[Intrastromal thermokeratoplasty for correction of spherical hyperopia: a 1-year prospective study]

Thermokeratoplasty (TKP) is a new procedure for surgical correction of hyperopia. It uses controlled thermal burns of the peripheral cornea with a retractable cautery probe tip in a radial pattern up to a premarked optical central zone. The thermal effect shrinks the peripheral cornea and steepens the central cornea. In this report, we prospectively evaluated for one year, anatomical, functional and refractive results of a group of 18 eyes treated with TKP (14 patients). Mean preoperative spherical equivalent of +3.62 diopters (D) was +1.85 D at 12 months resulting in a mean refractive variation of -1.76 D. The refractive effect was significant at the first postoperative month, and subsequently regressed so that the average refractive correction was 55% at one year. We did not observe any severe anatomical or functional complications during the follow up period. Regression of the refractive effect after TKP seems to be related to the remodeling response of corneal stroma surrounding points of coagulation. Like other current techniques of surgical correction of hyperopia (hexagonal keratotomy, TKP using Holmium-YAG laser, Excimer laser), TKP is a procedure for which optical results at one year show poor predictability and stability. We suggest that adjustments to the surgical prediction software and long term studies would allow to improve our results.