Prospective, randomized, paired comparison of laser epithelial keratomileusis and photorefractive keratectomy for myopia less than -6.50 diopters

PURPOSE: We compared predictability, efficacy, safety, and patient satisfaction following laser epithelial keratomileusis (LASEK) and photorefractive keratectomy (PRK) for low to moderate myopia with either the Nidek EC-5000 excimer laser or the Technolas 217C excimer laser. METHODS: Forty-two patients with spherical equivalent refraction in the range -1.00 to -6.50 D were enrolled in this prospective study, each randomized for choice and sequence of LASEK and PRK on each of their eyes. Patients were examined daily for 7 days, and at 1 and 3 months. Patient satisfaction and quality of vision were assessed using a subjective questionnaire. RESULTS: Mean baseline refraction was -3.57 +/- 1.25 D in LASEK eyes and -3.44 +/- 1.13 D in PRK eyes. Follow-up rates were 100% up to 1 month and 76% at 3 months. At 3 months, 32 (100%) of LASEK eyes and 31 (97%) of PRK eyes had uncorrected visual acuity > or = 20/40, 25 (79%) of LASEK eyes and 26 (82%) of PRK eyes had uncorrected visual acuity > or = 20/20, mean refraction was 0.08 +/- 0.53 D in LASEK eyes and 0.12 +/- 0.50 D in PRK eyes, 26 (81%) of LASEK eyes and 23 (72%) of PRK eyes had a refraction within +/- 0.50 D and 29 (91%) of LASEK eyes and 30 (94%) of PRK eyes had refraction within +/- 1.00 D. Epithelial healing time and pain in LASEK and PRK eyes were not statistically different, and patients were equally satisfied. CONCLUSION: LASEK had similar predictability, efficacy, safety, and patient satisfaction to PRK in the treatment of low to moderate myopia.     

Bilateral comparison of photorefractive keratectomy for myopia using two excimer lasers.

PURPOSE: The aim of this study was to compare the results of excimer laser photorefractive keratectomy (PRK) in patients who underwent PRK using the Summit Apex (Omnimed) excimer laser in one eye and the Nidek EC-5000 excimer laser in the other. METHODS: All consecutive patients who underwent PRK with the Summit Apex laser (Omnimed) in one eye and the Nidek laser (EC-5000) in the second and had at least 12 months of follow-up were included in this retrospective study (n=30). Uncorrected and spectacle-corrected visual acuity, final spherical equivalent refraction, and grade of subepithelial haze were compared. The average preoperative spherical equivalent refraction of eyes treated with the Summit laser was -6.00 D (range, -2.50 to -8.75 D), and for Nidek-treated eyes it was -5.57 D (range, -2.50 to -8.80 D). RESULTS: Forty-seven percent of Summit-treated eyes and 53% of Nidek-treated eyes had uncorrected visual acuity of 6/6 or better; 61% of Summit-treated eyes and 63% of Nidek-treated eyes had uncorrected visual acuity of 6/7.5 or better; 95% of Summit-treated eyes and 95% of Nidek-treated eyes had uncorrected visual acuity of 6/12 or better (difference not statistically significant). Seventy-three percent of eyes treated with the Summit laser and 80% of eyes treated with the Nidek laser had a postoperative refraction within +/-0.50 D of emmetropia; 97% of Summit-treated eyes and 87% of Nidek-treated eyes had a postoperative spherical equivalent refraction within +/-1.00 D of emmetropia; the difference between the two lasers was not statistically significant. However, the percent of eyes with persistent hyperopia was smaller in the Nidek group after 3 months (P=.0062) and after 6 months (P=.07) than in the Summit group. Videokeratography was not done. CONCLUSION: Both lasers were effective with relatively low side effects. No significant difference was found between the two lasers in postoperative uncorrected visual acuity or refractive outcome. Eyes operated with the Nidek laser had less persistent hyperopia and stabilized earlier.     

Multipass versus single pass photorefractive keratectomy for high myopia using a scanning laser.

