Abstract
Purpose To evaluate the outcomes of femtosecond laser-assisted implantation of a 355-degree intracorneal ring (ICR) (Keraring) in patients with keratoconus in the three-year follow-up. Setting Future Femtolaser Center, Sohag, Egypt. Design Prospective interventional case series. Patients and Methods A prospective case series of 38 eyes of 26 patients with keratoconus had implantation of the 355-degree ICR keraring after tunnel creation with a femtosecond laser. The uncorrected visual acuities (UCVA) and best-corrected visual acuities (BCVA), sphere, cylinder, and manifest refraction spherical equivalent (SE), and mean keratometry (K), K max, and K min were evaluated preoperatively and 3, 6, 12, 24, and 36 months postoperatively, and all complications were reported. Results 38 eyes of 26 patients with mean age 25.92 ± 5.44 years were enrolled in the study, 11 were males (42.3%). The mean UCVA improved from 0.93 ± 0.21 to 0.63 ± 0.21 logMAR (P ≤ 0.001) and the mean BCVA from 0.67 ± 0.22 to 0.43 ± 0.26 logMAR (P < 0.001). The mean sphere, cylinder, and spherical equivalent have been changed dramatically from preoperative to 3 month postoperative, which is statistically significant (P ≤ 0.001), and the changes between 1 and 2 years and 2 and 3 years are also considerable and statistically significant; the K max and K min and K mean improved and the changes were statistically significant (P ≤ 0.001), and the changes between one, two, and three years were also statistically significant. The safety and efficacy indices were changed through the three-year follow-up. The complications were corneal neovascularization (36.84%), corneal melting (26.3%), and ring extrusion (31.5%) at the end of the study. Conclusions Implantation of a 355-degree intracorneal keraring using femtosecond laser improved the visual, refractive, and topographic parameters in keratoconus patients, with a high rate of ICR extrusion and instability. The study has been registered for the Pan African Clinical Trial Registry (http://www.pactr.org) database within No: PACTR201810796878908 on 29 October 2018.
Highlights
Keratoconus is a disease characterized by stromal weakening followed by corneal protrusion leading to irregular astigmatism, which impairs the vision a lot, and its exact etiology cannot be determined; many factors are accused for keratoconus occurrence [1]
Discussion e aim of ICRS surgery is to induce a geometric change in the central corneal curvature, reducing the refractive error and the mean keratometry and improving the visual acuity
According to the results obtained from this study, the femtosecond laser implantation of a 355-degree intrastromal corneal ring segment was successful according to the definition of success defined by Jorge [15], who defined successful surgery as one of the following characteristics at six months postoperatively: either an improvement in one or more lines of uncorrected visual acuity (UCVA) or best-corrected visual acuities (BCVA) or a decrease in two or more D of spherical equivalent
Summary
Keratoconus is a disease characterized by stromal weakening followed by corneal protrusion leading to irregular astigmatism, which impairs the vision a lot, and its exact etiology cannot be determined; many factors are accused for keratoconus occurrence [1].In previous studies, the prevalence of keratoconus in different countries ranged from 0.3 per 100,000 in Russia to 23 per 1000 in central India (0.0003%–2.3%) [2, 3], and in recent studies about incidence in upper Egypt, the prevalence was as high as17.5% among the populations who are seeking refractive surgery [4].So, many techniques are introduced as therapeutic choices for the management keratoconus to give more stability and better optical improvement. e procedures are different, ranging from crosslinking, intracorneal ring segment, and lamellar keratoplasty.ICRS, small synthetic devices, are designed to be implanted within the corneal stroma aiming to induce a change in the geometry and refractive power of the tissue [5].e first idea of corneal rings was introduced by Blevatskaya in 1966 [6]. The prevalence of keratoconus in different countries ranged from 0.3 per 100,000 in Russia to 23 per 1000 in central India (0.0003%–2.3%) [2, 3], and in recent studies about incidence in upper Egypt, the prevalence was as high as17.5% among the populations who are seeking refractive surgery [4]. Many techniques are introduced as therapeutic choices for the management keratoconus to give more stability and better optical improvement. ICRS, small synthetic devices, are designed to be implanted within the corneal stroma aiming to induce a change in the geometry and refractive power of the tissue [5]. The design of ring segments was introduced to correct the myopic refractive error [5].
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