Abstract
Purpose: :
To investigate whether the riboflavin and UVA irradiation during LASIK enhance the biomechanical stability of cornea and improve the long-term stability and safety of refractive outcome.
Methods: :
One eye of 12 New Zealand white rabbits was treated with 0.1% riboflavin solution and surface UVA irradiances during LASIK surgery, and nothing but LASIK procedure was done in the other eye. After corneal flap was made by microkeratome, stromal bed was ablated by excimer laser (VISX S4, Abbott Medical Optics) with depth of 60 µm at 6 mm zone. And then a disposable solution of riboflavin 0.1% and dextrane 20% was instilled for 15 minutes on flap inner surface and stromal bed before flap was repositioned and UVA was irradiated for 30 minutes (3 mW/cm2). Before treatment, immediately and 1 month after treatment, corneal curvature, high resolution corneal imaging, Schiempflug imaging, and ocular hysteresis were measured. The animals were euthanized 1 month postoperatively. The corneas of the enucleated eyes were evaluated in routine histologic sections.
Results: :
Corneal curvature and corneal hysteresis were not significantly changed between immediately and 1 month postoperatively in both the treated eyes and the control eyes, but the amount of change in them was significantly smaller in the treated eyes. We found apoptosis of keratocytes down to mean depth of 81.2 ± 24.0 µm from flap interface in the treated eyes, 77.6 ± 16.3 µm in control eyes, which have no significant difference. Flap detachment was observed during glutar-aldehyde fixation in 6 of the control eyes, contrary to one of the treated eye. TEM imaging of collagen fiber beneath the interface have thicker diameter and denser arrangement in the treated eyes.
Conclusions: :
We identified that riboflavin with UVA irradiation treatment on flap interface had the effect to enhance the biomechanical stability after LASIK surgery, even though short-term observation. We expect that riboflavin/UVA treatment may prevent the refractive regression, further corneal ectactic change after LASIK.
Keywords: cornea: clinical science • refractive surgery: LASIK