Subsurface photodisruption in scattering biological tissue

Approximately 5 million people worldwide are blind due to complications from glaucoma. Current surgical techniques often fail hue to infection and scarring. Both failure routes are associated with damaging the surface tissues. Femtosecond lasers allow a method to create a highly precise incision beneath the surface of the tissue without damaging any of the overlying layers. However, subsurface surgery can only be performed where the beam can be focused tightly enough to cause optical breakdown; Under normal conditions, subsurface surgery is not possible since sclera is highly scattering. Using two independent methods, we show completely subsurface surgery in human sclera using a femtosecond laser. The first method is to make the sclera transparent by injecting a dehydrating agent. The second method is to choose a wavelength that is highly focusable in the sclera. Both methods may be applied in other tissues, such as skin. We show highly precise incisions in in vivo tissues. Subsurface femtosecond photodisruption may be a useful for in vivo surgical technique to perform a completely subsurface surgery.