LASIK Correction of Residual Refractive Error in Post Corneal Graft Patients

Anun Vongthongsri, M.D.
Kanitta Tantisirisomboon, M.D.
Pattaramon Bunnapradist, M.D.

ABSTRACT : Purpose : To study the surgical techniques and results of LASIK surgery in patients who had previous penetrating keratoplasty with residual high refractive error of astigmatism. The results in terms of efficacy, safety and accuracy will be analysed.
                      Method : The patients with significant spherical and cylindrical refractive error after penetrating keratoplasty that could not be adequately corrected by spectacles or contact lenses were included. All sutures had been removed from graft for several months until stability of refraction was achieved. Patients were scheduled for the Lasik procedure for correcting the residual refractive error in two different techniques. The first six patients were corrected in two-step procedure while the last two patients were corrected in one-step procedure.
                      Results : Eight eyes of eight patients who were diagnosed as keratoconus (2 patients), corneal scar (2 patiens), bullous keratopathy (1patient), Fuchs dystrophy (1 patient), lattice dystrophy (1 patient) and old interstitial keratitis (1 patient) were included in the study. Mean time from penetrating keratoplasty to LASIK flap creation was 21.07 ? 12.68 months (6.4-38.4 months). The mean follow up time was 15.27 months after LASIK (8.3 – 31.9 months). The mean spherical component of manifest refraction before LASIK was -3.56 ? 1.89 (-0.5 to -10 D). Postoperatively this has been reduced to -0.09 ? 0.63 (-0.5 to ? 1.00 D). Mean preoperative astigmatism (as measured by manifest refraction) decreased from -4.34 ? 2.84 (range -1.5 to -10.00 D) to -1.33 ? 1.24 (range -2.3 to + 0.5 D) postoperatively. Mean uncorrected vesual acuity was 20/440 (20/1000 to 20/200) preoperatively and improved to 20/40 (20/100 to 20/20) postoperatively.
                      Conclusion : LASIK procedure in post-op penetrating keratoplasty patient who has high refractive error or high anisometropia was effective, accurate and safe. The step of creating corneal flap was more difficult and need to be more careful than conventional LASIK procedure.

Thai J Ophthalmol 2002 ; January-June 16(1) : 15-20.