PURPOSE: To study photorefractive keratectomy (PRK) for high myopia using the Nidek EC-5000 slit scanning laser and to compare a single pass versus a multipass ablation approach. METHODS: We retrospectively studied 95 eyes (64 patients; range -10.00 to -27.00 D; mean -12.00 D) treated for high myopia using PRK with a single or multipass technique. Forty-two eyes were treated with the single pass technique and 53 eyes were treated with the multipass technique. RESULTS: Twelve months after PRK, 79.4% (27 eyes) of the multipass group and 48.1% (13 eyes) of the single pass group were within +/-1.00 D of emmetropia; 32.4% (11 eyes) of multipass eyes and 29.6% (8 eyes) of single pass eyes were within +/-0.50 D of emmetropia. Uncorrected visual acuity of 20/40 or better was reached by 85.3% (29 eyes) and 20/20 or better was reached by 55.9% (19 eyes) in the multipass group at 12 months postoperatively. For the single pass group, 74.1% (20 eyes) achieved 20/40 uncorrected and 18.5% (5 eyes) achieved 20/20 uncorrected visual acuity. No multipass-treated eyes lost 2 lines of spectacle-corrected visual acuity at 6 or 12 months postoperatively. Mean regression between 1 to 12 months after PRK was 0.46 D for the multipass group and 1.45 D for the single pass group. Most of the regression occurred within the first 6 months after surgery in both techniques. CONCLUSION: These PRK results showed that treating high myopia using the Nidek EC-5000 excimer laser combined with a multipass approach generated good refractive outcomes with no complications. Undercorrections with the single pass technique could be compensated for with new nomograms. The multipass technique resulted in less regression and better refractive outcomes.     

Comparison of photorefractive keratectomy and laser in situ keratomileusis for myopia of -6 D or less using the Nidek EC-5000 laser

PURPOSE: We compared the efficacy, predictability, and safety of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) for the surgical correction of low and moderate myopia. METHODS: A retrospective study was performed to evaluate uncorrected and spectacle-corrected visual acuity, and manifest refraction 1 year after PRK or LASIK. All procedures were done using an automatic microkeratome (Chiron Ophthalmic) and the Nidek EC-5000 excimer laser. RESULTS: PRK was performed in 75 eyes of 45 patients and LASIK in 133 eyes of 77 patients. Mean age for PRK patients was 32.8 years (range, 18 to 52 yr) and LASIK patients was 29.6 years (range, 18 to 49 yr). Mean preoperative spherical equivalent refraction for PRK patients was -3.28 D (range, -1.00 to -6.00 D) and LASIK, -3.86 D (range, -1.00 to -6.00 D). One year after surgery, mean spherical equivalent refraction for Group 1 (baseline, -1.00 to -3.00 D) PRK eyes was -0.18 +/- 0.61 D (range, -1.50 to +0.75 D) and for LASIK eyes, -0.08 +/- 0.61 D (range, -1.50 to +1.62 D), with no statistically significant difference. For Group 2 eyes (baseline, -3.25 to -6.00 D), mean spherical equivalent refraction for PRK eyes was -0.44 +/- 0.87 D (range, -2.00 to +2.12 D) and for LASIK eyes, -0.09 +/- 0.83 D (range, -1.50 to +1.75 D), with no statistically significant difference. The antilogarithm of the mean UCVA (antilogUCVA) in Group 1 for PRK was 0.79 +/- 0.21 (20/25) and for LASIK was 0.87 +/- 0.19 (20/23), with no statistically significant difference. The antilogUCVA in Group 2 for PRK eyes was 0.70 +/- 0.24 (20/28) and for LASIK eyes was 0.83 +/- 0.18 (20/24), with a statistically significant difference (0.7 vs. 0.83, P < .005). The percentage of eyes with a postoperative UCVA >20/40 in Group 1 for PRK was 91.5% (38 eyes) and for LASIK was 95% (50 eyes) (no statistically significant difference), and in Group 2 for PRK eyes, it was 82% (27 eyes) and 97.5% (78 eyes) for LASIK (statistically significant difference, P < .05). CONCLUSION: PRK and LASIK with the Nidek EC-5000 excimer laser are effective and safe for correcting low to moderate myopia, but LASIK eyes showed better results for moderate myopia in terms of uncorrected visual acuity.     

