SVOP reveals objective visual field information in visually impaired children

Abstract

Purpose: The Saccadic Vector Optokinetic Perimeter(SVOP) utilises eye-tracking to allow accurate perimetry results without a subjective response. Standard visual field machines are unsuitable for many children due to restricted head posture and prolonged testing time. This study aims to determine the clinical applicability of SVOP for children with visual impairment. Method: Visual field tests were conducted for 30 consecutive cases at the Blind Low Vision Education Network of New Zealand (BLENNZ) Clinic, Auckland,using the SVOP (i2eye Diagnostics). Visual acuity was measured on a back-lit Snellen chart. Children were40–50 cm from the SVOP LCD screen, with testing duration and visual field results automatically recorded by SVOP software. Other variables including binocular vs monocular fields, Goldmann size of stimulus and number of points tested were determined by clinical requirements, with 14-point binocular as the standard option. Test stimuli had a duration of 200 ms and luminance of 14dB. Results: Thirty children with a range of diagnoses attempted SVOP, 22 (14.33 ± 4.89 years) were successful and 8 (7.96 ± 5.07 years) were unable to complete due to count fingers or worse visual acuity, or other cognitive delays. The first field measurement of each child was analysed. The testing duration of those who successfully completed was 102.07 ± 92.95 seconds.Visual acuity of the children able to perform the test ranged from 6/6 to <6/120 with a median acuity of<6/38. Conclusion: SVOP can be successfully utilised in children with visual impairment and provide valuable clinical visual field information that cannot be achieved with other standard methods. Presented at the 46th Annual Scientific Congress of the Royal Australian and New Zealand College of Ophthalmologists.