AIMS/BACKGROUND--A prolonged choroidal filling phase on fluorescein angiography has been reported to be a common finding and associated with visual function abnormalities in patients with age-related macular degeneration (AMD). This investigation was carried out to determine whether this perfusion defect was related to the slowing of foveal cone electroretinogram (ERG) implicit time seen in patients with AMD. METHODS--Fluorescein angiograms and foveal cone ERGs were evaluated in the fellow eyes of 67 patients with unilateral neovascular AMD. RESULTS--Twenty eight (42%) of the eyes had a choroidal perfusion defect. ERG implicit times averaged 1 ms slower (p = 0.0167) and were more likely to be delayed (p = 0.0078) in eyes with abnormal choroidal perfusion than in eyes with normal choroidal filling; significant relations were found also after controlling for age. ERG implicit time was also inversely related to ETDRS visual acuity and positively related to the extent of macular drusen; and the latter showed a borderline significant tendency to be more prevalent in eyes with prolonged choroidal perfusion. However, an association of a delayed ERG implicit time with prolonged choroidal filling remained after controlling for age, acuity, and the extent of drusen. CONCLUSION--These findings further establish prolonged choroidal perfusion as a common finding in AMD and link it to retinal malfunction.