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PremNandhini Satgunam, Sourav Datta, Karthik Reddy, Dhruv Joshi; Development of a novel device to measure visual fields in infants and toddlers. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5978.
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© ARVO (1962-2015); The Authors (2016-present)
Measuring visual fields is particularly important for children with brain lesions who are known to have field defects. Performing perimetry in pediatric population however is challenging. Only few research instruments (e.g. double arc perimeter) can be used to test infants and toddlers but these are not commercially available. We developed a device to measure visual fields for this cohort.
A hemispherical dome (24 steel meridians separated by 15°, covering the entire 360°), embedded with LEDs and covered in black cloth was fabricated. The arrangement of the LEDs permitted measuring the fields at 10° radial intervals. Upper, left and right visual fields were measurable up to 80°. The lower visual field measured only up to 50°, as it provided the entrance to place the child in supine position under the dome. An infrared camera mounted on top of the dome provided live video to monitor the child’s eye movement. A computer program controlled the LED stimulus presentation. 4 infants with normal milestones (NM) and 18 infants and toddlers with neurological or ocular disorders and associated developmental delays (DD) were enrolled with parent's consent.
Average age of the DD group was 11.8 ± 7 months and that of the NM group was 7 ± 2.7 months. No gross visual field defects (hemianopia/quadrantanopia) were detected for any group. The median (± interquartile range) reaction time of the eye/head turn to the hemi/quadrant stimuli was 331 ± 226 ms for NM and 596 ± 741 ms for the DD group. Full visual field mapping was attempted in both groups. Out of 24 meridians, on average (± standard deviation) 8 ± 5 meridians and 9± 8 meridians were measured in the NM and DD groups respectively. The average field extent of the DD group was 35°, 52°, 46°, and 36° in the superior, left, right and inferior fields.
The newly developed device shows promise to map visual field isopters particularly for the DD group (Fig.1). The measured visual field extent in the tested DD and NM groups were comparable. The reaction time, while largely variable showed the DD group to be slower than the NM group by a factor of 1.8 (no statistical testing done). The longer duration may reflect processing delays in afferent, efferent or both systems. Studies with larger samples will be needed for better understanding the reaction time differences.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
Fig. 1: Binocular visual field isopter of a 9 months old with Developmental Delay (DD).
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