准分子激光散光性角膜切削术治疗复合性近视散光

目的 探讨准分子激光散光性角膜切削术（ｐｈｏｔｏａｓｔｉｇｍａｔｉｃ ｒｅｆｒａｃｔｉｖｅ ｋｅｒａｔｅｃｔｏｍｙ,ＰＡＲＫ）矫治复性近视散光的有效性、准确性和预测性。方法 采用Ｃｏｍｍｐａｋ－２００型准分子激光机,对３４例４６眼复性近视散光行角膜椭圆形切削,根据散光度大小分为２组;Ａ组（－１．７５～－２．７５Ｄ）,Ｂ组（－３．００～－５．２５Ｄ）,并随访０．５ａ以上,观察手术前后的视力、屈光度、     

One year clinical results of photoastigmatic refractive keratectomy for compound myopic astigmatism.

PURPOSE: To evaluate the efficacy, predictability, and safety of excimer laser photoastigmatic refractive keratectomy (PARK) to correct compound myopic astigmatism. SETTING: Departments of Ophthalmology, Robert Debré Hospital and Rothschild Foundation, Paris, France. METHODS: This retrospective study included 27 eyes with compound myopic astigmatism treated with a Nidek EC 5000 excimer laser. The refractive results were measured at 1 year, and the cylindrical component was analyzed by the Alpins method. Mean preoperative myopia was -4.50 diopters (D) (range -0.75 to -4.00 D) and mean preoperative cylinder, -1.64 D (range -0.75 to -4.00 D). RESULTS: At 1 year, the spherical equivalent was -0.47 D (range +1.00 to -3.00 D) and residual subjective astigmatism, -0.40 (range -0.25 to -1.50 D). Uncorrected visual acuity of 20/40 or better was obtained in 22 of the 27 eyes; 21 eyes were within +/- 1.0 D of emmetropia. Vector analysis showed a mean coefficient adjustment of 1.50 D +/- 0.53 (SD), a mean axis shift of 2.64 +/- 12.10 degrees, and a mean magnitude of error of 0.45 +/- 0.56 D. Haze was absent in 22 eyes and grade 1+ in 5 eyes. Five eyes gained 1 line of best corrected visual acuity and 3 lost 1 line. No patient lost more than 1 line. CONCLUSION: Excimer laser PARK successfully corrected low and moderate myopia combined with up to 4.0 D of astigmatism with a low mean angle of error. To increase the accuracy of toric ablation, specific algorithms for the cylinder component are needed.     

Excimer laser photorefractive keratectomy for high myopia and myopic astigmatism.

BACKGROUND AND OBJECTIVE: To determine the efficacy, safety, and predictability of excimer laser photorefractive keratectomy of high myopia and myopic astigmatism. PATIENTS AND METHODS: 76 eyes of 52 patients with myopia from -8.00 to -23.50 diopters (D) with or without astigmatism up to -5.50D were treated with the VISX 20/20 excimer laser (VISK, Santa Clara, CA) and a multi-zone ablation technique. Visual acuity, manifest refraction, corneal haze, and topography were evaluated at 1 week and 1, 3, 6, 12, and 18 months postoperatively. RESULTS: Postoperative refractions were generally stable after 12 months. At the last follow-up all patients were within - 1.96 D of the intended correction. Eighteen months postoperatively, 68% of patients undergoing photorefractive keratectomy (PRK), and 65% of patients undergoing photo astigmatic refractive keratectomy (PARK), were within 1 D of planned refraction. Furthermore, 87% of patients after PRK and 80% of patients after PARK had a visual acuity of 20/40 or better. CONCLUSIONS: High myopia with or without astigmatism was successfully treated in most of the patients using PRK. The stability of the postoperative refraction during the first 18 months seems to be good. The incidence of adverse effects was low but improvements in the future should further reduce complications, thus increasing the safety of refractive procedures.     

准分子激光再次角膜切削术治疗残余近视

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Excimer laser surgery for myopia and myopic astigmatism

Photorefractive keratectomy using the Summit Excimer Laser has been carried out on 1333 eyes with myopia or myopic astigmatism which have been followed up for six months or longer. Of those, 607 have been followed up for one year.
Of the eyes with myopia or myopic astigmatism of up to 3 dioptres spherical equivalent, at one year 85.6% had unaided vision of 6/6, 97.2% 6/9 or better, and 99.4% 6/12 or better. Of the eyes between -3.25 and -6.00 dioptres spherical equivalent, at one year 72.1% achieved 6/6 vision unaided, 88.8% 619 or better, and 94.2% 6112 or better. Of the eyes between -6.25 and -10.00 dioptres, at one year 49.6% achieved 616 vision unaided, 76.1% 619 or better and 88.0% 6/12 or better.
To achieve these figures, 28% of the patients had astigmatic keratotomy, either two or three weeks before photorefractive keratectomy, or at the same time as photorefractive keratectomy. Photorefractive keratectomy is as predictable as radial keratotomy in eyes of under 6 dioptres myopia, but is more predictable than radial keratotomy in higher myopia. Photorefractive keratectomy has the advantages of leaving an eye which is structurally sound, and without diurnal variation of focusing.     

