Contrast sensitivity was assessed in 47 children aged 5.4-9.8 years: 12 with phenylketonuria (PKU), six unaffected siblings and 29 children from the general population. Children with PKU, despite early and continuous treatment and despite phenylalanine (Phe) levels within accepted limits, were impaired across the range of spatial frequencies [1.5-18.0 cycles per degree of visual angle (c.p.d.)]...
