Using Femtosecond Laser to Create Customized Corneal Flaps for Patients with Low and Moderate Refractive Error Differing in Corneal Thickness

This study is designed to evaluate the visual outcomes, accuracy, and predictability of corneal flaps with different thicknesses created by 60-kHz femtosecond laser according to different corneal thicknesses in the patients with low and moderate refractive error. A total of 182 eyes were divided according to the central corneal thickness (470μm–499 μm in Group A, 500μm–549 μm in Group B, and 550μm–599 μm in Group C) and underwent femtosecond laser-assisted LASIK for a target corneal flap thickness (100 μm for Group A, 110 μm for Group B, and 120 μm for Group C). Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and refractive status were examined. The flap thickness of each eye was measured by anterior segment optical coherence tomography (AS-OCT) on 30 points at 1-month follow-up to assess the accuracy and predictability. Postoperatively, at least 75% of eyes had a UDVA of 20/16 or better, less than 2% of eyes lost one line, over 30% of eyes gained one or more lines in CDVA, at least 95% of eyes had astigmatism of less than 0.25 D, all eyes achieved a correction within ±1.00 D from the target spherical equivalent refraction. The visual and refractive outcomes did not differ significantly in all groups (P >0.05). The mean flap thickness was 100.36± 4.32 μm (range: 95–113 μm) in Group A, 111.64 ± 3.62 μm (range: 108–125 μm) in Group B, and 122.32 ± 2.88 μm (range: 112–128 μm) in Group C. The difference at each measured point among the three groups was significant (P < 0.05). The accuracy and predictability were satisfactory in all three groups. In conclusion, this customized treatment yielded satisfactory clinical outcomes with accurate and predictable flap thickness for patients with low and moderate refractive error.     

Preparing Uniform-Thickness Corneal Endothelial Grafts from Donor Tissues Using a Non-Amplified Femtosecond Laser

Corneal grafts for Descemet’s Stripping Automated Endothelial Keratoplasty are commonly prepared using mechanical microkeratomes. However, the cuts produced in such way render corneal lenticules that are thinner centrally than peripherally, thus inducing a hyperopic shift. Here we describe a novel device for preparing donor corneal grafts, in which a single low-energy femtosecond laser system is used as both a light source for optical coherence tomography and for cutting the graft illuminating from the endothelial side. The same laser is first utilized to obtain three-dimensional optical coherence tomography images of the donor tissue for guiding the dissection and obtaining grafts of uniform thickness with no applanation or contact. This device allows an optimal procedure for preparing consistently thin posterior grafts for transplantation.     

飞秒激光在白内障手术中的应用新进展

飞秒激光辅助的白内障手术是目前最热门的白内障手术之一。即在计算机系统引导下利用飞秒激光进行透明角膜切口的制作,晶状体核裂解和晶状体前囊膜的切开,明显降低了传统超声乳化手术中的并发症,具有十分广阔的临床应用前景。然而飞秒激光辅助的白内障手术目前仍然处于临床应用初级阶段,其昂贵的价格是影响其研究和应用的主要原因,手术安全性及远期屈光效果仍然需要长期的随访观察。本文根据文献资料,就飞秒激光在白内障手术中的优势及临床应用的局限性进行综述。     

Expression of Cytokines,Chmokines and Growth Factors in Patients Undergoing Cataract Surgery with Femtosecond Laser Pretreatment

Purpose

To describe cytokines, chemokines and growth factors profiles in patients undergoing cataract surgery with femtosecond laser pretreatment and investigate their relationships with the postoperative in vivo inflammation index.

Methods

Aqueous humor was collected from 22 eyes after femtosecond laser pretreatment and from 22 eyes at the beginning of routine cataract surgery. The levels of 45 inflammation-related mediators were measured using multiplex fluorescent bead-based immunoassays. Laser flare photometry was measured preoperatively and at 1 day, 7 days and 30 days postoperatively.

