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Noncontact holmium:YAG laser thermal keratoplasty to correct hyperopia: 18-month follow-up
T Kohnen1, D D Koch, P J McDonnell
1Cullen Eye Institute, Baylor College of Medicine, Department of Ophthalmology, Houston, Tex., USA. TBKMD@aol.com
Purpose:
To assess the safety and efficacy of noncontact holmium:yttrium aluminium garnet laser thermal keratoplasty (Ho:YAG LTK) for correction of low to moderate hyperopia.
Methods:
We performed noncontact Ho:YAG LTK on 1 eye each of 28 patients for correction of hyperopia up to +3.88 dpt. Treatments were conducted with 1 or 2 symmetrical octagonal rings of 8 spots/ring with centerline diameters of 6 mm (1 ring) or 6 and 7 mm (2 rings), 10 pulses of laser light at 5 Hz pulse repetition frequency, variable pulse energy in the range of 208-242 mJ and a nominal spot diameter between 615 and 623 microns.
Results:
At 18 months after surgery, 20 of 22 (91%) treated patient eyes had improved uncorrected distance visual acuity. The mean change in subjective manifest refraction (spherical equivalent) was -0.52 +/- 0.35 dpt and -1.41 +/- 0.53 dpt for 1- and 2-ring treatment groups, respectively, with good stability in the refractive change after 6 months. The mean induced refractive astigmatism was small (0.30 +/- 0.37 dpt/0.25 +/- 0.29 dpt for 1-/2-ring treatments). None of the eyes lost 2 or more lines of spectacle-corrected distance visual acuity. There were no clinically significant changes in glare and contrast sensitivity.
Conclusions:
Noncontact LTK treatment of low hyperopia is safe and effective, and it is more stable and less prone to induce astigmatism than previously reported contact mode LTK treatments.