Laser-assisted subepithelial keratectomy in children

PURPOSE: To evaluate whether laser-assisted subepithelial keratectomy (LASEK) achieves effective targeted myopic correction with less post-treatment corneal haze than observed with photorefractive keratectomy (PRK) in children who fail traditional forms of treatment for myopic anisometropic amblyopia and high myopia. SETTING: Nonhospital surgical facility with follow-up in a hospital clinic setting. METHODS: This prospective study comprised 36 eyes of 25 patients. The mean patient age at treatment was 8.27 years (range 1.0 to 17.4 years). Patients were divided into 3 groups: those with myopic anisometropic amblyopia (13 patients/13 eyes), those with bilateral high myopia (11 patients/22 eyes), and those with high myopia post-penetrating keratoplasty (1 patient/1 eye). All patients were treated with LASEK under general anesthesia using the Visx 20/20 B excimer laser and a multizone, multipass ablation technique. Although the myopia was as high as -22.00 diopters (D) spherical equivalent (SE) in some eyes, no eye was treated for more than -19.00 D SE. RESULTS: At 1 year, the mean SE decreased from -8.03 D to -1.19 D. Forty-four percent of eyes were within +/-1.0 D of the targeted correction; 78% of eyes had clear corneas with no haze. In the entire group, the mean best corrected visual acuity improved from 20/80 to 20/50. A functional-vision survey demonstrated a positive effect on the patients' ability to function in their environments after LASEK. CONCLUSIONS: Laser-assisted subepithelial keratectomy in children represents another method of providing long-term resolution of bilateral high myopia and myopic anisometropic amblyopia with minimal post-laser haze. The reduction in post-laser haze with LASEK compared to that with the standard PRK technique may represent an advantage in treating these complex 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.     

Topical thiotepa treatment for recurrent corneal haze after photorefractive keratectomy

PURPOSE: To describe the use of topical thiotepa in the treatment of recurrent haze after photorefractive keratectomy (PRK). SETTING: Gimbel Eye Centre, Calgary, Alberta, Canada. METHODS: Five patients with recurrent haze after myopic PRK were retreated with phototherapeutic keratectomy and topical thiotepa. Before retreatment, the best corrected visual acuity (BCVA) ranged from 20/40 to 20/200. Follow-up ranged from 3 to to15 months. RESULTS:Haze, uncorrected visual acuity (UCVA), and BCVA improved in all patients. Three eyes had a UCVA of 20/20(-2) or better and a BCVA of 20/20(-1) or better. The other 2 eyes experienced regression of the myopia and astigmatism and had a BCVA of 20/25(-1) or better. CONCLUSION: Topical thiotepa appeared to be an effective treatment for recurrent corneal haze following myopic PRK.     

Photorefractive keratectomy retreatment after LASIK

PURPOSE: To study the results of late photorefractive keratectomy (PRK) in corneas originally subjected to LASIK. METHODS: Seven eyes of seven patients who had LASIK for myopia were retreated with PRK at least 2 years after LASIK. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, and haze were evaluated before and after LASIK and after retreatment by PRK. RESULTS: Photorefractive keratectomy retreatment improved BSCVA in six (86%) of seven eyes, and one (14%) eye showed no changes. None of the eyes lost lines of BSCVA. Five of seven eyes developed mild haze, which disappeared before the last postoperative follow-up. CONCLUSIONS: Photorefractive keratectomy retreatment performed at least 2 years after LASIK can improve visual acuity. We hypothesize that LASIK-induced corneal nerve damage disturbs corneal wound healing by increasing the tendency for development of haze.     

