Comparison of photorefractive keratectomy with excimer laser in situ keratomileusis in correcting low myopia (from -2.00 to -5.50 diopters). A randomized study. Randomized bilateral comparison of excimer laser in situ keratomileusis and photorefractive keratectomy for 2.50 to 8.00 diopters of myopia. Photorefractive keratectomy versus laser in situ keratomileusis for moderate to high myopia. A randomized prospective study. Wavefront-guided laser in situ keratomileusis (Lasik) versus wavefront-guided photorefractive keratectomy (Prk): a prospective randomized eye-to-eye comparison (an American Ophthalmological Society thesis). Comparison of laser in situ keratomileusis and photorefractive keratectomy to correct myopia from -1.25 to -6.00 diopters. Photorefractive keratectomy with mitomycin C versus LASIK in custom surgeries for myopia: a bilateral prospective randomized clinical trial. A prospective, contralateral comparison of photorefractive keratectomy (PRK) versus thin-flap LASIK: assessment of visual function. Wavefront-guided excimer laser ablation using photorefractive keratectomy and sub-Bowman's keratomileusis: a contralateral eye study. A randomized paired eye comparison of two techniques for treating moderately high myopia: LASIK and artisan phakic lens.
To compare laser in situ keratomileusis (LASIK) with photorefractive keratectomy (PRK) in the correction of myopia from -2.00 to -5.50 diopters.
                Prospective, randomized, paired clinical trial.
                Fifty-two eyes of 26 myopic patients were enrolled in the study.
                Each patient received PRK on one eye (PRK eye) and LASIK on the other (LASIK eye); the procedure assigned to each eye, and the sequence of surgeries for each patient was randomized.
                Slit-lamp microscopy, manifest refraction, uncorrected and spectacle-corrected visual acuity, and videokeratography were done before operation, and 2 weeks, 6 weeks, 3 months, 6 months, and 12 months after operation. Patient satisfaction and preference were assessed by a subjective questionnaire.
                All LASIK eyes had fast, painless recovery. At 1 year, 24 patients (92.3%) were examined, the mean spherical equivalent refraction was -0.08 +/- 0.38 diopter in the PRK eyes and -0.14 +/- 0.31 diopter in the LASIK eyes, and the uncorrected visual acuity was 20/20 or better in 15 PRK eyes (62.5%) and 19 LASIK eyes (79.2%); no eye lost 2 or more Snellen lines of spectacle-corrected visual acuity. Both procedures were stable throughout the first year. One PRK eye developed dense subepithelial corneal haze. The strongest correlate to spectacle-corrected visual acuity after the two procedures was the coefficient of variation of corneal power over the pupil. Nineteen patients (79.2%) preferred the LASIK procedure because of the fast, painless recovery.
                In the current study, PRK and LASIK were found to be similarly effective, predictable, stable, and reasonably safe for the correction of myopia between -2.00 and -5.50 diopters. Laser in situ keratomileusis has the advantage of fast, painless recovery. Patients prefer LASIK. To compare effectiveness, safety, and stability of excimer laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) for low-to-moderate myopia.
                Prospective, randomized, bilateral study.
                Thirty-three patients with a manifest refraction of -2.50 to -8.00 diopters (D) participated.
                For each patient, one eye received LASIK and the other received PRK. The first eye treated, and surgical method in the first eye, were randomized. Both eyes were treated by the same surgeon during the same operative session with a Summit Omnimed I laser (6-mm-diameter ablation) and a Chiron Automated Corneal Shaper. Follow-up was 90% at 1 and 2 years.
                At baseline, mean (+/-standard deviation) spherical equivalent manifest refraction was -4.80 +/- 1.60 D in LASIK-treated eyes and -4.70 +/- 1.50 D in PRK-treated eyes. At 1 day after surgery, 81% of patients (21 eyes) reported no pain in the LASIK-treated eye, whereas no patient (0%) reported being pain-free in the PRK-treated eye. At 3 to 4 days after surgery, 18 (80%) LASIK-treated eyes either improved or remained within 1 line of baseline spectacle-corrected visual acuity; only 10 (45%) PRK-treated eyes achieved this result. At 2 years after surgery, 18 (61%) LASIK- and 10 (36%) PRK-treated eyes achieved an uncorrected visual acuity of 20/20 or better, with no statistically significant difference in refractive outcome between the two techniques. Quantitative videokeratography showed more regularity after LASIK. Complications were similar in the two groups. Patients preferred LASIK by a margin of 2 to 1 at 1 year but showed no preference at 2 years.