准分子激光散光性角膜切削术治疗复合近视散光

为评价准分子激光散光性角膜切削术（ｐｈｏｔｏａｓｔｉｇｍａｔｉｃ－ｒｅｆｒａｃｔｉｖｅｋｅｒａｔｅｃｔｏｍｙ，ＰＡＲＫ）治疗复合性近视散光的效果，采用ｋｅｒ－ａｔｏｍⅠ型准分子激光机，利用准分子激光对角膜浅表层的椭圆形切削，共对５７例８２只复合近视散光眼行治疗，随访１年以上。术前近视球镜平均为－６．２３±２．５０Ｄ，散光为－１．４７±０．８２Ｄ，角膜散光为１．２１±０．４８Ｄ，最佳矫正视力为０．９７±０．１５。结果：术后视力和屈光状态在３～６个月趋于稳定，术后１年随访，近视平均为－０．５２±１．００Ｄ，散光为－０．４３±０．４３Ｄ，相比术前散光平均降低７０．７％；在术前散光≤０．７５Ｄ、１．００～１．７５Ｄ及≥２．００Ｄ三组中，其术后散光分别比术前降低６０．３％、７０．０％和７４．９％，术后角膜散光平均为０．７２±０．２７Ｄ，比术前降低４０．５％；术后裸眼视力：９０．２％达到０．５或以上，７２％达到０．８或以上。无严重手术并发症。结论：ＰＡＲＫ是矫治散光的有效安全方法，主要用于矫正由规则对称角膜散光引起的复合近视散光     

Excimer laser photorefractive keratectomy (PRK) for myopia and astigmatism

The purpose of the Committee on Ophthalmic Procedures Assessment is to evaluate on a scientific basis new and existing ophthalmic tests, devices, and procedures for their safety, efficacy, clinical effectiveness, and appropriate uses. Evaluations include examination of available literature, epidemiologic analyses when appropriate, and compilation of opinions from recognized experts and other interested parties. After appropriate review by all contributors, including legal counsel, assessments are submitted to the Academy’s Board of Trustees for consideration as official Academy policy.     

Photorefractive keratectomy for compound myopic astigmatism

PURPOSE: To evaluate the safety and efficacy of photorefractive keratectomy for the treatment of primary compound myopic astigmatism. METHODS: In a prospective study, 93 eyes from 56 patients with a mean spherical equivalent of -4.98 +/- 1.80 diopters (range, -1.75 to -8.5) underwent photoastigmatic refractive keratectomy with the Summit Apex Plus excimer laser using erodible mask technology and were followed for 2 years. Primary outcome measures included an assessment of astigmatic correction through vector analysis, manifest refraction, uncorrected visual acuity, corneal clarity, and the presence of adverse symptoms.RESULTS: Eighty-five eyes (91.4%) were available for analysis at 6 months. Mean spherical equivalent refraction was reduced 85% (mean, -0.75 +/- 0.85 diopter) and the target-induced astigmatism was reduced 70% (mean, 0.98 +/- 1.88 diopters). Forty-eight eyes (56%) had an uncorrected visual acuity of 20/20 or greater, whereas 70 eyes (82%) had an uncorrected visual acuity of 20/40 or greater. Twenty-four eyes (26% ) required re-treatment because of undercorrection of the spherical equivalent and astigmatic components after the 6-month follow-up. Fifty-nine of the remaining eyes were available at the 24-month visit. Mean spherical equivalent refraction was reduced to -0.39 +/- 0.72 diopter (91.8%). The target-induced astigmatism was reduced 64% from 1.74 diopters. Forty-one eyes (81.3%) were within +/-1.0 diopter of attempted spherical equivalent correction. Stability within a spherical equivalent of +/-0.5 diopter occurred after the first postoperative month. Fifty-six eyes (94.9%) had an uncorrected visual acuity of 20/40 or greater, whereas 34 eyes (57.6 %) demonstrated an uncorrected visual acuity of 20/20 or greater. One eye (1.7%) lost 2 or more lines of best spectacle-corrected visual acuity.CONCLUSION: Photoastigmatic refractive keratectomy with the Summit Apex Plus excimer laser is a safe and effective method of reducing compound myopic astigmatism. However, higher re-treatment rates may result from significant undercorrections because of current laser algorithms and variability in the mean angle of error.     

