Complications of intrastromal corneal ring segment implantation using a femtosecond laser for channel creation: a survey of 850 eyes with keratoconus

Acta Ophthalmol. 2011: 89: 54–57

Abstract.

Purpose: To report complications after the implantation of intrastromal corneal ring segments (Keraring; Mediphacos, Belo Horizonte, Brazil) in keratoconic eyes using a femtosecond laser (IntraLase; Advanced Medical Optics, Santa Ana, California, USA) for channel creation. Methods: Retrospective chart review of 531 patients (850 eyes) who underwent Keraring insertion using a femtosecond laser for channel creation. Intraoperative and postoperative complications were recorded. Results: Intraoperatively, there were 22 (2.7%) cases of incomplete channel formation. The rest of the intraoperative complications were galvo lag error (system malfunction) [five eyes (0.6%)], endothelial perforation [five eyes (0.6%)] and incorrect entry of the channel [two eyes (0.2%)]. Postoperatively, there were 11 (1.3%) cases of segment migration, two (0.2%) cases of corneal melting and one (0.1%) case of mild infection. The overall complication rate was 5.7% (49 cases out of 850 eyes). Conclusion: In this study, intracorneal ring segment implantation using a femtosecond laser for channel creation was related to a number of complications. The most common complications were incomplete channel creation (intraoperatively) and segment migration (postoperatively).     

Treatment of moderate to severe keratoconus with 6-mm Intacs SK

AIM: To evaluate the effect of Intacs SK corneal ring segment implant for treatment of patients with moderate to severe keratoconus, who have clear central cornea and cannot tolerate contact lens. METHODS: In this prospective, non-comparative, interventional case series study performed in Dena Hospital, Shiraz, Iran, thirty-seven eyes of thirty-six patients with moderate to severe keratoconus, clear central cornea, and contact lens intolerance were enrolled and underwent Intacs SK corneal ring segment implantation. Preoperatively, uncorrected distance visual acuity (UCDVA), best-corrected distance visual acuity (BCDVA), central corneal thickness(CCT) and average keratometry (Av-K) were measured and compared with post-operative results at one week, one month, three months, and six months. RESULTS: Mean preoperative UCDVA and BCDVA were (1.32±0.31)logMAR and (1.07±0.27)logMAR, respectively. Av-K was (52.13±0.39)D, and the CCT was (432±39.5)μm. Post-operative examinations showed a clinically significant improvement in both UCDVA and BCDVA (P<0.001). There was also a significant effect based on the time of assessment on both UCDVA and BCDVA and both parameters had a continuous improvement during the follow-up period. Three months after operation there was a statistical significant reduction of Av-K (P=0.0001), but there were no significant changes in CCT (P=0.149). CONCLUSION: Intacs SK corneal ring segment implants seem to be a safe and effective treatment option for patients who have keratoconus, clear central cornea, and contact lens intolerance.     

圆锥角膜治疗进展

圆锥角膜是一种以角膜扩张为特征,病因不明的双侧进行性角膜病变。角膜接触镜是轻中度圆锥角膜最常用的矫正方法。角膜表层镜片术、深板层角膜移植术、角膜基质环植入术、角膜交联疗法及穿透性角膜移植术是临床上常用的手术治疗方法。     

Investigation of the efficiency of intrastromal ring segments with cross-linking using different sequence and timing for keratoconus

AIM:To evaluate and compare the efficacy and stability of intrastromal corneal ring segment (ICRs) implantation with cross-linking (CXL) using different sequence and timing.METHODS:In this single retrospective study, 86 keratoconic eyes subjected the ICRs implantation. We analyzed only 41 eyes that had complete follow-ups. They were divided into three groups:ICRs implantation was applied only (group normal), ICRs first followed by CXL immediately (group CXL-S), CXL first followed by ICRs long after (group CXL-B). The visual acuity, refractive results, keratometry were compared preoperatively and 1y postoperatively. Their differences among the three groups were also analyzed.RESULTS:Group normal comprised 25 eyes, group CXL-S 8 eyes, and group CXL-B 8 eyes. There were improvements in the mean uncorrected distance visual acuity (UDVA) and the mean corrected distance visual acuity (CDVA) compared preoperatively and 1y postoperatively {UDVA:0.31 (P=0.030) logarithmic minimum angle of resolution [logMAR] group normal, 0.4 (P=0.020) group CXL-S, 0.45 (P=0.001) group CXL-B; CDVA:0.21 logMAR (P=0.013) group normal, 0.30 (P=0.036) group CXL-S; 0.26 (P=0.000) group CXL-B}. The refractive and topographic outcomes also showed improvements. In terms of comparisons among the three groups, all the P values were above 0.05, showing no significant difference. But only group CXL-B had improvement in UDVA and CDVA for all the patients.CONCLUSION:With safety and good visual outcomes, ICRs implantation is a viable alternative for keratoconus. No significant difference was found among these three groups.     

