准分子激光屈光性角膜切削术治疗高度近视的疗效分析

目的探讨准分子激光角膜切削术治疗高度近视的疗效。方法应用德国Ｋｅｒａｃｏｒ１１６型准分子激光仪，采用多步分区切削法治疗高度近视。按屈光度分为二组，Ⅰ组：－６．００～－９．７５Ｄ，２３３只眼；Ⅱ组：－１０．００～－１４．００Ｄ，５５只眼。术后随访１年，并对结果进行分析。结果本组患者术后１年裸眼视力≥０．５者占７９．４％，≥１．０者占３１．６％（其中Ⅰ组≥０．５者占９２．３％，Ⅱ组≥０．５者占５８．３％）。术后最佳矫正视力大于术前者占３７．１％，小于术前者占６．２％，９３．８％术后最佳矫正视力不变或上升。术后１个月时角膜上皮下混浊最重；１年时最轻，８７．４％的术眼混浊度为０。术后１年实际矫正度在预测矫正度±１．００Ｄ内者占５２．０％，±２．００Ｄ内者占８０．９％。激素性高眼压占１４．９％。结论准分子激光多步分级切削法治疗高度近视是一种安全、有效且稳定性较好的方法，对于超高度近视其安全性较高，但预测性略差。     

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.     

Photorefractive keratectomy for myopia with the Meditec MEL 70G-Scan flying spot laser

PURPOSE: To evaluate the efficacy, predictability, stability, and safety of the Meditec MEL 70G-Scan flying spot excimer laser. METHODS: One hundred thirty myopic eyes were treated with the Aesculap Meditec Mel 70G-Scan ArF flying spot excimer laser with photorefractive keratectomy (PRK). Patient groups: low myopia (Group 1) from -1.50 to -6.00 D (90 eyes), medium myopia (Group 2) from -6.10 to -9.00 D (31 eyes), high myopia (Group 3) from -9.10 to -14.00 D (9 eyes). RESULTS: At 12 months in the low myopia group, uncorrected visual acuity (UCVA) of 20/40 or better was achieved in 95.5% (86 eyes), 20/20 or better in 77.7% (70 eyes); 2.2% (two eyes) lost two or more lines of best spectacle-corrected visual acuity (BSCVA); 73.3% (66 eyes) were within +/-0.50 D of the target correction and 98.8% (89 eyes) were within +/-1.00 D. In the medium myopia group, UCVA of 20/40 or better was achieved in 74.2% (23 eyes), 20/20 or better in 25.8% (eight eyes); 3.2% (one eye) lost two lines, 61% (19 eyes) were within +/-0.50 D of desired correction and 83.8% (26 eyes) were within +/-1.00 D. In the high myopia group, UCVA of 20/40 or better was achieved in 22.2% (two eyes); 20/25 or better in 11.1% (one eye); none of the eyes achieved 20/20 UCVA; 22.2% (two eyes) lost two lines of BSCVA; 44.4% (four eyes) were within +/-0.50 D and 66.6% (six eyes) were within +/-1.00 D of the target correction. Refractive stability was achieved between 3 and 6 months. Increased intraocular pressure was detected overall in 7.69%. CONCLUSIONS: The results of predictability, safety, and efficacy in low and medium myopia with the Meditec MEL 70G-Scan flying spot excimer laser were good, but poorer predictability, regression, and a significant loss of BSCVA were observed in the high myopia group.     

准分子激光屈光性角膜切削术矫正散光的准确性及预测性

目的 探讨准分子激光屈光性角膜切削术（ｅｘｃｉｍｅｒ ｌａｓｅｒ ｐｈｏｔｏｒｅｆｒａｃｔｉｖｅ ｋｅｒｅｃｔｏｍｙ,ＰＲＫ）矫正散光的准确性及预测性。方法 根据角膜地形图提供的角膜屈光力数值,用Ｈｏｌｌａｄａｙ法计算复性近视散光３０例（５３只眼）和单纯近视２３例（３３只眼）患者术前与术后６个月角膜屈光力的差值,确定实际矫正散光度及轴位,及预期矫正散光度及轴位进行对比分析。结果 复性近视散光组５３     

