Karen L. Preston

ASSESSMENT OF VISUAL ACUITY IN INFANTS AND CHILDREN; THE ACUITY CARD PROCEDURE

The ‘acuity card’ procedure described here is a simplified method of testing visual acuity of infants and young children, and has been developed to allow preferential looking to be assessed in a laboratory or clinic. A higher proportion of children can be tested successfully than has been reported for more traditional procedures. Initial studies indicate that the acuity card procedure is a fast, accurate method for assessing the acuity of normal infants and children, and those with visual or neurological impairments, across a wide age‐range and in both clinical and laboratory settings.

Validation of the Acuity Card Procedure for Assessment of Infants with Ocular Disorders

The acuity card procedure has been shown to be a rapid method for the assessment of monocular and binocular grating acuity in normal infants from birth through 36 months of age. The current study seeks to validate the procedure further by using the acuity cards to assess 20 2- to 8-month-old infant patients with ocular disorders, including aphakia, strabismus, ptosis, and orbital hemangioma. Assessments were made with the acuity cards by two different observers, both blind to the infants diagnosis, and by a third observer using a traditional forced-choice preferential looking (FPL) procedure. One hundred percent of the infant patients completed both binocular and monocular acuity card testing in an average time of 8 minutes per test. Interobserver agreement between acuity card observers and inter-technique agreement were high, and were sustained in individual cases in which the infants acuity was not predictable from its visible signs. These results help to establish the potential clinical utility of the acuity card procedure for the assessment of infant patients.

Monocular and binocular acuity estimation in 18- to 36-month-olds: acuity card results.

ABSTRACT The acuity card procedure is a useful method for measuring visual acuity in infants 1 to 12 months of age. The results of the present study indicate that the procedure is also a viable method for estimating acuity in children 18 to 36 months of age. Monocular and binocular estimates of acuity were obtained with the acuity card procedure on 36 normal children, 9 each at ages 18, 24, 30, and 36 months. At each of the ages, means and SDs of acuity estimates agreed well with acuity norms from established operant procedures. Mean durations for monocular and binocular estimates averaged 2 to 4 min, and nearly 100% of children were tested successfully both monocularly and binocularly. The flexibility of the required response and the short test times make the acuity cards a promising test of visual acuity in this typically difficult‐to‐test age range.

Polaroid Photoscreening for Amblyogenic Factors: An Improved Methodology

BACKGROUND The authors describe a new photoscreening camera designed to detect amblyogenic factors, including strabismus, asymmetric and abnormal refractive errors, and media opacities. The photoscreener uses eccentric photorefraction principles and provides two meridian photographs of the retinal reflex. METHODS Pass/fail screening data from the photographs of 202 nondilated children as determined by two masked observers were compared with data from complete ophthalmologic examinations. RESULTS The photoscreener had a sensitivity rate of 87%, a specificity rate of 89%, a positive predictive value of 93%, a negative predictive value of 80%, and an overall agreement rate of 88%. The prescreening probability for amblyogenic factors was 63%. Constant strabismus was detected in all cases. Five intermittent strabismus cases were missed. Two patients with myopia, three patients with hyperopia, and five patients with astigmatism were missed. All media opacities were detected. CONCLUSION This new two-flash photoscreening camera, which uses high-speed Polaroid film, is an accurate, reliable method of detecting amblyogenic factors in undilated children. The camera offers promise as a useful mass screening tool.

Obtaining a quantitative measure of eye movements in human infants : a method of calibrating the electrooculogram

We have developed a calibration procedure that combines the measurement of the EOG voltage with the concurrent assessment of the actual direction of gaze as revealed by the corneal reflection of a target light. Using this method, we have been able to calibrate the eye-position signal recorded from 2- and 3-month-old infants. Our results show that in young infants (1) the EOG is linearly related to eye position to at least +/- 20 deg; (2) the slopes of the calibration lines measured early and late in the same test session were not significantly different at the 0.1 level; (3) at the most eccentric eye position, the calibration was accurate to within +/- 1 deg; and (4) an abbreviated calibration at 0 and +/- 15 deg, which took less than 2 min, produced essentially the same slope (t-test not significant at the 0.1 level) as a longer procedure that tested at every 5 deg between +20 and -20 deg.

Polaroid Photorefractive Screening for Amblyopia

In the past 10 years, many investigators have shown eccentric (off-axis) photorefraction to be useful for screening preverbal children for amblyogenic factors, such as anisometropia, high hyperopia, strabismus and media opacities. Several studies (Kaakinen, 1986–7; Molteno 1983; Duckman, 1987; Hay, 1983; Morgan, 1987) have demonstrated the effectiveness of photographic screening with 35mm film; however, these systems do not allow for immediate abnormality identification, nor verification of proper alignment and photographic technique. Only a few have screened for astigmatism (Kaakinen, 1983, 1987 and Wanger, 1988). Screening cameras utilizing instant film have been developed by Kaakinen (1986), Day (1986), Hsu-Winges (1989) and Wanger (1988). The use of instant film allows for easy retesting if improper alignment occurs and allows for immediate detection of abnormalities.