Laser thermal keratoplasty (LTK) is a refractive surgery procedure that uses a Holmium laser to reshape the cornea for correction of low ranges of hyperopia (farsightedness). The Holmium laser is an infrared (thermal) laser that uses heat to shrink corneal tissue.
LTK is a non-contact laser procedure, as there is no cutting of the cornea, and nothing touches the eye before, during, or after the procedure except for the laser beam itself and an instrument to hold the eye open. The laser energy is applied in a predetermined pattern to shrink the collagen fibers in a way that steepens the cornea, changing the eye’s focal point. No eye tissue is removed in the procedure.
The LTK procedure is performed on an outpatient basis with topical anesthetic eye drops to numb the eye. Based on the patient’s prescription, the laser’s computer is calculated to deliver the number of pulses and the diameters of the circles needed to provide the proper amount of correction. After aligning the pupil with the use of a slit-lamp microscope, the surgeon activates the laser, and it transmits tiny beams of infrared light in two concentric rings around the periphery of the cornea. Because moisture in the cornea absorbs the energy in the laser pulses, the tissue shrinks slightly creating tiny craters, which tighten the cornea and result in a steeper surface. The laser never touches the eye, and the entire process takes just a few seconds per eye.
The LTK procedure is painless, although the patient may have blurry vision and a mild scratchy sensation for a couple of days. Antibiotic eye drops are normally used for about a week, and, if needed, Tylenol and ice packs can be used to relieve discomfort. Most eyes are fully healed in three days, and, although many patients report almost instant vision improvement, vision stabilization usually occurs within two weeks.
LTK is characterized by a very low incidence of side effects. Mild irritation, in the form of a foreign body sensation, was seen in under 2% of the cases and its incidence diminished over time. The greatest limitation of this procedure appears to be the possibility of reversion, or loss, of the vision correction over time. In general, about half of the corrective effect had been lost two years post-surgery.
Benefits of LTK
LTK treats mild farsightness and also provides a means of treating presbyopia (age-induced farsightedness). The procedure aims to allow patients to see near objects without glasses. For the FDA trial that led to approval of the procedure, at 12 months, 85.0% of the eyes were corrected to 20/40 or better and 37.4% were corrected to 20/20 or better visual acuity without spectacles or contact lenses. Due to the noninvasive and quick nature of the surgery, there was a lower incidence of complications for LTK than with LASIK, with less than 1% adverse events.
Other benefits unique to LTK are extremely fast procedure time (approximately 3 seconds of laser per eye), having the procedure done in the physiciaan’s office the ability to have both eyes done at once, and immediate positive results.