Results

Compared with the control group, the femtosecond laser treatment group showed significantly higher aqueous humor levels of fibroblast growth factor (FGF-2), tumor necrosis factor (TNF)-α, leukemia inhibitor factor (LIF), interleukin (IL)-1ra and IL-18, and significantly lower aqueous humor levels of IL-9, platelet-derived growth factor (PDGF)-BB, eotaxin and TNF-β. Postoperative aqueous flare was significantly greater in the manual cataract surgery group at 1 day (p<0.001), 7days (p<0.001) and 30 days (p = 0.002).No correlation was found between the analyzed mediators and the aqueous flare values.

Conclusions

The expression profiles of cytokines, chemokines and growth factors and the correlations of these profiles with the in vivo inflammatory indexes for patients undergoing cataract surgery with femtosecond laser pretreatment were identified. Our data indicate a disturbance of postoperative inflammation response after femtosecond laser treatment.     

全飞秒激光与飞秒激光辅助Lasik治疗高度近视患者的效果及对角膜曲率、视觉质量的影响分析

摘要 目的：探究全飞秒激光与飞秒激光辅助Lasik治疗高度近视患者的效果,并分析治疗对患者角膜曲率、视觉质量的影响。方法：选择2020年7月至2022年7月在我院接受治疗的120例（240眼）高度近视患者为研究对象,按照随机数字表法结合患者意愿的方式将其区分为研究组（n=60,接受飞秒激光辅助Lasik治疗）与对照组（n=60,接受全飞秒激光治疗）,对比两组患者术前术后调制传递函数截止频率（MTF）值及客观散射指数（OSI）、角膜曲率变化、屈光度差异、视力情况差异,统计两组患者各类并发症发生率并进行比较。结果：（1）两组患者术前MTF值及OSI组间差异无统计学意义（P>0.05）,术后研究组患者的MTF值和OSI值均明显低于对照组,差异具有统计学意义（P<0.05）;（2）术前、术后90 d两组患者的最佳矫正视力组间差异无统计学意义（P>0.05）,但组内前后比较两组患者的最佳矫正视力均较术前有明显提高（P<0.05）;（3）术前两组患者的角膜前表面曲率以及后表面曲率组间差异均无统计学意义（P>0.05）,术后90 d时开展组间比较,研究组患者角膜前表面曲率中K1、K2以及Km值均明显低于对照组（P<0.05）,但后表面曲率中K1、K2以及Km值组间差异无统计学意义（P>0.05）;进一步分析显示,两组患者术前术后前表面曲率K1、K2以及Km值有明显变化（P<0.05）,后表面曲率K1、K2以及Km值前后差异无统计学意义（P>0.05）;（4）统计研究组患者共出现弥漫性层间反应2例,感染1例,角膜内生1例,并发症总发生率3.33%（4/120）,明显高于对照组的0.00%（0/120）（P<0.05）。结论：全飞秒激光和飞秒激光辅助Lasik术对高度近视均具有较好的治疗效果,相比于全飞秒激光术,飞秒激光辅助Lasik术在改善患者视觉质量方面明显占优,但其并发症发生率同样更高,全飞秒激光术术后视觉质量,但安全性更高,建议临床上结合患者实际情况灵活选择术式,以改善高度近视患者预后。     

Partial Contact Indentation Tonometry for Measurement of Corneal Properties-Independent Intraocular Pressure

Inter-individual differences in corneal properties are ignored in existing methods for measuring intraocular pressure IOP, a primary parameter used in screening and monitoring of glaucoma. The differences in the corneal stiffness between individuals can be more than double and this difference would lead to IOP measurement errors up to 10 mmHg. In this study, an instrumented partial-contact indentation measurement and analysis method that can account for inter-individual corneal difference in stiffness is developed. The method was tested on 12 porcine eyes ex vivo and 7 rabbit eyes in vivo, and the results were compared to the controlled IOPs to determine the method's validity. Analyses showed that without corneal stiffness correction, up to 10 mmHg of measurement error was found between the existing approach and the controlled IOP. With the instrumented indentation and analysis method, less than 2 mmHg of differences were founded between the measured IOP and the controlled IOP. These results showed that instrumented partial-contact indentation can effectively account for inter-individual corneal variations in IOP measurement.     