                Using a 6-mm-diameter single-pass, large area ablation and an automated microkeratome to treat myopia of -2.50 to -8.00 D with 1.00 D or less astigmatism in 1994, the authors used LASIK to produce a higher percentage of eyes with an uncorrected visual acuity of 20/20 or better, more regular postoperative corneal topography, less postoperative pain, and more rapid recovery of baseline spectacle-corrected visual acuity than PRK. Both LASIK and PRK achieved successful correction of low-to-moderate myopia at 1 and 2 years after surgery. This report presents the results of a randomized clinical trial of photorefractive keratectomy (PRK) and laser-assisted in situ keratomileusis (LASIK).
                A randomized, prospective multicenter clinical trial.
                A total of 220 eyes of 220 patients entered the study cohort: 105 randomized to PRK and 115 to LASIK. The mean preoperative manifest refraction spherical equivalent was -9.23 diopters (D) in the PRK group and -9.30 D in the LASIK group.
                All patients received a one-pass, multizone excimer laser ablation as part of either a PRK or LASIK procedure using the Summit Apex excimer laser. Attempted corrections ranged from 6.00 to 15.00 D.
                Data on uncorrected and spectacle-corrected visual acuity, predictability,and stability of refraction, corneal haze, and flap complications were analyzed. Patients were observed for up to 6 months.
                One day after surgery, 0 (0.0%) and 3 (4.5%) eyes in the PRK group saw 20/20 and 20/40 or better uncorrected, respectively, while 7 (10%) and 48 (68.6%) eyes in the LASIK group saw 20/20 and 20/40 or better, respectively. At 6 months after PRK, 13 (19.1%) and 45 (66.2%) eyes saw 20/20 and 20/40 or better, respectively, while after LASIK, 16 (26.2%) and 34 (55.7%) eyes saw 20/20 and 20/40 or better, respectively (odds ratio = 0.56 for likelihood of uncorrected visual acuity < 20/40 for PRK vs. LASIK, 95% confidence interval [CI] = 0.31-1.19). After PRK, 39 eyes (57.4%) were within 1.0 D of attempted correction compared with 24 eyes (40.7%) in the LASIK group (odds ratio = 0.50 for likelihood fo undercorrection 1.0 D for PRK vs. LASIK, 95% CI = 0.24-1.04); however, the standard deviation of the predictability was similar between groups: 1.01 D for PRK and 1.22 D for LASIK. From months 1 to 6, there was an average regression of 0.89 D in the PRK group and 0.55 D in the LASIK group. After PRK, eight eyes (11.8%) had a decrease in spectacle-corrected visual acuity of two Snellen lines or more; after LASIK, two eyes (3.2%) had a decrease of two lines or more (odds ratio = 3.89 for risk of loss of spectacle-corrected visual acuity for PRK vs. LASIK, 95% CI = 0.71-21.30). Only two eyes had postoperative spectacle-corrected visual acuity less than 20/32, however.
                Although improvement in uncorrected visual acuity is more rapid in LASIK than in PRK, efficacy outcomes in the longer term generally are similar between the two procedures. There is a greater tendency toward undercorrection in LASIK eyes using the specific laser and nomogram in this study, but the scatter in achieved versus attempted correction is similar, suggesting little difference in the accuracy of the two procedures. A suggestion of decreased propensity for loss of spectacle-corrected visual acuity in LASIK eyes requires further investigation. To compare the safety and efficacy of wavefront-guided laser in situ keratomileusis (LASIK) vs photorefractive keratectomy (PRK) in a prospective randomized clinical trial.
                A cohort of 68 eyes of 34 patients with -0.75 to -8.13 diopters (D) of myopia (spherical equivalent) were randomized to receive either wavefront-guided PRK or LASIK in the fellow eye using the VISX CustomVue laser. Patients were evaluated at 1 day, 1 week, and months 1, 3, 6, and 12.
