Gaze changes with binocular versus monocular viewing in age-related macular degeneration.
OBJECTIVE
To determine and explain gaze changes during binocular versus monocular viewing in patients with age-related macular degeneration (AMD).


METHODS
Cross-sectional study.


METHODS
Twenty-nine patients with bilateral late-stage AMD.


METHODS
Distance acuity and fundus pathologic features were evaluated. Eye position was recorded while viewing a circular fixation target under monocular and binocular viewing conditions using an infrared eye tracker (SMI Gazetracker, SensoMotoric, Germany; Eyelink Software 2.04). Gaze changes were quantified by calculating the mean x-coordinate and y-coordinate eye position of the center of the bivariate contour ellipse area for a 30-second fixation task under both viewing conditions. Retinal loci used for monocular fixation for each eye were determined using the scanning laser ophthalmoscope (SLO; SLO 101, Rodenstock, Munich, Germany).


METHODS
Gaze position.


RESULTS
Nine patients showed no shift in gaze position from monocular to binocular viewing. Three patients demonstrated a shift in both eyes, and 17 patients demonstrated a shift in only 1 eye. The mean shift was 4.7+/-5 degrees (standard deviation). The shift in gaze position in the worse eye was predictive of the distance between the 2 monocular preferred retinal loci (PRLs; better and worse eye; r(2) = 0.59; P<0.0001), whereas there was no association between the shift in gaze position in the better eye and distance (r(2) = 0.00; P = 0.91).


CONCLUSIONS
Most AMD patients shift gaze position in 1 or both eyes when viewing binocularly compared with monocularly. These changes suggest that different retinal locations are used for fixation under the 2 viewing conditions. The SLO data showed that these patients are likely to demonstrate monocular PRLs that fall on noncorresponding areas. These results may have implications for the effective development of eccentric viewing and binocular behavior of AMD patients.
Kabanarou
Stamatina A
SA
Institute of Ophthalmology, London, United Kingdom. stamatina_k@hotmail.com
Crossland
Michael D
MD
Bellmann
Caren
C
Rees
Angela
A
Culham
Louise E
LE
Rubin
Gary S
GS
D000368:Aged; D003430:Cross-Sectional Studies; D005133:Eye Movements / Q000502:physiology*; D005403:Fixation, Ocular / Q000502:physiology*; D006801:Humans; D007834:Lasers; D008268:Macular Degeneration / Q000503:physiopathology*; D009887:Ophthalmoscopy / Q000379:methods; D015348:Vision, Binocular / Q000502:physiology*; D015349:Vision, Monocular / Q000502:physiology*; D014792:Visual Acuity / Q000502:physiology