Posters

New technique to reduce incidence of opaque bubble layer formation (OBL) during LASIK flap creation using VisuMax femtosecond laser

Poster Details

First Author: D. Hamilton UNITED STATES

Co Author(s):    N. Wu                    

Abstract Details

Purpose:

To identify risk factors for OBL formation and to compare the incidence of OBL using a new technique versus the original technique for LASIK flap creation using the VisuMax laser.

Setting:

UCLA Laser Refractive Center (Academic Center), Stein/Doheny Eye Institute, Los Angeles, CA

Methods:

Retrospective study examining videos of flap creation using VisuMax to identify flaps in which OBL occurred. Group 1: Eyes where OBL occurred using original technique. Group 2: Eyes where OBL did not occur using original technique. Pre-operative measurements including simKs, WTW, pachymetry, patient age/gender, amount of correction, flap parameters, energy setting and corneal resistance factor were analyzed to identify parameters with statistical difference between Groups 1 and 2. Group 3: Eyes in which a new technique was used for LASIK flap creation (larger flap diameter). Incidence of OBL was compared between original technique and new technique.

Results:

OBL incidence is significantly lower with the new technique 7.6% (7 of 92 eyes) than with the old technique 28.8% (34 of 118 eyes) (Fisher exact, P = 0.0009). Factors identified with a significant difference between eyes with and without OBL using the old technique are: pachymetry (OBL: 561.2, no OBL: 549.6, P=0.0132), WTW (OBL: 11.6, no OBL: 11.9 , P=0.0048), CRF (OBL: 10.4, no OBL: 9.6, P= 0.0329), K average (OBL: 44.4, no OBL: 43.6, P=0.0550), K2-K1 (OBL: 0.8, no OBL: 1.0, P=0.0472), Axis (refraction) (OBL: 57.6, no OBL: 93.5, P=0.0550).

Conclusions:

Steeper, thicker, denser and smaller corneas could be risk factors for OBL using the original technique for flap creation. A new technique for flap creation which allows for a larger flap diameter is associated with significantly lower risk of OBL formation, even in eyes with significant risk factors for OBL using the original technique.

Financial Disclosure:

NONE