Prevalence of amblyopia among defaulters of preschool vision screening

The prevalence of amblyopia among screening defaulters is an important determinant of the efficacy of amblyopia detection by preschool vision screening. A retrospective cohort study was therefore performed to assess an orthoptist-based preschool vision screening programme. The preschool vision screening status of children in the cohort was determined by reviewing their Community Child Health records. The prevalence of amblyopia among screening defaulters was determined by reviewing each child's school entry vision test (performed at 5.5 years of age), with retesting if a Snellen line acuity of 6/6 in each eye had not been documented. For comparison, the prevalence of amblyopia among screening attenders was also determined. The preschool vision screening status was known for 86.0% (772/898) of the cohort. The attendance rate at preschool vision screening was 79.2%. The prevalence of amblyopia among screening defaulters was 1.3% (95% CI 0.2% to 4.5%). The prevalence of amblyopia among screening attenders was 2.5% (95% CI 1.4% to 4.1%). There was no significant difference in the prevalence of amblyopia between screening defaulters and screening attenders (P=0.53). The efficacy of amblyopia detection by preschool vision screening is therefore highly dependent on its attendance rate. Preschool vision screening programmes with a low attendance rate will fail to detect a significant proportion of children with amblyopia.     

Prevalence of amblyopia among defaulters of preschool vision screening

The prevalence of amblyopia among screening defaulters is an important determinant of the efficacy of amblyopia detection by preschool vision screening. A retrospective cohort study was therefore performed to assess an orthoptist-based preschool vision screening programme. The preschool vision screening status of children in the cohort was determined by reviewing their Community Child Health records. The prevalence of amblyopia among screening defaulters was determined by reviewing each child's school entry vision test (performed at 5.5 years of age), with retesting if a Snellen line acuity of 6/6 in each eye had not been documented. For comparison, the prevalence of amblyopia among screening attenders was also determined. The preschool vision screening status was known for 86.0% (772/898) of the cohort. The attendance rate at preschool vision screening was 79.2%. The prevalence of amblyopia among screening defaulters was 1.3% (95% CI 0.2% to 4.5%). The prevalence of amblyopia among screening attenders was 2.5% (95% CI 1.4% to 4.1%). There was no significant difference in the prevalence of amblyopia between screening defaulters and screening attenders (P=0.53). The efficacy of amblyopia detection by preschool vision screening is therefore highly dependent on its attendance rate. Preschool vision screening programmes with a low attendance rate will fail to detect a significant proportion of children with amblyopia.     

Effectiveness of screening preschool children for amblyopia: a systematic review

Background  

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

Preschool vision screening for amblyopia and strabismus. Programs, methods, guidelines, 1983

Amblyopia and strabismus, which afflict at least 5% of children, require treatment early in life for best visual results. At present, many such children are treated late or not at all. Mass screening at preschool age, and perhaps ultimately of infants, appears the only viable solution to this problem. To ascertain the present status of preschool screening in the United States, on-site visits, mail questionnaires and telephone interviews were used to study existing preschool vision screening programs at the federal, state and private organization levels. We estimate that, at most, 21% of preschool children receive any form of vision screening. Only two states, Michigan and Minnesota, have legislated requirements for such screening. Several organizations have attempted to establish screening guidelines, with suggestions of specific test and referral criteria. These guidelines are reviewed. The guidelines are of particular interest because screening programs following them typically indicate far lower prevalence rates than most studies indicate actually exist, suggesting that the guidelines result in underreferrals. In order to assess this matter, vision screening methods appropriate for preschoolers or infants, based on current evidence, are reviewed. Stereoscopic testing, utilizing a random dot stereogram format, appears the best instrument available for amblyopia and strabismus screening, but large scale comparative studies of the different test methods are needed to arrive at a final determination. Suggestions are made for the physician interested in initiating preschool vision screening programs.     

学龄前儿童弱视及斜视的调查

目的早期发现并及时治疗弱视、斜视及其他眼病,减少可预防盲及低视力。方法济南市部分幼儿园内随机检查健康3～6岁6085例学龄前儿童,检查其标准远视力、近视力、屈光、眼位、眼前节及眼底。结果3～6岁儿童远视力低常率为12．16%,近视力低常率为4．40%；弱视患病率为5．23%,其中初次发现者占86．48%；共发现斜视患儿96例,其治疗率仅为14．58%。结论近视力可作为发现患儿视力不佳的线索之一,发现后重点核实其远视力。我市3～6岁儿童的弱视斜视的漏诊漏治情况相当严重,对幼儿尽早进行眼科普查意义重大,保健预防及宣教工作亟待加强。     