                At 1 month, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), 5% and 25% contrast sensitivity, induction of higher-order aberrations (HOAs), and subjective symptoms of vision clarity, vision fluctuation, ghosting, and overall self-assessment of vision were worse (P<0.05) in the PRK group. By 3 months, these differences had resolved (P>0.05). At 1 year, mean spherical equivalent was reduced 94% to -0.27 ± 0.31 D in the LASIK group and reduced 96% to -0.17 ± 0.41 D in the PRK group. At 1 year, 91% of eyes were within ±0.50 D and 97 % were within ±1.0 D in the PRK group. At 1 year, 88% of eyes were within ±0.50 D and 97% were within ±1.0 D in the LASIK group. At 1 year, 97% of eyes in the PRK group and 94% of eyes in the LASIK group achieved an UCVA of 20/20 or better (P=0.72). Refractive stability was achieved in both PRK and LASIK groups after 1 month. There were no intraoperative or postoperative flap complications in the LASIK group. There were no instances of corneal haze in the PRK group.
                Wavefront-guided LASIK and PRK are safe and effective at reducing myopia. At 1 month postoperatively, LASIK demonstrates an advantage over PRK in UCVA, BSCVA, low-contrast acuity, induction of total HOAs, and several subjective symptoms. At postoperative month 3, these differences between PRK and LASIK results had resolved. We evaluated the safety and efficacy of laser in situ keratomileusis (LASIK) for the correction of low to moderate amounts of myopia (-1.25 to -6.00 D).
                Photorefractive keratectomy (PRK) was performed on 432 eyes and LASIK on 137 eyes with a Chiron Keracor 116 excimer laser. Uncorrected and corrected visual acuity, corneal sensitivity, contrast sensitivity, and corneal topography were examined before and after surgery.
                One-year follow-up of 307 eyes in the PRK group and 103 eyes in the LASIK group was achieved. At 1 year, 83% (85 of 103) of LASIK eyes and 72% (221 of 307) of PRK eyes had an uncorrected visual acuity of 1.0 or better. Eighty-nine percent (92 of 103) of LASIK eyes and 83% (255 of 307) of PRK eyes had a refractive error within +/- 1.00 D of emmetropia; 71% (73 of 103) of LASIK eyes and 61% (188 of 307) of PRK eyes were within +/- 0.50 D of emmetropia. Contrast sensitivity and corneal sensitivity were reduced in both groups at the early postoperative stage but gradually returned to preoperative values; their recovery took about 3 months in LASIK eyes and 6 to 12 months in PRK eyes.
                LASIK is safe and more predictable than PRK to correct low to moderate amounts of myopia. Recovery from LASIK is faster than after PRK. To compare photorefractive keratectomy (PRK) with prophylactic use of mitomycin C (MMC) and LASIK in custom surgeries for myopic astigmatism.
                Eighty-eight eyes of 44 patients with a minimum estimated ablation depth of 50 microm were randomized to receive PRK with MMC 0.002% for 1 minute in one eye and LASIK in the fellow eye. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), cycloplegic refraction, slit-lamp microscopy, contrast sensitivity, specular microscopy, aberrometry, and a subjective questionnaire were evaluated. Forty-two patients completed 6-month follow-up.
                Mean spherical equivalent refraction error before surgery and mean ablation depth were -3.99+/-1.20 diopters (D) and 73.09+/-14.55 microm in LASIK eyes, and -3.85+/-1.12 D and 70.7+/-14.07 microm in PRK with MMC eyes, respectively. Uncorrected visual acuity was significantly better in PRK with MMC eyes 3 months (P=.04) and 6 months (P=.01) after surgery. Best spectacle-corrected visual acuity and spherical equivalent refraction did not differ significantly in the groups during follow-up (P>.05). Significant haze was not observed in any PRK with MMC eye. Mean higher order aberration was lower in PRK with MMC eyes postoperatively compared with LASIK eyes (P=.01). Better contrast sensitivity was observed in PRK with MMC eyes than LASIK eyes (P<.05). The endothelial cell count did not differ significantly between groups (P=.65). In terms of visual satisfaction, PRK with MMC eyes were better rated.
                Photorefractive keratectomy with MMC appears to be more effective than LASIK in custom surgery for moderate myopia. During 6-month follow-up, no toxic effects of MMC were evident. Long-term follow-up is necessary to attest its safety. To compare differences in visual acuity, contrast sensitivity, complications, and higher-order ocular aberrations (HOAs) in eyes with stable myopia undergoing either photo-refractive keratectomy (PRK) or thin-flap laser in situ keratomileusis (LASIK) (intended flap thickness of 90 μm) using the VISX Star S4 CustomVue excimer laser and the IntraLase FS60 femtosecond laser at 1, 3, and 6 months postoperatively.
