Distortions of iris and anterior lens capsule OCT images by ICRS.

Intracorneal ring segments (ICRS) have been used in patients with keratoconus for slowing keratoconic progression and delaying keratoplasty.1,2 However, we experienced anterior optical coherence tomography (OCT) image distortion of the iris in patients with ICRS insertion by chance. Some femtosecond laser cataract surgery systems use OCT images of the cornea, anterior lens capsule, and nucleus for reference.3-5 The ICRS and any other corneal implants or opacifi cation may interfere with the OCT imaging and femtosecond laser disruption. We reviewed anterior segment OCT images of patients with ICRS (Intacs; Addition Technology, Sunnyvale, CA) insertion, analyzing the patterns of the iris and anterior lens capsule image distortion behind the ICRS (Figure 1), the number of discontinuity lines in the iris, and whether the iris segments showed a ‘horizontal fl ip’ (ie, the iris segment is fl ipped horizontally along the vertical axis by ICRS). We investigated the forward or backward movement of the iris segment, thickening or thinning of the iris segment, the horizontal position of discontinuity lines, and the image distortion of the anterior lens capsule in the OCT images. The movement of the capsule segments was measured by Image J software (version 1.38x; Wayne Rasband National Institutes of Health, Bethesda, MD). Sixty-six eyes of 54 patients were included in this study. Mean age was 25.1 ± 9.2 years. Thirty-fi ve patients were men and 19 were women. There were two sections for two ICRS in one OCT image. Therefore, we investigated a total of 132 sections. The number of discontinuity lines of the iris was usually two (94%). When the ICRS was thin, there was only one or no discontinuous line (6%). Horizontal fl ip of the iris segments was uncertain in 70% and defi nite when the iris was transected near the pupil margin (22%, defi nite fl ip) (Figure 2A) or when the ICRS was thin (8%, no defi nite fl ip). The iris segments appeared to either move backward slightly (61%) (Figure 2B), not show any movement (23%), or move backward signifi cantly (2%). The iris segment thickened (35%) (Figure 2C) or did not change (42%). In some cases, Figure 1. Two sections in an optical coherence tomography image. Two discontinuity lines by intracorneal ring segment were observed in a section and they made an iris segment.