Related Experiment Video
Updated: Oct 2, 2025
Assessing Binocular Central Visual Field and Binocular Eye Movements in a Dichoptic Viewing Condition
Published on: July 21, 2020
Effect of Viewing Conditions on Fixation Eye Movements and Eye Alignment in Amblyopia
Jordan Murray1, Palak Gupta2,3, Cody Dulaney1
1Visual Neurosciences and Ocular Motility Laboratory, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States.
Purpose:
Patients with amblyopia are known to have fixation instability, which arises from alteration of physiologic fixation eye movements (FEMs) and nystagmus. We assessed the effects of monocular, binocular, and dichoptic viewing on FEMs and eye alignment in patients with and without fusion maldevelopment nystagmus (FMN).
Methods:
Thirty-four patients with amblyopia and seven healthy controls were recruited for this study. Eye movements were recorded using infrared video-oculography during (1) fellow eye viewing (FEV), (2) amblyopic eye viewing (AEV), (3) both eye viewing (BEV), and (4) dichoptic viewing (DcV) at varying fellow eye (FE) contrasts. The patients were classified per the clinical type of amblyopia and FEM waveforms into those without nystagmus, those with nystagmus with and without FMN. Fixational saccades and intersaccadic drifts, quick and slow phases of nystagmus, and bivariate contour ellipse area were analyzed in the FE and amblyopic eye (AE).
Results:
We found that FEMs are differentially affected with increased amplitude of quick phases of FMN observed during AEV than BEV and during DcV at lower FE contrasts. Increased fixation instability was seen in anisometropic patients at lower FE contrasts. Incomitance of eye misalignment was seen with the greatest increase during FEV. Strabismic/mixed amblyopia patients without FMN were more likely to demonstrate a fixation switch where the AE attends to the target during DcV than patients with FMN.
Conclusions:
Our findings suggest that FEM abnormalities modulate with different viewing conditions as used in various amblyopia therapies. Increased FEM abnormalities could affect the visual function deficits and may have treatment implications.
