Perifoveal function in patients with North Carolina macular dystrophy: the importance of accounting for fixation locus.
OBJECTIVE
To quantify the extent of visual function losses in patients with North Carolina Macular Dystrophy (NCMD) and to demonstrate the importance of accounting for eccentric fixation when making comparisons with normal data.


METHODS
Five patients with NCMD who were from a single family were examined. Multifocal electroretinograms (mfERGs) and psychophysical assessments of acuity and luminance visual field sensitivities were measured throughout the central retina. Comparisons of responses from equivalent retinal areas were accomplished by shifting normal templates to be centered at the locus of fixation for each patient.


RESULTS
Losses of psychophysically measured visual function in patients with NCMD extend to areas adjacent to the locations of visible lesions. The multifocal ERG amplitude was reduced only within the area of visible lesion. Multifocal ERG implicit times were delayed throughout the entire central retinal area assessed.


CONCLUSIONS
ERG timing is a sensitive assay of retinal function, and our results indicate that NCMD has a widespread effect at the level of the mid and outer retina. The findings also demonstrated that it is necessary to account for fixation locus and to ensure that equivalent retinal areas are compared when testing patients with macular disease who have eccentric fixation.
Seiple
William
W
Department of Ophthalmology, New York University School of Medicine, New York, New York 10016, USA. whs4@nyu.edu
Szlyk
Janet P
JP
Paliga
Jennifer
J
Rabb
Maurice F
MF
D000328:Adult; D002648:Child; D004596:Electroretinography; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology*; D005584:Fovea Centralis / Q000503:physiopathology*; D005799:Genes, Dominant; D006801:Humans; D008268:Macular Degeneration / Q000235:genetics / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009657:North Carolina; D014792:Visual Acuity / Q000502:physiology; D014794:Visual Fields / Q000502:physiology