ReLEx SMILE is a newer laser vision correction technique which is flapless and gentle on the eye.
LASIK involves making a thin corneal flap which is then lifted allowing the underlying cornea to be reshaped. ReLEx SMILE uses the precision of the Visumax femtosecond laser to create a precise corrective lens of tissue within the substance of the cornea which is then extracted through a tiny 2mm incision. As there is no flap lifted during SMILE the nerve endings in the cornea are preserved which may result in less dry eye related problems after the surgery.
The surface of the cornea is the most sensitive area of the body. Acute sensation at the surface of the eye protects one of our most vital senses, making us immediately aware of any injury or problem with the eye. These nerve endings are also important for normal tear production and are involved in a feedback loop that stimulates the tear gland to continue normal tear production. Nerve endings are most densely packed in the front part of the cornea where they form a branching network.
During LASIK surface nerve fibers are severed when the flap, which requires a circumferential incision, is lifted. In contrast, as SMILE does not involve a circumferential incision and because the corrective lens is cut deeper in the cornea there is a greater chance of preserving corneal nerves during the procedure.
In theory this should cause less disturbance to the feedback loop of tear production in the period immediately after surgery. With LASIK the nerve endings take some months to grow back and for the tear film to normalise.
In patients with normal eyes and without preexisting dry eye LASIK rarely causes significant dry eye problems and gives excellent results. For patients with a dry eye tendency ReLEx SMILE may be a better option.