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.     

不同大小透明角膜切口超声乳化术治疗放射状角膜切开术后白内障

目的：评估不同大小透明角膜切口超声乳化术治疗放射状角膜切开术（RK）后白内障的临床效果。方法：回顾性系列病例研究。收集2011 年1 月至2015 年8 月在首都医科大学附属北京同仁医院行白内障超声乳化手术且既往有RK史的患者16例（26眼）,其中RK角膜瘢痕为8刀者3例（6眼）,12刀者8 例（12 眼）,16 刀者5 例（8 眼）。由同一手术医师进行透明角膜切口白内障超声乳化术联合人工晶状体植入术,8 刀者中4 眼采用3.2 mm透明角膜切口,2 眼采用3.0 mm透明角膜切口;12 刀者中4 眼采用3.2 mm透明角膜切口,8 眼采用2.2 mm透明角膜切口;16 刀者中5 眼采用3.2 mm透明角膜切口,3眼采用2.0 mm透明角膜切口。分别于术后1 d,1 周,1、3、6、12、24、36 个月进行随访,观察并记录角膜RK瘢痕情况,术后视力恢复情况及术后有无并发症发生。对术前与术后1 个月、最后1 次随访时的各项参数采用配对t 检验进行比较。结果：RK角膜瘢痕为8 刀者和12 刀者术中均未发生RK瘢痕裂开,术毕切口密闭良好;16 刀者中采用3.2 mm透明角膜切口者2 眼术中发生角膜瘢痕裂开,前房注入无菌空气封闭切口,切口密闭良好,余6 眼均未发生术中角膜瘢痕裂开。术后随访时间为1~36（12.9±11.6）个月。26眼术后角膜切口密闭良好,均未出现新发角膜瘢痕裂开。最后1 次复查时最佳矫正视力（BCVA,LogMAR）为0.19±0.12,较术前提高（t =-6.913,P <0.001）;等效球镜度（SE）为（-0.43±1.64）D,较术前明显降低（t =-5.983,P <0.001）;角膜散光度为（1.92±0.85）D,与术前差异无统计学意义（t =-0.68,P =0.506）;角膜内皮细胞密度为（1 893±826）个/mm2,较术前明显降低（t =4.048,P =0.001）。结论：采用不同大小透明角膜切口超声乳化术治疗RK术后白内障临床效果均较好,相对安全,建议RK角膜瘢痕为8 刀者可采用3.2 mm及以下透明角膜切口,12 刀者可采用2.2 mm及以下透明角膜切口,16刀者可采用2.0 mm及以下透明角膜切口。     

Variations in corneal wound healing after radial keratotomy: possible insights into mechanisms of clinical complications and refractive effects.

Ultrastructural and histopathologic analysis was performed on three human corneal specimens for variable and complicated refractive outcomes 1-2 years after radial keratotomy. Specimens were obtained immediately postsurgery after microkeratome resection with homoplastic lamellar keratoplasty (two cases) and penetrating keratoplasty (one case) for correction of glare, severe astigmatism, overcorrection, and/or double vision. All three cases showed variability of wound healing and delayed corneal wound healing sites; epithelial retention cysts, and/or absence of stromal scar collagen that was not dependent on the length of time after surgery. Two of the three radial keratotomy specimens also contained extensive duplication of the superficial corneal epithelial basal lamina. When present, the thickened basal lamina (3-6 microns in thickness) was seen between all incisions evaluated and appeared to extend from the central optical zone out to the periphery of the lamellar button. The one full-thickness keratoplasty specimen showed focal loss of underlying endothelial cells with occasional migrating cells seen by scanning electron microscopy. These data support previous findings that delayed corneal wound healing with epithelial retention cysts remains the most common histopathologic alteration after radial keratotomy. The effects of variations and delay in wound healing between individuals could explain the lack of predictability of refractive outcome and continuing refractive instability in long-term follow-up after single or repeat radial keratotomy surgeries.     

Wound healing after astigmatic keratotomy in human eyes

The authors analyzed three full-thickness corneal buttons and two corneal scleral rims obtained 5 1/2 to 44 months after three trapezoidal keratotomies (Ruiz), one "L," and one "TL" procedure. The indications for the penetrating keratoplasty were photophobia, corneal edema, and loss of best-corrected vision after the astigmatic keratotomy procedures. Epithelial plugs were seen in all five specimens. Complete basal lamina lined the wounds in two cases. Tangential incisions of the Ruiz procedure were shallower and demonstrated more advanced wound healing than the corresponding semiradial incisions. Two of the three Ruiz procedures demonstrated peripheral separation of the semiradial incisions. Wound healing events after astigmatic keratotomy procedures appear similar to those reported previously after standard radial keratotomy with the exception that tangential incisions appear to heal faster than the semiradial incisions.     