Long-term prospective follow-up study of myopic photorefractive keratectomy

The aim of this study was to evaluate the long-term outcome of excimer laser myopic photorefractive keratectomy (PRK). We undertook an 11-year prospective follow-up study of visual and refractive outcomes in 46 patients (85 eyes). The main outcome measures were predictability, efficacy, stability and safety of PRK. At 11 years after the operation, 56.5% of eyes were within +/-0.5 D of attempted correction and 81.2% were within +/-1.0 D; 87% had vision of 20/40 or better, and 52% had 20/20 or better. The best spectacle-corrected visual acuity was unchanged or improved in 91% of eyes at 11 years. Eyes with moderate and severe myopia showed a significant change between 3 and 11 years. PRK surgery for myopia shows predictable and stable results in the long term, with a slight regression in refraction, mainly for patients with severe myopia.     

Ten-year follow-up of photorefractive keratectomy for myopia of more than -6 diopters

PURPOSE: To evaluate the long-term outcomes of excimer laser myopic photorefractive keratectomy (PRK) for myopia higher than -6 diopters (D). DESIGN: A long-term (10-year) follow-up retrospective, interventional case series. METHODS: The study included 267 eyes of 191 patients with myopia with spherical equivalent (SE) of more than -6 D treated with myopic PRK at the Instituto Oftalmológico de Alicante, Alicante, Spain, using the VISX 20/20 excimer laser (Santa Clara, California, USA). All patients were evaluated three months, one year, two years, five years, and 10 years after surgery. The main outcome measures were refractive predictability and stability, mean corneal keratometry, topographical cylinder, safety, efficacy, stability of visual acuity, and postoperative complications. RESULTS: At 10 years, 156 (58%) of 267 eyes were within +/- 1.00 D and 209 (78%) were within +/- 2.00 D. One hundred and twenty-four eyes (46.4%) underwent retreatments because of overcorrection, regression, or both. The mean SE decreased (myopic regression) in eyes that did not undergo retreatment, with a mean magnitude of -1.33 +/- 2.0 D over 10 years (-1.13 +/- 0.20 D per year). One hundred and twenty-one (48.3%) of 267 eyes demonstrated increase in best spectacle-corrected visual acuity, and only eight eyes lost lines of vision because of cataract and posterior segment-related complications. The mean corneal haze score decreased gradually from 0.48 +/- 0.69 at three months to 0.09 +/- 0.33 at 10 years. CONCLUSIONS: PRK for myopia of more than -6 D is a safe and effective procedure in the long-term.     

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.     

One-year results of photorefractive keratectomy with and without surface smoothing using the technolas 217C laser

PURPOSE: To assess the efficacy, predictability, stability, and safety of a smoothing technique in patients with myopia immediately after photorefractive keratectomy (PRK) using a scanning-spot excimer laser. METHODS: Using the Technolas 217C excimer laser, PRK was performed on 100 eyes of 54 patients. Ablation zone diameter was 6.0 mm and transition zone diameter was 9.0 mm. The eyes were randomized into two groups: in 50 eyes PRK alone was performed and in the other 50 eyes, a smoothing technique was performed after the initial ablation. Preoperative mean spherical equivalent refraction was -4.98 +/- 1.71 D in the PRK only group (range -2.25 to -8.60 D) and -4.82 +/- 1.61 D in the smoothing group (range -2.00 to -8.00 D). Follow-up was 12 months for all patients. RESULTS: At 1 year after surgery, mean manifest spherical equivalent refraction was -0.61 +/- 0.50 D (range -2.25 to +0.62 D) in the PRK only group and in the smoothing group, +0.02 +/- 0.32 D (range -0.75 to +0.75 D). Postoperative regularity topographic indices were lower in the smoothing group than in the PRK group (P<.001). CONCLUSIONS: Smoothing after PRK for correction of myopia up to -6.50 D increased surface regularity, as expressed by lower topography surface regularity indices, and reduced the incidence and severity of postoperative haze. We observed higher predictability throughout follow-up in the smoothing group, which may be addressed by a nomogram adjustment in the PRK only group.     