                In this prospective, masked, and randomized pilot study, refractive surgery was performed contralaterally on 52 eyes: 26 with PRK and 26 with thin-flap LASIK. Primary outcome measures were uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), contrast sensitivity, and complications.
                At 6 months, mean values for UDVA (logMAR) were -0.043 ± 0.668 and -0.061 ± 0.099 in the PRK and thin-flap LASIK groups, respectively (n = 25, P = 0.466). UDVA of 20/20 or better was achieved in 96% of eyes undergoing PRK and 92% of eyes undergoing thin-flap LASIK, whereas 20/15 vision or better was achieved in 73% of eyes undergoing PRK and 72% of eyes undergoing thin-flap LASIK (P > 0.600). Significant differences were not found between treatment groups in contrast sensitivity (P ≥ 0.156) or CDVA (P = 0.800) at postoperative 6 months. Types of complications differed between groups, notably 35% of eyes in the thin-flap LASIK group experiencing complications, including microstriae and 2 flap tears.
                Under well-controlled surgical conditions, PRK and thin-flap LASIK refractive surgeries achieve similar results in visual acuity, contrast sensitivity, and induction of HOAs, with differences in experienced complications. To explain the basic science and clinical evidence that has led to the development of a new technique in corneal refractive surgery--sub-Bowman's keratomileusis (SBK).
                A comprehensive review of the literature and report of a contralateral eye study of 50 patients (100 eyes) enrolled at 2 sites (25 patients per site) and randomized according to the dominant eye was conducted. All eyes underwent a wavefront-guided refractive correction using the Alcon LADARVision4000 System. In one eye, an 8.5-mm, ETOH-assisted photorefractive keratectomy (PRK) was performed. In the second eye, an 8.5-mm, 100-microm flap was attempted using a 60 kHz IntraLase FS femtosecond laser. Pre- and postoperative tests included best spectacle-corrected visual acuity, uncorrected visual acuity, corneal topography, wavefront aberrometry, retinal image quality, contrast sensitivity, and biomechanical response of the cornea. Patients completed subjective questionnaires at each follow-up.
                Clinical results demonstrate that SBK provides quicker visual recovery, although the data suggest that the 3- and 6-months results are similar in terms of visual outcomes. Reichert Ocular Response Analyzer results demonstrate that its impact on the cornea is similar to PRK.
                This study indicates that SBK provides the visual recovery of a LASIK procedure with the Optical Response Analyzer results similar to PRK. To compare refractive performance and safety of laser in situ keratomileusis (LASIK) and Artisan phakic intraocular lens (PIOL) for moderately high myopia.
                A prospective, randomized trial with paired eye control.
                Twenty-five patients with myopia ranging from -8.00 to -12.00 diopters (D).
                For each patient, one eye received LASIK and the other one was implanted with an Artisan phakic intraocular lens. The treated eye and the surgical technique were randomized.
                Primary outcome measure was spherical equivalent refraction. Main secondary outcome measures were the change of two or more lines and safety index (ratio postoperative to preoperative best-corrected visual acuity).
                One year after surgery, the mean spherical equivalent refraction was -0.74 +/- 0.67 D for LASIK-treated eyes and -0.95 +/- 0.45 D for Artisan-treated eyes, and the majority of LASIK-treated eyes (64%) and Artisan-treated eyes (60%) were within +/-1.00 D of the intended result. At 1 month, the mean spherical equivalent refraction was -0.28 +/- 0.71 D for LASIK and -1.07 +/- 0.59 D for Artisan (P < 0.01). The changes of two or more lines were in favor of Artisan (P < 0.05). The safety index was significantly better for Artisan (1.12 +/- 0.21) than for LASIK (0.99 +/- 0.17) at 1 year (P < 0.02).
                In cases of moderately high myopia, LASIK and Artisan phakic intraocular lenses seemed to produce a similar predictability. The best-corrected visual acuity and subjective evaluation of quality of vision were better for Artisan.
LASIK gives a faster visual recovery and is a less painful technique than PRK. The two techniques appear to give similar outcomes one year after surgery. Further trials using contemporary techniques are required to determine whether LASIK and PRK as currently practised are equally safe. Randomising eyes to treatment is an efficient design, but only if analysed properly. In future trials, more efforts could be made to mask the assessment of outcome.