放射状角膜切开术后残留屈光不正患者的LASIK手术治疗

目的:研究放射状角膜切开术后LASIK手术的效果和并发症。方法:本描述性研究在伊朗亚兹德LASIK手术中心进行,研究对象包括2003-04/2006-09的LASIK手术患者。数据通过特殊的量表收集,并采用SPSS软件和配对t检验进行分析。结果:患者23例33眼,其中女11例(48%),男12例(52%)。年龄介于28 ～49(平均31.6)岁。制上皮瓣时发现2例(6%)患者有放射状角膜开口和1例(3%)患者有中度非传染性角膜炎出现。术前等效球差为-2.17±0.94D,而术后等效球差为-0.17±0.19D,两者在统计学上具有显著性差异(P=0.0001)。术前平均裸眼视力(裸眼视力)为0.07±0.02,术后则为0.88±0.16,两者在统计学上具有显著性差异(P=0.0001)。手术前平均最佳矫正视力为0.93±0.08,而手术后为0.92±0.08,两者在统计学上不具有显著性差异(P=0.268)。结论:LASIK手术能改善放射状角膜切开术后残留的近视,术中和术后观察发现没有发生明显的并发症,但必须认真思考二次手术的必要性,同时小心选择和评估相关病例。     

Radial keratotomy: an overview of the Kansas City study

The first 290 consecutive eyes (192 patients) to undergo radial keratotomy by one surgeon were evaluated prospectively. All had had complete preoperative evaluation and 269 (93%) were examined one or more years after surgery. Preoperatively, all patients except one had worse than 20/100 uncorrected visual acuity, 65% had less than 20/400, and mean spherical equivalent (SE) was -4.8 diopters. One year postoperatively, 40% of the patients had uncorrected visual acuity of 20/20 or better and 83% had 20/40 or better. The mean change in SE after 1 year was 5.0 diopters, and 60% of eyes were within 1 diopter of emmetropia. Keratometric changes paralleled refractive changes, and both appeared stable within 1 to 3 months. Complications were few and most were transient or well-tolerated. One case of presumably viral disciform keratitis occurring 8 months postoperatively had a three Snellen line decrease in best-corrected acuity 1 year postoperatively. Factors affecting refractive outcome were studied using stepwise multiple regression analysis. Size of the optical zone, depth of incision, patient age, patient sex, intraocular pressure, number of incisions, preoperative average keratometry, and corneal diameter were each found to affect clinical outcome significantly.     

Radial Keratotomy in Monkeys: A One year Follow-up Report

Twelve adult rhesus monkey eyes underwent a radial keratotomy, consisting of 16, deep evenly spaced radial corneal incisions extending from the edge of a 3 mm central optical zone to the limbus. Peripheral deepening incisions were used. Keratometry and retinoscopy done before and after surgery monthly for one year revealed an average of 1.79 diopters decrease in the corneal curvature and an average increase of 2.49 diopters in the refractive error, which remained stable after one to two months. No significant complications were observed despite four perforations.     

准分子激光屈光性角膜切削术矫正放射状角膜切开术后残留近视

探讨准分子激光角膜切削术矫正放射状角膜切开术后残留近视的效果及影响因素,方法２９例３０眼ＲＫ术后８个月以上接受ＰＲＫ矫正残留近视,分为中低度近视组和高度近视组,平均随访６．４个月。结果ＰＲＫ术后第１组下降３．３０Ｄ,第２组下降５．２３Ｄ。     

A preliminary investigation into the direct measurement of intra-ocular light scatter after radial keratotomy

A glare score based on intra-ocular light scatter and a questionnaire-based subjective assessment of glare were determined for 18 patients who had undergone radial keratotomy (RK) two weeks to 27 months previously. Results were compared to those of 15 control subjects. T-tests showed no significant difference in glare experienced under photopic conditions by RK patients and control subjects. There was no systematic relationship between glare scores and the subjective assessment of glare, nor between glare scores or subjective assessment of glare and the time which had elapsed since surgery. However, a weak relationship (r²=0.36) was found between glare scores and absolute refractive error. It was concluded that RK did not produce significant levels of intra-ocular light scatter under photopic conditions (155 lux).     