Laser in situ keratomileusis using the Nidek EC-5000 or the Alcon LADARVision 4000 systems

PURPOSE: To compare the refractive results of eyes with low to moderate myopia that underwent laser in situ keratomileusis with either the Nidek EC-5000 or the Alcon LADARVision 4000 excimer laser systems. METHODS: We performed a retrospective review of 114 LASIK procedures with either the Nidek EC-5000 (54 eyes) or the Alcon LADARVision 4000 (60 eyes) excimer laser systems. Preoperative refractive errors were similar and both populations were treated during the same time period. Data analyzed included uncorrected visual acuity (UCVA), spherical magnitude, spherical equivalent refraction, astigmatism power, astigmatism axis, and vector astigmatism change. RESULTS: Results at 6 months were analyzed. Spherical correction change was a mean -3.95 D for Nidek treated eyes and a mean -4.53 D for LADARVision treated eyes (P = .20). Mean spherical equivalent refraction change was -3.70 D for Nidek eyes and -4.20 D for LADARVision eyes (P = .23). Mean change in UCVA (LogMAR) was 1.05 for Nidek eyes and 0.99 for LADARVision eyes (P = .40). Mean astigmatism magnitude change was 0.71 D for Nidek eyes and 0.77 D for LADARVision eyes (P = .63). Mean vector-corrected astigmatism change was 0.93 D for Nidek eyes and 1.00 D for LADARVision eyes (P = .63). Mean vector-corrected astigmatism axis for Nidek eyes was 3.08 D and for LADARVision eyes 6.58 D (P = .70). CONCLUSION: There was no significant difference in refractive results in eyes treated with the Alcon LADARVision 4000 or the Nidek EC-5000 excimer laser systems. Inherent differences between the two laser systems are highlighted.     

Laser in situ keratomileusis for myopia of -1.50 to -6.00 diopters

PURPOSE: To evaluate the results of laser in situ keratomileusis (LASIK) for the correction of low and moderate myopia and astigmatism using the Nidek EC-5000 excimer laser with a modified algorithm. METHODS: Three hundred and ninety-six eyes of 257 patients with myopia ranging from -1.50 to -6.00 D and astigmatism of no more than 4.00 D were included. Manifest spherical equivalent refraction, uncorrected and spectacle-corrected visual acuity were assessed at 1 month (357 eyes, 90%), 3 months (220 eyes, 56%), and 6 months (168 eyes, 42%) after LASIK. RESULTS: Mean preoperative spherical equivalent refraction was -3.60 +/- 1.27 D and mean cylinder was -1.01 +/- 1.08 D. Mean postoperative spherical equivalent refraction was -0.12 +/- 0.31 D and mean cylinder was -0.19 +/- 0.33 D. At 6 months follow-up, 158 eyes (94%) had a mean postoperative spherical equivalent refraction within +/- 0.50 D of emmetropia; 168 eyes (100%) were within +/- 1.00 D. Uncorrected visual acuity was 20/20 or better in 81% (136 eyes) and 20/40 or better in 100%. Two eyes (1.2%) lost 1 line of spectacle-corrected visual acuity due to a decentered ablation. No eye lost 2 or more lines of spectacle-corrected visual acuity. CONCLUSION: Our modified LASIK algorithm with the Nidek EC-5000 excimer laser resulted in safe and predictable outcomes for treatment of low and moderate amounts of myopia and astigmatism.     

Comparison of laser in situ keratomileusis and photorefractive keratectomy for the correction of myopia of -6.00 diopters or less. Melbourne Excimer Laser Group

PURPOSE: To evaluate the safety and efficacy of laser in situ keratomileusis (LASIK) compared to photorefractive keratectomy (PRK) for the correction of low or moderate myopia (-0.50 to -6.00 D) at 6 months after surgery. METHODS: The study population comprised a non-randomized consecutive series of 622 eyes of 392 patients who were treated with the Nidek EC-5000 excimer laser. LASIK was performed using the ACS Chiron microkeratome on 314 eyes and surface PRK on 308 eyes. All patients were treated using a standard protocol, then assessed at 1, 3, and 6 months postoperatively. RESULTS: Forty-four percent of the LASIK group and 67% of the PRK group attended their 6-month examination. Eighty percent of patients (111 eyes) after LASIK and 65% (136 eyes) after PRK had an uncorrected visual acuity of 20/20 or better. Spherical equivalent refraction was within +/-0.50 D of intended refraction in 78% (109 eyes) for LASIK and 82% (170 eyes) for PRK. Loss of two more lines of best spectacle-corrected visual acuity at 6 months occurred in 1.4% (2 eyes) of the LASIK group and 1.0% (2 eyes) of the PRK group. CONCLUSION: At 1 month follow-up, the percentage of eyes that achieved 20/20 uncorrected visual acuity was greater in the LASIK group than in the PRK group. At 6 months, visual and refractive outcomes of LASIK and PRK were similar. Although flap related complications occurred only after LASIK, the overall risk of loss of best spectacle-corrected visual acuity was not significantly greater than for PRK.     