Patterns of late corneal scarring after photorefractive keratectomy in high and severe myopia

OBJECTIVE: To study the correlation between scarring 1 year after photorefractive keratectomy (PRK), final refraction, and degree of myopia. DESIGN: A retrospective, noncomparative case series. PARTICIPANTS: One hundred twenty eyes of 78 patients underwent PRK for high and severe myopia. Thirty-nine eyes had a pre-PRK spherical equivalent (SE) between -9.5 and -18.25 diopters (D) (severe myopia). Eighty-one eyes had a pre-PRK SE between -6.25 and -9.25 D (high myopia). Follow-up time ranged between 12 and 37 months with a mean of 18.2 months. INTERVENTION: Multizone PRK with the VISX 20/20 excimer laser. MAIN OUTCOME MEASURES: Corneal scarring, final best-corrected visual acuity (BCVA), and refraction. RESULTS: There were 71.7% of eyes with severe myopia and 60.5% of eyes with high myopia found to have any pattern of stromal scarring, which was classified as focal, semiannular, annular, and discoid. Discoid scars were rare (6.6%) and found in 12.8% of severe myopic eyes compared to 3.7% of high myopic eyes. Only 50% of the eyes with a discoid scar achieved final BCVA between 6/6 and 6/9 compared to 81.6% of the eyes with a clear cornea. The severe myopic eyes with a discoid scar had the highest level of final undercorrection (-5.0 D) compared to a maximum of -1.5 D in the high myopia group. The severe myopic eyes with a discoid scar had a higher number of retreatments (4 of 5) compared to the high myopia group (1 of 3). Other types of scars were less clinically significant. CONCLUSIONS: Photorefractive keratectomy was efficient in the correction of high myopia but less so in severe myopia, in which discoid scarring was more frequent and more clinically significant, being associated with significant regression. Other types of scarring were less clinically significant.     

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.     

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。     

Fellow eye treatment in excimer photo refractive keratectomy

PURPOSE: To describe symmetry of response in fellow eyes of patients undergoing photorefractive keratectomy (PRK) for myopia, analyse the risk factors leading to asymmetry in response and to determine if delayed treatment of the second eye increases safety and predictability of PRK. METHODS: Retrospective review of case records of 133 patients who underwent bilateral myopic PRK and had a minimum follow up of 6 months in both eyes. RESULTS: Postoperative uncorrected visual acuity, spherical equivalent (SE) refraction within +/- 1 D of emmetropia, best-corrected visual acuity (BCVA) and corneal haze were not significantly different in fellow eyes of patients undergoing PRK for myopia. Of 87 eyes in group 1 (myopia < 6 D), 96.6% had uncorrected visual acuity > or = 6/12, 89.7% were within +/- 1 D of emmetropia, none lost > or = 1 line BCVA, and none had haze > or = grade 3. Similar results for 98 eyes in group II (myopia 6 to 9.9 D) were 75.6%, 55.1%, 2.0% and 2.0% respectively. For 81 eyes in group III (myopia > or = 10 D) the results were 42.7%, 33.3%, 8.6%, and 4.9% respectively. Among 84 patients with similar preoperative myopia in both eyes, 54 (64.3%) patients had a postoperative SE difference < or = 1 D in fellow eyes. Risk factors for asymmetric response among fellow eyes included increasing preoperative myopia (p < 0.001) and dissimilar treatment technique in the two eyes (p = 0.03). Corneal haze did not increase significantly after the third postoperative month. CONCLUSION: This study demonstrates that considerable symmetry of response exists in fellow eyes of patients undergoing myopic PRK. Early PRK in the fellow eye of patients with < 6 D myopia is safe and allows quick visual rehabilitation of the patient. In patients with myopia > or = 6 D, a 3-month interval before treating the second eye may improve the safety of the procedure.     

准分子激光角膜切削深度与术后角膜上皮下雾状混浊的关系

目的研究准分子激光角膜切削术（ｐｈｏｔｏｒｅｆｒａｃｔｉｖｅｋｅｒａｔｅｃｔｏｍｙ，ＰＲＫ）后角膜上皮下雾状混浊（ｈａｚｅ）与角膜切削深度之间的关系。方法选择治疗条件基本相同，对双眼同时接受ＰＲＫ治疗的３１例（６２只眼）近视性屈光参差（平均４．９７Ｄ）患者进行前瞻性自身对照研究，将高近视度数眼（－１４．１０±４．１７Ｄ）作为治疗组，低近视度数眼（－９．１３±３．５３Ｄ）作为对照组，术后随访６～１２个月，平均１０个月。结果术后两组的角膜上皮下雾状混浊程度经统计学分析差异有显著性（Ｐ＜０．０５）。结论准分子激光角膜切削术治疗近视，矫正度数越高，角膜切削越深，术后发生角膜上皮下雾状混浊的危险性则越大。     