Clinical outcomes after intrastromal corneal ring segments reoperation in keratoconus patients

AIM:To evaluate the clinical outcomes after Ferrara intrastromal corneal ring segments (ICRS) reoperation in patients with keratoconus.RESULTS: The mean follow-up time after the reoperation was 30.5±9.7 months. The mean UCVA improved from 20/300 to 20/80 (P=0.005); the mean BCVA improved from 20/160 to 20/50 (P=0.0002), the mean keratometry reduced from 49.33±4.19D to 46.16±3.90D (P=0.0001), the mean pachymetry at the thinnest point increased from 450±42.9mm to 469±40.8mm (P=0.0001). The asphericity increased from -0.84±0.74 to -0.35±0.81 (P=0.15) and the spherical equivalent reduced from -4.64±4.87D to -3.04±3.45D (P=0.137). The changes in the asphericity and spherical equivalent were not statistically significant.CONCLUSION: Ferrara ICRS implantation showed to be a reversible and readjustable surgical procedure for keratoconus treatment. Good outcomes can be obtained even after removal, addition, reposition or exchange of ICRS.     

Evaluation of anterior and posterior surfaces of the cornea using a dual Scheimpflug analyzer in keratoconus patients implanted with intrastromal corneal ring segments

AIM: To evaluate corneal parameters measured with a dual Scheimpflug analyzer in keratoconus patients implanted with intrastromal corneal ring segments (ICRS). METHODS: Fifty eyes of 40 keratoconus patients had Ferrara ICRS implantation from November 2010 to April 2014. Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refraction, keratometry, asphericity, elevation, pachymetry, root mean square (RMS), spherical aberration and coma were studied. All patients were evaluated using a dual Scheimpflug system. RESULTS: The mean follow-up time after the procedure was 12.7mo. The mean UCVA improved from 0.82 to 0.31 (P<0.001); the mean BCVA improved from 0.42 to 0.05 (P<0.0001), the mean spherical refraction changed from -3.06±3.80 D to -0.80±2.5 D (P<0.0001) and the mean refraction astigmatism reduced from -4.51±2.08 D to -2.26±1.18 D (P<0.0001). The changes from preoperative to postoperative, in parameters of the anterior and posterior surface of the cornea, were statistically significant except the elevation posterior at the apex of the cornea and posterior asphericity. CONCLUSION: The implantation of Ferrara ICRS induces changes in both anterior and posterior surfaces of the cornea.     

MyoRing植入术治疗圆锥角膜的疗效观察

目的：比较MyoRing植入前后圆锥角膜(KCN)患者角膜前后表面散光和全屈光散光。

方法：历史队列研究。比较植入360度全环植入物(MyoRing)的KCN患者的术前和术后全屈光、角膜前后表面散光,术后3、6、9、12 mo连续随访四次。

结果：共纳入KCN患者79例85眼,其中男43例,女36例,平均年龄29±7.41(17-48)岁。随访期间,全屈光散光、角膜前后表面散光呈减少趋势。MyoRing植入后12 mo,总屈光散光测量值显著下降2.09 D(4.27±3.15 vs 2.18±1.63 D,P<0.001)。此外,术后测量显示,角膜前表面和后表面散光分别改善约3.20 D和0.59 D\〖6.40±1.90 vs 3.20±1.75 D(P<0.001)和1.30±0.55 vs 0.71±0.35(P<0.001)\〗

