Results of photorefractive keratectomy for hyperopia using the VISX star excimer laser system

PURPOSE: To evaluate safety, efficacy, and predictability of photorefractive keratectomy (PRK) for hyperopic astigmatism of +1.75 to 00 D manifest refractive sphere and up to -2.50 D manifest refractive astigmatism using the VISX Star excimer laser system, version 2.5 software. METHODS: Treatment was performed on 32 eyes of 21 patients. Eighteen of 21 patients were 45 years of age or older. Manifest and cycloplegic refraction together with Pelli-Robson contrast sensitivity assessment was performed prior to surgery and 1, 3, 6, 12, and 24 months after treatment. RESULTS: Twenty-seven of 32 surgical procedures were reviewed 1 year after treatment (84%). Corneal epithelial healing was complete between day 4 and 10. Twelve months after treatment, 25 of 27 eyes (93%) achieved 20/40 or better uncorrected visual acuity and 19 eyes (70%) achieved 20/20. No patient lost two or more lines of Snellen visual acuity assessed 6 months and later after treatment. The mean spherical equivalent refraction was reduced from +2.90 at baseline to +0.10 D at 1 year and +0.40 D at 2 years; 65% of eyes had a refraction within +/- 0.50 D. Four patients had further treatment by laser in situ keratomileusis for undercorrection in three eyes and overcorrection in one eye. Pelli-Robson contrast acuity was significantly reduced 12 months after treatment from a mean 1.72 before to 1.66 after PRK (P = .02, t-test). CONCLUSIONS: PRK for hyperopia using the VISX Star excimer laser system was effective in the treatment of hyperopic astigmatism. Although no patient lost two or more lines of high contrast best spectacle-corrected Snellen visual acuity 1 year after treatment, there was a significant decrease in Pelli-Robson contrast acuity.     

准分子激光角膜切削术矫正近视的临床研究

本文报道193nm准分子激光角膜切削术（PRK）矫正139例近视、屈光度为-2．25～－9．00D的257只眼的疗效，随访6个月至1年。术后1年随访时，低中度组（≥－6．00D）81．25％的屈光度在±1．00D以内；高度组（＞－6．00D）则为69．57％。术后裸眼视力≥0．5和≥1．0者，低中度组为97．5％和77．5％；高度组为100％和73．3％。术后无3级及其以上的、具有临床意义的角膜上皮下混浊。看来，PRK为目前矫正近视的一种安全有效的术式。     

Contrast sensitivity after excimer laser photorefractive keratectomy for myopia

AIM: To evaluate contrast sensitivity in patients who had undergone uncomplicated excimer laser photorefractive keratectomy (PRK) for myopia. · METHODS: Monocular contrast sensitivity function was measured with the CSV-I000E chart in 41 patients who had received PRK by the Nidek EC-5000 excimer laser system. Mean preoperative refractive error was -2.62±1.33 D (range, -0.75 to -4.00 D). Contrast sensitivity function was measured preoperatively, 1week, 1, 3 and 6 months after surgery through the CSV-1000E contrast sensitivity unit (VectorVision). · RESULTS: Logarithmic values of contrast sensitivity at each spatial frequency were used for statistical analysis and normalized values were used for graphical representation. Contrast sensitivity decreased 1 week and 1 month postoperatively. Starting from the first month, there was rapid recovery of contrast sensitivity especially at low spatial frequencies, and at the third month, only at 6 and 12 cycles per degree (cpd) statistically significant decrease was seen. Six months after surgery, there was an increase in contrast sensitivity values at all spatial frequencies. · CONCLUSION: Photorefractive keratectomy can induce significant reductions in contrast sensitivity in the first month after surgery; these values returned to the preopereative values at 6 months after surgery.     

近视眼准分子激光角膜切削术后的对比敏感度评价

目的:评价近视患者PRK术后的对比敏感度变化.方法:应用CSV-1000E图表对41例接受Nidek EC-5000型准分子激光仪行PRK手术的患者,行单眼对比敏感度测量.患者术前平均屈光度为-2.62±1.33D(范围从-0.75至-4.00D).应用CSV-1000E对比敏感度仪分别在术前,术后1wk;1,3,6mo行对比敏感度检查.结果:将每个空间频率的对比敏感度对数值进行统计学分析,并应用图表与正常值进行比较.结果显示对比敏感度在术后1wk及术后1 mo时明显降低,从第1 mo开始,对比敏感度尤其是低空间频率的对比敏感度快速恢复,在第3mo,只有6和12cpd两种空间频率的对比敏感度明显降低,在术后6mo时,所有频率的对比敏感度功能都明显增加.结论:PRK术后患者第1 mo对比敏感度功能明显降低,但在术后6mo时对比敏感度功能即恢复至术前水平.     