Photorefractive keratectomy versus laser in situ keratomileusis: a control-matched study

OBJECTIVE: Photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) outcomes were compared at 1, 3, 6, and 12 months after surgery. DESIGN: Retrospective, nonrandomized, comparative study. PARTICIPANTS: One hundred seven LASIK-treated eyes (58 patients) and 107 PRK-treated eyes (91 patients) having myopia between -1 and -9.50 diopters (D). All LASIK-treated eyes were analyzed retrospectively and matched with PRK-treated eyes having sphere within +/-0.25 D, +/-1 D of cylinder, and +/-7 years of age. INTERVENTION: For PRK and LASIK, the refractive surgery was performed with the slit-scanning excimer laser Nidek EC-5000, (Nidek Co. Tokyo, Japan) MAIN OUTCOME MEASURES: Manifest refraction, best-spectacle and uncorrected Snellen visual acuity, haze, halos, and keratometry were evaluated before surgery and up to 12 months after surgery. RESULTS: Seventy percent of eyes were evaluated at the 12-month postoperative exam. Of these eyes, 83% of LASIK cases and 86% of PRK cases had uncorrected visual acuities of 20/20 or better. Refractions within +/-0.5 D represented 78% of the LASIK eyes and 83% of the PRK eyes at that follow-up. Patients who underwent LASIK reported halos twice as often as patients who underwent PRK using a subjective scale. The odds ratio of high halos for LASIK versus PRK was 3.50 (95% confidence interval, 1.89-6.46; P<0.0001). At 1 month after surgery, 64% of the LASIK eyes were within +/-0.50 D compared with 77% of the PRK eyes. No eye lost 2 Snellen lines of best corrected visual acuity at 6 or 12 months after surgery. Ten PRK eyes (9.3%) and three LASIK eyes (2.8%) were retreated. CONCLUSIONS: PRK and LASIK achieved equal refractive outcomes at all postoperative follow-ups, but LASIK patients were twice as likely to experience halos.     

Laser-assisted subepithelial keratectomy versus photorefractive keratectomy for the correction of myopia. A prospective comparative study

PURPOSE: To compare the early postoperative visual rehabilitation after laser-assisted subepithelial keratectomy (LASEK) and photorefractive keratectomy (PRK) for the correction of myopia. SETTING: CODET Aris Vision Institute, Tijuana, Mexico. METHODS: This prospective study included 50 eyes of 25 patients with myopia who received LASEK in 1 eye and PRK in the contralateral eye. Excimer laser corneal ablation was done using the Nidek EC-5000 excimer laser. Patients were seen at 1 and 3 days, 1 week, and 1 month. Discomfort, subjective uncorrected visual acuity (UCVA), objective UCVA, best corrected visual acuity (BCVA), corneal clarity (haze), and time for corneal reepithelialization were analyzed. RESULTS: Seventy-two percent and 80% of the LASEK eyes had more discomfort at 1 day and 3 days, respectively. Eighty percent and 96% of the PRK eyes had better subjective UCVA at 1 day and 3 days, respectively. Corneas were fully reepithelialized at a mean of 3.3 days +/- 0.5 (SD) and 3.6 +/- 0.5 days in the PRK and LASEK groups, respectively. At 1 month, the UCVA was similar in both groups; no eye had lost lines of BCVA or developed haze. CONCLUSIONS: Both LASEK and PRK were effective and safe procedures in the surgical correction of myopia at the 1-month postoperative visit. Patients reported less discomfort and better visual acuity in their PRK eye during the early postoperative period. Patients should be informed that LASEK, whose acronym is similar to that of laser in situ keratomileusis, has a recovery speed that is similar to that of surface laser refractive procedures such as PRK.     

