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Thickness and immunohistochemistry of LASIK flaps created by different femtosecond lasers in eye-bank corneas

Espessura e imunohistoquímica de flap de LASIK criado com diferentes laseres de femtosegundo em córneas de banco de olhos

ABSTRACT

Purpose:

The aim of this study was to compare the corneal cell viability and thickness of LASIK flaps created by 3 femtosecond lasers in eye-bank human corneas.

Methods:

Forty-five eye-bank human sclerocorneal buttons (15 corneas in each group) were examined after the creation of 120 mm-thick laser-assisted keratomileusis (LASIK) flaps with 150kHz iFS In­traLase™ (IL), Z6 Femto LDV™ (LDV), or 200kHz Wavelight™ FS200 (FS200). The thickness of the flaps was measured using anterior segment optical coherence tomography (AS-OCT; Visante™). Cell viability was blindly evaluated with immunohistochemistry for keratocyte apoptosis using anti-caspase 3 antibodies.

Results:

The standard deviation from the intended flap thickness was less than 10 mm in all the groups. There was a statistically significant difference in corneas treated with LDV and IL with regard to the flap thickness horizontally at +3.00 mm (p=0.0124), -0.5 mm (p=0.0082), and -1.00 mm (p=0.0425) from the corneal vertex and +0.5 mm from the flap edge (p=0.0240), and those treated with LDV and FS200 with regard to the flap thickness horizontally at -0.5 mm from the corneal vertex (p=0.0082). The mean keratocyte apoptosis numbers were 13.09 ± 1.10, 15.59 ± 3.28, and 17.72 ± 1.49 in corneas treated with IL, FS200, and LDV, respectively (p<0.001).

Conclusion:

All 3 assessed femtosecond lasers provided predictable LASIK flap thickness. The mean stromal keratocyte apoptosis number was low in all groups.

Keywords:
Keratomileusis, laser in situ; Femtosecond; Tomography, optical coherence, Anti-caspase 3; Cornea; Eye-bank

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