多光区准分子激光角膜切削术治疗高度近视眼

目的研究多光区准分子激光角膜切削术（multizonephotorefractivekeratectomy,PRK－MZ）治疗高度近视眼的疗效。方法229眼高度近视（－6．25～－9．00D）经PRK－MZ治疗后随访1a，观察视力、屈光稳定性和角膜Haze，用角膜地形图对PRK－MZ术后角膜形态及平均角膜屈光力（ACP）进行研究。结果PRK-MZ治疗1a后．197（86.03％）眼裸眼视力≥0．8，37（16．16％）眼屈光回退≥－1．00D，角膜Haze0．5～1级者5眼（2．18％），ACP值在PRK－MZ治疗后1mo、6mo及1a时较术前显著下降（P＜0.01），术后1a时ACP值较术后1mo和6mo时增加（P＜0．05）；角膜表面规则指数（SAI）在PRK-MZ术后无明显变化．角膜表面不规则指数（IAI）亦无变化。结论PRK-MZ治疗－6．25～－9．00D范围的高度近视仍有较好疗效，不影响角膜表面形态，但屈光稳定性降低，角膜Haze在随访1a中逐渐减退或消失。     

准分子激光角膜切削术治疗高度近视的并发症

评价准分子激光角膜切削术治疗高度近视的手术并发症。对PRK治疗的104例136眼高度近视散光术后12－18月随访，对手术并发症进行统计分析。近视回退90眼占66％；角膜上皮下混浊95眼占69.8％；低矫21眼占15.4％；最佳矫正视力下降2行以上14眼占11．1％。本组病例近视回退，角膜上皮下混浊和低矫的发生与试图矫正的屈光度有关，并发症的发生率远高于中低度近视。     

准分子激光角膜切削术治疗高度近视远期疗效分析

目的:评价准分子激光角膜切削术(photorefractive keratectomy, PRK)治疗高度近视的远期疗效.方法:将104例183眼屈光度>-6.00D患者分两组,Ⅰ组-6.25～-10.00D,Ⅱ组≥-10.25D,对PRK术后3年患者的视力、屈光度、角膜上皮下基质混浊进行随访分析.结果:3年时Ⅰ组裸眼视力达到术前最佳矫正视力的为73.3%(96眼),Ⅱ组为38.5%(20眼);屈光度在预期矫正度±1.00D以内者,Ⅰ组为76.3%(100眼),Ⅱ组为42.3%(22眼);角膜上皮下基质混浊,3年时0～0.5级的Ⅰ组为100%,Ⅱ组为90.4%.结论:PRK治疗-6.25～-10.00D的高度近视远期疗效较好,大于-10.00D的远期疗效不理想.     

准分子激光屈光性角膜切削术治疗重度近视

目的 探讨准分子激光屈光性角膜切削术（ＰＲＫ）治疗重度近视的疗效。方法 使用Ｃｈｉｒｏｎ Ｖｉｓｉｏｎ的Ｋｅｒａｃｏｒ１１６准分子激光机,采用多光区切削方法治疗重度近视４９例８９眼,屈光度范围：－１０．００～－２５．００Ｄ。术后随访１ａ,并对结果进行分析。结果 ８９眼重度近视ＰＲＫ术后１ａ时,裸眼视力≥１．０者１２眼,占３．４９％,０．５～０。８者１７眼,占１９．１０％,≤０．４者６０眼,占７６７     

准分子激光治疗近视眼疗效观察

目的了解准分子激光屈光性角膜切削术（ＰＲＫ）治疗近视眼的临床效果。方法对有１ａ随访资料的５６９人１０８２只眼ＰＲＫ治疗进行分析和总结。结果术后１ａ时，第１组（＜－６．００Ｄ），第２组（－６．２５～－９．００Ｄ）和第３组（＞－９．２５Ｄ）裸眼视力在１．０及１．０以上分别为７５．３４％、６１．３８％和１１．３９％，裸眼视力达到０．５以上３组病人的比例分别是９２．２４％、８６．２１％和４１．７７％；３组病人术后屈光度在±１．００Ｄ范围内的比例分别是８２．６５％、７４．４８％和１５．２％。没有严重并发症发生。结论ＰＲＫ手术是一种安全、疗效稳定的近视眼治疗方法     

Changes in corneal topography after excimer laser photorefractive keratectomy for myopia

