Eccentric fixation is often associated with residual amblyopia in children and may result in subpar best-corrected visual acuity, even after spectacle lens wear or patching. New research from the ARVO 2020 online meeting suggests OCT fixation shift may be helpful in detecting and quantifying eccentric fixation in pediatric patients with residual amblyopia, especially in those with strabismus.

A team of US researchers evaluated eccentric fixation with OCT in 56 children with residual amblyopia and a control group of 75 healthy children. Participants’ ages ranged from four to 17 years old. Amblyopia was associated with anisometropia (n=28), strabismus or both (n=28). Spectral-domain OCT was used to estimate fixation.

Participants were asked to focus on the internal blue dot target of the OCT, and OCT fixation shift—the distance between the fovea and the fixation point—was measured and adjusted with calculated axial length and converted into visual degrees. The researchers compared the fixation shift in the amblyopic eye, the fellow non-amblyopic eye and the left eye of the control group in addition to the fixation shift between the anisometropic and strabismic amblyopia types.

The study found the mean fixation shift was 0.17±0.29° for the control eyes, 0.94±1.24° for amblyopic eyes and 0.34±0.57° for fellow non-amblyopic eyes. The researchers observed a significant difference in fixation shift among the control, amblyopic and the fellow eyes, and the amblyopic eyes had a significantly larger fixation shift than the fellow eyes. No significant difference was found between the fellow eyes and the control eyes.

Fixation shift in the amblyopic eye was also significantly correlated with visual acuity. In addition, the anisometropic amblyopic eyes’ fixation shift was significantly smaller than the amount found in the strabismic and/or the combined types (0.34±0.46° vs. 1.54±1.48°).