Results of scanning and flying spot technologies in photorefractive keratectomy (PRK) for hypermetropia
Resch, M.ós.; Popper, M.ón.
Orvosi Hetilap 144(4): 179-185
2003
ISSN/ISBN: 0030-6002 PMID: 12621816 Document Number: 563471
To compare the results of scanning and flying spot laser beam technologies of photorefractive keratectomy (PRK) in eyes with hypermetropic refractive error. In Group I (n = 800) eyes were treated with scanning technology (Aesculap-Meditec MEL 60), in Subgroup I/1 (n = 482) those eyes, which had a preoperative refractive error between +1.0 and +3.5 D; in Subgroup I/2 (n = 318) the eyes between +3.75 and +6.5 D. In Group II (n = 200) eyes treated with flying spot technology (Aesculap-Meditec MEL 70 G-Scan) were evaluated; in Subgroup II/1 (n = 106) eyes between +1.0 and +3.5 D; in subgroup II/2 (n = 94) eyes between +3.75 and +7.5 D. Follow-up time was 12 months. The preoperative correction need decreased in Group I/1 from +2.88 +/- 1.34 D to +1.26 +/- 1.24 D; in Group I/2 from 64 +/- 2.96 D to +2.46 +/- 1.84 D; in Group II/1 from +2.94 +/- 1.42 D to +0.42 +/- 0.14 D and in Group II/2 from 48 +/- 2.62 D to +0.86 +/- 0.6 D 12 months after PRK. Postoperative uncorrected visual acuity (UCVA) was 1.0 or better in 75.7% within the eyes of Group I/1; it was 22.3% in Group I/2; 80% in Group II/1 and 64.8% in Group II/2. The percentage of the eyes within +/- 1.0 D of targeted refraction was: In Group I/1 86.1%, in Group I/2 45.3%, in Group II/1 92.4% and in Group II/2 78.7%. The best spectacle-corrected visual acuity (BSCVA) decreased by 2 or more Snellen lines among the eyes of Group I/1 in 12%; in Group I/2 in 21%; in Group II/1 in 2.8% and in Group II/2 in 9.6%. In Group I/1 2%, in Group II/1 3.8% of the treated eyes gained 2 or more lines of BSCVA. Among the eyes treated with the scanning model (Group I/2) a central bump-like opacity was observed in 4 eyes (1.2%); among the eyes treated with the flying spot model no similar complication occurred. The postoperative increase of intraocular pressure was observed in 7.5% in Group I/1; in 6.8% in Group I/2; in 7.0% in Group II/1; and in 6.4% in Group II/2. Flying spot technology was superior to scanning method in each treatment group, difference was greatest in eyes treated with a preoperative refractive error higher than +3.75 D. The upper limit of hypermetropic treatments has increased to +6.0 D in case of flying spot treatments from the previous +3.5 D upper limit of scanning technology.