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Vishal Jhanji, Waiying Li, Kasin Law, Peng Yi, Qian Wang; Histological Evaluation of Wound Healing in LASIK Flaps with 70 degrees and 120 degrees side cuts. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3951.
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© ARVO (1962-2015); The Authors (2016-present)
To examine early postoperative wound healing in rabbit corneas that had LASIK flaps created with 70 degrees and 115 degrees side cut angle using 150 KHz femtosecond laser.
Sixty-four rabbit corneas were randomized to receive either no surgery (n=36) or corneal flaps (n=36) created with 70 degrees and 115 degrees side cut. Eighteen eyes received only side cuts without lamellar flaps. Animals were sacrificed and corneas were processed as frozen sections. Frozen sections were evaluated with TUNEL assay to detect apoptosis, immunocytochemistry for Ki67 to detect cell mitosis, and immunocytochemistry for CD11b to detect mononuclear cells. Apoptotic cell counts were described in median counts with first to third quartiles. A generalized estimating equation with an exchangeable correlation structure was used for description of effect of surgery on the apoptotic cells. Boferroni adjustments were used for multiple comparisons.
Rabbit corneas with 70 degrees side-cut had exhibited more epithelial ingrowth compared to 120 degrees side cut corneas on hematoxylin and eosin staining. All corneas that had received femtosecond laser had TUNEL-positive cells in the anterior stroma in the central as well as peripheral cornea 24 hours after the procedure. No TUNEL-positive stromal cells were detected in control corneas. In the peripheral cornea, 70 degrees side cut generated more apoptotic cells than 120 degrees side cut (P=0.019). The same trend was observed in the central cornea where 70 degrees side-cut and 70 degrees side-cut+LASIK induced more apoptotic cells compared to the corneas with120 degrees side cut (P<0.001). Overall, Ki67 expression was significantly higher in corneas with 120 side cut compared to corneas with 70 degrees side cut and, control corneas. CD11b staining was negative in all samples.
In our study, 70 degrees side cut triggered more epithleial growth and TUNEL-positive cells in both central and peripheral cornea, compared to 120 degrees side cut. The corneas with 120 degrees side cut expressed more mitotic activity than those with 70 degrees side cut. This disparity may translate into different healing response in the two side cut angle profiles.
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