Cone-mediated multifocal electroretinogram in age-related macular degeneration: progression over a long-term follow-up.
OBJECTIVE
To evaluate the progression of change in the cone-driven multifocal electroretinogram (mfERG) responses in patients previously identified as having high-risk, soft drusen 63 mum or greater.


METHODS
Seventeen eyes of 14 patients were reevaluated after 28 to 41 months. Fundus changes were graded depending on drusen size and extent. Each of the 103 mfERG responses was analyzed and compared with age-matched normal controls and with the baseline measurement.


RESULTS
Stable visual acuity was found in 12 of the 17 eyes. Drusen size or extent was increased, decreased, and unchanged in 6, 3, and 8 eyes, respectively. The mfERG responses demonstrated a significant progression in the response density loss and in N1 and P1 implicit time delay compared with the baseline evaluation regardless of drusen change. The extent of response deterioration occurred over the entire retinal area tested. Eyes having decreased drusen at follow-up were typically associated with higher response delays at baseline and follow-up than eyes with stable or increased drusen.


CONCLUSIONS
Early age-related macular degeneration is associated with a progressive loss in the cone-driven mfERG response despite stable visual acuity. The response deterioration extended beyond the visible drusen area. Implicit times seem to be an important predictor of drusen regression.
Gerth
Christina
C
Department of Ophthalmology and Vision Sciences and Section of Neurobiology, Physiology, and Behavior, University of California, Davis, USA. chgerth@web.de
Delahunt
Peter B
PB
Alam
Suhail
S
Morse
Lawrence S
LS
Werner
John S
JS
D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D004596:Electroretinography / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008268:Macular Degeneration / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D017949:Retinal Cone Photoreceptor Cells / Q000503:physiopathology*; D014792:Visual Acuity / Q000502:physiology