Eight-year follow-up of photorefractive keratectomy for myopia

PURPOSE: We evaluated 8-year results of excimer laser photorefractive keratectomy (PRK) for myopia in terms of stability and late complications. METHODS: Ninety-two myopic eyes of 55 patients were treated with a single-step method using an Aesculap-Meditec MEL 60 excimer laser with a 5.0-mm ablation zone. Treated eyes were divided into three groups according to preoperative refraction: low myopes (< or = -6.00 D), medium myopes (-6.10 to -10.00 D), and high myopes (>-10.00 D). RESULTS: Change in myopic regression stabilized in all myopia groups within 12 months, although a small myopic shift occurred up to 8 years after PRK. Mean change in refraction between 2 and 8 years was -0.42 +/- 0.48 D for low myopes, -0.37 +/- 0.34 D for medium myopes, and -0.41 +/- 0.50 D for high myopes. The percentage of eyes within +/- 1.00 D of emmetropia 8 years after PRK was 78.3% in the low myopia group, 68.8% in the medium myopia group, and 57.1% in the high myopia group. One eye lost 2 lines of best spectacle-corrected visual acuity due to irregular astigmatism. In 13.0% of eyes, a residual trace corneal haze was observed, which had no effect on visual acuity. Apart from the loss of 2 lines of BSCVA in one eye, there were no other late complications during the study period. CONCLUSIONS: The mean change in refraction between 2 and 8 years was less than -0.50 D, regardless of preoperative refraction, and may be attributed to natural age-related refractive change. The appearance of residual corneal haze after 8 years correlated with the amount of myopic correction. PRK was a safe and stable surgical procedure in this group of patients.     

Ten-year follow-up of photorefractive keratectomy for myopia of less than -6 diopters

PURPOSE: To evaluate the long-term outcomes of excimer laser myopic photorefractive keratectomy (PRK) for myopia of less than -6 diopters (D). DESIGN: Long-term (10-year) follow-up retrospective, interventional case series. METHODS: The study included 225 eyes of 138 myopic patients with spherical equivalent (SE) between 0 and -6 D treated with myopic PRK at the Instituto Oftalmológico de Alicante, Alicante, Spain, using the VISX 20/20 excimer laser (Santa Clara, California, USA). The main outcome measures were refractive predictability and stability, mean corneal keratometry, topographical cylinder, safety, efficacy, stability of visual acuity, and postoperative complications. RESULTS: At 10 years, 169 (75%) of 225 eyes were within +/- 1.00 D and 207 (92%) were within +/- 2.00 D. Ninety-five (42%) eyes underwent retreatments because of overcorrection, regression, or both. The mean SE slightly decreased (myopic regression) with a mean magnitude of -0.10 +/- 1.08 D over 10 years (-0.01 +/- 0.11 D per year). Forty-one (58%) of 225 eyes demonstrated increase in best spectacle-corrected visual acuity after 10 years. Only one eye lost eight lines because of significant cataract, and two eyes lost vision (one lost seven lines and the other lost four lines) because of posterior segment-related complications. The mean corneal haze score gradually decreased from 0.22 +/- 0.39 at three months to 0.01 +/- 0.09 at 10 years. CONCLUSIONS: Photorefractive keratectomy for myopia of less than -6 D is a safe and effective procedure in the long-term.     

准分子激光屈光性角膜切削术后屈光回退的多因素分析

目的：探讨准分子激光屈光性角膜切削术后屈光回退的主要因素。方法：采用VISX20／20型准分子激光仪对121例214眼近视患者行准分子激光角膜切削术,术后随访2年。分二组进行比较,Ⅰ组为低中度近视（－1．00D－－6．00D）124眼,Ⅱ组为高度近视（－6．25D－－16．00D）90眼。结果：术后2年低中度近视回退率9．7％,高度近视回退率27．8％（P＜0．005）,高度近视中高龄组较低龄组回退率高（P＜0．005）,较严重的角膜上皮下雾状混浊与回退伴行。结论：准分子激光角膜切削术后屈光回退的主要因素有预期矫正屈光度,角膜Haze及年龄。     

Laser in situ keratomileusis with the VISX Star laser for myopia over -10.0 diopters.