Photorefractive keratectomy for post-penetrating keratoplasty myopia and astigmatism

PURPOSE: To determine the safety, effectiveness, and predictability of photorefractive keratectomy (PRK) for the correction of myopia and astigmatism after penetrating keratoplasty. SETTING: Gazi University, Medical School, Department of Ophthalmology, Ankara, Turkey. METHODS: Photorefractive keratectomy was performed in 16 eyes of 16 patients with postkeratoplasty myopia and astigmatism who were unable to wear glasses due to anisometropia and were contact lens intolerant. They were examined for uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and corneal transplant integrity before and after surgery. RESULTS: The mean follow-up after PRK was 26.0 months +/- 15.7 (SD) (range 12 to 63 months). The mean preoperative spherical equivalent refraction of -4.47 +/- 1.39 diopters (D) was -3.39 +/- 1.84 D (P >.05) at the last postoperative visit and the mean preoperative cylinder of -5.62 +/- 2.88 D was -3.23 +/- 1.70 D (P <.05); refractive regression correlated with the amount of ablation performed. The BSCVA decreased in 3 eyes (18.8%), and the UCVA decreased in 2 (12.5%). Six eyes (37.5%) had grade 2 to 3 haze, which resolved spontaneously in 4 eyes within a relatively long time but caused a decrease in BSCVA in 2 (12.5%). Two of the eyes (12.5%) had a rejection episode after PRK and were successfully treated with topical steroids. CONCLUSIONS: Photorefractive keratectomy to correct postkeratoplasty myopia and astigmatism appears to be less effective and less predictable than PRK for naturally occurring myopia and astigmatism. Corneal haze and refractive regression are more prevalent, and patient satisfaction is not good.     

Improvement of visual acuity following refractive surgery for myopia and myopic anisometropia

PURPOSE: To test the hypothesis that anisometropic adults without significant amblyopia suffer from mild visual impairment probably due to aniseikonia, which might be improved by corneal refractive surgery. METHODS: Fifty-seven patients presenting with myopic anisometropia > or = 3.25 diopters (D) and 174 myopic controls appropriate for refractive surgery were included. Photorefractive keratectomy (PRK) or LASIK was performed on 57 anisometropic eyes. As 43 of the 174 myopic control patients had bilateral surgery, PRK or LASIK was performed on 217 myopic control eyes. Best spectacle-corrected visual acuity (BSCVA), refraction, and refractive correction were measured preoperatively and at 1, 3, 5 to 7, 8 to 13, and 25 months following surgery. RESULTS: Preoperative mean spherical equivalent was -7.20 +/- 2.40 D for anisometropic patients and -6.40 +/- 1.90 D for myopic patients. At 8 to 13 months postoperatively, when 23 (40%) anisometropic eyes and 94 (43%) myopic eyes were examined, the mean spherical equivalent refractions were -0.80 +/- 1.60 D and -0.30 +/- 0.60 D, respectively. Preoperatively, the mean BSCVA on a logMAR scale was -0.0143 +/- 0.0572 (Snellen 0.98 +/- 0.12) in the anisometropic group and 0.0136 +/- 0.0361 (Snellen 1.04 +/- 0.09) in the control group (P = .001). Eight to 13 months postoperatively, these values were 0.0076 +/- 0.0659 (Snellen 1.03 +/- 0.15) and 0.0495 +/- 0.0692 (Snellen 1.13 +/- 0.18) and this difference remained statistically significant (P = .012). For the myopic patients, the improvement in BSCVA reached almost maximum at 3 months, and this improvement was found to be highly significant 3 months after surgery (P = .001). The improvement in BSCVA was significantly slower for anisometropic patients and became statistically significant only after 8 to 13 months postoperatively (P = .041). CONCLUSIONS: Anisometropia reduces visual acuity in the more myopic eye and can be at least partially reversed by refractive correction. The slower improvement in BSCVA for anisometropic patients suggests plastic changes in the visual cortex following refractive surgery.     

