Corneal Collagen Crosslinking and Intracorneal Ring Segments: Simultaneous vs Sequential Surgery

Abstract

Purpose : Intacs® (implantable intracorneal ring segments (ICRS)) and corneal collagen crosslinking (CXL) are used for the treatment of keratoconus and corneal ectasia. In previous work, using symmetric 350µm segments, we found no clinical difference between sequential and simultaneous treatment. In this prospective randomized controlled clinical trial, we compare the 6-months clinical outcomes of eyes with one 450µm Intacs® segment placed, CXL performed simultaneously or 3 months later.

Methods : 26 eyes of 18 patients (19 eyes in the simultaneous group, and 7 eyes in the sequential group) received one 450µm segment of Intacs® (Addition Technology Inc, Illinois, USA) followed by CXL. The first group had Intacs® placed followed by CXL on the same day (simultaneous group), and the second group received Intacs® followed by CXL 3 months later (sequential group). Principal outcomes included uncorrected distance visual acuity (UCDVA) and best-corrected distance visual acuity (BCDVA), maximum and average keratometry (K), inferior-superior (I-S) ratio, and point of maximum flattening, as measured by the Pentacam (Oculus Inc, Wetzlar, Germany).

Results : UCDVA improved by -0.28 ± 0.28 LogMAR (P < 0.01) and -0.2 ± 0.43 LogMAR (P = 0.41) in the simultaneous and sequential group, respectively. BCDVA improved by -0.07 ± 0.12 LogMAR (P = 0.065) and -0.16 ± 0.12 LogMAR (P = 0.056) in the simultaneous and sequential group, respectively. With regards to topography, average K flattened by -1.67 ± 1.07D (P < 0.01) and -3.72 ± 3.33D (P = 0.054), and maximum K flattened by -3.01 ± 2.09D (P < 0.01) and -5.78 ± 4.45D (P = 0.034) in the simultaneous and sequential group, respectively. The I-S ratio improved by -4.9 ± 2.24D (P < 0.01) in the simultaneous group, and by -6.05 ± 4.47D (P = 0.03) in the sequential group. The point of maximum flattening flattened by -8.0 ± 2.64D compared to -11.68 ± 5.65D. There was no statistically significant difference between the simultaneous and sequential group with regards to all of the primary outcomes (P_UCDVA = 0.66, P_BCDVA =0.18, P_{average K} = 0.24, P_{maximum K} = 0.2, P_I-S = 0.60, P_{max flattening} = 0.18).

Conclusions : Intacs®, with a single 450µm segment, followed by corneal collagen crosslinking, performed sequentially or simultaneously, appear to have similar efficacy.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.