Abstract
Purpose: :
Develop a method for assessment of peripheral visual fields (VF) in young children treated with Vigabatrin (VGB), an anti-epileptic medication. Bilateral VF constriction occurs in ~30% of VGB treated adults. In children too young for conventional VF testing, current practice is to use electroretinography for surveillance of adverse effects of VGB.
Methods: :
VF extent on the diagonal meridia in four quadrants was assessed monocularly and binocularly with two kinetic methods: white sphere kinetic perimetry (WSKP; Delaney et al, 2000), using a 6° white sphere on a black background, and Goldmann kinetic perimetry (GKP), using a 1.7° diameter light on a 10 cd/m2 background. In addition, thresholds for detecting 2°, 50 ms lights at 10° and 30° eccentric were determined in the dark adapted condition and in the presence of a 10 cd/m2 background (Hansen & Fulton, 1995). These procedures were evaluated in five VGB treated children, one with known VF constriction (9 years old) and four younger children (3-8 years old). Their data were compared to data from age-similar controls.
Results: :
For the 9 year old, there was good agreement between GKP and WSKP in VF extent on all four meridia. In all four quadrants, this child’s GKP and WKSP fields were significantly constricted by 25° or more (>2SD from the normal mean). Three of the other children (age 4-8 years) could be tested monocularly with both GKP and WSKP, and both methods showed extents within 1SD of the normal mean. In these children, the binocular VF extent equaled the temporal monocular VF. In the 3 year old, monocular testing could not be completed; binocular testing showed the extent in each quadrant equaled the temporal monocular VF in normal 4 year old. All five children had measurable dark and light adapted thresholds. The only abnormality was elevation of the light adapted thresholds in the 9 year old with VF constriction.
Conclusions: :
Assessment of VF extents using WSKP and psychophysical threshold measurements was feasible in VGB treated children. The results suggest that VF extent using these procedures will be sensitive to VGB induced VF deficits.
Keywords: perimetry • visual impairment: neuro-ophthalmological disease • visual development: infancy and childhood