Evaluation of the iScreen digital screening system for amblyogenic factors

The positive predictive value of photoscreening devices for amblyogenic conditions

PURPOSE

To determine the positive predictive value (PPV) of four photoscreening devices in detecting amblyogenic risk factors (ARFs).

METHODS

This is a retrospective cohort study of 1,200 failed vision screenings (FVS) referred to a pediatric eye care practice from general pediatric practices over a 5-year period. Comprehensive eye examinations and cycloplegic refractions were performed. Examination findings and FVS parameters were collected through chart review after completion of visits. Inclusion criteria were age 1-8 years, eye examination within 3 months of initial FVS, and availability of FVS and visit documentation.

RESULTS

A total of 689 patients met inclusion criteria and were included in final analysis. The PPVs were 64.3% (95% CI, 62.73-65.81) for iScreen (n = 455), 26.8% (95% CI, 26.32-27.25) for Spot (n = 113), 18.9% (95% CI, 17.95-19.92) for Plusoptix (n = 38), and 18.5% (95% CI, 17.86-19.19) for GoCheck Kids (n = 55). For comparison, patients referred for failed Titmus tests were also analyzed. The PPV for Titmus testing was 39.3% (95% CI, 36.65-41.99; n = 28).

CONCLUSIONS

The only screening device with a PPV >50% was the iScreen. PPV is a useful metric, because it enables referring providers to guide patients on a post-screening plan and to choose devices that minimize over-referral. Device PPV in the general pediatric population can be markedly different from device PPV in already existing pediatric eye care populations due to inherently different prevalence of ARFs. The iScreen also detected conditions such as cataracts, anisocoria, eyelid abnormalities, esotropia, exotropia, hypertropia, and amblyogenic astigmatism.

Smartphone photography for screening amblyogenic conditions in children

Purpose

To validate the smartphone photography as a screening tool for amblyogenic conditions in children.

Methods

Children between 5 to 8 years attending eye out patient department (OPD) were photographed (by an optometrist) with a smartphone to capture their pupillary red reflexes followed by clinical examination by the principal investigator (PI). The PI on the basis of clinical examination identified children with significant amblyogenic conditions and, subsequently, two ophthalmologists independently categorized the photographs on the basis of color, symmetry, and shape of the pupillary reflex into normal or abnormal. The identification of amblyogenic conditions on clinical examination was compared to that on photography. Refractive errors <3D and anisometropia <2D were excluded. Sensitivity, specificity, positive predictive value, and negative predictive value of smartphone photography screening were determined.

Results

In all, 250 children were screened. Clinically 23.6% were harboring amblyogenic conditions. The mean sensitivity and specificity of screening by smartphone were 94% and 91%, respectively.

Conclusion

Smartphone photography is a reliable tool for detection of amblyogenic conditions in children.

Positive predictive value and screening performance of GoCheck Kids in a primary care university clinic

PURPOSE

To determine the positive predictive value (PPV) of GoCheck Kids, a smartphone-based photoscreener, to detect refractive amblyopia risk factors (ARFs) in children 3-48 months of age.

METHODS

The medical records of all children ≤48 months of age who failed GoCheck Kids photoscreening at a University of California, San Francisco, pediatric clinic between February 2017 and August 2018 and subsequently examined at the pediatric ophthalmology clinic were reviewed retrospectively. The PPV of GoCheck Kids was determined, where a true positive represents an abnormal cycloplegic refractive error according to the 2013 American Association of Pediatric Ophthalmology and Strabismus Vision Screening Committee criteria. For patients ≤12 months of age, refractive error thresholds were based on the 2017 American Academy of Ophthalmology Preferred Practice Patterns Pediatric Eye Evaluation guidelines.

RESULTS

A total of 2,963 children were screened with GoCheck Kids. Of these, 172 (5.8%) failed the screening, of whom 115 (67%) were evaluated in the pediatric ophthalmology clinic. The mean age was 24.9 ± 11.1months (range, 3-48). Fifty-seven patients met ARF criteria yielding a PPV of 50% (95% CI, 41%-60%). The PPV was higher in patients of Latino/hispanic ethnicity (75%; 95% CI, 57%-100%; P < 0.01) and changed significantly with increasing age (P = 0.03). Patients who were screened between age 3-12 months had the lowest PPV at 26% (95% CI, 14%-47%).