Correction of myopic astigmatism by combined treatment with PRK and T-incision and photoastigmatic refractive keratectomy

Background: In contrast to the correction of simple myopia there is no widely accepted technique for the correction of myopic astigmatism. Currently two techniques are available: the photoastigmatic refractive keratectomy (PARK) and the combination of arcuate keratotomies with standard PRK (PRK-T). Methods: In two groups, 67 patients underwent a correction of myopic astigmatism in a total of 87 eyes (19 by PRK-T and 68 by PARK), and were followed for 1 year. The spherical equivalent was − 6.7 D in both groups and the refractive astigmatism ranged from − 1.0 to − 6.5 D. The PARK procedure was performed by means of an elliptic ablation (Kertom I, Schwind) with a 5.8 × 8.1 mm zone. The PRK-T technique consisted of two arcuate keratotomies with a free optical zone of 7 mm and a standard myopic PRK at least 6 weeks later. Results: The 1 year follow-up was completed in 57 out of 87 eyes included in the study. At 1 year post-operation, 83 % of the PRK-T group and 80 % of the PARK group had an uncorrected visual acuity of 20/40 or better. The refractive astigmatism was reduced by 76 % in the PRK-T group and by 67 % in the PARK group. The spherical equivalent was − 0.59 ± 1.1 D at 1 year after PRK-T and − 0.28 ± 1.04 D after PARK. In three eyes of the PARK group (6.7 %) a visual loss of more than one Snellen line occured. Two of these eyes had a preoperative myopia of more than − 6 diopters. Conclusion: Both techniques have the potential to reduce myopic astigmatism, however, the success rate is not as high compared to spherical PRK. Also, the complication rate of 2.5 % in corrections to − 6 D is significantly higher than that with spherical myopic PRK.      

Excimer laser photorefactive keratectomy retreatment following photokeratectomy under-correction]

PURPOSE: Results of excimer laser photorefractive keratectomy are well accepted for the correction of low to moderate myopia. However, the occurrence of a regression is still a frequent complication. The purpose of the present study is to evaluate the interest and risk of excimer photorefractive keratectomy retreatment of eyes that underwent a regression of the refractive effect. PATIENTS AND METHODS: A retreatment was achieved in 27 eyes of 22 patients. This reshaping was required because of either an expected undercorrected initial treatment, either a regression of the refractive effect of the first photorefractive keratectomy that did not respond to the topical steroid therapy. As we used two different types of excimer laser to achieve the retreatments, we formed two subgroups. In the first sub-group, 13 eyes were retreated with an Excimed (Summit), and in the second one, that included 14 eyes, a laser EC5000 (Nidek) was used. The delay between the first procedure and the retreatment was 16.38 +/- 7.56 months in the first sub-group and 29.85 +/- 13.09 months in second one. The mean attempted correction for the reshaping was -3.01 +/- 1.25 diopters in the first sub-group and -1.63 +/- 0.80 diopters in the second one. RESULTS: No specifical problem was encountered during the retreatment. Specifically, we did not observe any decentring. By the third post-operative month, patients recovered a mean uncorrected visual acuity of nearly 7/10 in both sub-groups. This mean uncorrected visual acuity did not regressed during the follow-up. In addition, the mean post-operative refraction was 0.11 +/- 0.78 diopters in the first sub-group and -0.20 +/- 0.59 diopters in the second, three months after reshaping. The final refraction was -0.15 +/- 0.30 dioptres in the first sub-group and -0.70 +/- 0.62 dioptres in the second one. Nine eyes exerienced a regression during the follow-up period, from which three responded to the topical steroids. These regressions occurred in 4 eyes from the first sub-group and 5 of the second one. No other complication were observed. DISCUSSION: Although there is a aggreement about the efficacy of excimer laser in the treatment of low or moderate myopia, regressions of the refractive effect is not unfrequent. It can warrant a reshapping. Our results demonstrate the simplicity and the predictive value of excimer laser in the retreatment of these regressions after photorefractive keratectomy. This method seems more accurate than radial keratotomy. CONCLUSION: Excimer laser retreatment is highly effective in the correction of undercorrection after a previous procedure of photorefractive keratectomy, especially when the attempted correction of the initial treatment was under -6 diopters.     

