准分子激光治疗性切削联合屈光性切削治疗伴有角膜混浊的近视眼

目的　了解准分子激光治疗性切削 (PTK)联合屈光性切削 (PRK)治疗伴有角膜混浊近视眼的方法及疗效。方法　激光加刮除去除角膜上皮 ,PTK切削混浊角膜 ,直径为 7 0mm。PRK作近视切削 ,直径为 6 0mm。对于角膜不平者术中用黏弹剂填平后再行上皮去除及PTK。PTK切削深度为影响视力的角膜混浊深度减去PRK及上皮切削厚度。结果　 5 4例 (79只眼 )伴有角膜混浊的近视眼治疗后随访 1年以上 ,术前平均屈光度数为 (- 6 73± 4 17)D ,平均最佳矫正视力为 0 6 3,角膜混浊原因包括感染、机械外伤、化学烧伤、热烧伤、手术后瘢痕及其他原因。术中PTK联合PRK平均切削深度为 (12 4 6 3± 5 3 31) μm。术后 5 0只眼 (6 3 3% )切削区角膜上皮下雾状混浊 (Haze)≤Ⅰ级 ,6 9只眼(89 9% )裸眼视力等于或超过术前最佳矫正视力 ,平均为 0 74。角膜表面较术前光滑 ,散光减轻。结论　PTK联合PRK是治疗伴有角膜混浊近视眼的一种安全有效的方法。     

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.     

激光屈光性角膜切削术联合丝裂霉素C矫治近视的临床观察

目的评价准分子激光屈光性角膜切削术（PRK）术中预防性使用丝裂霉素C（MMC）矫治角膜较薄的近视的作用。方法角膜较薄的近视（-2．00D--0．00D）128例（243眼）采用PRK＋MMC治疗。术后随访6个月。结果128例（243眼）均未出现2级或2级以上角膜上皮下雾状浑浊（haze）,术后1周裸眼视力≥0．8者206眼（84．77％）,术后6个月裸眼视力≥0．8者216眼（88．89％）,术后6个月裸眼视力达到或超过术前最佳矫正视力233眼（95．88％）。术后6个月与术后1周屈光状态相比无回退。使用MMC未见明显毒副作用。结论角膜较薄的近视治疗采用PRK＋MMC,在术后减少haze、预防屈光回退及改善视力方面安全有效。     

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.     

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.     

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.     

准分子激光角膜原位磨镶术矫治高度近视准分子激光屈光性角膜切削术后屈光回退的临床观察

目的评价准分子激光角膜原位磨镶术（LASIK）矫治高度近视准分子激光屈光性角膜切削术（PRK）后屈光回退的疗效。方法回顾性临床研究。对PRK术后2年以上、屈光回退且屈光度稳定的患者8例14眼行LASIK,对LASIK术后术眼进行评价。患眼PRK术前屈光度为-6.25～-12.50 D,PRK术后屈光度为-1.50～-6.25 D。随访观察LASIK矫正1年后术眼的裸眼视力、最佳矫正视力、屈光度、上皮下雾状混浊（haze）形成和角膜厚度的变化。结果所有患眼术后主观症状较轻。LASIK术后1年平均球镜度数为（-0.62±0.94）D。LASIK术后0.5≤裸眼视力〈0.8者4眼,≥0.8者9眼,1眼（7.1%）最佳矫正视力下降2行。4眼术后出现不同程度的haze,包括2级haze 3眼、3级haze 1眼。应用氟米龙滴眼液1个月后,haze及屈光回退减轻;术后1年,1级haze 2眼,2级haze 2眼,3级haze 1眼。LASIK术前角膜厚度为（467±38）μm,术后为（422±21）μm。结论高度近视PRK术后屈光回退行LASIK矫治是一种可行的方法,但少数患者术后可出现haze,仍需治疗。     

