Intracorneal ring segment implantation has good results with mechanical or laser tunnelization

Ophthalmology. 2009;116(9):1675-1687.

Intracorneal ring segment implantation with either femtosecond laser tunnelization or mechanical tunnelization yielded positive visual and refractive outcomes in eyes with keratoconus, a study showed.

"Intracorneal ring segment implantation using both mechanical and femtosecond laser-assisted procedures provide similar visual and refractive outcomes," the study authors said. "A more limited aberrometric correction is observed for eyes with mechanical implantation."

The retrospective study included 146 eyes; 68 patients had unilateral keratoconus and 39 patients had bilateral keratoconus. Sixty-three eyes underwent mechanical tunnelization, and 83 eyes underwent femtosecond laser-assisted tunnelization.

In the mechanical group, 55 eyes received an Intacs implant (Addition Technology) and eight eyes received a Keraring implant (Mediphacos). In the femtosecond laser group, 25 eyes received the Intacs implant and 58 eyes received the Keraring implant.

At 6 months, uncorrected visual acuity and refraction improved in both groups (both P ≤ .02). Best corrected visual acuity improved in the femtosecond laser group (P < .01). The femtosecond laser group had reduced root mean square astigmatism (P = .03) but increases in some higher-order aberrations (P = .03).

Eyes in the femtosecond laser group implanted with Intacs had lower primary spherical aberrations, coma and other higher-order aberrations (P ≤ .01).

The mechanical group showed a significant negative correlation between preoperative corneal aberrations and postoperative BCVA (P ≤ .04), the authors said.