PURPOSE: To evaluate the efficacy, predictability, stability, and safety of laser in situ keratomileusis (LASIK) for myopia over -10.00 diopters (D). SETTING: The Eye Institute of Utah, Salt Lake City, Utah, USA. METHODS: The prospective study included 332 eyes of 183 patients having LASIK with the VISX Star laser to correct myopia of -10.00 to -18.00 D. The eyes were divided into 3 groups according to the preoperative refraction: Group A (n = 208), -10.00 to -11.90 D; Group B (n = 94), -12.00 to -14.00 D; Group C (n = 30), -14.10 to -18.00 D. The mean follow-up was 12.0 months +/- 5.6 (SD) (range 6 to 37 months). RESULTS: Overall, the mean spherical equivalent decreased 96%, from -11.69 +/- 1.46 D preoperatively to -0.37 +/- 0.80 D postoperatively. The mean astigmatism decreased 72%, from 1.66 +/- 1.22 D to 0.46 +/- 0.53 D. At the last visit, 84.0% of eyes were within +/-1.00 D of emmetropia and 96.4% were within +/-2.00 D. An overcorrection of more than +1.00 D was experienced by 1.8% of patients. The uncorrected visual acuity (UCVA) was 20/20 or better in 45.8% of eyes and 20/40 or better in 89.5%. Six eyes (1.8%) lost 2 or more lines of best corrected visual acuity; this included 1 eye in which iatrogenic keratectasia developed 18 months after LASIK retreatment. Retreatment was done in 37.0% of eyes at a mean of 6.3 +/- 5.3 months (3 to 32 months) after the initial treatment. At the last examination, 86.0% of eyes in Groups A and B and 70.0% in Group C were within +/-1.00 D of emmetropia. A significant difference was found between Groups A and C (P =.032). The UCVA was 20/20 in 52.0% of Group A eyes, 38.0% of Group B eyes, and 23.0% of Group C eyes. The difference between Groups A and C was significant (P =.001), but the difference between Groups A and B was not (P =.055). CONCLUSIONS: In this study, LASIK was effective in correcting myopia up to -14.00 D. The efficacy, predictability, and safety were significantly less in eyes with myopia greater than -14.00 D.     

One-year results of PRK in low and moderate myopia: fewer than 0.5% of eyes lose two or more lines of vision

PURPOSE: To retrospectively evaluate the results of myopic photorefractive keratectomy (PRK) for different levels of intended correction, including analysis of loss of best spectacle-corrected visual acuity. METHODS: Four hundred seventy-five consecutive eyes with 1 year of follow-up that had PRK for the correction of 1-7 diopters (D) of myopia by using the Summit SVS Apex excimer laser. Three hundred forty-eight eyes were examined at 1 year. This study was confined to the 236 eyes with 1 year of follow-up that had PRK without astigmatic keratotomy. Eyes also were analyzed according to the range of attempted correction (0-3 D, low; 3.1-6D, moderate; and > or =6.1 D, high moderate). Manifest refraction, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), surface regularity index (SRI), and surface asymmetry index (SAI) were evaluated for each group. RESULTS: One year after PRK, 91% of all eyes were within 1 diopter and 73% of eyes were within 0.5 diopter of emmetropia. Uncorrected visual acuity was 20/25 or better in 79% and 20/40 or better in 96% of eyes. Two lines of BSCVA were lost in only 0.4% of eyes (one of 236). No eye lost >2 lines of BSCVA, and 30% gained one line. Mean SRI and SAI were increased as compared with preoperative values, but were within the normal range for our patient population (ranges, 0.2-1.0 and 0.1-0.7, respectively). UCVA, BSCVA, and predictability decreased, whereas SAI and SRI increased, with increasing attempted correction. CONCLUSION: PRK effectively reduced myopia in all eyes with 12 months' follow-up. Predictability tended to decrease with increasing attempted correction, even for low to moderate myopia. PRK may induce mild surface asymmetry and irregularity, and these alterations tend to increase with higher attempted correction. Fewer than 0.5% of eyes lost > or =2 lines of best-corrected visual acuity.     

