Visual and refractive outcomes of intracorneal ring segments in the treatment of keratoconus: the RETICS multicentrical study

Purpose Analyze the outcomes of intracorneal ring segment (ICRS) implantation for the treatment of Keratoconus based on preoperative visual impairment. Design: Multicenter, retrospective, nonrandomized study. Methods 611 eyes of 361 keratoconic patients were evaluated. Subjects were classified according to their preoperative corrected distance visual acuity (CDVA) into five different groups: Grade I, CDVA of 0.90 or better, Grade II, CDVA equal or better than 0.60 and worse than 0.90, Grade III, CDVA equal or better than 0.40 and worse than 0.60, Grade IV CDVA equal or better than 0.20 and worse than 0.40 and Grade Plus, CDVA worse than 0.20. Success and failure indexes were defined based on visual, refractive, corneal topographic and aberrometric data and evaluated in each group six months after ICRS implantation. Results Significant improvement after the procedure was observed regarding uncorrected distance visual acuity in all grades (p<0.05). CDVA significantly decrease in Grade I (p<0.01), but significantly increases in all other grades (p<0.05). 37.9% of patients with preoperative CDVA 0.6 or better gained 1 or more lines of CDVA, while 82.8% of patients with preoperative CDVA 0.4 or worse gained 1 or more lines of CDVA (p<0.01). Spherical equivalent and keratometry readings showed a significant reduction in all Grades (p≤0.02). Corneal higher order aberrations did not change after the procedure (p≥0.05). Conclusion Based on preoperative visual impairment, ICRS implantation provides significantly better results in patients with a severe form of the disease. A notably lost of CDVA lines can be expected in patients with a milder form of Keratoconus.