Photorefractive keratectomy in children

PURPOSE: To evaluate photorefractive keratectomy (PRK) in pediatric patients who fail traditional methods of treatment for myopic anisometropic amblyopia and high myopia. SETTING: Nonhospital surgical facility with follow-up in a hospital clinic setting. METHODS: Photorefractive keratectomy was performed in 40 eyes of 27 patients. The patients were divided into 4 groups based on the type of myopia: myopic anisometropic amblyopia (15 eyes/13 patients), bilateral high myopia (20 eyes/10 patients), high myopia post-penetrating keratoplasty (3 eyes/2 patients), and combined corneal scarring and anisometropic amblyopia (2 eyes/2 patients). All procedures were performed under general anesthesia using the VISX 20/20 B laser and a multizone, multipass ablation technique. Appropriate corneal fixation was achieved with appropriate head positioning (turn and tilt) and an Arrowsmith fixation ring. Myopia was as high as -25.00 diopter (D) spherical equivalent (SE), but no treatment was for more than -17.50 D SE. RESULTS: The mean SE decreased from -10.68 D to -1.37 D at 1 year, a mean change of -9.31 D. At 1 year, the mean best corrected visual acuity improved from 20/70 to 20/40 in the entire group. Forty percent of eyes were within +/-1.0 D of the targeted refraction. There was no haze in 59.5% of eyes. Three eyes initially had 3+ haze; 1 improved to 2+ and 2 required repeat PRK with significant haze reduction. Five eyes (3 patients) with greater than -17.00 D SE myopia before PRK (range -17.50 to -25.00 D) had 3.42 D more effect than predicted (range 0.50 to 5.50 D). A functional vision survey demonstrated a positive effect on the children's ability to function in their environments after the laser treatment. CONCLUSION: Photorefractive keratectomy in children represents another method of providing long-term resolution of bilateral high myopia and myopic anisometropic amblyopia.     

近视眼PRK后角膜上皮延迟愈合及其对视力的影响

目的：了解ＰＲＫ后角膜上皮延迟愈合发生的原因及其对视力、角膜上皮下混浊（ｈａｚｅ）等的影响。方法：统计对比分析角膜上皮去除方法，炎症，屈光度等对上皮延迟愈合的影响，延迟组与非延迟组的视力及发生ｈａｚｅ的差别。结果：１７０５眼ＰＲＫ后２７４眼（１６．１％）发生延迟愈合，最长达６天。炎症是影响愈合的最主要因素（５７．３％）其次为上皮机械刮除范围过大等；近视屈光度高低无明显影响。术后半年，延迟组视力较非     

Long-term outcomes of photorefractive keratectomy in eyes with previous epikeratophakia for keratoconus

PURPOSE: To determine the long-term safety and effectiveness of photorefractive keratectomy (PRK) in the treatment of refractive errors after epikeratophakia (EP) for keratoconus. METHODS: Ten patients (14 eyes) who had refractive errors after EP for keratoconus received PRK surgery. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refractive error, corneal astigmatism, pachymetry, corneal topography, and complications were monitored. RESULTS: Mean follow-up after PRK was 63.4 +/- 19.8 months. Mean spherical equivalent was -5.5 +/- 3.9 D before PRK, -0.9 +/- 0.5 D at 1 month after PRK, and -1.5 +/- 1.0 D at 3 years. Mean astigmatism was 4.2 +/- 2.1 D before PRK, 1.2 +/- 0.5 D at 1 month after PRK, and 1.5 +/- 0.6 D at 3 years. Thirteen (93%) eyes had an UCVA <20/40, and 12 (86%) had a BSCVA of 20/40 or better before PRK. At 1 year, the UCVA was 20/40 or better in 8 (57%) eyes, and the BSCVA was 20/40 or better in all eyes. Mean central corneal thickness was 749 +/- 35 microm before PRK and 621 +/- 56 mum at 3 years. During the follow-up period, haze (grade no more than 1.0) was observed in 2 eyes. No immune rejection episode or recurrent keratoconus was found. CONCLUSIONS: PRK appears to be reliable and safe for the correction of residual ametropia after EP for keratoconus, and the visual acuity can remain stable after PRK for a long time.     

