Effect of myopic femto-LASIK on anterior chamber flare count and endothelial cell density. Preliminary Report

Abstract

Purpose:

To investigate whether femto-lasik surgery causes inflammation in the anterior chamber and its effect on endothelial cell density

Setting:

Department of Ophthalmology Istanbul University, Istanbul Faculty of Medicine,, Istanbul, Turkey

Methods:

38 eyes of 19 patients who underwent femtosecond assisted lasik surgery due to myopia and/or myopic astigmatism were included in our prospective clinical study. All patients underwent preoperative complete ophthalmologic examination, manifest and cycloplegic refraction values were recorded. Endothelial density was measured withspecular microscopy and anterior chamber flare count was measured by Laser Flare Photometry. Refractive surgeries were performed with iFS™ Advanced Femtosecond Laser System and VISX STAR S4 IR Wavescan Excimer Laser. Complete ophthalmological examination and flare measurements were performed on the postoperative 1st day, 7th day, 1st month and 3rd month. Endothelium count was repeated at 3rd month.

Results:

Uncorrected visual acuity (UCVA) increased from pre-op 1.18 ± 0.44 logMAR to post-op -0.005 ± 0.07 logMAR. (p=0.0001) While the pre-op spherical equivalent (SE) was -2.88 ± 2.49 diopters (D), this dropped to -0.22 ± 0.26 D postop. (p<0.0001) Pre-op mean central corneal thickness (CCT) was 561.3 ± 31.1 microns and mean ablation amount was 62.29 ± 24.06 microns. While the pre-op flare was 5.32 ± 1.01 photons / ms, it was 5.54 ± 1.62 photons/ms on the first day, 5.72 ± 2.27 photons/ms on day 7, 5.65 ± 3,72 photons/ms in the first month and 5,95 ± 1,73 photons / ms in the third month. There was no significant difference in flare counts between pre-op and 1st day (p = 0.411), 7th day (p = 0.309), 1st month (p = 0.594) and in cross comparisons. A statistically significant but minimal difference was observed between the pre-op flare count and only the third month value. (p=0.05) While pre-op endothelium density was 2858.9 ± 249.4 cells / mm2, it decreased to a mean value of 2767 ± 243.4 cells / mm2 in the third post op month, with a mean decrease of 91 ± 237.9 cells / mm2 . This difference was observed to be statistically significant. (p=0.024). In Pearson correlation and linear regression analysis; there was a negative, mild-moderate, statistically significant relationship between the decrease in the count of endothelial cells and pre-op cylindrical refractive error. (R = -0.381, p = 0.009) And no relationship was found with age, gender, pre-op spherical, SE values and ablation amount. There was no relationship between pre-op, 1st day, 7th day, 1st month flare values and other parameters, whereas there was a weak but statistically significant relationship between 3rd month flare value and pre-op spherical (R = 0.308, p = 0.03) and SE (R = 0.269, p = 0.05). When flare values were analyzed among themselves, no correlation was detected.

Conclusions:

According to the present study, femto-lasik excimer laser does not cause serious inflammation in the anterior chamber and does not increase the amount of flare. To the best of our knowledge, this is the first study to evaluate anterior chamber inflammation using flare count measurements in femto-lasik refractive surgery. In addition, according to our limited number of cases, it was observed that it caused a statistically significant but clinically insignificant decrease in endothelial cell density.