ERG AND EOG ABNORMALITIES IN CARRIERS OF X-LINKED RETINITIS-PIGMENTOSA

The diagnosis of X-linked retinitis pigmentosa (XL-RP) relies on the i dentification of the female carriers, in whom fundal abnormalities are often minimal and variable. The electroretinogram (ERG) has been repo rted as abnormal in 54-96% of heterogygote females. This study examine s the combined use of electro-oculogram (EGG) and standardised ERG in 31 obligate and 33 non-obligate carriers of XL-RP. In the obligate car rier group, the EOG was abnormal in 13 carriers (41%), the ERG abnorma l in 21 carriers (68%) and a combined EOG and ERG abnormality occurred in 24 carriers (77%). An EOG abnormality alone occurred in 2 carriers (6.5%). Fourteen obligate carriers (45%) showed a peak to peak delay of the ERG scotopic b wave, this being a previously unreported phenome non. Similarly, in the non-obligate carrier group, the EOG was abnorma l in 11 carriers (44%) and the ERG abnormal in 19 carriers (73%). The results of this study suggest that the use of both tests, including me asurement of the scotopic b wave latency, may increase the carrier det ection rate.