Laser-assisted subepithelial keratectomy for myopia: two-year follow-up

PURPOSE: To assess and compare the clinical results (efficacy, safety, stability, and postoperative pain or discomfort) of laser-assisted subepithelial keratectomy (LASEK) and conventional photorefractive keratectomy (PRK) for the correction of low to moderate myopia. SETTING: Department of Ophthalmology, Masaryk University Hospital, Brno, Czech Republic. METHODS: A prospective comparative study was performed in 184 eyes of 92 patients who had surface excimer ablation for the correction of myopia. The preoperative mean spherical equivalent (MSE) was -4.65 diopters (D) +/- 3.14 (SD) (range -1.75 to -7.50 D). In each patient, LASEK was performed in 1 eye and PRK in the fellow eye by the same surgeon. The first eye treated and the surgical method used in the first eye were randomized. Both procedures were performed with the Nidek EC-5000 excimer laser using the same parameters and nomogram. The postoperative pain level, visual recovery, complications (haze), uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and refractive outcome were evaluated and compared. All eyes completed a 24-month follow-up. RESULTS: The postoperative MSE was -0.18 +/- 0.53 D in the PRK eyes and -0.33 +/- 0.46 D in the LASEK eyes. At 1 week, the mean UCVA was 0.64 +/- 0.21 and 0.87 +/- 0.23, respectively. No LASEK eye lost a line of BSCVA. There were no statistically significant differences between PRK and LASEK eyes in the safety and efficacy indices at 2 years. The mean pain level was significantly lower on days 1 to 3 in the LASEK eyes (P <.05). The mean corneal haze level was lower in the LASEK eyes (0.21) than in the PRK eyes (0.43) (P <.05). Seventy-nine patients preferred LASEK to PRK. CONCLUSIONS: Laser-assisted subepithelial keratectomy provided significantly quicker visual recovery, eliminated post-PRK pain, and reduced the haze level in eyes with low to moderate myopia compared with conventional PRK. It provided good visual and refractive outcomes. There were no serious complications.     

Clear lens extraction with intraocular lens followed by photorefractive keratectomy or laser in situ keratomileusis

OBJECTIVE: To study photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK) after clear lens extraction (CLE) with intraocular lens (IOL) implantation for hyperopia or astigmatism. DESIGN: Retrospective, noncomparative interventional case series. PARTICIPANTS: Sixty-five eyes (55 subjects) had CLE with posterior chamber IOL implants for hyperopia up to 12.25 diopters (D); 31 eyes were retreated with PRK, and 34 eyes were retreated with LASIK for residual ametropias. INTERVENTION: For PRK and LASIK, the refractive surgery was performed with the slit-scanning excimer laser Nidek EC-5000, Nidek Co., Tokyo, Japan. MAIN OUTCOME MEASURES: Manifest refraction, best-spectacle and uncorrected Snellen visual acuity, haze, and halos were evaluated before surgery and at 1, 3, 6, and 12 months postoperative. RESULTS: Forty-seven eyes were evaluated at the 12-month postoperative examination: 96% of these eyes had spherical equivalents (SE) within +/-2 D of emmetropia, 79% of eyes had SE within +/-1 D of emmetropia and 51% of eyes had SE within +/-0.50 D of emmetropia. Eighty-five percent of the eyes at 12 months postoperative had uncorrected visual acuity of 20/40 or better, and 46% of eyes had uncorrected visual acuity of 20/20 or better. Eighty-seven percent of the eyes at 12 months postoperative had uncorrected visual acuity within 1 Snellen line of their initial best spectacle-corrected visual acuity (BSCVA) before all treatment. No eye lost 2 Snellen lines of BSCVA at 3, 6, or 12 months after PRK or after LASIK. CONCLUSIONS: IOL implantation for CLE, although an invasive technique, resulted in better refractive outcomes without laser-related clinical complications after PRK or LASIK adjustment.     

Laser in situ keratomileusis to correct residual myopia after cataract surgery

PURPOSE: To evaluate the effectiveness, predictability, and safety of laser in situ keratomileusis (LASIK) for correcting residual myopia after cataract surgery with intraocular lens implantation. METHODS: Twenty-two eyes of 22 patients underwent LASIK for the correction of residual myopia after cataract surgery. LASIK was carried out using the Chiron Automated Corneal Shaper and the NIDEK EC-5000 excimer laser. In all eyes, the follow-up was 12 months. RESULTS: Before LASIK, 1 eye (4.5%) had an uncorrected visual acuity of 0.5 or better; 12 months after LASIK, 10 eyes (45.4%) achieved this level of visual acuity and 0 eyes achieved 1.00 or better. Before LASIK, mean refraction was -2.90 +/- 1.80 D; 12 months after LASIK it decreased significantly to 0.40 +/- 0.60 D (P < .01). In 18 eyes (81.8%) at 12 months after LASIK, spherical equivalent refraction was within +/-1.00 D of emmetropia; 11 eyes (50%) were within 0.50 D. No vision-threatening complications occurred. CONCLUSION: LASIK with the Automated Corneal Shaper and Nidek EC-5000 excimer laser was an effective, predictable, stable, and safe procedure for correcting residual myopia after cataract surgery. No intraocular lens or cataract incision related complications occurred when LASIK was performed at least 3 months after phacoemulsification.     