Computer-assisted analysis of corneal topography was performed in 17 normally sighted human eyes during the first year after excimer laser photorefractive keratectomy (PRK) for myopia. Laser ablation of the central cornea produced an optical zone with a smooth power transition to the peripheral cornea. Decentration of the ablation was noted in some eyes (less than 0.5 mm in 3 eyes, 0.5 to 1.0 mm in 10 eyes, 1 to 1.5 mm in 3 eyes, and 2.1 mm in 1 eye), suggesting that careful alignment of the laser beam is critical. Improved methods to align the ablation within the center of the entrance pupil are needed. In 12 of 17 eyes, the topographic pattern appeared to stabilize between 3 and 7 months after PRK. In the remaining five eyes, central ablation power changed by more than 0.5 diopters (D) between the 6- and 12-month examinations. Regression was more common and more pronounced in eyes with intended corrections more than 5 D, whereas the majority of eyes with intended corrections of 5 D or less showed good correspondence between the final change in central ablation power and the attempted correction. Two eyes had a loss of at least two lines of best spectacle-corrected visual acuity that was attributable to irregular astigmatism, decentration of the ablation, and/or corneal opacification.     

Early corneal topography patterns after excimer laser photorefractive keratectomy for myopia

OBJECTIVES: We defined early patterns of corneal topography following excimer laser photorefractive keratectomy (PRK) with a Summit Apex laser without pretreatment software, investigated changes in patterns over time, and identified factors associated with different topography patterns. METHODS: Fifty-eight eyes of 39 myopic patients were studied. EyeSys videokeratography data were analyzed at 1 week and 1, 2, and 3 months after surgery and were classified using a standardized classification system. RESULTS: At 1 week, 4.3% (n = 2) of corneas showed a homogeneous topography, 0.0% showed a toric-with-axis configuration, 2.2% (n = 1) showed a toric-against-axis configuration, 8.7% (n = 4) showed an irregularly irregular topography, 17.4% (n = 8) showed a keyhole pattern, 23.9% (n = 11) showed a semicircular pattern, 41.3% (n = 19) showed a central island pattern, and 2.2% (n = 1) showed focal topographic variants. From 1 week to 1 month, 78.9% of maps changed; from 1 to 2 months, 33.3% of maps changed; and from 2 to 3 months, 40.0% of maps changed, generally to more regular patterns. The central island pattern, which predominated at 1 week, was not seen at 3 months; most had changed to the keyhole or semicircular pattern. An association was found between the central island pattern and irregularity of reflected rings on the video-image of the cornea (P = .05). CONCLUSIONS: The central island pattern is an early and usually transient topography pattern following PRK. Keyhole and semicircular patterns taken together were the most prevalent in the early postoperative period. In some cases, central islands may be a consequence of corneal epithelial irregularity, and the meridional orientation of the keyhole and semicircular patterns suggests an influence of epithelial healing over time.     

PRK治疗近视远期疗效分析

目的　评价PRK治疗近视及散光的远期疗效。方法　 1995年 11月～ 1997年 5月PRK手术 3 46例 (619眼 ) ,按术前等值球镜度分为 3组 ,A组 :-1.0 0D～ -6.0 0D ,3 40眼 ;B组 :-6.2 5D～ -10 .0 0D ,189眼 ;C组 :-10 .2 5D～ -2 4.0 0D ,90眼。术后随访 5年。结果　术后 5年屈光度在预定矫正度± 1.0 0D以内者 ,A、B、C组依次为 93 .2 % ;82 .5 % ;2 7.8%。裸眼视力≥0 .5者 ,3组依次为 94 1% ;78 8% ;3 5 6%。最佳矫正视力达到或超过术前最佳矫正视力得依次为 99 1% ;95 2 % ;92 2 %。有3级以上角膜上皮下雾状浑浊 (haze)者依次为 0 .5 9% ;1.0 6% ;6 67%。结论　PRK是治疗近视安全有效的方法 ,其预测性及稳定性与近视度呈负相关     

準分子激光屈光性角膜切削術治療近視、散光術后3年療效分析

目的爲了評價準分子激光屈光性角膜切削術治療近視、近視散光的遠期療效.方法應用美國VISX20/20型準分子激光儀,治療132例(259眼),采用多切削區治療屈光度-1.5D～-16.0D的近視觀察3年以上,按術前球鏡屈光度分爲二組Ⅰ組-1.5D～-6.0D(196眼),Ⅱ組-6.25D～-16.0D(73眼).結果術后3年裸眼視力≥0.5,在Ⅰ、Ⅱ中組中分别爲94.6%、89.3%;術后3年裸眼視力≥1.0,在Ⅰ、Ⅱ組中分别爲90.7%、70.5%,角膜HazeⅠ組0級90.3%,0.5級9.7%,無1級以上Haze;Ⅱ組0級63.0%,0.5級34.2%,1級2.8%,無2級以上Haze.結論準分子激光屈光性角膜切削術對低、中、高度近視、近視散光均取得良好的遠期效果,但對低、中度近視效果更佳,對高度近視預測性較差.     