Phototherapeutic keratectomy with mitomycin C for corneal haze following photorefractive keratectomy for myopia

PURPOSE: To evaluate the safety and efficacy of phototherapeutic keratectomy (PTK) with single application of mitomycin C for patients with severe corneal haze following photorefractive keratectomy (PRK) for high myopia. METHODS: Eight eyes of seven patients were treated with PTK and intraoperative topical application of mitomycin C (0.02%) for severe corneal haze (grade 3) following PRK for myopia. RESULTS: All patients' visual performance improved significantly. Mean preoperative visual acuity (20/200 for both UCVA and BSCVA) improved significantly to 20/33 (0.6) and 20/30 (0.7) for UCVA and BSCVA, respectively. Six eyes (85.7%) had improved UCVA to 20/40 or better and gained five or more lines of UCVA. The corneal haze score decreased from grade 3 initially (for all eyes prior to PTK and mitomycin C) to a final mean haze score of 0.3 (range 0 to 0.5). Mean final spherical equivalent refraction achieved was -1.30 +/- 1.60 D (range -3.75 to +1.25 D). One eye gained only three lines of visual acuity due to regression and residual haze. No adverse effects related to the use of mitomycin C were recorded. CONCLUSION: PTK with a single intraoperative application of mitomycin C was safe and effective in reducing corneal haze and improving visual acuity in patients with severe corneal haze following PRK.     

准分子激光屈光性角膜切削术后的再治疗

目的 评价准分子激光屈光性角膜切削术（ｐｈｏｔｏｒｅｆｒａｃｔｉｖｅ ｋｅｒａｔｅｃｔｏｍｙ,ＰＲＫ）术后因屈光回退,欠矫出现的残留近视及严重角膜上皮下雾状混沌（ｈａｚｅ）而再次手术治疗的疗效及安全性。方法 采用准分子激光仪对－１．００～－１６．５０Ｄ的近视眼及近视散光患者进行治疗。ＰＲＫ术后３５例（５１只眼）患者出现残留近视及严重ｈａｚｅ。结合ＰＲＫ手术及准分子激光治疗性角膜切削术（ｐｈｏｔｏｐ     

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.     

Photorefractive keratectomy for residual myopia after cataract surgery

PURPOSE: To evaluate the effectiveness, predictability, and safety of photorefractive keratectomy (PRK) for correcting residual myopia and myopic astigmatism after cataract surgery with intraocular lens implantation. SETTING: Refractive Surgery and Cornea Unit, Instituto Oftalmológico de Alicante, Alicante, Spain. METHODS: Thirty consecutive eyes (30 patients) had PRK for residual myopia after cataract surgery. Surface PRK with a VISX Twenty-Twenty excimer laser was used in all patients. Follow-up was 1 year. RESULTS: Before PRK, no eye had an uncorrected visual acuity (UCVA) of 20/40 or better. Twelve months after PRK, 16 eyes (53.33%) had a UCVA of 20/40 or better. After PRK, best corrected visual acuity (BCVA) improved 1 line or more in 14 eyes (46.66%) over the preoperative values, and 15 eyes (50.00%) had the same BCVA as before PRK. Mean pre-PRK refraction of -5.00 diopters (D) +/- 2.50 (SD) decreased significantly to -0.25 +/- 0.50 D at 12 months (P < .001). At 12 months, the spherical equivalent was within +/- 1.00 D of emmetropia in 27 eyes (90.00%). No vision-threatening complications occurred. CONCLUSION: Photorefractive keratectomy was an effective, predictable, and safe procedure for correcting residual myopia and myopic astigmatism after cataract surgery.     