The Morphology of Corneal Cap and Its Relation to Refractive Outcomes in Femtosecond Laser Small Incision Lenticule Extraction (SMILE) with Anterior Segment Optical Coherence Tomography Observation

Purpose

To investigate the morphology of corneal caps in femtosecond laser small incision lenticule extraction (SMILE) and its relation to the refractive outcomes.

Methods

A prospective study of fifty-four corneal caps created with VisuMax femtosecond laser were examined using an Fourier-domain optical coherence tomography at 1 day, 1 week, 1 month and 6 months after SMILE. The cap thickness at nine points on each of the four meridians (0°, 45°, 90°, 135°) and the diameter were measured. Cap morphology, changes over time and its correlation with refractive outcomes were assessed.

Results

The mean achieved central cap thickness were (108.74±5.06) µm at 6 months and (107.32±4.81 ) µm at 1 month postoperatively, significantly thinner than that at 1 day (110.81±7.95) µm and 1 week (109.58±7.48 ) µm (P<0.05). The mean diameter on 0° meridian was (7.61±0.07) mm, significantly larger than that on 90° meridian (7.57±0.06) mm (P = 0.001). Cap morphology showed good regularity, except that the differences of points in two pairs were significant at 1 day postoperatively. The uniformity was consistent over time and the central cap thickness was thinner than those in the paracentral and peripheral areas. The refractive outcomes stabilized within 1 month. Uncorrected distance visual acuity (UDVA) was correlated to the central cap thickness at 1 day and 1 week (both r_s = 0.33, p<0.05). The uniformity index was correlated with UDVA (r_s = 0.34, p<0.05) and corrected distance visual acuity (r_s = 0.32, p<0.05) at 1 week postoperatively.

Conclusions

Corneal caps of SMILE are predictable with good reproducibility, regularity and uniformity. Cap morphology might have a mild effect on refractive outcomes in the early stage. Further study should focus on the impact on the visual quality.     

Confocal Comparison of Corneal Reinnervation after Small Incision Lenticule Extraction (SMILE) and Femtosecond Laser In Situ Keratomileusis (FS-LASIK)

Purpose

To evaluate corneal reinnervation, and the corresponding corneal sensitivity and keratocyte density after small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK).

Methods

In this prospective, non-randomized observational study, 18 patients (32 eyes) received SMILE surgery, and 22 patients (42 eyes) received FS-LASIK surgery to correct myopia. The corneal subbasal nerve density and microscopic morphological changes in corneal architecture were evaluated by confocal microscopy prior to surgery and at 1 week, 1 month, 3 months, and 6 months after surgery. A correlation analysis was performed between subbasal corneal nerve density and the corresponding keratocyte density and corneal sensitivity.

Results

The decrease in subbasal nerve density was less severe in SMILE-treated eyes than in FS-LASIK-treated eyes at 1 week (P = 0.0147), 1 month (P = 0.0243), and 3 months (P = 0.0498), but no difference was detected at the 6-month visit (P = 0.5277). The subbasal nerve density correlated positively with central corneal sensitivity in both groups (r = 0.416, P<0.0001, and r = 0.2567, P = 0.0038 for SMILE group and FS-LASIK group, respectively). The SMILE-treated eyes have a lower risk of developing peripheral empty space with epithelial cells filling in (P = 0.0005).

Conclusions

The decrease in subbasal nerve fiber density was less severe in the SMILE group than the FS-LASIK group in the first 3 months following the surgeries. The subbasal nerve density was correlated with central corneal sensitivity.     

Intraocular microablation of choroidal tissue by a 308 nm AIDA excimer laser for RPE-transplantation in patients with age-related macular degeneration.