Effect of age on the refractive outcome of myopic photorefractive keratectomy

PURPOSE: To evaluate the effect of age on the outcome of myopic photorefractive keratectomy (PRK). SETTING: University-based refractive surgery practice. METHODS: A retrospective analysis of 197 eyes that had PRK for myopia was performed. Four groups of patients were compared: Group 1, patients < 30 years (n=35); Group 2, patients 31 to 40 years (n=56); Group 3, patients 41 to 50 year s (n=47); Group 4, patients > 50 years (n=59). The percentage of eyes with an uncorrected visual acuity of 20/20 or better and 20/40 or better and the percentage of eyes with spherical correction within +/-0.5 and +/-1.0 diopter (D) of the attempted correction were derived for each age group. The percentage of patients overcorrected and undercorrected by 1.0 D or more in each age group was also calculated.The difference between the percentage of patients who achieved a visual acuity of 20/20 or better in Group 4 and in the younger groups was statistically significant at 3 months (P =.02) but not at 6 months (P =.70) and 12 months (P =.55). The difference between the percentage of patients who achieved an acuity of 20/40 or better was not significant at any time. The difference between the percentage of patients who were within +/-0.5 D of intended correction in Group 4 and in the younger groups was statistically significant at 3 months (P =.001), 6 months (P =.006), and 12 months (P =.008); the difference between the percentage of patients who were within +/-1.0 D of intended correction was not significant at any time. The difference between the percentage of patients overcorrected and undercorrected by 1.0 D or more in Group 4 and in the younger groups was not significant at any time.In the 3 younger groups, age did not significantly affect visual outcome or predictability. However, there was a significant difference between Group 4 and the 3 younger groups in predictability of the refractive outcome at 3, 6, and 12 months. Age may play a role in the outcome of refractive surgery.     

Photorefractive keratectomy for hyperopia in 800 eyes with the Meditec MEL 60 laser

PURPOSE: To evaluate the refractive results of 800 hyperopic eyes undergoing PRK treatment. METHODS: Eight hundred hyperopic eyes were treated with PRK. An Aesculap-Meditec MEL 60 scanning ArF excimer laser used. Treatment Group 1 consisted of eyes with a preoperative refractive error of +3.50 D or less (n = 482) and Group 2, of +3.75 D or more (n = 318). RESULTS: Preoperatively, Group 1 required an average correction of +2.88+/-1.34 D and Group 2 required +5.64+/-2.96 D. One year after PRK, average residual correction was +1.26+/-1.24 D in Group 1, and in Group 2, +2.46+/-1.84 D. In Group 1, uncorrected visual acuity (UCVA) was 20/40 or better in 88.4% (426/482); 20/20 or better in 75.7% (365); 2.1% (10/482) of eyes lost 2 lines, 2.1% (10/482) gained 2 lines; 3.1% (15/482) gained 2 or more lines of BSCVA; 74.4% (359/482) of eyes were within +/-0.50 D of target correction and 84.8% (408/482) were within +/-1.00 D. In Group 2, 47.5% (151/318) had UCVA of 20/40 or better; 34.2% (109/318) saw 20/20 or better uncorrected; 19.1% (61/318) lost 2 lines; 11.6% (37/318) lost 3 lines; none of the eyes gained 2 or more lines of BSCVA; 22.3% (71/318) were within +/-0.50 D and 46.8% (149/318) were within +/-1.00 D of target correction. Refractive stability was achieved after 6 months; a slight regression after 6 months was still observed. In Group 1, 10.5% (42/482) and in Group 2, 21.6% (69/318) complained of problems with daytime vision (glare and ghost image); during night-driving in Group 1, 17.6% (85/482) and in Group 2, 40.5% (129/318) had problems. CONCLUSION: PRK with the Aesculap-Meditec MEL 60 scanning ArF excimer laser offered the best long-term results with +3.50 D or less preoperative refractive error. With higher corrections, regression, decrease in BSCVA, and daytime visual problems were encountered.     

