Comparison of outcomes of 2 channel sizes for intrastromal ring segment implantation with a femtosecond laser in eyes with keratoconus

PURPOSE: To compare the outcomes of 2 channel sizes for intrastromal ring segment (Intacs, Addition Technology, Inc.) implantation using a femtosecond laser in eyes with keratoconus. SETTING: Kudret Eye Hospital, Ankara, Turkey. METHODS: A retrospective outpatient study included 159 consecutive keratoconic eyes of 103 patients. Patients were classified into 2 groups according to channel dissection size: wide (6.7 mm x 8.2 mm) and narrow (6.6 mm x 7.6 mm). Dissections were created with an IntraLase femtosecond laser (IntraLase Corp.). The 2 groups were compared according to uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refractive error (manifest sphere, manifest cylinder, and manifest refractive spherical equivalent), mean K-value, and complications within 6 months postoperatively. RESULTS: The wide-channel group comprised 97 eyes of 65 patients (37 men, 28 women) with a mean age of 27.64 years +/- 8.61 (SD). The narrow-channel group comprised 62 eyes of 38 patients (23 men, 15 women) with a mean age of 26.62 +/- 6.13 years. At 6 months, the UCVA and BCVA had significantly improved in 63.9% and 70.1% of eyes, respectively, in the wide-channel group and in 72.5% and 75.8% of eyes, respectively, in the narrow-channel group. The change in mean BCVA and change in mean UCVA in both groups were not statistically significant (P < .05, independent samples t test). There was no between-group difference in the improvement in manifest spherical refraction, cylindrical refraction, manifest refractive spherical equivalent, or mean K-readings (P < .05, independent samples t test). Epithelial plug, yellow-white deposits, tunnel haze around segments, and upward movement of the inferior segment without extrusion were observed more frequently in the narrow-channel group than in the wide-channel group. CONCLUSIONS: The refractive outcomes of wide channels and narrow channels for Intacs treatment in eyes with keratoconus were similar 6 months postoperatively. The narrow-channel group had a higher rate of mild to moderate complications than the wide-channel group.