Corneal astigmatic change after photorefractive keratectomy and photoastigmatic refractive keratectomy

PURPOSE: To evaluate and compare the efficacy, safety, predictability, and surgically induced astigmatism (SIA) of photorefractive keratectomy (PRK) and photoastigmatic refractive keratectomy (PARK). SETTING: Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan. METHODS: In this retrospective study, 70 eyes were treated for myopia and 70 eyes were treated for myopic astigmatism. Refraction, corneal topography, slitlamp findings, and visual acuity in the 2 groups at 1, 3, and 6 months were evaluated and compared. Vector analysis was performed to determine the SIA in both groups. RESULTS: The mean preoperative spherical equivalent at the glasses plane in the PRK and PARK groups was -6.06 diopters (D) and -7.18 D, respectively. At 6 months, the mean reduction in astigmatism in the PARK group was 61.0%. Predictability was within +/-1.0 D in 85.2% of eyes in the PRK group and 62.5% in the PARK group. An uncorrected visual acuity of 20/40 or better was achieved in 91.8% and 83.9% of eyes, respectively. The mean SIA was 0.64 D in the PRK group, with a general with-the-rule axis shift. The results of vector analysis were more favorable when calculated from refractive values than from Sim-K corneal topography values. The mean astigmatism correction index and index of success calculated from refractive data were 0.75 and 0.38 in the PARK group. The mean magnitude and angle of error were 0.22 +/- 0.52 D and -2.13 +/- 24.41 degrees, respectively. CONCLUSIONS: Photorefractive keratectomy and PARK were effective and safe procedures for the correction of myopia and myopic astigmatism. However, SIA occurred with spherical myopic treatments. This small SIA may be a confounding factor in low astigmatic treatments.     

Twelve-year follow-up of photorefractive keratectomy for low to moderate myopia

PURPOSE: To evaluate long-term safety and stability in a group of myopic patients who underwent photorefractive keratectomy (PRK) > or =12 years ago. METHODS: Myopic PRK was performed on 120 eyes of 80 patients using the Summit UV200 excimer laser with a 5-mm ablation zone. Of the original group, most of whom were followed for > or =2 years (mean 2.6 +/- 1.7 years), 34 patients (58 eyes) returned at 12 years (mean 12.7 +/- 0.79 years) and had refractive stability, refractive predictability, best spectacle-corrected visual acuity (BSCVA), corneal haze, and subjective patient symptoms, such as glare/halos, recorded. RESULTS: Preoperative mean refractive spherical equivalent (MRSE) ranged from -1.75 to -7.25 diopters (D) and astigmatism from 0.00 to 1.50 D. All eyes underwent a change in manifest refraction over 12 years. At 2 years, MRSE was -0.27 +/- 0.55 D and at 12 years was -0.58 +/- 0.72 D. In 87.9% of eyes, the level of preoperative BSCVA was maintained or improved, whereas 34.5% of eyes gained one line, and 12.1% lost one line of BSCVA. Uncorrected visual acuity > or = 20/20 was noted in 67% of eyes, whereas 62.1% were within +/- 0.50 D of emmetropia. Trace haze was noted in 17.2% of eyes at 12 years. One patient had a rhegmatogenous retinal detachment, but this was unlikely due to the PRK procedure. With respect to the small optical zone, 14 (41.1%) patients had night visual problems, particularly halos, which were severe in 2.7%. All patients questioned stated they would have the procedure done again. CONCLUSIONS: Photorefractive keratectomy with the Summit UV200 excimer laser effectively reduced myopia and showed good refractive stability from year 2 to 12 with good patient satisfaction.     

PRK矫治近视远期临床疗效观察

目的 评价准分子激光角膜切削术(PRK)治疗近视远期临床疗效.方法 回顾性分析23例(45只眼)PRK术后8年以上(8.78±1.54)年的视力、屈光度、对比敏感度、波前像差及haze情况.分低度近视(＜-3D)、中度近视(≥-3D且＜-6D)和高度近视(≥-6D)三组比较.结果 低度近视组术后裸眼视力(UCVA)均≥1.0,中度近视组术后UCVA≥0.5和≥1.0者分别为:23只眼(85.19％),14只眼(51.85％);高度近视组达0.5以上为4只眼(40％).术后最佳矫正视力下降者三组眼数分别为0、5(18.52％)和3(30％).术后屈光度在预期矫正值±1D以内者三组眼数分别为8(100％)、17( 62.96％)、3(30％).中低度近视组对比敏感度均正常,高度近视组仅1只眼在正常值范围内.术后总高阶像差均方根三组间差异明显(P＜0.05),其中球差增大明显,且随矫正度数增加而增大(P＜0.05).haze低度近视组无,中度组仅1只眼(3.70％)为0.5级,高度组0.5级2只眼,1级2只眼.结论 PRK治疗中低度近视远期疗效满意,治疗高度近视远期效果欠佳,haze可在PRK术后长期存在,尤其在高度近视眼中.     

