Hyperopia correction using an erodible mask excimer laser delivery system coupled to an axicon: preliminary results

This paper presents the results of the first human trial on the correction of hyperopia using an erodible mask excimer laser delivery system coupled to an axicon.

We treated 17 eyes of 17 patients (age range 34-62 years) for the correction of +3.21 +/- 1.04 D (range +1.00 to +4.00 D). The hyperopic correction was made using an erodible mask inserted on the laser optical pathway, to produce a circular ablation measuring 6.5 mm in diameter. An axicon was then used to create a blend transition zone from 6.5 mm up to 9.4 mm in diameter. Eyes were evaluated at one, three and six months after surgery.

Reepithelization was always observed by the fifth postoperative day, despite the large area of deepithelization (diameter 9.5 mm). Mean refractive error one month after treatment was -2.44 +/- 1.59 D (range 0.00 to -6.50 D). Five eyes (29.4%) had a best corrected visual acuity loss more than two to three lines; all eyes showed mild annular haze not involving the central part of the cornea. Six months after treatment, mean refractive error was -0.88 +/- 0.99 D (range +0.50 to -3.00 D). Compared to preoperative status, 13 eyes (76.5%) showed an improvement in uncorrected distance visual acuity (1-8 lines), and 14 eyes (82.4%) showed an improvement in uncorrected vision at reading distance (3-7 lines). Two eyes (11.7%) showed a best corrected visual acuity loss of two of three lines.

These preliminary results indicate this approach is effective in reducing hyperopia, while its predictability has still to be proved in a larger treatment group with longer follow-up. A cautious approach to this technique is still advisable, especially for higher hyperopic corrections, in view of the large best corrected visual acuity loss seen in two eyes at six months.