Wavefront-guided photorefractive keratectomy for myopia and myopic astigmatism

PURPOSE: To evaluate the results of wavefront-supported customized ablation (WASCA) in eyes treated with photorefractive keratectomy (PRK) to correct spherical myopia and myopic astigmatism. METHODS: One-hundred fifty eyes of 104 patients (mean age 33.4 +/- 4.4 years) were included in the study. An Asclepion Shack-Hartmann wavefront aberrometer was used to assess lower and higher order refractive aberrations of eyes, and customized PRK treatments were carried out using the Asclepion-Meditec MEL 70 G-Scan excimer laser. Follow-up time was 6 months. RESULTS: The mean preoperative spherical equivalent refraction was -4.02 +/- -1.04 D, and mean uncorrected visual acuity (UCVA) was 0.06 +/- 0.02. Postoperatively, mean UCVA was 1.04 (better than 20/20), mean best spectacle-corrected visual acuity was 1.22 (20/16), and average spherical equivalent refraction was -0.12 D; 98.6% (148 of 150 eyes) were within +/-0.50 D of intended refraction, and 100% were within +/-1.00 D. Concerning safety, in 71.1% of eyes (107 of 150) BSCVA was the same as preoperatively, and in 8.2% (11 of 150) it increased by two or more Snellen lines. None of the eyes lost two or more lines of BSCVA. The root mean square value for higher order aberrations increased 1.4 times following PRK. CONCLUSIONS: WASCA-guided PRK was efficacious, safe and predictable; BSCVA may be improved by the WASCA method compared to results achievable with a traditional PRK technique, in spite of an increase in the root mean square value for higher-order aberrations.     

Excimer laser keratectomy for correction of astigmatism

We treated 13 eyes (12 patients) with excimer laser surgery for correction of astigmatism using linear corneal T-excisions. All eyes were followed up for a minimum of three months. We used a newly developed delivery system and special contact masks to deliver the 193-nm excimer light. Astigmatic corrections of up to 4.16 diopters were obtained. The actual corrections corresponded well with the intended values as predicted by a biomechanical theory. The refractive change over time was different than that observed after knife incisions, suggesting different repair mechanisms. An epithelial plug filling the whole T-excision persisted for over one year in all eyes.     

准分子激光角膜切削术治疗近视和近视散光的临床研究

目的 评价准分子激光角膜切削术矫正近视的结果。方法 我院自１９９６年９月到１９９７年１０月,应用ＳＶＳＡＰＥＸ型（Ｓｕｍｍｉｔ Ｔｅｃｈｎｏｌｏｇｙ Ｉｎｃ．ＵＳＡ）准分子激光治疗仪,对１６８例近视患者（３１６只眼）行ＰＲＫ手术,对其中的１５０例（２６０只眼,占８４％）患者随诊至少３ｍｏ以上,最长１ａ;男６８例（１１６只眼,占４０．１％）,女８２例（１４４只眼,占５９．９％）。１５０例（２６０只眼     

准分子激光角膜切削术治疗角膜表面镜片术后散光

评价准分子激光角膜切削术治疗角膜表面镜片术后散光的效果。采用Ｃｏｈｅｒｅｎｔ产ＳＣＨＷＩＮＤＫＥＲＡＴＯＭ准分子激光治疗系统对８例１２只眼角膜表面镜片术后散光进行治疗，均为圆锥角膜术后病例，术前柱镜屈光度为－１．７５—－１０．００Ｄ，平均－５．４９Ｄ±３．２１Ｄ。术后随访６—１５月，平均１１．８月，显示裸眼视力均明显提高，矫正视力与术前相比提高者７只眼（５８．３３％）。柱镜平均屈光度由－５．４９Ｄ下降至－２．７７Ｄ，均无明显术后痛疼，术后角膜雾状混浊均不显著。说明准分子激光角膜切削术可有效地治疗角膜表面镜片术后的角膜散光，能显著地提高角膜表面镜片术治疗圆锥角膜的最终效果。     

准分子激光光学性柱镜矫治术治疗单纯性近视散光临床疗效分析

目的　评价准分子激光光学性柱镜矫治术 (photoastigm atic refractive keratectom y,PARK)治疗单纯近视性散光的疗效。方法　 7例 (9眼 )平均单纯近视性散光度为 - 2 .6 9± 1.0 4D,角膜散光 2 .5 0± 0 .72 D。实施PARK后随访 12～ 2 4个月。对术后视力、角膜表面形态及角膜散光的改变进行临床分析。结果　 9眼单纯近视性散光术后裸眼视力为 1.0 7± 0 .14,角膜散乐 1.16± 0 .0 9D。无角膜 Haze、“眩光”和上皮的并发症。结论　 PARK治疗单纯近视性散光安全、临床疗效好。     

