Abstract
Purpose: To evaluate long-term visual, refractive, and topographic outcomes of KeraRings intrastromal implantation combined with accelerated transepithelial cross-linking for management of different stages of progressive keratoconus. Materials and Methods: This retrospective cohort study included 70 eyes of 70 patients with Amsler-Krumeich grades 1 to 4 keratoconus. They were divided into two groups: group-A included 37 eyes with grades 1-2 keratoconus, and group-B included 33 eyes with grades 3-4 keratoconus. Both groups underwent combined Keraring implantation with TCXL treatment. The main outcome measures included the preoperative and postoperative visual acuity, refraction, keratometry readings, and pachymetry. Results: At postoperative month 60, group-B exhibited significantly higher values of all mean uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), sphere/cylinder/spherical equivalent/defocus equivalent (DEQ), and K1/K2/Kaverages/Kmax parameters compared to that of group A. However, group-A exhibited better stability of postoperative improvements. Keratoconus progression (KCP) was greater in group-B (45.5%) than group-A (10.8%). Two eyes revealed segments' migration while one eye showed tunnel vascularization and opacification with segments' migration. Conclusion: The diagnostic criteria of preoperative-KCP are not adequate for the diagnosis of postoperative-KCP following ICRS implantation. UDVA and K average posterior seemed to be more sensitive parameters than K max in documenting early postoperative-KCP. We suggest that deterioration of UDVA≥0.10 log MAR and/or K average posterior ≥0.25 D are highly suspicious of post-ring implantation keratoconus progression (PR-KCP). The occurrence of two of the following parameters: Kmax≥0.50 D, Kaverageanterior≥0.50 D, K average posterior ≥0.25 D, or pachymetry≥1.5% thinning, is diagnostic of PR-KCP. The occurrence of two or more of the following parameters: Kmax≥0.50 D, Kaverageanterior≥0.50 D, Kaverageposterior ≥0.25 D, pachymetry≥ 1.5% thinning or UDVA≥0.10 logMAR, is diagnostic of PR-KCP. We also suggest that Kmax≥0.75 D alone is diagnostic of PR-KCP.
Highlights
Keratoconus (KC) is a bilateral progressive asymmetrical ectatic disease of the cornea with multifactorial etiological factors lead to stromal thinning and corneal protrusion [1].Vernal keratoconjunctivitis [2], chronic eye rubbing [3], thyroid disease [4, 5], pregnancy, and lactation [6] are known risk factors that could promote keratoconus progression (KCP) [7, 8].The first known effective treatment that halts KCP is the corneal collagen standard cross-linking (SCXL) that was introduced by Wollensak et al in 2003 [9]
Our findings suggest that the values regularly used to document preoperative KCP were not ideal to document postoperative KCP, especially in eyes implanted with Intracorneal ring segments (ICRS)
As regards the efficacy of combined treatment with transepithelial CXL (TCXL), postoperative stability is achieved in the first few years, we demonstrated that nineteen eyes (27%) showed definite KCP at the fifth postoperative year
Summary
Keratoconus (KC) is a bilateral progressive asymmetrical ectatic disease of the cornea with multifactorial etiological factors lead to stromal thinning and corneal protrusion [1].Vernal keratoconjunctivitis [2], chronic eye rubbing [3], thyroid disease [4, 5], pregnancy, and lactation [6] are known risk factors that could promote keratoconus progression (KCP) [7, 8].The first known effective treatment that halts KCP is the corneal collagen standard cross-linking (SCXL) that was introduced by Wollensak et al in 2003 [9]. Keratoconus (KC) is a bilateral progressive asymmetrical ectatic disease of the cornea with multifactorial etiological factors lead to stromal thinning and corneal protrusion [1]. Vernal keratoconjunctivitis [2], chronic eye rubbing [3], thyroid disease [4, 5], pregnancy, and lactation [6] are known risk factors that could promote keratoconus progression (KCP) [7, 8]. The first known effective treatment that halts KCP is the corneal collagen standard cross-linking (SCXL) that was introduced by Wollensak et al in 2003 [9]. Intracorneal ring segments (ICRS) are introduced as a refractive device that helps to support the cone, flatten the corneal surface, and improve the spherical and astigmatic status, improving the patients’ visual acuity and quality [24, 25]. Keraring segments (Mediphacos Inc., Belo Horizonte, Brazil) are common ring segments that are used as corneal implants worldwide [35, 37]
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