Photoastigmatic refractive keratectomy in myopes. Nidek US Investigators Group

PURPOSE: Photoastigmatic refractive keratectomy (PARK) was studied in a multi-center clinical trial. The Nidek EC-5000 excimer laser was evaluated for its effect on refraction, visual acuity, and safety measures as part of a U.S. Food and Drug Administration (FDA) regulated study. METHODS: Eight U.S. centers enrolled adults with eyes having refractive astigmatism up to 4.00 D and a myopic spherical equivalent refraction up to -8.00 D. Results are reported for 749 eyes of 486 patients with at least 6 months follow-up. The rectangular beam scanning Nidek EC-5000 used a 5.5-mm-diameter treatment zone, a 7.0-mm-diameter peripheral blend zone, and a 40 Hz pulse rate for surface treatment of myopic astigmatism. Nomogram corrections to machine settings were required to achieve the desired results. RESULTS: Preoperative average spherical equivalent refraction of -4.90+/-1.74 D was reduced to -0.02+/-0.79 D at 6 months. Refractive stability was established at 3 months. Over 62% of eyes were within +/-0.50 D of desired correction at 6 months, with over 86% within +/-1.00 D. Uncorrected visual acuity improved by an average of 10 Snellen lines; over 64% of eyes saw 20/20 or better uncorrected and over 93% saw 20/40 or better uncorrected at 6 and 12 months. PARK treatment effectively reduced astigmatism with little average axis error or magnitude error. Corneal haze and safety concerns were minimal. CONCLUSIONS: Photoastigmatic refractive keratectomy using the Nidek EC-5000 excimer laser provided significant reduction of myopia and astigmatism, with minimal complications.     

准分子激光上皮瓣下角膜磨镶术治疗近视的疗效观察

目的:评价准分子激光上皮瓣下角膜磨镶术(LASEK)治疗近视的疗效观察。方法:应用日本产。NIDEK EC-5000型准分子激光机对78眼不同程度近视(-1.50-12.00D)行LASEK治疗,术后3-12个月对视力、屈光度及角膜雾样混浊(Haze)进行随访。结果:术后3～12个月96.2％裸眼视力均达到0.5以上,≥1.0者达92.3％,78眼最后一次复查屈光度在±1.00D以内者为74眼,Ⅱ级Haze者为4眼。结论:LASEK是治疗近视的安全有效的方法之一,但尚需临床进一步随访、观察,及基础理论的研究。     

Natural history of corneal topography after excimer laser photorefractive keratectomy

Purpose

To investigate the natural history of corneal topography after excimer laser photorefractive keratectomy (PRK).

Design

A prospective, single center clinical study.

Participants

A total of 40 eyes of 34 patients with myopia were studied.

Intervention

Excimer laser photorefractive keratectomy and computer-assisted videokeratography were performed.

Main outcome measures

Preoperative, 1 week, and 1,2, and 3 months postoperative topography patterns were compared and changes assessed by averaging defined sectors of the ablation zone in individual maps to produce composite “average” topography maps.

Results

Corneal topography was generally not homogeneous at 1 week after PRK. By 3 months, there had been considerable smoothing of corneal contour. A general “central island” effect early in the postoperative period flattened over time. When right and left eyes were evaluated independently, a tendency toward a keyhole-semicircular pattern was seen on average; the maximum flattening was nasal and the least flattening was inferotemporal for both right and left eyes.

Conclusions

A tendency, on average, toward central island and keyhole-semicircular patterns is seen early in the postoperative course after PRK. Central islands tend to evolve into the keyhole-semicircular pattern, and the corneal topography in general after PRK tends to smooth considerably with time.     