CONCLUSIONS

Modifying refractive error thresholds based on patient age and prevalence of ARFs in a population may improve the PPV of GoCheck Kids in a community-based screening program.

Preschool Vision Screening: Where We Have Been and Where We Are Going

PURPOSE

To discuss the evolution of instrument-based screening to detect amblyopia and its risk factors, and to summarize the importance of preschool vision screening.

DESIGN

Expert commentary.

METHODS

Author experiences were supplemented by a review and interpretation of pertinent medical literature.

RESULTS

Amblyopia remains a public health problem, as it is a common cause of monocular visual impairment. As a disease, amblyopia detection is best obtained by appropriate vision screening rather than by yearly mandated comprehensive eye examinations for all children; the US Preventative Services Task Force (USPSTF) recently reaffirmed their recommendations for vision screening in preschool children. Vision screening devices have evolved over the past 4 decades ranging from photoscreeners that use instantaneously developing film, to autorefractors that detect amblyopia risk factors, to nerve fiber layer scanners that detect the microtropia that nearly always accompanies amblyopia. When it is detected early, effective treatment for amblyopia can be initiated.

CONCLUSIONS

Amblyopia is a reversible cause of vision loss in children. Vision screening devices and screening programs have been extensively studied-experts and literature agree: vision screening devices and programs are cost-effective, are efficient, and are effective methods for amblyopia detection. The authors support the regular use of instrument-based vision screening in the medical home for all children until they reach a developmental stage where they can participate reliably in optotype-based vision screening.

Comparison of the iScreen and the MTI photoscreeners for the detection of amblyopia risk factors in children

BACKGROUND

The iScreen and Medical Technology and Innovations, Inc, (MTI) photoscreeners objectively screen for amblyopia risk factors in children. The MTI photoscreener has been extensively validated as a device that objectively screens for amblyopia risk factors in children, but limited availability of the instant film it uses may soon render it obsolete. More recently the iScreen photoscreener has been introduced. This device captures images digitally and transmits them electronically to be interpreted. We compared the newer iScreen's ability to detect amblyopia risk factors in children with the established MTI photoscreener.

METHODS

The medical records of consecutive subjects screened by both the iScreen and MTI photoscreeners on the same day were retrospectively reviewed. The iScreen images were analyzed by the device's central interpretation center; MTI images were analyzed by an expert masked examiner using the delta crescent method. Referrals by both instruments were compared to the results of cycloplegic examination as per the American Association for Pediatric Ophthalmology and Strabismus 2003 referral criteria.

RESULTS

A total of 169 children were included in the study. Of these, 107 (63%) were found to have amblyopia risk factors. The iScreen was found to have an accuracy rate of 81%, sensitivity of 87%, and specificity of 76%. The MTI was found to have an accuracy rate of 81%, sensitivity of 81%, and specificity of 81%.

CONCLUSIONS

The iScreen and MTI performed similarly in detecting amblyopia risk factors when compared to a comprehensive pediatric ophthalmology examination.

The effect of developmentally-at-risk status on the reliability of the iScreen® photorefractive device in young children

INTRODUCTION AND PURPOSE

We evaluated the impact of developmentally-at-risk status on the results of photorefractive screening with iScreen®.

PATIENTS AND METHODS

We sequentially recruited 169 children (aged 2-5 years) to participate in a blinded, prospective study of a photoscreening device. The principle investigator examined the children after photoscreening. Using established standards for amblyogenic factors, the principle investigator and photoscreen interpreters separately made a determination of "normal" or "needs referral" for each child. Sensitivity, specificity, positive predictive value, and negative predictive value for the photoscreening device were determined.