Preschool vision screening: negative predictive value for amblyopia

BACKGROUND/AIMS: Single optotype tests of visual acuity are widely used for preschool vision screening in order to optimise cooperation with testing. These tests may, however, underestimate the visual acuity deficit in amblyopia because they lack visual crowding. This study assessed the resultant negative predictive value (NPV) for amblyopia. METHODS: Cohort study of 936 children in the Cambridge Health District selected by date of birth. The presence of amblyopia among children who had passed preschool vision screening was determined using Snellen line acuity as the reference test. Preschool vision screening was conducted at 3.5 years of age by community orthoptists. The screening assessment comprised Sheridan-Gardiner single optotype test of visual acuity (referral criterion 6/9 or worse in either eye), cover test, ocular movements, 20(Delta) prism test, and TNO stereotest. RESULTS: The overall NPV of preschool vision screening for amblyopia was 100% (95% CI 99.4% to 100%). Most children with amblyopia were detected by the Sheridan-Gardiner single optotype test of visual acuity, but the other screening tests were necessary to prevent any false negatives. In isolation, the Sheridan-Gardiner single optotype test of visual acuity has a NPV for amblyopia of only 99.6% (95% CI 98.7% to 99.9%). CONCLUSION: Preschool vision screening using a single optotype test of visual acuity does achieve a high NPV for amblyopia, but only under certain conditions. These comprise a low threshold for referral (6/9 or worse in either eye) and the inclusion of a cover test and tests of binocular function in the screening assessment.     

斜视弱视患者的双眼视觉状况及其矫治

本文在复习正常双眼视觉的概念及检查双眼视觉的常用方法和双眼视觉正常范围的基础上,介绍了单眼深度感知和双眼立体视觉近年来神经生理学及神经解剖学的研究进展,即单眼深度线索和双眼深度线索获得的深度感知在顶叶皮层的CIP区（顶尾侧）被整合,强调了单眼及双眼均可感知立体视觉。重点阐述斜视、弱视患者双眼单视及双眼立体视觉受到损害的状况,以及应用脱抑制训练、融合训练、立体视训练等方法矫治双眼视觉缺陷的结果。     

摄影验光法在学龄前儿童弱视普查中的意义

目的分析研究摄影验光法对有关弱视致病因素阳性诊断的敏感度和特异度,探讨其在弱视普查中的作用.方法用美国MTI照相筛查仪对91例3～6岁儿童进行摄影验光,随后进行临床眼科检查和阿托品散瞳验光.针对屈光不正、屈光参差、斜视等主要弱视致病因素拟定观测指标及相应的照片量化分析标准和临床诊断标准,应用标准分析法进行评价.结果照片普查的敏感度为70.37%,特异度为62.16%,符合率为67.03%.结论摄影验光法方便、客观,对发现有关弱视致病因素有一定的准确性,是学龄前儿童弱视普查的有效手段.     

Diagnostic accuracy of vision screening tests for the detection of amblyopia and its risk factors: a systematic review

Aim

This systematic review evaluates the diagnostic accuracy of preschool vision screening tests for the detection of amblyopia and its risk factors.

Methods

The literature searches were conducted in nine bibliographic databases. No limitation to a specific study design, year of publication or language was applied. Studies were included if they compared a vision screening test with a reference test (gold standard) in children from the general population. In addition, the studies had to provide sufficient data to calculate diagnostic accuracy (sensitivity and specificity). Full-text articles were assessed for studies that satisfied the inclusion criteria using the “Quality of Diagnostic Accuracy Studies (QUADAS)” checklist.

Results

Two studies with a longitudinal design and 25 cross-sectional studies met the inclusion criteria. One of the longitudinal studies compared a screening programme in children between 1 and 2 years of age with a re-examination at the age of 8. The sensitivity for the screening programme was 86% (range: 64–97%) and the specificity 99% (range: 98–99%). The second longitudinal study compared screening examinations at 8, 12, 18, 25 and 31 months, with a re-examination at the age of 37 months. In this study, the sensitivity of the screening examination increased with age, while the specificity remained unchanged. The cross-sectional studies evaluated different screening settings, visual acuity tests, auto- or photorefractors and stereo tests. A large variety of reference tests, differing criteria for defining amblyopia and its risk factors and methodological limitations of the studies prevented a valid data interpretation.

Conclusion

Diagnostic test accuracy of preschool vision screening tests can only be sufficiently investigated after establishing age-related values defining amblyopia, refractive errors and binocular disorders. To address these questions, we recommend a controlled longitudinal study design.     