Hyperopic laser in situ keratomileusis with the Nidek EC-5000 excimer laser

OBJECTIVE: To evaluate the efficacy, safety, and predictability of hyperopic laser in situ keratomileusis (H-LASIK) using modified software. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: The first 72 consecutive eyes of 44 patients with up to +5.00 diopters (D) hyperopia. INTERVENTION: Hyperopic LASIK using the Automatic Corneal Shaper (ACS; Chiron Vision, Claremont, CA) and the Nidek EC-5000 excimer laser (Nidek, Tokyo, Japan). MAIN OUTCOME MEASURES: Uncorrected visual acuity, manifest spherical equivalent (MSE), best-corrected visual acuity (BCVA), and complications were studied. RESULTS: At 6 months, in the low hyperopia group (<3.00 D), mean MSE was +0.30 +/- 0.71 D, with 88.9% eyes within 1 D of emmetropia compared with +1.09 +/- 0.92 D and 51.8% within 1 D of emmetropia in the moderate hyperopia group (> or =3.00 D; P = 0.003). Uncorrected visual acuity was 20/40 or better in 43 of 45 eyes (95.6%) and in 21 of 27 (77.8%) eyes in the low and moderate hyperopia groups, respectively. Only one eye (1.4%) from the moderate hyperopia group lost two lines of BCVA. Eighteen eyes (25%) required retreatment to correct residual hyperopia, 9 eyes (20.0%) in the low hyperopia group and 9 eyes (33.3%) in the moderate hyperopia group. Retreatments resulted in an MSE of +0.02 +/- 0.45 D and +0.04 +/- 0.73 D in the low and moderate hyperopia groups, respectively. No flap-related complications were seen. CONCLUSIONS: Hyperopic LASIK with the ACS and the Nidek EC-5000 excimer laser using our modified software is a safe, effective, and predictable procedure for low hyperopia. Results are satisfactory up to moderate hyperopia. Significant regression can occur for low and moderate hyperopia. Retreatment can be performed safely and effectively to improve the visual and refractive results.     

眼轴长度与角膜屈光力对准分子激光屈光性角膜切削术疗效的影响

目的 探讨眼轴长度、角膜屈光力对准分子激光屈光性角膜切削术（ｐｈｏｔｏｒｅｆｒａｃｔｉｖｅ ｋｅｒａｔｅｃｔｏｍｙ,ＰＲＫ）疗效的影响。方法 应用美国Ｋｅｒａｃｏｒ－１１７型准分子激光仪对８０例（１２１只眼）近视患者进行治疗。按眼轴（ａｘａｉｌ ｅｇｎｔｈ,ＡＬ）及角膜屈光力（ｋｅｒａｔｏｍｅｔｒｉｃ ｖａｌｕｅ,ＫＶ）进行分组：１组４９只眼,ＡＬ〉２６ｍｍ,ＫＶ≤４５Ｄ;２组３６只眼,ＡＬ≤２６     

Laser in situ keratomileusis for myopic astigmatism with the Nidek EC-5000 laser

PURPOSE: We studied the efficacy, predictability, and safety of laser in situ keratomileusis (LASIK) for moderate to high simple and compound myopic astigmatism. METHODS: Ninety-two eyes of 46 consecutive patients who had LASIK for myopic astigmatism (64 eyes, astigmatism 3.00 to 9.00 D; myopia 0 to -20.00 D), or simple myopia (28 eyes, myopia -4.00 to -20.00 D; astigmatism 0 to 0.50 D) were retrospectively studied. Mean baseline spherical equivalent refraction (SE) in the myopia group was -8.11 +/- 3.94 D and in the astigmatism group, -8.55 +/- 4.49 D. All eyes underwent LASIK using the Nidek EC-5000 laser by the same surgeon. RESULTS: At 6 months after LASIK in the myopia group versus the astigmatism group, 24 eyes (85%) vs. 54 eyes (84%) were available for follow-up, 12 eyes (50%) vs. 13 eyes (24%) had uncorrected visual acuity (UCVA) of 20/20, 19 eyes (79%) vs. 44 eyes (81%) had UCVA of 20/40, 8 eyes (33%) vs. 18 eyes (33%) had SE within +/- 0.50 D, 15 eyes (62%) vs. 39 eyes (72%) had SE within +/- 1.00 D, and mean SE was -1.22 +/- 1.17 D vs. -0.74 +/- 1.46 D. Mean astigmatism (vertexed to the corneal plane) in the astigmatism group was 2.77 D at 0 degrees before surgery and 0.32 D at 7 degrees at 6 months. None of the myopic eyes and three of the astigmatic eyes (5%) lost > or = 2 lines of best spectacle-corrected visual acuity. CONCLUSION: LASIK with the Nidek EC-5000 laser for myopic astigmatism was reasonably effective, predictable, and safe. Astigmatism was under-corrected with the nomogram implemented in this study.     

