Regional cone-mediated dysfunction in age-related maculopathy evaluated by focal electroretinograms: relationship with retinal morphology and perimetric sensitivity

Purpose: To assess regional cone-mediated function in age-related maculopathy (ARM) by focal electroretinograms (FERGs), and to compare FERGs with morphologic changes and perimetric sensitivity at corresponding locations.

Methods: Twenty-six ARM patients and 12 age-matched controls were evaluated. FERGs were elicited by either a central (0-2.25 degrees , C) or a paracentral annular (2.25-9 degrees , PC) flickering (41 Hz) field, presented on a light-adapting background. Morphological changes (soft drusen and/or retinal pigment epithelium defects) at matched locations were assessed by fundus photography and fluorescein angiography. Perimetric sensitivity was measured by Octopus 10 degrees program (tM2).

Results: When compared to controls, mean C and PC FERG amplitudes of patients were reduced (p < 0.01), and the mean PC FERG phase was delayed (p < 0.01). Both FERG delays and morphologic lesions tended to involve to a greater extent the PC compared to the C region. In the C region, perimetric losses were correlated with the extent of morphologic lesions (p < 0.05). In the PC region, perimetric losses were correlated with FERG amplitudes (p < 0.05).

Conclusions: In ARM, FERG losses are eccentricity-dependent, not quantitatively linked to retinal morphology, and correlated with perimetric losses, suggesting a heterogeneous dysfunction with loss of both C and PC perimetric sensitivities.