its remote and rapid measurement of both eyes simultaneously is able to assess the oculomotor response in a variety of unrestricted viewing conditions and patient types.

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.

Amblyopia: detection, prevention, and rehabilitation

This year's literature on the detection, prevention, and rehabilitation of amblyopia is again somewhat dominated by the topic of vision screening, specifically photoscreening and also by the therapeutic challenges of compliance and late treatment. Basic scientists also have added to our knowledge and understanding of certain interesting and clinically significant characteristics of the visual perception of amblyopes.

Screening for amblyopia in preverbal children with photoscreening photographs. III. improved grading criteria for hyperopia

OBJECTIVE

To examine the ability of the Medical Technology and Innovations (MTI), Inc., Photoscreener (Cedar Falls, IA) to detect hyperopia and to improve the photograph grading criteria to screen for amblyopiogenic levels of hyperopia.

DESIGN

Cross-sectional study and reanalysis. PARTICIPANTS AND TESTING: In previous work, 392 participants received a complete ophthalmologic examination and were photographed using the MTI Photoscreener. For this study, all 209 participants with normal examination findings (65 children) or hyperopia without anisometropia (144 children) were selected. The data were reanalyzed using modified photograph grading and ophthalmologic examination failure criteria. Potential reasons for why many children with hyperopia passed photoscreening were explored.

MAIN OUTCOME MEASURES

We determined whether a study participant would pass or fail screening with a given photograph grading and ophthalmologic examination failure criteria.

RESULTS

Most children with hyperopia of +2.00 to +3.50 diopters (D) passed screening with the MTI instrument, in most cases because their photographs lacked bright crescents. When bright crescents in at least two of the four possible meridians were the grading guideline for screening failure and the pediatric ophthalmologists' consensus hyperopia failure criteria (> +3.50 D) were adopted, the sensitivity for hyperopia detection was 100% and the specificity was 88%. Identical results were obtained using the American Academy of Ophthalmology Preferred Practice Pattern hyperopia failure criteria (>/= +4.50 D).

CONCLUSIONS

The MTI photograph grading guidelines can be simplified, and the ophthalmologic examination failure criteria for hyperopia can be improved. The presence of a bright crescent in the lower or the left pupillary margin indicate hyperopia in an amblyopiogenic range (> +3.50 D).