结论：MyoRing植入可显著改善散光参数,包括全屈光散光以及角膜前后表面散光。     

圆锥角膜的治疗进展

本文通过对圆锥角膜治疗方法的综述,为临床医生选择合适的治疗方法做出参考。通过数据库对“圆锥角膜”“隐形眼镜”“角膜胶原交联”“Intacs(角膜环)”“角膜成形术”“基因治疗”“不规则散光”等关键词进行搜索,并根据相关文献对圆锥角膜的治疗方法进行综述。眼镜和隐形眼镜可用于圆锥角膜早期,而疾病晚期时可采用前弹力层移植术、穿透性角膜成形术(PK)和深层前板层角膜成形术(DALK)、传导性角膜成形术和基因治疗。此外,角膜胶原交联可以阻止圆锥角膜进展,角膜基质环植入术(ICRS)通过使变形角膜变平,减少屈光不正以达到治疗目的。总得来说,眼科诊断技术和治疗方法的发展可以减缓圆锥角膜进展,从而减少晚期角膜圆锥患者对角膜移植的需要。选择恰当的圆锥角膜治疗方案可以帮助患者改善视力和预防失明。     

Clinical outcomes after implantation of a new intrastromal corneal ring with 140-degree of arc in patients with corneal ectasia

AIM: To evaluate the clinical and tomographic outcomes after implantation of a new intrastromal corneal ring segment (ICRS) with 140-degrees of arc in eyes with corneal ectasia. METHODS: We evaluated patients with corneal ectasia implanted with Ferrara 140° ICRS from April 2010 to February 2015. Outcome measures included preoperative and postoperative corrected distance visual acuity (CDVA), keratometry simulated (K) reading, tomographic astigmatism and asphericity. All patients were evaluated using the Pentacam Scheimpflug system. RESULTS: The study evaluated 58 eyes. The mean follow-up was 16.81±10.8mo. The CDVA (logMAR) improved from 0.5±0.20 (20/60) to 0.3±0.21 (20/40) (P<0.01). The average K reduced from 49.87±7.01 to 47.34±4.90 D (P<0.01). The asphericity changed from -0.60±0.86 to -0.23±0.67 D (P<0.01). The mean preoperative tomographic astigmatism decreased from -8.0±3.45 to -4.53±2.52 D (P<0.01). CONCLUSION: The new ICRS model with 140-degrees of arc effectively improve the visual acuity and reduce the high astigmatism usually found in patients with corneal ectasia.     

Clinical effectiveness of intrastromal corneal ring segments among keratoconus patients

AIM: To evaluate the clinical effectiveness of intrastromal corneal ring segments (ICRS) among the patients suffering from keratoconus. METHODS: A retrospective and non-comparative interventional design had been utilized on the basis of postoperative follow-up among 56 keratoconus patients. Visual acuity was significantly assessed during complete ophthalmic examination of the patients. The femtosecond laser had been used to create the corneal tunnels in 15 eyes; whereas, the corneal tunnels were created in 72 eyes mechanically. RESULTS: The ranges and standard deviations had been used to obtain results. It had been revealed through ophthalmic assessment that the mean preoperative uncorrected visual acuity observed was 1.38±0.37 logarithm of Minimal Angle of Resolution. Moreover, a significant improvement was observed postoperatively in visual acuity by 0.58±0.32 during the 4th month. The improvement was also witnessed in the 16th month by 0.48±0.30. CONCLUSION: The implantation of ICRS is an efficient and effective surgical intervention for the treatment of keratoconus. Thus, identified intervention seems to be associated with appropriate visual outcomes and safety after the development of femtosecond as well as mechanical tunnels.     

角膜基质环植入术治疗圆锥角膜的临床疗效

目的：评估角膜基质环植入术治疗圆锥角膜的临床疗效。

方法：这一回顾性对照干预性研究对56例87眼圆锥角膜患者进行手术后随访。所有患者完善眼科检查,评估视力。15眼使用飞秒激光制备角膜隧道。72眼使用机械的方法制备角膜隧道。

结果：所有患者术前裸眼视力1.38±0.37。术后4mo裸眼视力达到0.58±0.32。术后16mo达到0.48±0.30。

结论：角膜基质环植入术是治疗圆锥角膜的有效方法。有效的干预与理想的术后视力相关。飞秒激光角膜隧道制备和机械方法一样安全。     

【In Press】 Clinical outcomes after implantation of a new intrastromal corneal ring with 140-degree of arc in patients with corneal ectasia

