Femtosecond laser-assisted implantation of complete versus incomplete rings for keratoconus treatment

PURPOSE To compare complete versus incomplete ring implantation for keratoconus correction. METHODS We investigated 25 eyes of keratoconic patients, of which 15 had femtosecond-assisted MyoRing corneal implantation (Group 1) and 10 had femtosecond-assisted Keraring segments (Group 2). Uncorrected distance visual acuity (UCVA), best corrected distance visual acuity (BCVA), mean K (K m), sphere, topographic cylinder, and corneal asphericity value (Q-value) were measured in all eyes preoperatively and at 4 weeks postoperatively (1 month). RESULTS In Group 1, the K m change was -6.15±2.16 D, with a mean change in sphere of 4.45±2.18 D and a mean change in refractive cylinder of 2.32±3 D. UCVA change was -0.57±0.273 logarithm of the minimum angle of resolution (LogMAR), BCVA change was -0.2±0.27 (LogMAR), and the Q-value change was 0.43±2.6. In Group 2, the K m change was -3.15±1.68 D, UCVA change was -0.48±0.37 (LogMAR), BCVA change was -0.09±0.15 (LogMAR), and the Q-value change was 0.5±0.21. Changes in the means did not significantly differ between groups, except for the K m change, which was significantly greater in Group 1 than in Group 2 (P=0.05). CONCLUSION Both complete ring and ring segment implantation are effective for improving corneal and visual parameters in keratoconus. Complete ring implantation may have a greater flattening effect on the anterior corneal surface.