Age-related macular degeneration (AMD) is the leading cause of legal blindness in the western nations beyond 50 years of age. The most frequent cause for severe visual loss is the growth of neovascular membrances from the choroid into the subretinal space. This usually results in irreversible degeneration of the overlying retina. Surgical removal of the membrane is feasible, however, usually results in functional loss of apposing retinal photoreceptors since retinal pigment epithelial (RPE) cells are removed concurrently due to their tight adherence to the neovascular complex. Therefore, various attempts have been undertaken to fill the resulting RPE cell defect with either heterologous or autologous RPE cell transplants. So far cell survival, function and subsequent visual function has been disappointing. To minimize trauma and resulting dedifferentiation harvesting in the eye and transplantation in whole sheets and without temporary removal from the eyes would be desirable. This may be achieved by isolating grafts consisting of choroid, Bruch's membrance and RPE cells from the peripheral retina and transplantation of this graft under the neurosensory retina after removal of the choroidal neovascularization. However, the choroidal component of such a graft would be expected to interfere with diffusion of metabolites to and from the retina. Therefore, outcome would be expected to be better if the choroidal tissue would be removed before translocation. In preclinical experiments we used a 308 nm UV AIDA excimer laser to microablate choroidal tissue from such a graft in human donor eyes.     

透明角膜切口白内障术后角膜曲率的临床观察*

目的:观察年龄相关性白内障行透明角膜切口超声乳化吸除及人工晶体植入术后角膜曲率的变化及相对稳定的时间。方法:收集2016年6月-8月在哈尔滨医科大学附属第一医院伍连德纪念医院进行的3.0 mm透明角膜切口白内障超声乳化吸除及人工晶体植入术的患者200例216眼,其中男88例、女128例,平均年龄71.2岁,进行相应的术前检查,并检查术前、术后第一天、一周、一个月、和三个月时的角膜曲率、视力、眼压并行相应的统计学分析。结果:术后不同时间点视力0.5的恢复情况:第一天为147眼(68.05%)、一周为175眼(81.02%)、一个月为193眼(89.35%)、三个月为197眼(91.20%);术前角膜曲率为43.94±1.35、术后第一天、术后一周的角膜曲率分别为44.98±1.06、44.45±1.18,与术前相比有显著性差异(p0.05),术后一个月、三个月的角膜曲率分别为44.13±1.27、44.02±1.24,与术前相比无显著性差异(p0.05);术源性散光于术后一天达到最大,随后逐渐减小,术后一个月、三个月与术后一天比较有显著性差异(p0.05),术后三个月与一个月比较无显著性差异(p0.05),术源性散光术后逐渐下降,并于一个月时趋于稳定。结论:3.0 mm透明角膜切口白内障超声乳化吸除及人工晶体植入术患者在术后一个月的角膜曲率基本稳定,恢复至术前状态,屈光状态趋于稳定,术源性角膜散光较小,术后视力恢复至较好状态。     

Evaluation of the Corneal Test as a Laboratory Method for Rabies Diagnosis

The corneal test (CT) for rabies diagnosis was evaluated in samples from 313 subjects of different species. Some of the subjects were inoculated experimentally and others were naturally infected. When the CT was compared with immunofluorescence staining and mouse inoculation tests on brains of the same subjects, a sensitivity of 41.7% and a specificity of 100% were found. The authors conclude that a positive CT result would confirm the diagnosis of rabies, but a negative one would not exclude the possibility of disease.     

Exposure of Chlorpromazine to 266 nm Laser Beam Generates New Species with Antibacterial Properties: Contributions to Development of a New Process for Drug Discovery

Introduction

Phenothiazines when exposed to white light or to UV radiation undergo a variety of reactions that result in degradation of parental compound and formation of new species. This process is slow and may be sped up with exposure to high energy light such as that produced by a laser.

Methods

Varying concentrations of Chlorpromazine Hydrochloride (CPZ) (2–20 mg/mL in distilled water) were exposed to 266 nm laser beam (time intervals: 1–24 hrs). At distinct intervals the irradiation products were evaluated by spectrophotometry between 200–1500 nm, Thin Layer Chromatography, High Pressure Liquid Chromatography (HPLC) - Diode Array Detection, HPLC tandem mass spectrometry, and for activity against the CPZ sensitive test organism Staphylococcus aureus ATCC 25923.