AIM: To evaluate the clinical and tomographic outcomes after implantation of a new intrastromal corneal ring segment (ICRS) with 140-degrees of arc in eyes with corneal ectasia. METHODS: We evaluated patients with corneal ectasia implanted with Ferrara 140° ICRS from April 2010 to February 2015. Outcome measures included preoperative and postoperative corrected distance visual acuity (CDVA), keratometry simulated (K) reading, tomographic astigmatism and asphericity (Q). All patients were evaluated using the Pentacam Scheimpflug system. RESULTS: The study evaluated 67 eyes. The mean follow-up was 16.81±13.96mo. The CDVA (logMAR) improved from 0.5±0.20 logMAR (20/60) to 0.3±0.21 logMAR (20/40) (P<0.01). The average K reduced from 49.8±7.01 D to 47.34±4.90 D (P<0.01). The asphericity changed from -0.60±0.86 to -0.23±0.67 (P<0.01). The mean preoperative tomographic astigmatism decreased from -8.0±3.45 D to -4.53±2.52 D (P<0.01). CONCLUSION: The new ICRS model with 140-degrees of arc effectively improved the visual acuity and reduced the high astigmatism usually found in patients with corneal ectasia.     

飞秒激光联合紫外光核黄素角膜交联术治疗圆锥角膜的一年效果

目的 评估飞秒激光联合紫外光核黄素角膜交联术(femtosecond laser-assisted intrastromal crosslinking, F-CXL)治疗圆锥角膜的有效性。设计 前瞻性病例系列。研究对象2015年10月至2016年5月北京同仁医院眼科进展性圆锥角膜患者22例（30眼）。方法 所有患者采用在表面麻醉下行飞秒激光联合紫外光核黄素角膜交联术F-CXL进行治疗。术前,术后1天,1周,1、3、6、12个月检查视力、屈光度、角膜地形图、角膜共聚焦显微镜、角膜内皮镜及角膜生物力学。主要指标 最佳矫正视力（best corrected visual acuity, BCVA）、最薄角膜厚度（thinnest corneal thickness, TCT）、角膜陡峭子午线屈光力（corneal steep K-reading, Ks）、角膜平坦子午线屈光力（corneal flat K-reading , Kf）以及角膜平均屈光力（average K-reading , Avek）、角膜中央厚度（corneal central thickness, CCT）、角膜滞后量（corneal hysteresis,CH）、角膜阻力因素（corneal resistence factor,CRF）、角膜交联线以及角膜共聚焦显微镜所见。结果 所有患者未发生术中、术后严重不良反应及并发症。术后1天出现轻度刺激症状,均于术后3天自行缓解或消失。术后12个月角膜Ks、Kf以及Avek均未见显著增加,CCT无显著降低,CH及CRF均未见显著下降（P均＞0.05）,并且交联效果在术后3~6个月最佳,随后逐渐下降。术前K值＞53.08 D的圆锥角膜患者术后Ks值显著提高,但相关分析并未显示年龄、基线BCVA、基线TCT与术后柱镜、Ks、Avek以及CCT有关。术后1周18眼（60%）中可观察到交联线,随后交联线逐渐变清晰和致密,术后3个月交联线深度约（320.31±51.32）μm。角膜共聚焦显微镜显示,在术后1个月后在角膜基质内可以观察到活跃的角膜细胞核以及新生成的、结构紧密的胶原纤维。在随访过程中均未观察到显著的角膜内皮数量损失。结论 飞秒激光联合紫外光核黄素角膜交联法能有效阻止圆锥角膜进展,术后角膜生物力学无明显下降,安全性较好,能够为后续开展联合囊袋内透镜植入术提供安全依据。     

Visual rehabilitation in low-moderate keratoconus:intracorneal ring segment implantation followed by same-day topography-guided photorefractive keratectomy and collagen cross linking

AIM:To present the results of same-day topography-guided photorefractive keratectomy (TG-PRK) and corneal collagen crosslinking (CXL) after previous intrastromal corneal ring segment (ISCR) implantation for keratoconus.METHODS:An experimental clinical study on twenty-one eyes of 19 patients aged 27.1±6.6y (range 19-43y), with low to moderate keratoconus who were selected to undergo customized TG-PRK immediately followed by same-day CXL, 9mo after ISCR implantation in a university ophthalmology clinic. Refraction, uncorrected distance visual acuities (UDVA) and corrected distance visual acuities (CDVA), keratometry (K) values, central corneal thickness (CCT) and coma were assessed 3mo after TG-PRK and CXL.RESULTS:After TG-PRK/CXL:the mean UDVA (logMAR) improved significantly from 0.66±0.41 to 0.20±0.25 (P<0.05); Kflat value decreased from:48.44±3.66 D to 43.71±1.95 D; Ksteep value decreased from 45.61±2.40 D to 41.56±2.05 D; Kaverage also decreased from 47.00±2.66 D to 42.42±2.07 D (P<0.05 for all). The mean sphere and cylinder decreased significantly post-surgery from, -3.10±2.99 D to -0.11±0.93 D and from -3.68±1.53 to -1.11±0.75 D respectively, while the CDVA, CCT and coma showed no significant changes. Compared to post-ISCR, significant reductions (P<0.05 or all) in all K values, sphere and cylinder were observed after TG-PRK/CXL.CONCLUSION:Same-day combined topography-guided PRK and corneal crosslinking following placement of ISCR is a safe and potentially effective option in treating low-moderate keratoconus. It significantly improves all visual acuity, reduced keratometry, sphere and astigmatism, but causes no change in central corneal thickness and coma.     