3.2 mm透明角膜切口超声乳化术治疗放射状角膜切开术后白内障的效果及安全性

目的  评估3.2 mm透明角膜切口超声乳化术治疗放射状角膜切开术（radial keratotomy,RK）后白内障的效果与安全性。设计  回顾性病例系列。研究对象  既往有RK手术史的白内障患者8例13眼,其中RK角膜瘢痕为8刀者2例4眼,12刀者3例4眼,16刀者3例5眼。方法  由同一手术医师进行3.2 mm透明角膜切口超声乳化人工晶状体植入术。8刀RK组中,角膜主切口位于相邻两条放射状角膜瘢痕之间,未与瘢痕接触;12刀RK组中,主切口跨越1条角膜瘢痕;16刀RK组中,主切口跨越2条角膜瘢痕。于术后1天,1周,1、3、6个月,1、2、3年进行随访,观察角膜RK瘢痕情况、并发症处理及术后视力恢复情况。主要指标 有无RK瘢痕裂开、术后最佳矫正视力、角膜散光、角膜内皮细胞密度。结果  8刀RK组和12刀RK组术中均未发生角膜RK瘢痕裂开,术毕切口密闭良好;16刀RK组中,2眼发生术中角膜瘢痕裂开,1眼采用前房注气封闭切口,另1眼采用主切口下注入黏弹剂,侧切口前房注气封闭切口。随访过程中,所有13眼术后角膜切口密闭良好,均未出现新发角膜瘢痕裂开。最后1次复查时,最佳矫正视力为（0.67±0.18）较术前（0.29±0.20）提高（t=-6.077,P=0.000）,角膜散光（1.69±1.23 D）较术前（1.28±0.78 D）无明显变化（t=-0.758,P=0.470）,角膜内皮细胞密度（1716.95±906.79/mm2）较术前（2383.97±833.39/mm2）降低（t=2.995,P=0.012）。结论  8刀、12刀RK术后白内障患者行超声乳化手术时采用3.2 mm透明角膜切口是安全的,16刀者术中易发生角膜瘢痕裂开,对此应采用更小的角膜切口或采用传统的角巩膜隧道切口。     

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.     

Prospective Clinical,Study of Radial Keratotomy

A prospective clinical study of radial keratotomy was conducted at the University of Maryland. Results of surgery on 33 eyes of 19 patients with a minimum follow-up of seven months and a mean of 13.8 months are reported. There were eight patients (15 eyes) who needed adequate unaided visual acuity for occupational purposes. Preoperative visual acuity was 20/400 in 79% of eyes. Postoperative visual acuity was 20/50 or better in 48% of cases. However, in patients with preoperative refractive errors of 5 diopters or less, postoperative visual acuity was 20/50 or better in 84% of cases. Average decrease in myopia was 2.5 diopters. Decrease in myopia following radial keratotomy did not correlate with corneal curvature or whether 8 or 16 incision technique was used. However, there was a very significant (P = 0.001) difference in postoperative visual acuity of patients with refractive error of 5 diopters or less, as compared to those with greater than 5 diopters of myopia. Complications included corneal scarring, vascularization, and glare. No microperforation or endothelial cell loss was observed.     

Radial keratotomy complicated by sterile keratitis and corneal perforation. Histopathologic case report and review of complications

A 35-year-old physician had radial keratotomy (RK) for correction of myopia. Combined radial and transecting circumferential incisions were used which resulted in wound gape, persistent epithelial defect, and severe sterile keratitis. Progressive corneal decompensation required an initial patch graft followed by a penetrating keratoplasty four months after RK. Histopathology of the cornea demonstrated epithelial edema and persistent incisional epithelial plug formation, deep and superficial vascularization, variable incision depth (superficial to full thickness), endothelial cell loss, and inflammatory cell infiltration at all levels of the cornea. A review of the reported complications of RK is included in the discussion of this case.     