Randomized bilateral comparison of excimer laser in situ keratomileusis and photorefractive keratectomy for 2.50 to 8.00 diopters of myopia

OBJECTIVE: To compare effectiveness, safety, and stability of excimer laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) for low-to-moderate myopia. DESIGN: Prospective, randomized, bilateral study. PARTICIPANTS: Thirty-three patients with a manifest refraction of -2.50 to -8.00 diopters (D) participated. INTERVENTION: 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. RESULTS: 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. CONCLUSIONS: 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.     

Predictability and outcomes of photoastigmatic keratectomy using the Nidek EC-5000 excimer laser

PURPOSE: To evaluate the effect of astigmatic correction on the accuracy of the myopic and astigmatic correction in patients having photorefractive astigmatic keratectomy (PARK) and in those having photorefractive keratectomy (PRK). SETTING: Specialist excimer laser refractive clinic. METHODS: This prospective consecutive case series comprised 6097 eyes with a preoperative mean spherical equivalent (MSE) of -4.63 diopters (D) +/- 1.95 (SD) (range -0.75 to -13.00 D) and a mean cylinder of -1.13 +/- 0.73 D (range -0.50 to -6.00 D) having PARK with a Nidek EC-5000 excimer laser. Visual and refractive outcomes were assessed 12 months postoperatively and compared with those in 3004 eyes that had spherical PRK. RESULTS: At 12 months, the MSE was -0.02 +/- 0.79 D and the mean cylinder was -0.49 +/- 0.47 D in the PARK group; the MSE was -0.07 +/- 0.66 D in the PRK group. An MSE within +/-0.05 D of emmetropia was achieved by 69.8% and within +/-1.00 D, by 87.9%. The uncorrected visual acuity (UCVA) was 20/20 or better in 42.6% and 20/40 or better in 91.2%. Statistical significance (P <.001, analysis of variance) was achieved for MSE, sphere, cylinder, haze, and visual acuity (best corrected [BCVA] and UCVA) based on the preoperative cylinder. The loss of BCVA varied from 1.1% to 5.8% depending on the degree of astigmatism treated. Accuracy varied with the attempted myopic correction and the attempted astigmatic correction. CONCLUSIONS: Excimer laser PARK was an effective treatment for compound myopic astigmatism, but predictability decreased and complications increased as the attempted astigmatic correction increased.     

Laser-assisted subepithelial keratectomy and photorefractive keratectomy for the correction of hyperopia. Results of a 2-year follow-up

PURPOSE: To evaluate and compare the efficacy, safety, predictability, and stability of laser-assisted subepithelial keratectomy (LASEK) and photorefractive keratectomy (PRK) for low to moderate hyperopia with a 2-year follow-up. SETTING: Department of Ophthalmology, Masaryk University Hospital, Brno, Czech Republic. METHODS: This prospective comparative single-surgeon study included 216 eyes of 108 patients with hyperopia who received PRK in 1 eye and LASEK in the contralateral eye. The mean patient age was 38.3 years (range 25 to 58 years). The mean preoperative spherical equivalent (SE) cycloplegic refraction was +3.67 diopters (D) +/- 1.15 (SD) (range +2.00 to +5.00 D), and astigmatism was less than 1.00 D. In each patient, PRK was performed in 1 eye (Group A) and LASEK was performed in the other eye (Group B) using the Nidek EC-5000 excimer laser. Postoperative uncorrected visual acuity (UCVA), best corrected visual acuity, contrast sensitivity, manifest and cycloplegic refractions, refractive stability and predictability, postoperative pain, and corneal haze were examined and statistically analyzed. A P value less than 0.05 was considered significant. RESULTS: At 1 week, the UCVA was 20/40 or better in 58% of PRK eyes and 85% of LASEK eyes (P =.037); at 2 years, it was 20/40 or better in 81% and 91%, respectively (P =.076). At 2 years, the UCVA for near was N8 or better in 73% of PRK eyes and 89% of LASEK eyes (P =.064). No patient lost 2 or more lines of Snellen visual acuity. The safety index was 1.03 in PRK eyes and 1.08 in LASEK eyes. Refractive stability was achieved at 6 months in LASEK eyes and at 12 months in PRK eyes. The mean SE cycloplegic refraction decreased from +3.58 D (PRK eyes) and +3.76 D (LASEK eyes) at baseline to +0.74 D and +0.32 D, respectively, at 2 years; in 57% and 78% of eyes, respectively, the refraction was within +/-0.50 D of the targeted refraction. Peripheral corneal haze scores at 3 to 9 months and pain scores at 1 to 3 days were significantly lower in the LASEK group than in the PRK group. CONCLUSIONS: Laser-assisted subepithelial keratectomy for hyperopia up to +5.00 D provided good visual and refractive results. It significantly reduced postoperative pain, grade of peripheral ring-shaped corneal haze, and regression of hyperopia. Hyperopic LASEK provided quicker visual recovery and achieved better efficacy, predictability, and refractive stability than hyperopic PRK.     