Evaluation of intrastromal corneal ring segments for treatment of keratoconus with a mechanical implantation technique

Purpose:

To evaluate the clinical outcomes of intrastromal corneal ring segment (ICRS) implantation in patients with keratoconus using a mechanical implantation technique.

Materials and Methods:

Thirty eyes of 17 patients with keratoconus were enrolled. ICRSs (Keraring) were implanted after dissection of the tunnel using Tunc''s specially designed dissector under suction. A complete ophthalmic examination was performed, including uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical equivalent, keratometric readings, inferosuperior asymmetry index (ISAI), and ultrasound pachymetry. All 3-, 6-, and 12-month follow-ups were completed, and statistical analysis was performed.

Results:

The mean preoperative UDVA for all eyes was 1.36 ± 0.64 logMAR. At 12 months, the mean UDVA was 0.51 ± 0.28 logMAR (P = 0.001), and the mean preoperative CDVA was 0.57 ± 0.29 logMAR, which improved to 0.23 ± 0.18 (P = 0.001) at 1 year. There was a significant reduction in spherical equivalent refractive error from –6.42 ± 4.69 diopters (D) preoperatively to –1.26 ± 1.45 D (P = 0.001) at 1 year. In the same period, the mean K-readings improved from 49.38 ± 3.72 D to 44.43 ± 3.13 D (P = 0.001), and the mean ISAI improved from 7.92 ± 3.12 to 4.21 ± 1.96 (P = 0.003). No significant changes in mean central corneal thickness were observed postoperatively. There were no major complications during and or after surgery.

Conclusion:

ICRS implantation using a unique mechanical dissection technique is a safe and effective treatment for keratoconus. All parameters improved by the 1-year follow-up.     

Pentacam眼前节分析仪对散光患者中圆锥角膜和亚临床圆锥角膜的临床研究

目的:Pentacam眼前节分析仪对＞2.0D散光眼患者圆锥角膜和亚临床圆锥角膜的研究.方法:本研究收集散光≥2.0D患者107例201眼.所有的患者进行验光、视力、矫正视力、裂隙灯、眼底镜、传统角膜地形图、Pentacam眼前节分析仪检查.观察包括K1:3mm直径范围水平中央曲率,K2:3mm直径范围垂直中央曲率、角膜前表面最大屈光力(Kmax)、角膜散光(CYL)、角膜最薄处的厚度(MinPachy)、表面变异指数(ISV)、垂直不对称指数(IVA)、圆锥角膜指数(KI)、角膜前表面高度(AE)、角膜后表面高度(PE)等指标变化.并作ROC曲线,对比各组的cutoff值及其敏感指标.Pentacam获得的几个参数分析采用Mann-Whitney U检验.通过ROC曲线分析确定出最佳诊断界点.结果:本研究人群的平均年龄为25.7±6.6岁.前表面Kmax、IVA、KI、AE、PE临床和亚临床组明显高于散光组,角膜最薄处厚度临床和亚临床组明显低于散光组(P＜0.05).Pentacam诊断临床期圆锥角膜的敏感指标(曲线下面积AUC≥0.9),分别为AE、PE、IVA、ISV、KI、Kmax.诊断亚临床圆锥角膜的敏感指标(曲线下面积AUC≥0.9)为PE.结论:研究表明,2D以上散光的人群即使视力正常,也应该进行角膜地形图筛查.Pentacam眼前节分析仪可以提供精准的角膜前后表面解剖信息,尤其是角膜后表面高度测定,对亚临床期圆锥角膜的筛查起重要作用.