Results

CPZ exposure to 266 nm laser beam of given energy levels yielded species, whose number increased with duration of exposure. Although the major species produced were Promazine (PZ), hydroxypromazine or PZ sulfoxide, and CPZ sulfoxide, over 200 compounds were generated with exposure of 20 mg/mL of CPZ for 24 hrs. Evaluation of the irradiation products indicated that the bioactivity against the test organism increased despite the total disappearance of CPZ, that is due, most probably, to one or more new species that remain yet unidentified.

Conclusions

Exposure of CPZ to a high energy (6.5 mJ) 266 nm laser beam yields rapidly a large number of new and stable species. For biological grade phenothiazines (in other words knowing the impurities in the samples: solvent and solute) this process may be reproducible because one can control within reasonably low experimental errors: the concentration of the parent compound, the laser beam wavelength and average energy, as well as the duration of the exposure time. Because the process is “clean” and rapid, it may offer advantages over the pyrogenically based methods for the production of derivatives.     

Comparison of Dry Eye and Corneal Sensitivity between Small Incision Lenticule Extraction and Femtosecond LASIK for Myopia

Purpose

To investigate the changes in dry eye symptoms and clinical signs and corneal sensitivity after small incision lenticule extraction (SMILE) and femtosecond LASIK (femto-LASIK).

Design

Prospective, non-randomized comparative study.

Methods

The study included a total of 71 eyes of 71 patients; the SMILE group comprised 38 eyes of 38 patients, and the femto-LASIK group comprised 33 eyes of 33 patients. Ocular Surface Disease Index (OSDI), Tear film breakup time (TBUT), the Schirmer test without anesthesia (S1T), corneal fluorescein staining, and central corneal sensation were evaluated before surgery and at 1 week, 1 month, 3 months, and 6 months after surgery.

Results

OSDI scores in both groups were increased immediately and returned to preoperative level at 1 month after surgeries. The TBUT values in both groups were reduced after surgeries relative to their preoperative scores. Patients in SMILE group were less likely to have corneal staining compared with those in the femto-LASIK group ([odds ratio] OR = 0.50, 95% [confidence interval] CI 0.28 to 0.93, P = 0.03). Central corneal sensitivity was decreased at all postoperative time points in both groups. However, the central corneal sensation scores in the SMILE group were greater than that in the femto-LASIK group at all of the postoperative time points (all P<0.05).

Conclusions

SMILE surgeries resulted in a short-term increase in dry eye symptoms, tear film instability, and loss of corneal sensitivity. Furthermore, SMILE surgeries have superiority over femto-LASIK in lower risk of postoperative corneal staining and less reduction of corneal sensation.     

Parametric Interaction of High-Power Laser Radiation with Plasma in a Strong Magnetic Field

Plasma Physics Reports - The article deals with interaction of an extraordinary laser wave of high amplitude with inhomogeneous plasma in a strong magnetic field in the vicinity of twice the...     

XeCl（308nm）准分子紫外激光对生物大分子酵母甘露聚糖分子结构的辐照效应

激光在农业和医疗等方面已有广泛应用,并且取得增产和一定疗效,但也有费介现象(暂称后继效应或潜在效应).激光辐照生物体虽然是局部的有限时间,但对由多种生物大分子组成的牛物体的影响可能是综合的.为了探索激光生物学效应的分子机理,以便进一步认识和掌握激光的生物学效应,对激光直接辐照有生物活性的生物大分子一酵母甘露聚糖产生的效应进行电镜扫描观察和紫外及红外光谱法分析研究.实验结果表明:308 nm 激光(单脉冲25 mJ,33.3 ml-34.4 ml,脉冲频率2次/s)无论是固定辐照时间(45 s)变化样晶所置距离,或反之固定样品所置距离(290 mm)改变辐照时广开J为15 s、30 s、45 s或60 s,都能引起受照样品的结构(构象)变化,特别足糖分子结构中富含的-OH、-CH-OH、-C-O-c-、-N-C=0、-C=0等结构部件处的IR谱线对激光能最变化影响敏感.它们既是糖分子内或分子间形成氧键和糖苷键的结构基础部件,又是甘露聚糖(Man-nan)糖基化其他生物大分子进而影响它们在生物信息流中作用的重要结构部件.结果显示糖在激光牛物效应中起了不可忽视的作用,这为综合探索激光生物效应分子机理和糖在生物信息传递中的作用提供了重要线索,为选择甘露聚糖作为生物导弹载体提供了参考依据.     