Refraction problems after refractive surgery

While refractive surgery such as radial keratotomy, epikeratophakia, and corneal relaxing incisions offer many potential benefits to patients, they can also generate optical problems such as overcorrection or undercorrection of the prior refractive error and variable vision. The authors offer suggestions for avoiding problems through proper patient selection; candid preoperative communication with the patient about possible difficulties and limitations; under-standing of the physiological changes that may occur; and optical techniques for alleviating postoperative vision problems.     

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.     

Repeat Radial Keratotomy in Monkeys

Six adult rhesus monkey eyes underwent a repeat radial keratotomy consisting of eight additional incisions one year following the initial procedure. An additional 1.07 diopters (63%) flattening of the corneal curvature and +0.82 diopters (33%) of refractive error change was produced when compared with the control eyes.     

New corneal shapes in keratorefractive surgery

The corneal shape change as measured by the Humphrey keratometer and the corneascope after radial keratotomy in 50 patients was compared. The Humphrey keratometer analyzes a unique curve fit algorithm of the aplanatic corneal surface and designates this comparison as a shape factor. Both the corneascope photographs and the Humphrey keratometer demonstrated central corneal flattening after successful radial keratotomy. In addition, the normal "plus" shape factor was routinely converted to a "negative" shape factor after the procedure. This is analogous to converting the aplanatic central cornea, which normally approximates the end of an ellipse, to a topography which appears in cross section as the side of an ellipse. This alteration in topography is directly correlated to the magnitude of cycloplegic refractive change seen with this operation. The corneascope map topography of the cornea confirms this alteration in curvature.     

Combined astigmatic keratotomy with corneal valvular incision in the treatment of high surgical astigmatism

Background: Astigmatic keratotomy is used conventionally to correct moderate surgical astigmatism. However, cases with very high surgical astigmatism due to wound compression can show a dramatic response to relaxing keratotomies made in the steeper meridian. The effect obtained cannot be predicted pre-operatively by using standard nomograms. Methods: Coupled arcuate keratotomies combined with corneal valvular incisions were performed in a case of high astigmatism post-cataract surgery. Results/Conclusion: Coupled arcuate keratotomies were combined with a corneal valvular incision enabled a surgical correction of nearly 9 D of astigmatism.     

Map-fingerprint-dot changes in the corneal epithelial basement membrane following radial keratotomy

Corneal epithelial opacities similar to those seen in corneal epithelial basement membrane dystrophy were seen in 33 of 71 eyes following radial keratotomy. These changes were clinically indistinguishable from those seen in map-fingerprint-dot dystrophy with map type changes seen most often. Basement membrane changes tended to be transient (persisting less than 3 months in 75.3% of eyes) and not usually visually significant. However, three eyes had changes which persisted for 12 months. Most eyes with basement membrane changes had involvement of less than one-half quadrant of the corneal (68%). Involvement of two or more quadrants occurred in 9.4% of eyes with these changes. One eye had visually significant changes which persisted for 3 months. There were no episodes of recurrent erosion.     

Queratitis infecciosa tardía en paciente con queratotomía radial y síndrome del párpado flácido tratado con puntos sueltos

A 55-year-old male presented with an infectious keratitis in his left eye, affecting one of the incisions of the radial keratotomy he had undergone thirty-four years ago. Suturing the incision with two simple interrupted stitches was key to the resolution of the infection. Floppy eyelid syndrome was also found in this patient. Could this act as a risk factor for infectious keratitis in radial keratotomy? To our knowledge, this is the first reported case describing the association between both conditions, and the second reported case where sutures have been used as an adjuvant treatment in these types of cases.     

Radial Keratotomy in Fresh Human Cadaver Eyes

Radial keratotomy in fresh human cadaver eyes produced corneal flattening varying from 6 to 11 diopters (0). There was no significant difference in the effectiveness of the incisions to the limbus compared to incisions through the limbus. Eighty to ninety percent of the flattening effect was obtained after the first eight incisions. The preoperative keratotomy reading was not helpful in predicting the final result. Histopathology of the incised corneas revealed considerable variation in incision depth and demonstrates the difficulty in achieving deep incisions safely.     