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     

PRK+MMC与LASEK治疗高度近视效果比较

目的比较PRK术中预防性使用丝裂霉素C（MMC）治疗高度近视和LASEK治疗高度近视的疗效.方法将高度近视（-6.0～-10.0D）随机分为PRK＋MMC组40例（80眼）和LASEK组38例（76眼）.另以早年PRK手术屈光状态与之相似的40例（80眼）作为对照.PRK＋MMC组在PRK术中使用0.02%MMC,LASEK组采用常规LASEK,评价术后角膜上皮下雾状浑浊（haze）,屈光回退、视力及角膜内皮细胞改变等情况.结果PRK＋MMC组未出现2级或2级以上haze,无术后矫正视力下降者,术后欠矫小于-0.5D者70眼;LASEK组有6眼出现2级及2级以上haze,有6眼出现术后矫正视力下降,术后欠矫小于-0.5D者56眼.两组的差异有显著性.使用MMC未见明显毒副作用.结论PRK术中预防性使用MMC,在术后减少haze、防止屈光回退、改善视力方面较LASEK为优.     

准分子激光上皮下角膜磨镶术治疗中高度近视的效果分析

目的探讨准分子激光上皮下角膜磨镶术（LASEK）治疗中高度近视的疗效。方法40例（79眼）行LASEK,屈光度-3．50D～-15．00D,平均-8．50D;随访6个月,观察早期眼部症状、视力、眼压、屈光状态、雾状角膜浑浊（haze）程度及屈光回退等情况。结果LASEK术后早期眼部刺激症状较重;术后角膜上皮愈合时间为3～7d,平均为5d;术后2周裸眼视力（UCVA）〉0．5者71眼（89．87％）,术后6个月UCVA等于或优于术前最佳矫正视力（BCVA）者74眼（93．67％）;术后6个月发生（haze）：0级76眼（96．20％）;0．5级2眼（2．53％）;2级1眼（1．27％）;无1级及2级以上haze。结论LASEK治疗中高度近视有一定的疗效,但手术后早期跟部刺激症状重,视力恢复慢,haze和屈光回退有待观察与研究。     

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

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

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.     

准分子激光原位角膜磨镶技术分步多区切削治疗高度近视的疗效分析

目的:探讨准分子激光原位角膜磨镶技术(laser in situker-atomileusis,LASIK)治疗高度近视的疗效。方法:应用日本Nidek EC5000Ⅱ准分子激光仪,采用多步分区切削法治疗高度近视。按屈光度分为两组,I组:-6.00～-9.00D,128眼;II组:-9.00～-14.00D,147眼。术后随访1a,并对结果进行分析。结果:两组患者术后1a裸眼视力≥0.6者占89.6%,≥1.0者占55.6%(其中I组≥0.6者占95.1%,Ⅱ组≥0.6者占88.9%)。术后最佳矫正视力大于术前者占38.1%,小于术前者占6.0%,94.0%术后最佳矫正视力不变或上升。术后1a实际矫正度在预测矫正度±1.00D内者占81.3%,±2.00D内者占90.2%。激素性高眼压占0.04%。结论:准分子激光原位角膜磨镶技术多步分区切削法治疗高度近视伴薄角膜及超高度近视是一种安全、有效,且稳定性较好的方法,能有效预防屈光回退的发生,同时可以减少术后眩光和暗视力下降等现象。     

Laser in situ keratomileusis for residual myopia after photorefractive keratectomy

PURPOSE: To evaluate the efficacy and safety of laser in situ keratomileusis (LASIK) for myopic regression and undercorrection after photorefractive keratectomy (PRK). SETTING: The Eye Institute, Sydney, Australia. METHODS: Fifty eyes of 32 patients were treated by LASIK for residual myopia following primary PRK. The mean spherical equivalent refraction (SEQ) was -2.92 diopters (D) +/- 1.57 (SD) (range -0.75 to -7.88 D). The mean refractive cylinder was 0.96 +/- 0.74 D (range 0 to 3.50 D). For analysis, the eyes were divided into 2 groups: those with 0 or low corneal haze (Group 1) and those with severe corneal haze (Group 2). In Group 1, the SEQ was -1.99 +/- 0.79 D (range -0.75 to -3.75 D) and in Group 2, -3.77 +/- 1.62 D (range -0.75 to -7.90 D). The procedure was performed using the Chiron Automated Corneal Shaper and the Summit Apex Plus laser. The mean interval between PRK and LASIK was 25 months (range 9 to 59 months). The following parameters were studied before and after LASIK retreatment: SEQ, mean refractive cylinder, uncorrected visual acuity (UCVA), and best corrected visual acuity (BCVA). Complications after LASIK retreatment were evaluated. RESULTS: Six months after LASIK, the mean SEQ in all eyes was -0.65 +/- 0.86 D (range +1.50 to -3.35 D); 70.0% of eyes were within +/-1.00 D of emmetropia and the UCVA was 6/12 or better in 72.5%. The mean SEQ in Group 1 was -0.22 +/- 0.55 D (range -0.88 to -1.50 D) and in Group 2, -0.97+/- 0.92 D (range 0.12 to -3.25 D); the UCVA was 6/12 or better in 94.0% of eyes in Group 1 and in 56.0% in Group 2. No statistically significant between-group difference was found in lines of Snellen acuity lost or gained at 6 months. No eye lost more than 1 line of BCVA. CONCLUSIONS: Laser in situ keratomileusis appears to be a safe, effective, and predictable procedure for treating eyes with 0 or low haze with residual myopia after PRK. It is less predictable in eyes with severe haze.     

