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Femtosecond channel creation poses risks in corneal ring segment insertion
Acta Ophthalmol. 2011;89(1):54-57.
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Intrastromal corneal ring segment implantation using a femtosecond laser for channel creation in eyes with keratoconus yielded multiple complications, a large study found.
The study is believed to be the first to elucidate complications related to implantation of Keraring segments (Mediphacos) using a femtosecond laser for channel creation, the study authors said.
The retrospective study included 850 eyes of 531 patients with mild to moderate keratoconus. Mean patient age was 28.32 years. Patients underwent a comprehensive ophthalmologic examination preoperatively.
A 60-kHz IntraLase femtosecond laser (Abbott Medical Optics) was used to create ring channels. Duration of channel creation was 15 seconds.
Results showed complications occurring in 49 cases (5.7%).
Intraoperatively, incomplete channel formation occurred in 22 eyes (2.6%). Galvanometer lag error, or system malfunction, occurred in five cases (0.6%). Endothelial perforation occurred in five cases (0.6%). Incorrect entry of the channel occurred in two eyes (0.2%).
Postoperatively, segment displacement was identified in 11 cases (1.3%), corneal melting occurred in two cases (0.2%) and vacuum loss occurred in one eye (0.1%).
Intraoperative endothelial perforation, corneal melting and infection were deemed the most severe and sight-threatening complications. Superficial ring placement, thin cornea and inaccurate corneal pachymetry pose the highest risks for corneal melting, the authors said.
Limitations of the study included retrospective design, lack of a control group undergoing mechanical channel creation and a lack of data on visual and refractive outcomes, they said.
The authors have performed the largest series (850 eyes) of intrastromal ring segments for the treatment of keratoconus. In this series all of the pockets were created with a femtosecond laser. These patients generally have moderately advanced keratoconus and the alternative is commonly a lamellar or penetrating keratoplasty. The authors do not document visual results but have concentrated on surgical and postoperative complications. They document a complication rate of 5.7% with the overwhelming majority of problems not being visually threatening. This paper supports the overall safety of intrastromal ring segments for the management of keratoconus.
–Eric D. Donnenfeld, MD
OSN
Cornea/External Disease Board Member
Disclosure: Dr. Donnenfeld is a
consultant for Abbott Medical Optics.