PMC3699302_01
Corneal topography and wavefront aberration measurements prior to the ring placement.. Notes: Corneal topography shows central coned keratoconus pattern (A). Wavefront aberrations map shows primary and secondary vertical coma dominance (B).. Abbreviation: OD, right eye.
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Corneal topographical findings measured with Pentacam corneal topography system (Oculus Opticgerate GmbH, Wetzlar, Germany) revealed a keratoconus pattern in both eyes (Figure 1A). In the corneal wavefront map, measured with the WaveScan WaveFront  System (Abbott Medical Optics, Santa Ana, CA, USA), primary and secondary vertical coma dominance was observed (Figure 1B).
Imaging of cornea after ring implantation.. Notes: Slit-lamp photo and anterior segment optical cohorence tomography show optimal-centralized Ferrara ring segments (A and B). Corneal topography shows diminishing keratometric values (C). The Zernike Analysis with Pentacam shows increase in vertical coma and trefoil (D).. Abbreviation: OD, right eye.
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After Ferrara ring segment implantation, the corrected distance visual acuity was 20/40 with optimal centralization of the ring segments (Figure 2A and B). Corneal topography revealed diminishing keratometric values (Figure 2C), and the Zernike analysis with Pentacam (Oculus Opticgerate GmbH) showed an increase in vertical coma and trefoil (Figure 2D).
Wavefront analyses shows HOAs and total coma aberration continues 1 year after the ring segment removal (A). Six months after wavefront-guided PRK and CXL, wavefront analyses shows reduction in HOAs and coma aberrations (B). One year after wavefront-guided PRK and CXL, corneal topography (C) and wavefront analyses (D) show stability in keratometric and aberrometric values.. Abbreviations: CXl, corneal collagen cross-linking; HOAs, high order abberations; OD, right eye; PRK, photorefractive keratectomy.
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The aberrometric measurements taken from the right eye by WaveScan demonstrated that HOA root mean square error was 0.75 mum and coma domination was 0.404 mum (Figure 3A). The high order root mean square score was drawn back to 0.39 mum, and coma aberration was reduced to 0.277 mum (Figure 3B). At the 12 month visit, refractive status, visual acuity, wavefront analyses, and topograpgical measurements were unchanged (Figure 3C and D).