RESULTS

Overall, sensitivity was 85% with a positive predictive value of 98%, and specificity was 87% with a negative predictive value of 47%. Developmentally-at-risk status in 34 children (three refused imaging) did not reduce sensitivity (89%) or specificity (100%) when compared with 130 children (two refused imaging) who did not have developmentally-at-risk factors (sensitivity = 84% and specificity = 80%).

CONCLUSION

The efficacy of photorefractive screening in young children with developmentally-at-risk status is comparable to results found in normal children.

Clinical accuracy of the AAPOS pediatric vision screening referral criteria

BACKGROUND

The American Association for Pediatric Ophthalmology and Strabismus (AAPOS) referral criteria for amblyogenic risk factors are consensus criteria that were determined by the best-available data as well as survey results of pediatric ophthalmologists. In 2003 the AAPOS Vision Screening Committee published guidelines to standardize reporting the ability of vision screening devices to detect these factors. We attempted to assess the accuracy of the AAPOS referral criteria.

METHODS

Billing records of one pediatric ophthalmologist were reviewed to identify all children who were seen in 2002. Records were excluded if photoscreening had not been performed at the initial visit or if photoscreening results were not available in the record. Of the remaining records, one-half were randomly selected for analysis. Cycloplegic refraction and binocular alignment were evaluated to determine whether the child would have been considered to be at risk for amblyopia on the basis of AAPOS referral critera. The sensitivity and specificity of these factors for detecting amblyopia was then determined.

RESULTS

A total of 1,575 records were identified, of which 529 were randomly selected; 7 were excluded for incomplete data. AAPOS referral criteria would have referred 266 patients, of whom 255 had amblyopia and 11 did not; of the 256 patients who would not have been referred, 46 had amblyopia and 210 did not. In this population, the AAPOS referral criteria would have had an 85% sensitivity, 95% specificity, a 5% false-positive rate and a 15% false-negative rate for detecting amblyopia.

CONCLUSIONS

Application of the AAPOS referral criteria resulted in underreporting of amblyopia in this study. We propose modifications that may result in increased sensitivity and a lower false-negative rate.

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.

A pilot study evaluating the use of EyeSpy video game software to perform vision screening in school-aged children

PURPOSE

To compare the vision-screening results of school-aged children tested with EyeSpy software and those of children examined by a pediatric ophthalmologist. We also compared combined results of an electronic visual acuity (EVA) tester and stereopsis testing to the results of a professional eye examination.

METHODS

In this pilot study, all children were tested with an EyeSpy and ETDRS EVA tester, followed by ocular examination including stereopsis assessment and cyclopegic refraction. The order of presentation of the EVA and EyeSpy assessments was assigned randomly. The EyeSpy test was performed twice (with an occlusive eyepatch and red-blue dissociative goggles). EyeSpy registered pass or refer results for visual acuity testing at a threshold of 20/32 visual acuity and stereopsis of 300 arcsec. Similar threshold values were used in the EVA/stereopsis testing.

RESULTS

The average age of 72 subjects was 11.4 +/- 2.2 years. Prevalence of visual impairment was 25 (34.7%) of 72 as reported by the professional examination. The sensitivity, specificity, and conventional positive likelihood ratio were 88%, 87%, and 6.8 when EyeSpy was used with a patch; 88%, 74%, and 3.44 when EyeSpy was used with goggles; and 88%, 94%, and 13.79 for EVA/stereospsis, respectively, compared with the gold-standard professional eye examination. EyeSpy screening results using a patch were not significantly different than those of a professional examination (p = 0.508). The 2 results concurred in 63 (87.5%) of 72 subjects.

CONCLUSIONS

EyeSpy software has potential for use as a vision-screening device. The use of EyeSpy with an occlusive patch outperformed EyeSpy with dissociative glasses.

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.