Modification of corneal curvature following radial keratotomy in primates

Radial keratotomy was performed on six stumptail monkey eyes (Macaca speciosa) and 22 owl monkey eyes (Aotus trivirgotus). Changes in keratometry, specular microscopy, and tonometry have been studied postoperatively for three to six months. Sixteen radial incisions in stumptail monkey eyes resulted in a significant mean corneal flattening of 2.75 diopters (P less than 0.005). This effect was stable with a mean 2.50 diopters flattening remaining six months after surgery. Sixteen radial incisions in ten owl monkey eyes resulted in a much greater short-term effect, with a mean 10.50 diopters of flattening present at two weeks postoperatively. This flattening deteriorated over the observation period, and no significant effect was noted three months after surgery. A comparison of 8 vs 16 incisions on owl monkey eyes demonstrated that these two procedures are equally effective in initially flattening the cornea. Complications and side effects encountered included perforations, irregular astigmatism, corneal neovascularization, transitory increase in pachometry, and decrease in central corneal endothelial cell density in isolated cases.     

A Clinical Investigation of the Surgical Correction of Myopia by the Method of Fyodorov

The surgical correction of myopia using the method of Fyodorov known as radial keratotomy consists of 16 partial thickness, radial incisions in the cornea, which result in central flattening and peripheral bulging, reducing the degree of myopia. The purpose of this investigation was to determine: (1) the amount of myopia correctable; (2) the time required for stabilization of corneal curvature changes; (3) the degree to which the variables affect the results; (4) the surgical and postoperative complications; and (5) patient motivation and satisfaction. Preliminary results revealed a significant reduction of the myopia. The keratometry readings and refractive correction required appeared to stabilize by the third month. Fluctuating vision and increased glare were the most frequent complications encountered. The preliminary results of 20 cases followed for six months postradial keratotomy are reported.     

Rationale for and design of the National Eye Institute Prospective Evaluation of Radial Keratotomy (PERK) Study

A five-year, multicenter, collaborative clinical trial of radial keratotomy for myopia is being carried out at nine clinical centers. The study, funded by the National Eye Institute, is recruiting approximately 500 patients aged 21 years or older with -2.00 to -8.00 diopters of physiologic myopia who also meet other clearly defined eligibility criteria. Surgeons use a diamond-bladed micrometer knife to make eight radial incisions in the anterior cornea. The diameter of the central clear zone is determined by the amount of myopia and the depth of the incisions by intraoperative ultrasonic pachymetry. Investigators other than the surgeon gather all pre- and post-operative data. Examinations include measurement of visual acuity with standardized charts, verification of refractions by a second observer, measurement of corneal curvature by keratometry and photokeratoscopy, quantitation of glare with a glare tester, and measurement of the size of individual endothelial cells from specular photomicrographs with a computerized digitizer. A formal psychometric questionnaire is used to evaluate the patients' subjective response. Physician monitors insure adherence to the protocol during site visits and members of the Data and Safety Monitoring Board oversee the progress of the study. Biostatisticians at the Coordinating Center insure complete data collection, process the data, and assist in the interpretation of results.     

Evaluating the predictability of radial keratotomy

The predictability of radial keratotomy surgery for both the steel and diamond knife cases is evaluated in a long-term prospective study. Over 500 cases are used to build predictability models for both types of knives at 1, 3, 6, and 12 months after surgery. A predictability model is also presented at 24 months after surgery for the steel knife. R2 values range from 54 to 80% for the various models. Over 75% of cases are predicted within 2 D of their obtained result for the steel knife at all time periods and over 78% for diamond knife cases. Each model is also evaluated for how well it predicts future cases.     

Radial keratotomy and glare effects on contrast sensitivity

After radial keratotomy (RK) to correct myopia, some patients complain of ‘glare’. Effects of a glare source on contrast sensitivity were measured in fifteen patients after unilateral RK. With each eye, determinations were made of the contrast required for detection of steady gratings (spatial frequencies of 0.7 and 2.9 cycles/deg), and for detection of flicker (unpatterned field flickering at rates of 8, 16, and 32 Hz). Grating or flicker was presented on a centrally fixated 4 deg test target (34 cd/m² mean luminance), surrounded by a diffuse glare source (1700 cd/m² mean luminance). For each stimulus, contrast thresholds were determined with glare-sourceoff and with glaresourceon. ‘Glare loss’ was defined as the decrement in contrast sensitivity measured with the glare source on. Significant findings were: (1) Both eyes showed glare losses for detection of gratings and for detection of flicker; (2) Spectacle lenses increased glare losses both for gratings and for flicker; (3) The RK eye showed a larger glare loss for flicker than the unoperated eye, but a smaller glare-loss for gratings; (4) For both flicker and gratings, glare loss tended to be greater in the RK eye, compared to the unoperated eye, in subjects who hadlarger pupil diameters in the testing situation; (5) The psychophysical measurements obtained in this study were not significantly correlated either with a questionnaire index of glare complaints or with the score obtained with the Miller-Nadler GlareTester.     