Phototherapeutic keratectomy in children: 5-year results

PURPOSE: To evaluate the efficacy and safety of phototherapeutic keratectomy (PTK) for the treatment of superficial corneal opacities, surface irregularities, epithelial instability, and reepithelialization failure in pediatric patients and study the visual and refractive changes after combined PTK and photorefractive keratectomy (PRK). SETTING: Department of Ophthalmology, Masaryk University Hospital, Brno, Czech Republic. METHODS: This retrospective clinical study comprised children who had PTK or PTK combined with PRK from September 1996 to January 2000. The goals of treatment were to improve visual acuity and reduce or eliminate subjective ocular discomfort (eg, pain, lacrimation, and photophobia). A Nidek EC-5000 excimer laser was used in PTK mode with a 3.0 to 6.0 mm optical zone and a 4.0 to 7.5 mm transition zone. RESULTS: Forty-one pediatric patients (41 eyes) were included. Twenty-three eyes had PTK only, and 18 eyes had PTK combined with PRK to reduce preoperative myopia (11 eyes) or hyperopia (7 eyes). The mean patient age was 11.4 years (range 8 to 18 years) and the mean follow-up, 4.8 years (range 3 to 6 years). The best spectacle-corrected visual acuity (BSCVA) improved in all patients, and episodes of ocular pain or discomfort, lacrimation, and photophobia diminished. The mean preoperative BSCVA of 6/38 (range 6/10 to 1/60) improved to 6/12 (range 6/6 to 6/38) at the last postoperative examination. Eight eyes gained 5 or more Snellen lines of BSCVA; 11 gained 4 lines, 9 gained 3 lines, 7 gained 2 lines, 5 gained 1 line, and 1 eye was unchanged. No eye lost a line of BSCVA. The mean preoperative spherical equivalent (SE) decreased from -5.32 to -1.16 diopters (D) in the 11 myopic eyes and from +4.72 to +1.51 D in the 7 hyperopic eyes within 3 years of the combined procedure. CONCLUSIONS: Phototerapeutic keratectomy is an effective and safe procedure for the treatment of various surface corneal disorders in children. It can improve best corrected visual acuity and eliminate ocular pain and irritation. Preoperative myopia and hyperopia were effectively reduced by a combination of PTK and PRK.     

Photorefractive keratectomy using a scanning-slit laser, rotary epithelial brush, and chilled balanced salt solution

PURPOSE: To evaluate photorefractive keratectomy (PRK) using a scanning-slit excimer laser combined with removal of the epithelium using a rotary epithelial brush and prebrush and postoperative cooling of the cornea with chilled balanced salt solution (BSS(R)). SETTING: Johannesburg Laser Center, Johannesburg, South Africa. METHODS: In a prospective study, 500 consecutive eyes with myopia ranging from 1.00 to 12.75 diopters (D) and astigmatism up to 6.50 D were treated with PRK using a Nidek EC-5000 scanning-slit excimer laser, removal of the epithelium with a rotary epithelial brush, and prebrush and postlaser cooling of the cornea with chilled BSS (4 degrees C to 6 degrees C). The mean follow-up was 9.32 months (range 1 week to 39 months). Bilateral simultaneous PRK was performed in 238 patients (95.2% of eyes). RESULTS: After 1 week, uncorrected visual acuity was 20/20, 20/25, 20/30, 20/40, 20/60, and 20/80 in 9.80%, 38.60%, 68.20%, 89.40%, 97.80%, and 97.20% of eyes. After 6 months, in 405 eyes, it was 20/15, 20/20, 20/25, 20/30, and 20/40 in 9.38%, 69.88%, 91.11%, 94.81%, and 98.52%. After 12 months, in 222 eyes, it was 20/15, 20/20, 20/25, 20/30, and 20/40 in 6.76%, 68.92%, 83.78%, 91.89%, and 97.30%. After 18 months, in 95 eyes, it was 20/15, 20/20, 20/25, 20/30, and 20/40 in 6.32%, 69.47%, 88.42%, 91.58%, and 96.84%. Six eyes (1.20%) required retreatment. CONCLUSIONS: Scanning-slit laser PRK after rotary epithelial scrubbing and prescrub and postlaser cooling allows accurate correction of myopia and astigmatism with minimal regression.