伴眼球震颤的近视准分子激光屈光手术的观察

目的　探讨对伴有先天性眼球震颤的近视施行准分子激光角膜屈光手术的方法及疗效。方法　对16例(3 2眼)以水平震颤为主的先天性运动性眼球震颤的近视(矫正视力>0 .5 )施行准分子激光PRK13例(2 6眼) ,LASIK 3例(6眼) ,术中采用2 %利多卡因球周麻醉。术后随访时间6月。结果　视力:PRK 2 4眼、LASIK 5眼共2 9眼术后裸眼视力达到术前最佳矫正视力。屈光度:PRK 2 6眼术前平均为(-4 .86±0 .5 5 )D ,术后6月平均为( 0 . 5 2±0 . 46)D ;LASIK 6眼术前平均为(-6 . 72±0 . 76)D ,术后6月平均为(-0 .75±0 .87)D。结论　对矫正视力较好的伴有先天性眼球震颤的近视施行准分子角膜屈光手术和普通的近视一样可获得良好的临床效果。     

Topography-controlled excimer laser photorefractive keratectomy

PURPOSE: To assess whether photorefractive keratectomy (PRK) controlled by videokeratography can successfully treat refractive errors in eyes with corneal irregularities and improve spectacle-corrected visual acuity. METHODS: In a prospective clinical study, PRK was performed in 10 eyes of 10 patients. Reason for surgery was irregular astigmatism after penetrating keratoplasty, corneal irregularity after corneal scarring, corneal astigmatism in keratoconus, and decentration after myopic and hyperopic PRK. Excimer ablation was controlled by preoperative videokeratography (Orbscan II, Orbtek) using the MEL-70 system from Aesculap Meditec. Follow-up was 6 months. RESULTS: Concerning manifest refraction, the sphere was reduced on average from +1.92 to +0.57 D, 6 months postoperatively. Cylinder changed from -1.95 D on average to -0.30 D at 6 months postoperatively. There was improvement of uncorrected visual acuity of 2 or more lines in 5 eyes and no change in 5 eyes 6 months postoperatively. Spectacle-corrected visual acuity improved in 2 eyes by 2 to 3 lines, in 9 eyes by 1 to 3 lines, and showed no change in 1 eye. CONCLUSION: Videokeratography-controlled PRK improved refractive errors in irregular corneas with improvement of spectacle-corrected visual acuity.     

Glare sensitivity and visual acuity after excimer laser photorefractive keratectomy for myopia

BACKGROUND—Following excimer laser photorefractive keratectomy (PRK), an increase in glare sensitivity and a reduction in contrast sensitivity can occur owing to changes in the cornea (structure and topography). In this study, an attempt was made to quantify and document objectively a change in those subjective perceptual factors.
METHODS—Snellen visual acuity and disability glare were measured with the Berkeley glare test preoperatively as well as 1, 3, 6, 9, and 12 months postoperatively, after excimer laser photorefractive keratectomy (PRK) on 32 myopic patients (46 eyes). During the postoperative progress checks, haze was graded and contrast sensitivity was measured with the Vistech chart. All the data were statistically analysed by multiple regression.
RESULTS—One year after PRK, a reduction in visual acuity (VA) measured with the low acuity contrast chart (10%) with and without glare could still be found, despite the fact that acuity measurements with a high contrast Snellen chart showed the same VA 6 months postoperatively as well as before the treatment. The lowest VA could be measured 1 month postoperatively; thereafter, the acuity increased despite the increase in haze that occurred during the first 3 months.
CONCLUSION—Disability glare and a reduction in contrast sensitivity could be observed in most patients after PRK treatment with the Meditec laser system with its scanning slit. The future will show if new technology and a broader flattening area of 6 to 7 mm can minimise these postoperative complications.

     

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     

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.     

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。     

准分子激光屈光性角膜切削术治疗近视和近视散光一年临床观察

采用ＶＩＳ×２０／２０型准分子激光仪对１６９例（２８１眼）近视患者进行屈光性角膜切削术（ＰＲＫ）。术前等值球镜屈光度为－１．７５—１６．００Ｄ（－８．１９Ｄ±１．５２Ｄ）。分为两组：Ⅰ组：－１．７５—－６．００Ｄ，１５３眼：Ⅱ组：－６．２５—－１６．００Ｄ，１２８眼。随防一年以上。术后１年实际矫正屈光度在预测矫正度±１．００Ｄ者在Ⅰ、Ⅱ组分别为８７．６％，５４．７％，裸眼视力≥０．５，１．０者在Ⅰ组分别为９７．４％，７４．５％，Ⅱ组分别为８６．７％，３５．９％。并发症主要有角膜上皮下雾状混浊（Ｈａｚｅ），其中Ⅱ组有９．５％的术眼发生了２—３级的Ｈａｚｅ。全组１．９％术眼发生了激素性高眼压