Rapid, high-accuracy detection of strabismus and amblyopia using the pediatric vision scanner

Purpose. The Pediatric Vision Scanner (PVS) detects strabismus by identifying ocular fixation in both eyes simultaneously. This study was undertaken to assess the ability of the PVS to identify patients with amblyopia or strabismus, particularly anisometropic amblyopia with no measurable strabismus. Methods. The PVS test, administered from 40 cm and requiring 2.5 seconds of attention, generated a binocularity score (BIN, 0%-100%). We tested 154 patients and 48 controls between the ages of 2 and 18 years. BIN scores of amblyopic children and controls were measured, and 21 children received sequential PVS measurements to detect any changes in BIN resulting from amblyopia treatment. Results. With the pass/refer threshold set at BIN 60%, sensitivity and specificity were 96% for the detection of amblyopia or strabismus. Assuming a 5% prevalence of amblyopia or strabismus, the inferred positive and negative predictive values of the PVS were 56% and 100%, respectively. Fixation accuracy was significantly reduced in amblyopic eyes. In anisometropic amblyopia patients treated successfully, the BIN improved to 100%. Conclusions. The PVS identified children with amblyopia or strabismus with high sensitivity and specificity, while successful treatment restored normal BIN scores in amblyopic patients without strabismus. The results support the hypothesis that the PVS detects strabismus and amblyopia directly. Future strategies for screening by nonspecialists may thus be based on diagnostic detection of amblyopia and strabismus rather than the estimation of risk factors, allowing for rapid, accurate identification of children with amblyopia early in life when it is most amenable to treatment.     

SureSight手持验光仪在3～6岁儿童屈光不正筛查中的应用

目的 探讨SureSight手持验光仪在3～6岁儿童屈光不正筛查中的应用价值.方法 横断面研究.对徐汇区康健街道内321例经初步筛查后视力可疑低常儿童,进行非睫状肌麻痹下SureSight手持式验光仪及睫状肌麻痹下Topcon台式验光仪检查.将所得检测结果进行Bland-Altman相关性检验,并利用ROC曲线计算SureSight屈光不正筛选标准以进行诊断性试验评价.结果 非睫状肌麻痹下SureSight验光测得的球镜度、柱镜度及SE均与睫状肌麻痹下Topcon验光仪所测得相应度数差异有统计学意义,在测量结果上两者有中度(球镜度:r=0.59,P＜0.05;SE:r=0.54,P＜0.05)到高度(柱镜度:r=0.89,P＜0.05)相关性.进一步以散瞳后Topcon测量值为金标准作ROC曲线,发现当SureSight SE测量值≤+1.13 D时,可划定为可疑近视,SE测量值≥+1.44 D时,划定为可疑远视,散光测量值≥0.88 D时,划定为可疑散光.散光、近视及远视的Youden指数分别为0.679、0.298及0.270.结论 3～6岁儿童非睫状肌麻痹下SureSight检测结果在散光的筛查中具有一定的临床意义,可协助划定可疑参考值范围,操作方便.但用于近视以及远视的筛查界定有一定的局限性.     

Home-based screening tools for amblyopia: a systematic review

Amblyopia is an important public health concern. While home-based screening may present an effective solution, this has not been rigorously assessed in a systematic review. A systematic review was performed using Ovid MEDLINE, PubMed, The Cochrane Library, Embase, Web of Science Core Collection, and Clinicaltrials.gov. All studies reporting the diagnostic accuracy of home-based screening tools for amblyopia among children were included. Studies involving orthoptist or ophthalmologist-led screening and adult subjects were excluded. The main outcome measure was the diagnostic accuracy expressed as sensitivity and specificity. Among 3670 studies identified, 28 were eligible for inclusion in our systematic review. The age range of patients were less than 1 month to 16 years old. 7 studies used internet-based tools, 16 used smartphone/tablet applications, 3 used digital cameras, and 3 used home-based questionnaires and visual acuity tools. All studies included a reference standard except one, which was a longitudinal study. 21 studies had full ophthalmological examination whilst 6 studies had validated visual acuity measurement tools as gold standards. Of the 27 studies which compared against a reference test, only 25 studies reported sensitivity and specificity values. Using the QUADAS-2 tool, 50% of studies were deemed to have applicability concern due to patient selection from tertiary centres and unclear methods for recruitment. There is a need to improve the quality of diagnostic accuracy studies, standardise thresholds for detecting amblyopia, and ensure consistent reporting of results. Further research is needed to evaluate the suitability of these tools for amblyopia screening.Subject terms: Medical research, Eye diseases