An FMRI study of saccadic and smooth-pursuit eye movement control in patients with age-related macular degeneration.
OBJECTIVE
To compare the cortical networks that underlie oculomotor function in patients with age-related macular degeneration (AMD) with those in normally sighted control subjects, using functional magnetic resonance imaging (fMRI).


METHODS
Six patients with bilateral geographic retinal atrophy due to AMD (age range, 55-83 years) were recruited for the study. The visual acuities of the patients ranged from 20/76 (0.58 logMAR) to 20/360 (1.26 logMAR). An additional six younger (age range, 22-31 years) and six older (age range, 54-78 years) normally sighted individuals were recruited as control subjects. fMRI data were acquired on a 3.0-Tesla, scanner while subjects performed visually guided saccade (VGS) and smooth-pursuit (SmP) tasks.


RESULTS
Contrasts between VGS and fixation on a stationary target identified a network of activation that included the frontal eye fields (FEFs), supplementary eye fields (SMA/SEFs), prefrontal cortex (PFC), intraparietal sulci (IPS), and the areas of the visual cortex (MT/V5, V2/V3, and V1) in control subjects and patients. A similar network was identified for comparisons between SmP and periods of fixation. Marked variability was observed in the performance of both tasks across all patients. For both tasks, the patients generally showed increased PFC and IPS activation, with decreased activation in visual cortex compared with the control subjects. The patients showed significantly increased activation of the FEFs and SMA/SEFs in the SmP task, compared with the control subjects.


CONCLUSIONS
These data suggest that performance of both eye movement tasks required greater involvement of the cortical regions generally implicated in attention and effort in patients with AMD.
Little
Deborah M
DM
Department of Neurology and Rehabilitation, University of Illinois at Chicago College of Medicine, Chicago, Illinois 60612, USA. little@uic.edu
Thulborn
Keith R
KR
Szlyk
Janet P
JP
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D005260:Female; D006801:Humans; D008268:Macular Degeneration / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009802:Oculomotor Nerve / Q000502:physiology; D011597:Psychomotor Performance; D012438:Saccades / Q000502:physiology*; D014792:Visual Acuity; D014793:Visual Cortex / Q000502:physiology