超声乳化白内障手术后患者角膜内皮细胞损伤的研究

目的:探讨超声乳化白内障手术患者角膜内皮细胞的损伤情况。方法:收集我院确诊为白内障的患者121例,随机分配为微切口组与常规切口组。常规切口组采用3.0 mm切口超声乳化白内障手术方案,微切口组采用1.8 mm小切口超声乳化白内障手术。手术前、手术后1日、7日、1个月、3个月监测患者角膜内皮细胞密度、六角形细胞比例、角膜内皮细胞变异系数及中央角膜厚度。结果:与治疗前相比,两组患者手术后1日、7日、1个月、3个月的角膜内皮细胞密度、六角形细胞比例及角膜内皮细胞变异系数均较治疗前显著降低(P0.05);手术后1日、7日时,两组患者的中央角膜厚度均较手术前明显变薄,有统计学差异(P0.05);手术后1个月、3个月,两组患者的中央角膜厚度均呈降低趋势,最终与手术前相似。微切口组患者不同时点六角形细胞比例与同期常规切口组比较均显著升高,角膜内皮细胞变异系数与同期常规切口组比较均明显降低有统计学差异(P0.05)。两组患者手术前后不同时间点角膜内皮细胞密度、中央角膜厚度组间比较均无统计学差异(P0.05)。结论:超声乳化白内障手术后患者角膜内皮细胞损伤与手术切口有相关性,缩小手术面积的小切口手术使术后修复增快,安全有效,适宜临床推广。     

Correlation between Lamina Cribrosa Tilt Angles,Myopia and Glaucoma Using OCT with a Wide Bandwidth Femtosecond Mode-Locked Laser

Purpose

To measure horizontal and vertical lamina cribrosa (LC) tilt angles and investigate associated factors using prototype optical coherence tomography (OCT) with a broad wavelength laser light source.

Design

Cross sectional study.

Methods

Twenty-eight no glaucoma eyes (from 15 subjects) and 25 glaucoma eyes (from 14 patients) were enrolled. A total of 300 optic nerve head B-scans were obtained in 10 µm steps and the inner edge of Bruch''s membrane opening (BMO) was identified as the reference plane. The vertical and horizontal angles between BMO line and approximate the best-fitting line for the surface of the LC were measured and potential associated factors were estimated with univariate and multivariate logistic regression analyses.

Results

The median (interquartile range) horizontal and vertical tilt angles were 7.10 (2.43–11.45) degrees and 4.15 (2.60–6.85) degrees in eyes without glaucoma and 8.50 (4.40–14.10) degrees and 9.30 (6.90–14.15) degrees in glaucoma eyes, respectively. The refractive errors had a statistically significant association with horizontal LC tilt angles (coefficients, −1.53 per diopter) and glaucoma had a significant correlation with vertical tilt angles (coefficients, 6.56) using multiple logistic regression analysis (p<0.001).

Conclusions

OCT allowed evaluation of the internal tilting of the LC compared with the BMO. The horizontal internal LC tilt angle was correlated with refractive errors, corresponding to myopic physiological changes, and vertical internal LC tilt was correlated with glaucoma, corresponding to glaucomatous pathological changes. These parameters have important implications for investigation of the correlation between myopia, glaucoma and LC morphological features.