Age norms for grating acuity and contrast sensitivity measured by Lea tests in the first three years of life

Comparison of current paediatric contrast sensitivity assessments using simulated reduced contrast thresholds

PURPOSE

There are limited tests of contrast sensitivity (CS) for use in children. The Hiding Heidi (HH) is suitable for all cognitive abilities, but has a ceiling effect. The Double Happy (DH) test has comparable thresholds to the Pelli Robson (PR), however the ability to detect changes in contrast has not been established. This study aims to compare contrast thresholds and agreement between HH and the DH, comparing to the PR chart in normal conditions and under reduced visual and lighting conditions.

METHODS

Tests were repeated under different conditions to reduce the contrast. Room illumination was 20,900{plus minus}2% lux in bright conditions and 2,000{plus minus}2% lux in dim conditions, both conditions were repeated with the addition of simulation spectacles to reduce the clarity of vision. Participants' CS was measured uniocularly using the PR, HH and DH tests.

RESULTS

50 participants, age 18-62 years (mean{plus minus}standard deviation: 24.5{plus minus}7.98), were assessed. On HH 94% (n = 47) reached the maximum score, with the DH it was 18% (n = 9). The difference in reduction between conditions was smaller with HH in comparison to PR and DH, but significantly different from baseline conditions. Under dim conditions the reduction in PR and DH was -0.21 logCS units, but only -0.04 logCS for HH.

CONCLUSION

The DH test has better agreement with PR than HH and is better at detecting CS changes, highlighting the advantages of use in clinical practice.

Clinical assessment, investigation, diagnosis and initial management of cerebral visual impairment: a consensus practice guide

Cerebral Visual Impairment (CVI) is a common condition in the UK. Patients with conditions associated with CVI are frequently seen in paediatric ophthalmology clinics offering eye care professionals an opportunity to identify children proactively. In most cases CVI occurs as part of a neurodevelopmental condition or as a feature of multiple and complex disabilities. However, CVI can also be seen in children with apparently typical development. In some cases, high contrast visual acuity is normal and in other cases severely impaired. As such, identification of CVI requires evaluation of aspects of visual performance beyond high contrast acuity and consideration that visual function of those with CVI may fluctuate. Few paediatric ophthalmologists have received formal training in CVI. The detection and diagnosis of CVI varies across the UK and patients report hugely different experiences. A diagnosis of CVI is made based on professional clinical judgement and it is recognised that individual perspectives and local practice in the specific methodologies of assessment will vary. A systematic review and survey of professionals is underway to attempt to reach agreement on diagnostic criteria. Nonetheless, established pathways and published protocols can offer guidance on how a paediatric ophthalmology service can approach assessment of the child with suspected CVI. The purpose of this paper is to present a summary of research and clinical practice methods for detecting and diagnosing CVI in a paediatric ophthalmology outpatient setting. It represents current understanding of the topic and acknowledges the evolving nature of both practice and the evidence-base. A rapid literature review was undertaken to identify articles relating to clinical investigation of children with CVI. A focus group of QTVI and subject matter experts from sight loss charities was undertaken to address areas which were not covered by the literature review.

Grating acuity tests for infants, young children and individuals with disabilities: A review of recent advances

BACKGROUND

Accurate measurement of visual acuity is important in managing any ocular condition. Measuring visual acuity has always remained a challenge in infants, young children and individuals with disabilities who are unable to respond verbally. A variety of pediatric acuity tests that include both grating and recognition acuities have been described in the literature, some of which are outdated. This review paper aims to summarize the currently available and recently developed grating acuity tests that can be used for infants, young children and individuals with disabilities.

METHODS

A review of literature was carried out to identify tests that were currently available and recently developed. Additionally, search was also done on popular search engines and websites of companies. Tests identified were screened for availability and investigated for validity through published research in peer-reviewed journals.

RESULTS

A total of eight grating acuity tests were identified, out of which six of them were paper-based tests. The remaining two tests were app-based tests with established data for the typically developing pediatric cohort. The repeatability indices were available only for four grating acuity tests.

CONCLUSIONS

This review paper summarizes the basic features of the grating acuity tests and importantly, the parameters that determine the clinical utility of the tests such as the testability, acuity range, specific cohort studied, testing time and reliability indices. The paper also discusses the recent technological advancements in the field of acuity testing for the pediatric cohort and its comparisons with the conventional methods when available.

Age norms for grating acuity and contrast sensitivity in children using eye tracking technology

KEY MESSAGES

Visual acuity is the most used method to assess visual function in children. Contrast sensitivity complements the information provided for visual acuity, but it is not commonly used in clinical practice. Digital devices are increasingly used as a method to evaluate visual function, due to multiple advantages. Testing with these devices can improve the evaluation of visual development in children from a few months of age. Visual acuity and contrast sensitivity tests, using eye tracking technology, are able to measure visual function in children across a wide range of ages, objectively, quickly and without need of an experienced examiner.

PURPOSE

To report age-normative values for grating visual acuity and contrast sensitivity in healthy children using a digital device with eye tracking technology and to validate the grating acuity test.

