Vigabatrin examination

Of 12 vigabatrin-treated patients with visual field defects re-examined 2-10 years after vigabatrin withdrawal, all stiU had visual field defects (28). In five cases there was apparent worsening. Exceptional cases of reversible visual field defects have been reported in children (61). However, perimetry assessment in children is burdened with multiple methodological problems that usually preclude reliable results. 

In two mothers, the placental transfer at time of birth, and breast milk concentrations after birth, of vigabatrin enantiomers were examined [172]. Both women had measurable concentrations of vigabatrin in the cord and maternal venous blood. The umbilical vein maternal vein concentrations ranged widely from 7% to 139% in the two women, although the ratios were greater for the R enantiomer than for the S enantiomer in both women. In the breast milk, the level of stereoselectivity was similar to that found in cord blood. The milk plasma concentration ratios of the enantiomers were... 

Since the probability of vigabatrin-associ-ated visual field loss is positively associated with treatment duration, careful assessment of the balance of benefit to harm in continuing treatment with vigabatrin is recommended in patients who are currently taking it. In those who continue to take it, visual field examination at least every 6 months is recommended. 

In eight patients with visual field constriction, who were examined 4-6 years after they had stopped taking vigabatrin visual field constriction was unchanged [42T]. The amplitude of the 30 Hz flicker response was still reduced. The authors concluded that vigabatrin causes permanent retinal damage. 

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