Can the visual acuity of infants be predicted from a measurement of contrast sensitivity?

Preoperative visual acuity and contrast sensitivity in children with small, partial, or non-central cataracts

BACKGROUND

While there is clear evidence that dense central cataracts >3 mm diameter warrant prompt intervention to prevent deprivation amblyopia, guidelines for management of small, partial and non-central cataracts are not evidence-based. Consensus guidelines advise managing affected infants and preschool children by monitoring for possible progression in size or density and pharmacologic pupillary dilation, if indicated. Extraction is deemed necessary if the cataract progresses sufficiently to obscure the visual axis or if strabismus or nystagmus develops. We evaluated the long-term visual acuity outcome of the consensus guidelines and whether sensory testing during infancy and early childhood may be helpful in guiding treatment.

METHODS

A total of 40 consecutive children diagnosed with small, partial, or non-central cataracts at 1 week to 2.5 years of age were enrolled in a prospective study of forced-choice preferential looking visual acuity and contrast sensitivity development. Long-term visual acuity outcome was assessed by crowded HOTV or ETDRS at 4-11 years.

RESULTS

Of the 40 children managed by consensus guidelines, 24 (60%) had abnormal visual acuity at 4-11 years of age, including 9 (23%) who had moderate to severe visual impairment (20/80 or worse) in 1 or both eyes. Abnormal visual acuity and contrast sensitivity during development were predictive of abnormal long-term visual acuity outcomes.

CONCLUSIONS

Visual acuity and contrast sensitivity tests were sensitive to the effects of visual deprivation on the developing visual system and may be useful in early identification of children with small, partial, or non-central cataracts who could benefit from cataract extraction.

Accuracy of the contrast sensitivity card test for infants: retest variability and prediction of spatial resolution

PURPOSE

We assessed the retest variability of a new contrast sensitivity (CS) card procedure and its ability to predict spatial resolution.

METHODS

Twenty-four 3-month-olds were tested twice with the CS cards and once with the Teller acuity cards (TAC) within a single session.

RESULTS

Coefficient of repeatability (COR) analysis revealed that retest variability of the new cards is superior to that of an earlier prototype at low to mid spatial frequencies. Furthermore, retest variability is comparable to that of infant visual evoked potential studies and the Vistech 6500, a chart commonly used to measure CS in adults. Finally, estimates of visual acuity based on the CS cards were consistent with those provided by the TAC (although CS-based estimates were generally lower overall).

CONCLUSIONS

Given its reliability and accuracy, the new CS card procedure has good potential as a clinical tool for assessing spatial vision in infants and toddlers.