Opaque bubble layer: incidence, risk factors, and clinical relevance

Abstract

Purpose: To assess the incidence, risk factors, and impact on visual outcomes of an opaque bubble layer (OBL) produced by an Intralase femtosecond laser (60 kHz) during laser in situ keratomileusis (LASIK).

Setting: Laser Vision Center, Chang Gung Memorial Hospital, Keelung, Taiwan.

Design: Case series.

Methods: Patients had femtosecond laser-assisted LASIK surgery. The surgical procedures were videotaped, and the patterns and sizes of the OBLs noted during the operations were analyzed. Preoperative and postoperative data included patient demographics, visual acuity, contrast sensitivity, refractive status, keratometry, and intraoperative data (eg, flap size, flap thickness, and docking times).

Results: The study analyzed 23 patients (40 eyes). Twenty-one eyes (52.5%) developed an OBL, 40.0% with a hard pattern and 12.5% with a soft pattern. The hard OBLs covered a mean area of 28.6% ± 10.1% (SD) and the soft OBLs, of 7.4% ± 5.6% (P = .002). The preoperative central cornea was significantly thicker in eyes that developed an OBL (P = .045). The visual outcomes 1 month postoperatively were comparable between the 2 groups except that eyes with an OBL had slightly decreased contrast sensitivity under scotopic conditions.

Conclusions: Thicker corneas tended to develop an OBL during femtosecond laser-assisted LASIK surgery. An OBL did not affect postoperative visual acuity except for a mild decrease in scotopic contrast sensitivity.