Iris and knot configuration after Single Pass Four Throw (SFT) pupilloplasty as imaged by the spectral-domain optical coherence tomography

Purpose: To analyze the morphological changes in the iris-knot complex configuration using spectral-domain optical coherence tomography (SD-OCT) following the single pass four throw (SFT) pupilloplasty. Methods: In this retrospective case series, eyes with SFT pupilloplasty were examined by SD-OCT (Optovue). Iris morphology compared to the normal iris, presence of specific patterns (single hump, double humps, peaks and valleys, tethering), prolene suture, knot complex (length and orientation), and intraocular lens (IOL) vault were evaluated. Results: Overall, 41 knots of 26 patients with a mean time duration of 3.1 ± 2 months from surgery were analyzed. Iris configurations seen were single hump (n = 28, 63.8%), double humps (n = 7, 17%), loop (n = 2, 4.8%), flat (n = 3, 7.3%), and mulberry (n = 1, 2.4%). The mean length and the height of the knot complex was 784.1 ± 433.7 μm and 317.7 ± 110.4 μm, respectively. Knot positions were at 3 clock hours in 9 eyes (21.9%), 9 in 8 eyes (19.5%), and others in 24 eyes (58.5%). Cut end of the prolene suture was detectable in 26 eyes (63.4%) as hyper-reflective line, and the mean cut length was 465.8 ± 321.1 μm. The suture was predominantly vertically oriented (80.6%) to the iris with a mean distance of 3.6 ± 0.3 mm (2.6–4 mm) away from corneal endothelium. The mean distance from the knot complex and the IOL was 289.2 ± 146 μm and the mean anterior chamber depth was 4.1 ± 0.1 mm. Conclusion: A significant change in iris configuration was noted after SFT pupilloplasty, and vertically oriented retained prolene suture was predominant with good endothelial vault.