Computer-based real-time analysis in mobile ocular screening

Mobile ocular telemedicine is potentially an effective method to provide service in medically underserved areas and to screen large populations for abnormalities. Currently, digital images are acquired, stored, and transferred to readers for evaluation, after which the results are provided to the subjects. The transfer of large image files and the timeliness of the subsequent reading of images are significant factors for practical implementation of effective telemedicine screening. This work examines the feasibility of in situ real-time computer analysis of digital images to determine and classify the image results as normal and abnormal. This retrospective study used a photoscreening database of 360 patients ranging in ages from 6 months to 18 years. Computer analysis automatically classified the binocular photorefraction (PR) images, and these PR results were compared to those of the subjective clinical eye examinations provided. With an average processing time of approximately 15 seconds per examinee, the analysis found that the PR results can be categorized as: a positive group that requires referral (186 cases) with a predictive value of 98.9% (2 false-positives); a negative group (144 cases) with a predictive value of 89.6% (15 false-negatives); and an uncertain group (30 cases or 8.3%) that required resolution by readers. The real-time analysis code reduces by approximately 92% the manpower for image grading and electronic transmission at this stage of ocular evaluation. These results indicate the feasibility of this approach.

Amblyopia: diagnostic and therapeutic options

PURPOSE

To provide an overview of the current state of knowledge of amblyopia and highlight recent advances in diagnosis and treatment.

DESIGN

Review of literature and perspective.

METHODS

MEDLINE search for amblyopia, with a review of all recent literature adding authors' personal perspectives on the findings.

RESULTS

Increased awareness of amblyopia and better screening techniques are required to identify children who are at risk for amblyopia at a younger age. Randomized, controlled trials have established atropine penalization as a viable alternative to occlusion therapy, have suggested that less treatment may be better tolerated and as effective as more traditionally used dosages, and have found no compelling evidence that treatment is beneficial clinically for older (over age 10) children with amblyopia.

CONCLUSION

Early detection and treatment of amblyopia can improve the chances for a successful visual outcome. Considering that the conditions that place a patient at risk for amblyopia can be identified, that amblyopia responds to treatment, and that well-tolerated treatments for the condition are now recognized, it is not unreasonable to imagine that, in the near future, severe amblyopia could be eliminated as a public health problem.

Pediatric Vision Screener 2: pilot study in adults

Amblyopia is a form of visual impairment caused by ocular misalignment (strabismus) or defocus in an otherwise healthy eye. If detected early, the condition can be fully treated, yet over half of all children with amblyopia under age 5 escape detection. We developed a Pediatric Vision Screener (PVS) to detect amblyopia risk factors. This instrument produces a binocularity score to indicate alignment and a focus score to indicate focus. The purpose of this study is to assess the performance of the PVS by testing adults who were fully cooperative for testing. The study group includes 40 subjects (20 controls, 20 patients) aged 22 to 79 years. 12 patients had constant strabismus (8 to 50Delta), and eight had variable strabismus (12 to 55Delta). All controls had binocularity scores >50%. Binocularity was <50% in 11/12 patients. The patient with binocularity >50% had a well-controlled intermittent exotropia and was not at risk for amblyopia. Focus scores were highly sensitive for good focus but not specific. The PVS shows high sensitivity and specificity for detection of strabismus in adults. Future studies will determine whether this performance can be achieved in preschool children, who are at greatest risk for vision loss.

Vision screening for children: current trends, technology, and legislative issues

PURPOSE OF REVIEW

The purpose of this review is to examine current trends in vision screening for children.

RECENT FINDINGS

Literature within the past year regarding children's vision screening has been dominated by clinical validation studies of autorefractors or photoscreeners that allow the detection of amblyogenic refractive errors, misalignment of the eyes, or media opacities. New technologies reported include wave-front analysis for amblyogenic factors and a visual evoked potentials-based screening tool for the preverbal child. Studies evaluating the goals of the screening program, the target population, and the physical limitations of the screening environment have prompted multipronged or hybrid studies designed to more accurately detect vision problems, particularly in the preschool child, in whom cooperation and cognitive development affect reliability of results. State and federal legislation in the United States has been proposed or adopted to regulate and partially fund pediatric vision screening and comprehensive examinations.

SUMMARY

Through improvements and new developments in technology, study design, the efforts of organized medicine, and legislative initiatives, vision screening for children continues toward the goal of bringing all children with eye disease or vision problems to treatment in a timely fashion.

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.