METHODS

In the first project of the study, we examined healthy children aged between 6 months and 7 years with normal ophthalmological assessment. Grating visual acuity (VA) and contrast sensitivity (CS) were assessed using a preferential gaze paradigm with a DIVE (Device for an Integral Visual Examination) assisted with eye tracking technology to provide age norms. For the validation project, we compared LEA grating test (LGT) with DIVE VA in a group of children aged between 6 months and 4 years with normal and abnormal visual development.

RESULTS

Fifty-seven children (2.86 ± 1.55 years) were examined with DIVE VA test and 44 successfully completed DIVE CS test (3.06 ± 1.41 years). Both, VA and CS values increased with age, mainly along the first two years of life. Sixty-nine patients (1.34 ± 0.61 years) were included in the DIVE VA test validation. The mean difference between LGT and DIVE VA was - 1.05 ± 4.54 cpd with 95% limits of agreement (LoA) of - 9.95-7.84 cpd. Agreement between the two tests was higher in children younger than 1 year with a mean difference of - 0.19 ± 4.02 cpd.

CONCLUSIONS

DIVE is an automatic, objective and reliable tool to assess several visual function parameters in children, and it has good agreement with classical VA tests, especially for the first stage of life.

A New Contrast Sensitivity Test for Pediatric Patients: Feasibility and Inter-Examiner Reliability in Ocular Disorders and Cerebral Visual Impairment

Purpose

Assess feasibility and interexaminer reliability of a new test of contrast sensitivity (CS) for pediatric populations.

Methods

The Double Happy (DH) measures CS using a method similar to the Teller Acuity Cards. The schematic DH face is 16 degrees in diameter with features of 0.3 c/d and a channel frequency of 0.8 c/d. DH log₁₀ CS is in 0.15 log unit steps, 0.05 to 2.1. Participants were 43 unselected patients, ages 2 to 18 years: 23 were diagnosed with ocular disorders only; 20 were diagnosed with cerebral visual impairment (CVI). Two examiners measured DH log₁₀ CS. Visual acuity (VA) was also measured.

Results

All 43 participants were tested for binocular DH log₁₀CS. Cohen's kappa values for interexaminer reliability were fair. The between examiner ICC was +0.92 (P < 0.001). The mean difference between examiners was near zero, and the 95% CI was −0.44 to 0.45 log₁₀CS. DH log₁₀CS was near normal in the ocular disorder group and reduced in the CVI group. VA was reduced in both groups. DH log₁₀ CS and VA were correlated (r = −0.65). DH log₁₀ CS was a marginally better predictor of diagnosis than VA.

Conclusions

DH log₁₀CS test was successful in a diverse pediatric population diagnosed with ocular disorders or CVI. Interexaminer reliability was comparable to that of adults tested previously using the same stimuli and methods. Both CS and VA are reduced in CVI.

Translational Relevance

CS and VA both should be tested in pediatric clinical populations, especially in those at risk of CVI.

Prevalence of Visual Impairment and Associated Factors Among Primary Schoolchildren in Addis Ababa, Central Ethiopia

BACKGROUND

Visual impairment (VI) refers to reduction of vision resulting in a lower than normal visual acuity (VA). Although school programs are recommended for early detection and timely interventions of VI, available information with regard to prevalence of VI and associated factors among primary schoolchildren near to the main city, Addis Ababa is inadequate. Thus, we assessed the prevalence of VI and the associated factors among children attending government primary schools of Lideta sub-city, Addis Ababa, Ethiopia.

METHODS

This was a school-based cross-sectional study conducted from April to May 2019, using a two-stage cluster sampling method in Lideta sub-city, Addis Ababa, Ethiopia. From the total 18 government primary schools in Lideta sub-city, six were selected using probability proportionate to size (PPS) method. The study population was primary schoolchildren aged 7 to 17 years in the selected six primary schools. A total of 816 eligible primary schoolchildren were identified to be included in the study. The selected children were examined for the presence of VI. Children's parents/guardians were interviewed using structured pre-tested questionnaires. In this study, myopia and hyperopia were defined as difficulty in viewing distant and near objects, respectively. Similarly, astigmatism was a refractive error which results from an uneven cornea surface, which results in distorted images. Epi-data 3.1 and SPSS version 20 were used for data entry and analysis, respectively. Binary logistic regression was performed to check association between dependent and independent variables. Significance was set at p-value <0.05.

RESULTS

From a total of 816 eligible primary schoolchildren, 773 children were examined for VI, making the response rate 94.7%. Out of the 773 children, 370 (47.9%) were male and 403 (52.1%) were female. The mean age of the participants was 11.69 years (SD 2.64 years). The prevalence of VI among schoolchildren was 4.4%. The causes of VI included myopia (43%), astigmatism with or without amblyopia (31%), hyperopia with or without amblyopia (20%), and others. The parents/guardians not being aware of their children's eye problem (AOR=2.2, 95% CI: 1.2-4.4) was the only significantly associated factor with VI.

CONCLUSION

In this study, the prevalence of VI among schoolchildren was high. The students being unaware about their eye problem was significantly associated with VI. Thus, close monitoring and regular screening for VI in schoolchildren are highly recommended to allow timely intervention.