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Steven Greenstein, Peter Hersh; Concurrent vs Sequential Corneal Collagen Crosslinking and Intacs® for Keratoconus and Corneal Ectasia. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5264.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the effect of concurrent vs sequential corneal collagen crosslinking (CXL) and Intacs® on visual and topographic outcomes in patients with keratoconus (kc) and corneal ectasia.
41 eyes with KC and ectasia were analyzed in a prospective randomized control clinical trial. All patients were initially treated with symmetric 350µm Intacs® segments (Addition Technology Inc, Illinois, USA). Following this Intacs® procedure patients were randomized into 2 groups. 1 group received standard CXL immediately following the Intacs® procedure (concurrent group, n=23), and the second group received the identical CXL treatment 3 months after the initial Intacs® procedure (sequential group, n=18). All outcomes were analyzed 1 year after CXL therapy. The outcomes analyzed included uncorrected (UCVA) and best corrected (BCVA) visual acuity, and maximum (Kmax), flat (Kf), steep (Ks), and average (Kavg) keratometry as measured by the Pentacam (Oculus Inc, Wetzlar, Germany).
Visually, UCVA significantly improved from logMAR 0.96±0.31 to 0.82±0.31 (p=0.03), and 1.03±0.19 to 0.85±0.31 (p=0.01), and BCVA changed from 0.36±0.17 to 0.34±0.21, and 0.29±0.23 to 0.21±0.15, in the concurrent and sequential group respectively; although these latter changes were not statistically significant (pconcurrent=0.7, psequential=0.06). Topographically, in the concurrent group, Kmax, Kavg, Kf, Ks, changed from 61.9±8.2D to 61.0±7.8D (p=0.15), 51.5±5.2D to 50.1±5.0D (p<0.01), 49.2±4.7D to 48.3±4.6D (p=0.01), 54.0±6.1D to 52.2±5.8D (p<0.01), respectively. In the sequential group, Kmax, Kavg,, Kf, Ks, changed from 58.2±9.3D to 58.4±8.8D (p=0.9), 49.7±5.3D to 48.8±5.0D (p=0.02), 47.6±5.1D to 47.3±4.8 D (p=0.5), 50.3±5.4D to 52.2± 5.8D (p<0.01), respectively. When the sequential vs concurrent groups were compared at 1 year, there were no statistical differences between the changes in any of the visual or topographic outcomes except for Kflat (PUCVA=0.1, PBCVA=0.6, Pkmax=0.6, Pkavg=0.5, Pkflat=0.03, Pksteep=0.6).
All patients who were treated with symmetric Intacs® and CXL therapy experienced an improvement in corneal topography and UCVA 1 year after therapy. There was no meaningful difference between sequential vs concurrent treatment 1 year after therapy.
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