Use of a binocular optical coherence tomography system to evaluate strabismus in primary position: Automated, quantitative assessment of strabismus using binocular OCT

Importance: Current clinical methods for assessing strabismus can be prone to error. Binocular OCT has the potential to assess and quantify strabismus objectively and in an automated manner.Objective: To evaluate the use of a binocular optical coherence tomography (OCT) prototype to assess the presence and size of strabismus.Design, Setting, and Participants: Fifteen participants with strabismus recruited from Moorfields Eye Hospital NHS Foundation Trust, London, UK, and fifteen healthy volunteers underwent automated anterior segment imaging using the binocular OCT prototype. All participants had an orthoptic assessment including alternating prism cover test (APCT) prior to imaging. Simultaneously acquired pairs of OCT images, captured with one eye fixating, were analysed using ImageJ to assess the presence and angle of strabismus.Main Outcomes and Measures: The direction and size of strabismus measured using binocular OCT was compared to that found using APCT.Results: The median age for participants with strabismus was 55 years (interquartile range 33-66.5 years), and 50 years (interquartile range 41-59 years) for healthy group. The median magnitude of horizontal deviation was 20∆ (interquartile range 13-35∆), and 3∆ for vertical deviation (interquartile range 0-5∆). Binocular OCT imaging correctly revealed the type and direction of the deviation in all 15 strabismus participants, including both horizontal and vertical deviations. APCT and OCT measurements were strongly correlated for both horizontal (Pearson’s r = 0.85, 95% confidence interval (CI) 0.60-0.95; P < 0.001) and vertical (r = 0.89, CI 0.69-0.96; P < 0.001) deviations. In the healthy cohort, 9 participants had a latent horizontal deviation on APCT (median magnitude 2∆, range 2-4∆). Six were orthophoric. Horizontal deviations were observed on OCT imaging in 12 of the 15 participants, and a vertical deviation was visible in 1 participant.Conclusions and Relevance: These findings suggest that binocular anterior segment OCT imaging can provide clinicians with a precise measurement of strabismus. The prototype can potentially incorporate several binocular vision tests that will provide quantitative data for the assessment, diagnosis, and monitoring of ocular misalignments.