Corneal haze among blue eyes and brown eyes after photorefractive keratectomy

BACKGROUND: To compare the incidence and severity of corneal haze after photorefractive keratectomy (PRK) among white patients with blue eyes and Saudi patients with brown eyes. DESIGN: Retrospective, nonrandomized, comparative trial. PARTICIPANTS: A total of 150 patients (71 females and 79 males) were included in this study. Two hundred sixty-six eyes of 150 patients were subjected to PRK. One hundred blue eyes of 50 white patients and 166 brown eyes of 100 Saudi patients were included in this study. METHODS: Two hundred sixty-six eyes of 150 patients were subjected to PRK with the Chiron Technolas Keracor 117C for the correction of myopia and astigmatism. MAIN OUTCOME MEASURES: All patients had complete ophthalmologic examinations, visual acuity testing, intraocular pressure, pachymetry, corneal haze assessment (0-4+), and computerized corneal topography. RESULTS: There were 266 eyes of 150 patients with 100 blue irides and 166 brown irides. The spherical equivalent was -0.50 diopter (D) to -8.75 D. The mean postoperative spherical equivalent at 6 months was -0.063 D (standard deviation [SD], +/-0.595) in blue eyes compared to -0.28 D (SD, +/-0.683) in brown eyes (P = 0.006). Ninety-five (95%) of 100 of the blue eyes achieved +/- 1 D of attempted correction compared to 148 (89.2%) of the 166 brown eyes. All patients with blue eyes had a visual acuity of 20/30 or better compared to 153 (92.2%) of the 166 brown eyes (P = 0.009). Forty-eight (18.04%) eyes had minimal to mild haze, 3 (1.12%) eyes had moderate haze, and 2 (0.75%) eyes had severe haze. The incidence of corneal haze among brown eyes was 48 (28.9%) of 166 eyes compared to 5 (5%) of 100 in blue eyes (P < 0.001). The difference remained significant after adjustment for age and gender with a P value of 0.0283. The relative risk for developing haze in brown eyes was found to be 7.72. CONCLUSION: The incidence of corneal haze after PRK was significantly higher among Saudi patients with brown irides than among white patients with blue irides. This suggests that racial factors may play a role in the development of corneal haze.     

影响准分子激光屈光性角膜切削术疗效的多因素分析

目的:观察准分子激光屈光性角膜切削术(PRK)治疗近视、散光的疗效,探讨影响疗效的相关因素。方法:采用VISX20/2O型准分子激光仪对306例(529眼)近视、散光患者进行PRK手术。术前等值球镜屈光度为-1.00～16.00D(-6.55±3.19D),分为两组:Ⅰ组:-1.00～6.00D,294眼;Ⅱ组:-6.25～16.00D,235眼。随访3～12个月。结果:术后12个月,裸眼视力≥0.5、1.0者在Ⅰ组分别为97.5％、77.5％,在Ⅱ组分别为80.3％、32.8％;实际矫正度在预测矫正度±1.00D内者在Ⅰ、Ⅱ组分别为92.5％、42.6％。影响术后屈光度变化的因素:术后角度上皮下雾状混浊(Haze)程度、去上皮的方法、眼压、术前中央角膜厚度。结论:PRK治疗-6.00D以内的近视是一种安全、稳定、预测性强、有效的方法。术前应根据屈光度、年龄、角膜厚度、眼压、设计手术方案,术中强调采用激光去除上皮。眼科学报1997;13:75～78     

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.