Eighteen months follow-up of VISX 20/20 excimer laser PARK for mild keratoconus

Purpose. To investigate the long-term effect of photoastigmatic refractive keratectomy (PARK) on mild keratoconus. Methods. Seven eyes of 5 patients with stable compound myopic astimgatism and topography features of keratoconus were included in the study. No corneal thinning, ectasia, iron ring, nor scarring were noted. Their myopia ranged between -0.75 amd -8.25 diopters and the astigmatism between -1.50 and -7.50 diopters. All patients were treated by the VISX 20/20 excimer laser, with the sequential node. Results. In 6 out of 7 eyes the uncorrected visual acuity (UVA) before PARK ranged between 6/30 and finger counting; following PARK it ranged between 6/7 and 6/15 and the patients could manage without contact lenses or glasses in everyday life. In these 6 eyes, the post-PARK sphere ranged between plano and +0.75 diopter, and the post-PARK cylinder ranged between plano and -1.50 diopters. In one eye, the treatment failed as the UVA remained the same as before PARK. The spherical equivalent of this eye was -5.0 diopters and remained the same 18 months following PARK. The cylinder of this eye was reduced only by 50% and the sphere increased by -1.0 diopter. Topography revealed progression of the keratoconus during this time. Conclusions. Park is an effective and safe treatment for mild degrees of stable keratoconus. However, it may fail in rare cases of progression.