To Study Anatomical And Intraoperative Factors Responsible For Gas Bubble Formation In Anterior Chamber During Femtosecond Laser Flap Creation

TO study and investigate the factors responsible for gas bubble formation in anterior chamber(AC) during femtosecond laser (FS) Laser in situ keratomileusis (LASIK)  flap creation

Retrospective study

20 patients, 10 in each group, undergoing LASIK surgery for refractive error at our center. Preoperative and intraoperative data including refractive error, keratometry, white to white (WTW) corneal diameter using Pentacam, flap diameter, pulse  energy parameters, suction time, angle parameters and anterior chamber depth using CASIA asoct, recorded and compared between the gropus. To determine the anatomical and intraoperative factors, univariate and multivariate logistic regression were used, the eye was unit of analysis.

Median WTW in the study group(group-1)-11.5+/-0.377mm and in control group(group-0)-11.78+/- 0.181mm,was statistically significant (p-0.04). The median anterior chamber depth on Pentacam in group-1 was 3.39+/-0.372 mm and in group-0 was 3.86+/-0.284mm, was stastically  significant(p-0.005).Anterior chamber width,in group1 was 11.37+/-0.435mm and in group0 was 11.83+/-0.264mm,was statistically significant (p-0.01).Trabecular iris area 500,in group1 (42.92+/-10.61)and in group0(55.99+/-11.80), statistically significant(p-0.01).Angle on Pentacam in group1 was 35.22+/-4.28 and in group0 was 41.79+/-3.95,statistically significant( p-0.002). Suction time in group1(62+/-12.89) secs and in group0(62+/-12.89)secs,p-0.0009,statistically significant.

The gas bubble formationin anterior chamber during femtosecond lasik is a common event. The WTW being smaller in Asian eyes predispose them to this complication. The eye anatomy plays a major role in incidence of such event. Pentacam and Casia ASOCT can play a role in predicting such cases in preoperative workup only, acting as an adjuvant technology while planning refractive surgery