四与八切口放射状角膜切开术的角膜地形图评估

应用计算机辅助的角膜地形图检测仪等手段对３２例４８只轻中度近视眼（－２．２５Ｄ至－５．００Ｄ）的放射状角膜切开术（ＲＫ）的疗效及安全性进行系统检测与分析，结果表明：四与八条切口、３．２５ｍｍ至３．５０ｍｍ光学区、取瞳孔缘最薄一点角膜厚度的切口深度的ＲＫ可安全有效地矫正轻中度近视眼的屈光不正。过多的角膜切口、过小的光迩区及角膜微穿孔措施可能不会对ＲＫ疗效带来有益的帮助。正确选择病例，合理设计手术方案     

白内障术中飞秒激光弧形角膜切开术矫正角膜散光的疗效

目的：研究白内障术中飞秒激光弧形角膜切开术（FSAK）矫正术前角膜散光的临床疗效。方法：回顾性病例对照研究。连续纳入北京爱尔英智眼科医院2017年3月至2021年12月术前规则角膜散光为0.75~2.00 D且接受飞秒激光辅助白内障手术的患者89例（89眼）。所有患者按照术前角膜散光轴位分为顺规散光组（90°±30°）、逆规散光组（180°±30°）及斜轴散光组（45°±15°、135°±15°）。飞秒激光辅助白内障手术及弧形角膜切开术使用Lensx平台。观察患者总体和顺规、逆规散光组术前及术后3个月角膜散光的变化及分布情况。使用配对样本t检验或Wilcoxon符号秩检验比较总体及各亚组术前、术后的散光差异；使用独立样本t检验或Mann-Whitney U检验比较顺规散光组及逆规散光组的差异；散光变化的分析采用Alpins矢量分析法。结果：纳入的89例（89眼）患者中，顺规散光组38例，逆规散光组44例，斜轴散光组7例。所有患者角膜水平径为（11.48±0.57）mm，垂直径为（10.66±0.60）mm。患者总体术后裸眼远视力、最佳矫正远视力相比术前有显著改善（Z=8.01、-7.49，P<0.001）。总体术前角膜散光为（1.28±0.33）D，术后3个月残余散光（0.67±0.37）D，散光矫正量为（0.61±0.33）D。顺规及逆规散光组角膜散光矫正量分别为（0.48±0.27）D、（0.74±0.34）D。总体及顺规、逆规散光组术后平坦轴角膜曲率均有明显升高，而陡峭轴角膜曲率则出现明显下降。矢量分析法显示总体散光矫正指数为0.63±0.30，平坦指数为0.58±0.30，成功指数为0.51±0.25，误差角为-1.83°±12.59°。逆规散光组矫正效果最佳，矫正指数为0.81±0.25，平坦指数为 0.75±0.26，成功指数为0.40±0.24；顺规散光组次之，矫正指数为0.42±0.21，平坦指数为0.39±0.21，成功指数为0.63±0.21。结论：白内障术中FSAK矫正术前角膜散光具有良好的有效性和安全性，相同的弧形切口设计方式在逆规散光中取得了更好的疗效，角膜直径可能是产生影响的重要因素。     

Corneal sensitivity after radial keratotomy

Corneal sensitivity was tested in 76 eyes of 40 patients who underwent radial keratotomy for the correction of myopia, and radial keratotomy plus transverse incisions for the correction of myopia and astigmatism. There was a decrease in corneal sensitivity in 30.9 and 9.5% of patients undergoing radial keratotomy after 6 and 12 months, respectively. Approximately 70% of patients in this group had a recovery of lost sensitivity after 6 months. There was a similar decrease in sensitivity in 79.4 and 47.0% of patients undergoing radial keratotomy with the addition of transverse incisions for astigmatism at 6 and 12 months, respectively. The recovery rate in this group was 40.7%. The most significant loss of corneal sensation was in the areas central to the transverse incisions. The depth of the transverse incision, as well as the preoperative astigmatism, appeared to be factors in the loss of corneal sensation as well as in the recovery of the corneal sensitivity. There were no complications noted in this study as a result of decreased corneal sensitivity.     

放射状角膜切开术—临床疗效的追踪观察

本文对连续119例放射状角膜切开术后3年的临床疗效进行了分析。结果显示术后第1年和第3年间,术眼屈光度的平均改变为-0.12D。72.3％的术眼屈光度的变化在-1.00D与 1.00D之间,16.8％的术眼屈光度的变化在-1.00D与-2.50D之间,10.9％的术眼屈光度的变化在 1.00D与 3.50D之间。术后术眼屈光的改变与患者的年龄无关,与术前近视的度数有关,近视度高的患眼术后屈光的波动较近视度低的患眼大。绝大多数术眼术后3年内裸眼视力无改变,术后角膜内皮细胞密度也无显著改变。