Repeated photorefractive keratectomy for undercorrection and regression

PURPOSE: Regression (often combined with significant haze) and undercorrection are the most frequent complications after photorefractive keratectomy (PRK) for myopia. PRK retreatment has been used to treat both of these complications. METHODS: Sixty-three eyes (55 patients) were reoperated (PRK) because of initial regression or undercorrection. The mean interval between the operations was 17.2 months (range 5 to 37 mo). Residual myopia before retreatment was less than -5.00 D in 62 eyes (mean -2.21 +/- 0.99 D) and was -10.50 D in one eye. The same surgical PRK technique (Aesculap-Meditec MEL 60 excimer laser with 5 or 6-mm ablation zone) was used in both operations. RESULTS: One-year results were available for 51 eyes. In the group of eyes with low residual myopia (<-5.00 D), mean refraction 1 year after retreatment was -0.42 +/- 0.96 D and 43 eyes (86%) were within +/-1.00 D of emmetropia. Uncorrected visual acuity of 20/40 or better was achieved in 43 eyes (86%) after 1 year. One eye lost two lines of best spectacle-corrected visual acuity after two procedures because of haze. Mean haze was the same before and 12 months after reoperation (grade 0.39 vs. 0.38). Significant haze (>2) and high regression after the first PRK occurred after reoperation. The one eye with -10.50 D residual myopia after the first PRK showed high regression, and 1 year after the reoperation refraction was -9.50 D with grade 2 haze. CONCLUSIONS: Repeated PRK was safe and in most cases effective in treating regression and undercorrection in eyes with low residual myopia after initial PRK. High regression and especially haze after the initial PRK often reappeared after reoperation.     

Ten-year follow-up of laser in situ keratomileusis for high myopia

PURPOSE: To evaluate the long-term outcomes of laser in situ keratomileusis (LASIK) for high myopia. DESIGN: A long-term (10 years) follow-up retrospective interventional case series study. METHODS: The study included 196 myopic eyes of 118 patients with a mean preoperative spherical equivalent of -13.95 +/- 2.79 diopter (D) treated with myopic LASIK at the Instituto Oftalmológico de Alicante, Spain using the VISX 20/20 excimer laser (VISX Inc, Santa Monica, California, USA) and the Automated Corneal Shaper microkeratome (Chiron Vision, Irvine, California, USA). All patients were evaluated three months, one year, two years, five years, and 10 years postoperatively. The main outcome measures were refractive predictability and stability, mean corneal keratometry, topographical cylinder, safety, efficacy, stability of visual acuity, and postoperative complications. RESULTS: At 10 years, 82 (42%) of 196 eyes were within +/-1.00 D and 119 (61%) were within +/-2.00 D. Fifty-four (27.5%) eyes underwent retreatments attributable to under correction and/or regression. The myopic regression decreases with time in eyes that did not undergo retreatment with a mean rate of -0.25 +/- 0.18 D per year. Eleven eyes (5%) lost more than 2 lines of best spectacle-corrected visual acuity (BSCVA) and 78 eyes (40%) showed a postoperatively uncorrected visual acuity of 20/40 or better. Two eyes (1%) with more than 15 D myopic correction developed corneal ectasia. CONCLUSIONS: LASIK for myopia over -10 D is a safe procedure with myopic regression that slows down with time and a high rate of BSCVA increase in the long-term.