Optometry & Visual Performance 235 Volume 13 | Issue 4 | December 2025 Viewpoint • On the Etiology of Eccentric Fixation Kenneth J. Ciuffreda, OD, PhD • SUNY College of Optometry • New York, New York Daniella Rutner, OD, MS, MBA • SUNY College of Optometry • New York, New York ABSTRACT Amblyopia is a complex visual condition consisting of abnormal and interactive sensory, motor, and perceptual aspects. One such abnormality is eccentric fixation (EF). A description of EF, along with its proposed etiology, will be considered. Introduction The condition of human amblyopia is a major public health concern, as it affects at least 2% of the U.S. population.1 It is a complex phenomenon, with a range of abnormal and interactive sensory, motor, and perceptual components (Table 1).2 One of the most interesting, and important, visual abnormalities is eccentric fixation (EF), not to be confused with eccentric viewing (EV).2 EF is an anomaly of monocular vision in which the time-average position of the fovea is off the object of regard.2 That is, with the fellow eye fully occluded with a black eye patch, the amblyopic eye fixates, and localizes, a target as "straight-ahead" using a non-foveal point (i.e., abnormal oculocentric localization). EF is found in approximately 80% of amblyopic eyes3 and is therefore a major factor to consider in its diagnosis and remediation. However, the question remains: "What is the etiology of EF?" This important question has had a long history. One of the most interesting and logical proposals was expounded by Worth in 1943.4 He believed that EF resulted from binocular suppression. Worth conceptualized the central, retino-cortical pathway as having a foveal "invagination" of sensory depression, with the immediately surrounding region exhibiting relatively higher visual acuity (Figure 1). Thus, one eccentrically fixated to maximize the residual visual acuity. This seemed like a plausible explanation. However, if true, then the EF point could logically occur anywhere along this rim of equi-acuity, with equal probability, and moreover vary its position over time (e.g., nasal retina one moment and temporal retina the next moment). However, EF is typically located at one relatively fixed retinal position (e.g., nasal 0.5 degrees), with some variability centered around this point. In a careful experiment performed in 1978,5 Worth's idea was disproven. Essentially, the researchers trained the amblyopic eye of adults to fixate centrally and steadily over a 5-10 hour pre-test period. Then, visual acuity was assessed across the horizontal retinal Figure 1. Retinal profile reflecting Worth's concept of binocular suppression effect and resultant central depression of visual acuity as a function of retinal eccentricity. Equi-visual acuity rim depicted by arrow. Symbols: F=fovea, T=temporal retina, and N=nasal retina. Kenneth J. Ciuffreda, OD, PhD New York, New York SUNY College of Optometry, Distinguished Teaching Professor Emeritus PhD, UC-Berkeley/Optometry, 1977 OD, Massachusetts College of Optometry, 1973 BA, Seton Hall University, 1969 Fellow Dipl-AAO, ARVO, COVD, & NAP Table 1. Major Sensory, Motor, and Perceptual Abnormalities in the Amblyopic Eye • Reduced visual acuity • Eccentric fixation • Reduced stereoacuity • Monocular spatial distortion • Abnormal eye movements • Reduced accommodation • Impaired threshold and suprathreshold contrast perception • Abnormal pupillary responses • Abnormal visually evoked responses • Abnormal visual-motor control
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