准分子激光角膜切削术治疗近视及近视散光远期疗效观察

目的:评价准分子激光角膜切削术治疗近视、近视散光的远期疗效,分析术后远期视力回退的相关因素。方法:测量、比较79例(137眼)不同程度的近视及近视散光患者PRK术后1和7a的视力、屈光度、角膜屈光力、角膜厚度、角膜Haze变化,并对术后视力回退的影响因素进行分析及回归分析。结果:术后7a视力、屈光度与术后1a比较差异均有显著意义(P <0.05);术后不同时期屈光度低组与高组比较视力及屈光度差异均有非常显著意义(P <0.01)。角膜厚度术后7a较术后1a差异有非常显著意义(P <0.01),角膜屈光力差异无显著意义(P >0.05)。术后裸眼视力回退(Y)与术后等效球镜屈光度变化(X)呈正相关(r =0.49,P <0.01),与术前球镜屈光度呈负相关(r =-0.20,P <0.05),建立多元逐步回归方程为:Y =0.08 0.12X。结论:PRK术后远期视力及屈光度均有轻度回退,以高度近视眼明显,影响术后远期视力回退的主要因素是术后屈光度的变化。     

Photorefractive keratectomy for compound myopic astigmatism with the MEL-70 G-Scan excimer laser

PURPOSE: To assess the safety, efficacy, predictability and stability of photorefractive keratectomy in compound myopic astigmatism with a moderate and high cylinder component. METHODS: Photorefractive keratectomy was done in 42 eyes with compound myopic astigmatism with the spherocylindrical algorithm of the MEL-70 excimer laser, with wide ablation zones. RESULTS: Spherical equivalent refraction changed from -4.19 +/- 1.65D to -0.05 +/- 0.31D, refractive cylinder from -2.01 +/- 0.71D to -0.09 +/- 0.20D and mean sphere from -3.22 +/- 1.76D to -0.02 +/- 0.26D. Mean uncorrected visual acuity rose from 0.12 +/- 0.17 to 0.91 +/- 0.10. No eye lost lines of spectacle-corrected visual acuity. The safety index was 1.03 and the efficacy index 0.98. Six months from the treatment all eyes were within +/- 1D, 8.9% of eyes were within 0.50D and 44% were plano of target refraction. Refractive and topographical stability were achieved between one and three months after treatment. Transient haze was observed between one and three months after PRK. CONCLUSIONS: Photorefractive keratectomy with the MEL-70 excimer laser to correct myopic astigmatism was a safe and effective procedure with good stability at six months' follow-up. Refractive and visual outcome confirmed that excellent predictability can be expected.     

Customized photoastigmatic refractive keratectomy using combined topographic and refractive data for myopia and astigmatism in eyes with forme fruste and mild keratoconus

PURPOSE: To examine the outcomes of photoastigmatic refractive keratectomy using corneal and refractive parameters for myopia and astigmatism in eyes with forme fruste and mild keratoconus. SETTING: Private practice, Melbourne, Australia. METHODS: Photoastigmatic refractive keratectomy was performed with a Star 1 or Star 2 laser (Visx) in 45 eyes with forme fruste or mild keratoconus using the Alpins vector planning technique. Inclusion requirements were best corrected visual acuity (BCVA) 20/40 or better, no slitlamp signs of keratoconus, mean keratometry less than 50.00 diopters (D), and corneal and refractive stability for at least 2 years. RESULTS: Thirty-two eyes had follow-up of 5 years and 9 eyes, of 10 years. Preoperatively, the mean refractive astigmatism was -1.39 DC +/- 1.08 (SD) (range 0.45 to -5.04 DC) and the mean corneal astigmatism was 1.52 +/- 1.18 D (range 0.35 to 4.75 D) by manual keratometry and 1.70 +/- 1.42 D (range 0.32 to 5.32 D) by topography. Twelve months postoperatively, the mean refractive astigmatism was -0.43 +/- 0.40 D and the mean corneal astigmatism was 1.05 +/- 0.85 D by keratometry and 1.02 +/- 0.83 D by topography. At 12 months, the uncorrected visual acuity was 20/20 or better in 56% of eyes and 20/40 or better in all eyes. The BCVA was 20/20 or better in 89% of eyes and 20/30 or better in all eyes. Seven eyes had a loss of BCVA, and 16 eyes had a gain. There were no cases of keratoconus progression. CONCLUSIONS: Photoastigmatic refractive keratectomy in eyes with forme fruste and mild keratoconus was safe and effective for myopia and astigmatism in carefully selected patients with refractive and corneal stability. The incorporation of the corneal astigmatism data into the applied treatment parameters may improve visual and total astigmatism results.