Abstract
Abstract: :
Purpose:Femtosecond laser pulses tuned to 1.7 µm wavelength can be delivered through the translucent conjunctiva and sclera to create partial thickness drainage channels in the sclera. Our goal was to evaluate the potential of femtosecond laser created partial thickness fistulas in order to increase the rate of aqueous outflow in ex vivo porcine eyes. Methods:Freshly enucleated porcine globes were first perfused at 10, 15, 25 and 35 mmHg pressure. The outflow rate was measured at each pressure after achieving a steady state, for approximately 15 minutes. The globes were then mounted on a motion controlled translation stage. Tissue hydration was ensured by surrounding the globes with moist cotton. Creation of the partial thickness fistulas was achieved by scanning the focal spot of the laser beam from the inner surface of the sclera towards the outer surface along rectangular patterns close to the limbus. The scanning was stopped before the fistulas reached the outer surface of the sclera. The outflow rate was again measured after the laser treatment at the same perfusion pressures. Baseline measurements were obtained in untreated globes kept in the same environment as treated globes over the same period of time. Results:An increase of the outflow rate from 0.4 µl/minute up to 1.2 µl/minute was observed after femtosecond laser treatments during the initial studies. In comparison, base line measurements provided outflow fluctuations over a considerably smaller range, indicating that the increase of the outflow is due to the presence of the partial thickness drainage channels. Conclusions:Results from these initial tissue experiments indicate that partial thickness drainage channels may potentially increase the outflow rate of aqueous humor. This demonstrates that minimally invasive femtosecond laser treatments may have a future potential for the surgical treatment of glaucoma.
Keywords: aqueous • outflow: trabecular meshwork • sclera