Four-year follow-up of intrastraomal corneal ring segments in patients with keratoconus

PURPOSE: To report long-term efficacy and safety of Intacs intracorneal ring segments (ICRS) in mild to moderate keratoconus. SETTING: Instituto Microcirugia Ocular (IMO), Barcelona, Spain. METHODS: Retrospective case series. Intacs ICRS were implanted to 46 eyes of 36 patients with keratoconus who exhibited intolerance to contact lenses. Manifest refraction, uncorrected visual acuity (UCVA) and best-spectacle corrected visual acuity (BSCVA), keratometry (K), biomicroscopy, applanation tonometry, and funduscopy were performed before surgery, at 3 months and at yearly intervals up to 5 years. Intraoperative and postoperative complications were also recorded. RESULTS: Intacs implanted were: 2 symmetric segments (19(41.3%)eyes), 2 segments of different thickness (23(50%)eyes), and one segment implanted inferiorly (2(4.34%) eyes). Mean spherical equivalent (SE) improved from –3.50±2.84D to –0.5±1.48D. Mean refractive cylinder was –2.68±1.7D preoperatively, and –2.9±1.7D, postoperatively. Mean K decreased from 46.14±3.42 to 44.35±3.66 D. UCVA improved in 43 (93.4%) eyes, and BSCVA remained stable or improved in 38 (82.6%) eyes. Eight (17.4%) eyes lost 1 line of BSCVA. Both BSCVA and SE refraction improved progressively during the first 6 months, and remained stable over the 4-year follow-up period. Cylinder results were unpredictable. No intraoperative complications occurred. One eye required penetrating keratoplasty due to unexplained loss of BSCVA one year after Intacs implantation. CONCLUSIONS: Over a 4-year follow-up period, ICRS have been effective to improve UCVA, BSCVA and SE in eyes with keratoconus. Intacs implantation may be an option to delay penetrating keratoplasty in keratoconic patients who become contact lens intolerant.