Relationship of glare to uncorrected visual acuity and cycloplegic refraction 1 year after radial keratotomy in the prospective evaluation of radial keratotomy (PERK) study

This study examines the relationship of subjective glare to refraction and visual acuity, respectively, 1 year after surgery in 435 patients who underwent radial keratotomy for nearsightedness in the Prospective Evaluation of Radial Keratotomy (PERK) study. Patients were asked if they experienced glare in bright light. Of the 425 responding, 200 patients responded "no" and 225 patients responded "yes." We found no statistically significant difference in the mean value of the cycloplegic refraction 1 year after surgery in these two patient groups. (Mean cycloplegic refraction: no = -.48, yes = -.52, p = .73). We also found no difference between these groups with respect to the percent of patients with uncorrected visual acuity of 20/40 or better 1 year after surgery (no = 79%, yes = 76%, p = .46).     

Factors affecting predictability of radial keratotomy

A major criticism of radial keratotomy (RK) has been its lack of predictability, a lack due in large measure to the use of simple correlational statistics assessing the relationship between refractive result and each predictor-variable being evaluated separately. This report utilizes multivariate analysis in an attempt to account for the effects of a number of predictor-variables simultaneously. Variables studied are patient age, optical zone size, number of incisions, mean incision depth, preoperative average keratometry, preoperative average applanation tension, patient sex, and age-sex interrelationship. The area of the optical clear zone selected by the surgeon was found to be the most important factor determining refractive change as a result of RK, explaining one-quarter to one-half of the variability of the procedure. The effects of the other factors and the limitations of the method are discussed. Although this method cannot produce a fully predictive equation, we believe this analysis can serve as a good starting point for beginning RK surgeons and a method by which experienced RK surgeons can improve their techniques.     

放射状角膜切开术术后视网膜脱离的手术治疗

目的探讨放射状角膜切开术(radial keratotomy,RK)后视网膜脱离的手术治疗情况。方法回顾性分析我院眼科2007年2月至2010年2月间收治的RK术后视网膜脱离6例患者的临床资料,其中4例采用硅海绵巩膜外扣压术;2例采用23G微创玻璃体切割术治疗,1例填充C3F8,1例填充硅油。我们主要分析手术治疗的特点、效果和并发症发生情况。本组患者的RK手术时间在视网膜脱离发生前9～18a。结果本组患者手术后视网膜解剖复位率100%,术后最佳矫正视力均得到不同程度提高。1例硅油填充眼术后出现高眼压,未发生角膜伤口裂开,行部分硅油取出术后眼压得到良好控制。1例发生少量前房积血经治疗后吸收。结论单纯硅海绵巩膜外扣压术和23G微创玻璃体切割术治疗RK术后视网膜脱离是有效的,要重视术前检查裂孔定位、术中对角膜内皮的保护和术后严格监测眼压。     

UCLA Clinical Trial of Radial Keratotomy: Preliminary Report

A clinical trial of radial keratotomy was begun under a strict research protocol at the Jules Stein Eye Institute in November 1979. The results for the first 52 eyes undergoing radial keratotomy are reported three months after surgery. Preoperatively uncorrected visual acuity was less than 20/200 in all 52 eyes, and postoperative visual acuity was less than 20/200 in 11 eyes (21 %). Three months postoperatively, uncorrected visual acuity was 20/40 or better in 27 eyes (52%) and 20/20 or better in 13 eyes (25%). Postoperatively the best-corrected visual acuity decreased in 10 eyes (20%), but maximum decrease in any eye was one line of Snellen letters. Preoperatively mean refractive error was ?4.9 (±2.2) diopters, and postoperatively the mean decrease in myopia was 3.4 (±2.2) diopters. Postoperatively 13 eyes (25%) had a hyperopic refractive error of +0.25 to +3.25 diopters, put all of these eyes were able to accommodate and obtain 20/20 visual acuity without glasses. Postoperatively there was no statistically significant change in axial length, anterior chamber depth, or scleral rigidity, but there was a mean corneal endothelial cell loss of 10% (P = 0.0002). Decrease in myopia achieved by radial keratotomy did not correlate with the steepness of corneal curvature, corneal diameter, or scleral rigidity. Three months after surgery, significant symptoms of glare were present in 10 eyes (20%), and annoying variable visual acuity was noted in five eyes (10%).