LASIK术后20年患者远期视力效果与安全性

目的:评估准分子激光原位角膜磨镶术(LASIK)术后20a患者远期视力效果与安全性。方法:回顾性研究。收集1998-01/2001-12在我院准分子治疗中心接受LASIK手术治疗的患者资料。采用电话通知患者至门诊复查的方式,进行调查研究。收集的数据包括人口统计学特征(性别和年龄)、LASIK术前裸眼视力(UCVA)及最佳矫正视力(BCVA)、术前屈光度数、术中角膜瓣厚度及术中角膜基质层残余厚度。主要观察指标:长期疗效指数、安全性指数、UCVA、BCVA、角膜厚度及眼轴长度。同时进行裂隙灯、眼底及OCT检查。结果:本研究纳入95例190眼,术后末次复查时,71例142眼(74.7%)UCVA≥1.0;82例164眼(86.3%)BCVA≥1.0。其中2眼分别因黄斑劈裂及青光眼,导致BCVA不良(≤0.6),其余患者BCVA为0.8。术后20a患者UCVA及BCVA与手术时年龄、术前屈光度数、角膜厚度均无明显相关性(P>0.05),而与眼轴增长值存在负相关性(r=-0.32、-0.31,均P<0.05)。术后末次复查时UCVA及BCVA与剩余角膜基质层厚度(RST)相关(P<0.05)。LASIK术后20a的安全性和有效性指数分别为1.00±0.10和0.83±0.27。本组随访期间,未发现患者存在角膜扩张及角膜瓣相关并发症,也无二次增效手术患者。裂隙灯检查,未见明显角膜干燥病变患者。结论:LASIK术后20a显现出良好的安全性及有效性。

Iontophoresis-assisted corneal crosslinking using 0.1% riboflavin for progressive keratoconus

AIM：To report the clinical results of iontophoresis-assisted epithelium-on corneal crosslinking（I-CXL） using 0.1% riboflavin in distilled water for progressive keratoconus. METHODS：In this prospective clinical study, we examined 94 eyes of 75 patients with progressive keratoconus who were treated with I-CXL using 0.1% riboflavin in distilled water. Best correct visual acuity（BCVA）, Scheimpflug tomography, corneal topography, anterior segment optical coherence tomography, intraocular pressure, and endothelial cell density were evaluated at baseline and 1, 3, 6, 12, and 24 mo after I-CXL.RESULTS：After 24 mo I-CXL, compared to the level at baseline, BCVA significantly improved 0.14±0.07（P=0.010）; mean keratometry signifi cantly decreased 0.72±1.97（P=0.021）; maximum keratometry significantly reduced 2.30±5.01（P=0.014）; central keratoconus index significantly reduced 0.04±0.08（P=0.007）. The demarcation line was visible in 83.1% of eyes at 1mo after treatment, with a depth of 298.95±51.97 μm, and gradually indistinguishable. One eye had repeat treatment. Intraocular pressure and endothelial cell density did not change significantly.CONCLUSION：I-CXL using 0.1% riboflavin halts keratoconus progression within 24 mo, resulting in a significant improvement in visual and topographic parameters. Moreover, the depth of the demarcation line is similar to that previously reported in standard epithelium-off CXL procedures.

Progress of corneal collagen cross-linking combined with refractive surgery

As a photochemical reaction that can stiffen the cornea,corneal collagen cross-linking(CXL) is the only promising method of preventing the progress of keratectasia,such as keratoconus and secondary ectasia following refractive surgery. The aim of CXL is to stabilize the underlying condition,with a small chance of visual improvement. Combining CXL with refractive surgery targeting both stabilization and reshaping of the corneal tissue for visual function improvement is a good treatment option. This review aims to provide a comprehensive and unbiased summary of the published research regarding combined CXL and refractive surgery,including measures and results,to help elucidate the future direction of CXL.

Riboflavin concentration in corneal stroma after intracameral injection

AIM: To evaluate the enrichment of riboflavin in the corneal stroma after intracameral injection to research the barrier ability of the corneal endothelium to riboflavin in vivo.METHODS: The right eyes of 30 New Zealand white rabbits were divided into three groups. Different concentrations riboflavin-balanced salt solutions(BSS)were injected into the anterior chamber(10 with 0.5%, 10 with 1%, and 10 with 2%). Eight corneal buttons of 8.5mm in diameter from each group were dissected at 30 min after injection and the riboflavin concentrations in the corneal stroma were determined using high-performance liquid chromatography(HPLC) after removing the epithelium and endothelium. The other two rabbits in every group were observed for 24 h and sacrificed. As a comparison, the riboflavin concentrations from 16 corneal stromal samples were determined using HPLC after instillation of 0.1% riboflavin-BSS solution for30 min on the corneal surface(8 without epithelium and 8with intact epithelium).RESULTS: The mean riboflavin concentrations were11.19, 18.97, 25.08, 20.18, and 1.13 μg/g for 0.5%, 1%, 2%,de-epithelialzed samples, and the transepithelial groups,respectively. The color change of the corneal stroma and the HPLC results showed that enrichment with riboflavin similar to classical de-epithelialized corneal collagen crosslinking(CXL) could be achieved by intracameral 1%riboflavin-BSS solution after 30min; the effect appeared to be continuous for at least 30 min.CONCLUSION: Riboflavin can effectively penetrate the corneal stroma through the endothelium after an intracameral injection in vivo, so it could be an enhancing method that could improve the corneal riboflavin concentration in transepithelial CXL.

Iontophoresis-assisted versus standard corneal crosslinking for progressive keratoconus

Background:To compare the safety and efficacy of iontophoresis-assisted epithelial-on corneal crosslinking(I-CXL)using 0.1%riboflavin-distilled water solution with standard epithelium-off corneal crosslinking(S-CXL)for progressive keratoconus.Methods:In a retrospective analysis,progressive keratoconus patients treated with I-CXL(17 eyes of 17 patients)or S-CXL(13 eyes of 13 patients)were included.All patients were followed up at least 12 months.All patients underwent detailed ophthalmologic examinations involving pre-and postoperative visual acuity,topographic parameters and pachymetry.Intra-and postoperative complications were recorded.Results:No statistically significant differences were observed between the two groups at baseline with respect to visual acuity,age and thinnest corneal thickness(TCT).The postoperative decreases of K1 and Kmean in the S-CXL group represented statistically significantly better results than in the I-CXL group(t=2.093 and 2.123,P=0.046 and 0.043,respectively).Alterations of other parameters showed no significant differences between the two groups.There were no failure cases in the two groups.Conclusions:I-CXL using 0.1%riboflavin-distilled water solution provided effective treatment for progressive keratoconus at 12-month follow-up.However,the decreases of K1 and Kmean caused by I-CXL were less than those by S-CXL.Although treatment time,postoperative patient pain and risk of infection in I-CXL are all less than those in S-CXL,I-CXL is unable to completely replace S-CXL for progressive keratoconus temporarily.