Photorefractive keratectomy for myopia with a 15 Hz repetition rate

PURPOSE: To evaluate excimer laser photorefractive keratectomy (PRK) for myopia using a repetition rate of 15 Hz instead of 10 Hz. SETTING: The Cornea and Laser Eye Institute, Teaneck, and Department of Ophthalmology, UMDNJ-New Jersey Medical School, Newark, New Jersey, USA. METHODS: Photorefractive keratectomy using a 15 Hz repetition rate was performed in 23 eyes of 14 patients by a single surgeon at 1 center. The attempted corrections ranged from -2.8 diopters (D) to -5.5 D. Preoperative and postoperative uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), predictability, corneal haze, and subjective glare/halo were evaluated over 6 months. RESULTS: At 6 months, UCVA was 20/32 or better in all eyes and at least 20/20 in 14 eyes (73.7%). Two eyes (10.5%) lost 2 or more Snellen lines of BSCVA; postoperative BSCVA was at least 20/25 in 100% of eyes and 20/20 or better in 95.0%. Fifteen eyes (78.9%) were within +/-0.5 D of attempted correction, and 19 (100%) were within +/-1.0 D. Mean spherical equivalent refraction was -4.62 D preoperatively, +0.15 D at 1 month, -0.09 D at 3 months, and -0.37 D at 6 months. At 6 months, 4 eyes (21.0%) had no corneal haze and 14 (73.7%) had trace subepithelial haze. Fifteen eyes (78.9%) had no glare/halo effect at 6 months, and 4 (21.0%) had minimal glare/halo effect. CONCLUSIONS: Clinical outcomes after excimer laser PRK for myopia using an increased repetition rate of 15 Hz were good and similar to those in studies conducted with a 10 Hz repetition rate.     

Photorefractive keratectomy for pediatric anisometropia: safety and impact on refractive error, visual acuity, and stereopsis

PURPOSE: To establish the safety and possible efficacy of excimer laser photorefractive keratectomy (PRK) for treatment of pediatric anisometropia. DESIGN: Interventional case series METHODS: This is a prospective, noncomparative interventional case series at an individual university practice of photorefractive keratectomy in 11 children aged 2 and 11 years with anisometropic amblyopia who were unable or unwilling to use contact lens, glasses, and occlusion therapy to treat the amblyopia. The eye with the higher refractive error was treated with PRK using a standard adult nomogram. The refractive treatment goal was to decrease the anisometropia to 3 diopters or less. Main outcome measures were cycloplegic refraction, refractive correction, degree of corneal haze, uncorrected and best spectacle-corrected visual acuity, and stereopsis over 12 months. RESULTS: All patients tolerated the procedure well. The mean refractive target reduction was -10.10 +/- 1.39 diopters for myopia and +4.75 +/- 0.50 diopters for hyperopia. The mean achieved refractive error reduction at 12 months for myopia was -10.56 +/- 3.00 diopters and for hyperopia was +4.08 +/- 0.8 diopters. Corneal haze at 12 months was minimal. Uncorrected visual acuity improved by 2 or more lines in 6 (75%) of the eight children able to perform psychophysical acuity tests. Best spectacle-corrected visual acuity improved by 2 lines in 3 (38%) of patients. Stereopsis improved in 3 (33%) of nine patients. CONCLUSIONS: Pediatric PRK can be safely performed for anisometropia. The refractive error response in children appears to be similar to that of adults with comparable refractive errors. Visual acuity and stereopsis improved despite several children being outside the standard age of visual plasticity. Photorefractive keratectomy may play a role in the management of anisometropia in selected pediatric patients.