THE RELATIONSHIP BETWEEN VISUAL-FIELD SIZE AND ELECTRORETINOGRAM AMPLITUDE IN RETINITIS-PIGMENTOSA

Purpose. To determine to what degree visual held size is correlated wi th electroretinogram (ERG) amplitude among patients with the common fo rms of retinitis pigmentosa (RP). Methods. Visual field equivalent dia meter to the V4e white test light of the Goldmann perimeter was correl ated with log ERG amplitude elicited by 0.5 Hz or 30 Hz full-field fla shes of white light. Primary analyses were conducted on data from 583 patients with the common forms of RP. Subset analyses were performed o n data from patients with ERG responses with different ranges of ampli tude to assess to what extent the correlation depends on ERG amplitude , as well as on data from patients of a given genetic type to determin e whether the correlation depends on the mode of transmission. Data fr om patients with the rhodopsin, Pro23His mutation (n = 38) or with the rhodopsin, Pro347Leu mutation (n = 24) were analyzed to determine the correlation between visual field size and ERG amplitude for patients with the same mutation. Results, Visual field size was significantly c orrelated with ERG amplitude for every comparison (P less than or equa l to 0.0003). Correlations generally were higher for ERGs elicited by 30 Hz flashes (r = 0.62 for the entire sample) than they were for thos e elicited by 0.5 Hz flashes (r = 0.53 for the entire sample). They we re lower for truncated ranges of ERG amplitude, higher for patients wi th dominant or recessive disease than for patients with x-linked disea se or for patients of all genetic types combined, and strong for patie nts with the same rhodopsin mutation (reaching a value of 0.87). Concl usions, Visual field size is significantly correlated with ERG amplitu de for patients with RP. Correlation depends on the range of ERG ampli tudes, the inheritance type, and, particularly, on whether the analysi s is confined to a single gene mutation.