Abstract
Purpose :
Cerebral visual impairment (CVI) is the leading cause of vision loss in children in industrialized nations, and results from an insult to the developing brain. There is still much to be learned about the visual impairments associated with CVI. Preferential looking procedures using gratings and the Cardiff picture cards successfully measure visual acuity in non-verbal patients; but both grating acuity and Cardiff cards tend to underestimate the visual acuity reduction associated with amblyopia. It is anticipated that Cardiff likely would underestimate vision acuity loss in children with CVI due to the lack of contour interaction effects. A comparison of Cardiff cards to Lea symbols with contour bars at 100% and 50% spacing was evaluated through a retrospective, observational clinical study.
Methods :
Binocular visual acuity was measured during a comprehensive vision examination of 15 children (ages 4-18 years; mean 8.6 years) presenting with a diagnosis of CVI. Single Lea symbols with contour flanker bars at 50% and 100% spacing were presented in a two-alternative forced choice task using the apple and the house as the test optotypes. Binocular visual acuity was measured with the Cardiff Visual Acuity Test which required detection of a single shape on a grey background. Visual acuity thresholds were determined using the modified acuity card procedure by observation of the child’s eye gaze, pointing, and/or naming of the optotype.
Results :
The ranges for visual acuity were: Cardiff logMAR 0 to 0.6; Lea 100% logMAR 0 to 1.18; Lea 50% logMAR 0.23 to 1.38. A Bland Altman analysis (mean vs. difference in visual acuity) comparing Cardiff to 100% Lea and 50% Lea was performed. Cardiff acuity underestimated the vision loss compared to 100% and 50% Lea by -0.35 logMAR and -0.54 logMAR, respectively. The difference in acuity measures increased with worse acuity.
Conclusions :
For 93% of the patients with CVI, 50% and 100% Lea symbols yielded a more reduced acuity compared to the Cardiff Acuity Test; the latter only requires detection of the symbols, whereas the Lea symbols require discrimination between an apple and a house optotype. Reporting visual acuity in the presence of contour interaction in children with CVI would be helpful when making educational recommendations to the child’s parents and care team.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.