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Outcomes of Ferrara-type intracorneal ring segments for the correction of central, hyper-prolate keratoconus

Session Details

Session Title: Cornea Surgical II

Session Date/Time: Wednesday 09/10/2013 | 08:00-10:30

Paper Time: 08:12

Venue: Forum (Ground Floor)

First Author: : C.Lisa SPAIN

Co Author(s): :    L. Fernandez-Vega Cueto   G. Ferrara   J. Alfonso        

Abstract Details


To assess the visual, refractive and corneal aberrometric outcomes after the implantation of intrastromal corneal ring segments (ICRS) in central hiperprolate keratoconus.


Instituto Oftalmol├│gico Fern─»ndez-Vega, Oviedo, Spain


Eight eyes with central hiperprolate keratoconus that were implanted with a Ferrara-type ICRS of 210? (KeraRing SI6, Mediophacos Inc., Brazil) of arc inferiorly placed were evaluated. Snellen uncorrected distance visual acuity (UDVA) and best corrected distance visual acuity (CDVA), corneal spherical aberration Z (4,0), horizontal coma Z (3, 1), vertical coma Z (3, -1), Root Mean Square (RMS) value of higher order aberrations (HOAs) and residual refractive errors analyzed using vector analysis, were recorded before and 6 months after the ICRS implantation.


Mean UDVA was 0.11 ± 0.09 before and 0.44 ± 0.20 after surgery (P=0.002). CDVA was 0.51 ± 0.23 before and 0.69 ± 0.09 after surgery (P = 0.006). None of the eyes lost lines of CDVA, 2 eyes (25%) had their CDVA unchanged, 1 eyes (12.5%) gained 1 line, 5 eyes (62.5%) gained ? 2 lines of CDVA. The safety index was 1.35. Spherical equivalent was highly reduced after ICRS implantation (P= 0.02). Vertical coma Z (3, -1) changed from -1.29 ± 0.52 ?m before surgery to -0.60 ± 0.48 ?m after surgery (P= 0.0002). There were not statistically significant changes in the horizontal coma Z (3, -1) and spherical aberration Z (4, 0) values between before and after surgery. The RMS values of HOAs decreased from 1.72 ± 0.99 ?m before surgery to 1.09 ± 0.97 ?m after surgery (P= 0.0002).


One Ferrara-type ICRS of 210? of arc implanted inferiorly may reduce refractive error, vertical coma Z (3, -1), and RMS value of HOAs aberrations in eyes with central hiperprolate keratoconus, providing an improvement of UDVA and CDVA values.

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