Assessment of visual acuity in children with trisomy 18

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tests that include both grating and recognition acuities have been described in the literature, some of which are outdated.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.

Which ocular and neurologic conditions cause disparate results in visual acuity scores recorded with visually evoked potential and teller acuity cards?

PURPOSE

We investigated whether disparity between visually evoked potential (VEP) acuity scores and Teller Acuity Card (TAC) scores varied according to presence of ocular or neurologic conditions.

METHODS

Charts from 175 children (mean age, 34.8 months; range, 3 to 158 months) referred for visual acuity testing were examined. All children had been tested with pattern-alternation VEP and TAC and had undergone a complete eye examination. VEP and TAC acuity scores were relative to age-expected acuity scores for each acuity test. The absence and degree of macular abnormality, retinal abnormality, optic nerve hypoplasia, optic nerve atrophy, cortical visual impairment, developmental delay, cerebral palsy, seizures, and nystagmus were noted. Analysis of variance models were used to determine whether differences between VEP and TAC scores varied according to the presence of specific deficits. Logistic regression analysis determined whether degree of specific deficits was associated with a greater chance of inconsistency between VEP and TAC scores (>0.3 log unit difference).

RESULTS

Inconsistent scores were found in 48% of children. Developmental delay was associated with relatively poorer TAC than VEP score, and the chance of inconsistency increased with severity of developmental delay.

CONCLUSIONS

Diagnosis-dependent variability exists between TAC and VEP scores. Therefore knowledge of the clinical picture is necessary in interpretation of VEP and TAC scores. It is not clear which test is more useful when a disparity exists, either from this or previous studies. When visual acuity is assessed longitudinally in a given child, then consistency in method for acuity assessment is important.

Comparison of grating and Vernier acuity in infants with developmental delay

BACKGROUND

Grating acuity measured by Teller cards is mildly reduced in children with developmental delay. Vernier acuity, the ability to detect offsets, also can be measured, but has not been studied in children with developmental delay.

METHODS

In a prospective cross-sectional pilot study, 12 nonverbal children with developmental delay established by pediatric assessment of developmental milestones were tested binocularly with vernier and Teller cards. Ages ranged from 4 to 24 months. Vernier offsets ranged from 2 to 64 minutes of arc.

RESULTS

All children were testable with Teller acuity cards. Binocular grating acuity ranged from 1.7 to 7.4 cpd (median, 1.0 octaves below normal). Binocular vernier acuity ranged from unrecordable to 8 minutes of arc (median, "unrecordable"). Only four of the 12 children demonstrated a measurable vernier acuity. Normal children of this age have a vernier acuity of 2 to 16 minutes of arc measured by this technique.

CONCLUSION

The response to vernier acuity cards appears to be more severely degraded by developmental delay than the response to Teller cards.