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Intrastromal ring segment reduces K values, boosts visual acuity in keratoconic eyes
Eur J Ophthalmol. 2010;20:865-873.
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An intrastromal ring segment enhanced corneal integrity and improved visual acuity in patients with keratoconus, a study showed.
"The progression of [keratoconus] was stopped and the cornea thickness minimally, but regularly, improved," the study authors said.
The authors set out to study the effectiveness of Ferrara intrastromal ring segments in treating keratoconus, minimizing the need for corneal transplantation and improving visual acuity in keratoconic eyes.
The study included 130 eyes of 83 patients who had keratoconus and were contact lens-intolerant. After implantation of Ferrara intrastromal ring segments, patients were followed for an average of 37 months and a maximum of 5 years.
Investigators assessed manifest refraction as well as logMAR uncorrected and best corrected visual acuity. They also undertook corneal mapping, corneal topography and intraoperative pachymetry.
Study results showed that 122 eyes (93.84%) gained lines of UCVA, and two eyes (1.53%) lost lines. In addition, 127 eyes (97.69%) gained lines of BCVA; no eyes lost lines of BCVA.
UCVA improved from 0.14 lines before surgery to 0.32 lines after surgery. BCVA improved from 0.40 before surgery to 0.59 after surgery.
Spherical equivalent improved from –8.34 D before surgery to –2.83 D after surgery.
Keratometry values diminished significantly during a 5-year period; the average K dropped from 49.27 D before surgery to 4.68 D after surgery, the authors reported.
Ferrara ICRS are a good clinical tool for the management of keratoconus because they allow a corneal modeling that leads to an improvement in visual acuity and refraction. However, it is difficult from my point of view to state that this type of implant is able to stop the keratoconus progression. We need an evaluation of corneal biomechanics and to be sure that we are implanting ICRS in progressive keratoconus.
– David Pinero, MD
Vissum Instituto
Oftalmologico de Alicante Alicante, Spain
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