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Mechanical and femtosecond corneal ring tunnel creation methods prove similarly effective
J Cataract Refract Surg. 2010;36(9):1556-1561.
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Mechanical and femtosecond laser-assisted tunnel creation methods for intrastromal corneal ring segment implantation offered comparable visual and refractive outcomes in eyes with keratoconus, a study found.
However, mechanical tunnel creation was associated with intraoperative complications, the study authors said.
"Results in this prospective randomized clinical trial suggest that visual and refractive results of femtosecond-assisted tunnel creation are comparable to those of mechanical tunnel creation," the authors said. "However, the femtosecond method is faster, easier and more comfortable for both patient and surgeon."
The study included 100 eyes of 90 patients. The mechanical tunnel creation group included 50 eyes of 46 patients with a mean age of 26.6 years. The femtosecond laser tunnel group comprised 50 eyes of 44 patients with a mean age of 27.6 years. Only patients dissatisfied with spectacle and contact lens use were included.
All patients underwent implantation of a Keraring ICRS (Mediphacos). Investigators assessed uncorrected and corrected Snellen distance visual acuity, refraction and keratometry before surgery and 1 year after surgery.
At 1 year, uncorrected and corrected distance visual acuity, keratometry readings, spherical equivalent, manifest sphere and cylinder had improved significantly in both groups (P < .05). However, there were no statistically significant between-group differences in visual or refractive outcomes.
Complications in the mechanical tunnel creation group included anterior corneal perforation, superficial segment placement and segment extrusion in one eye each. Segment extrusion was found in one eye in the femtosecond tunnel creation group.
The femtosecond tunnel creation method enabled precise implantation depth, particularly in thin corneas, the authors said.
"Therefore, larger comparative studies focusing on outcomes of both techniques in eyes with advanced keratoconus are needed," they said.