Combination of anterior segment optical coherence tomography modalities to improve accuracy of rectus muscle insertion location

Anterior segment optical coherence tomography (AS-OCT) is useful for locating the extraocular muscle insertion prior to strabismus surgery; however, its accuracy decreases in reoperations. This masked retrospective study investigated whether a combination of AS-OCT modalities improves accuracy. The distance between the corneoscleral limbus and extraocular muscle insertion was measured with AS-OCT, first using the standard grayscale modality alone and then refined with the color modality. The AS-OCT measurement was considered accurate when within 1.00 mm of the intraoperative caliper measurement. A total of 139 AS-OCT images were analyzed from 74 patients (mean age, 52 years), including 60 medial rectus (19 reoperations), 61 lateral rectus (11 reoperations), 10 superior rectus, and 8 inferior rectus muscles. Compared to grayscale alone, the combination grayscale/color modalities improved AS-OCT accuracy from 77% to 87% (P = 0.03), reflecting an increase from 83% to 94% (P = 0.01) in primary surgeries and from 53% to 60% (P = 0.60) in reoperations.