Atomic Force Microscopic Observations on the Crystalline Morphology of Poly(ethylene naphthalate)/Clay Nanocomposites

Atomic force microscopic observations on an isothermally crystallized poly(ethylene naphthalate) (PEN)/clay nanocomposite suggest that the presence of nanoclay alters the lamellar organization in PEN mainly in three ways: 1) physically blocking the crystal growth front and creating wide amorphous regions within the spherulites, which may then be filled by secondary lamellae branching out from the primary lamellae of the same spherulite, or primary lamellae developed from other nearby nucleating centers; 2) inducing random twisting of lamellae; and 3) causing irregular crystallite growth fronts, with the protrusion of some leading lamellae. In particular, the physical hindrance imposed by clay tends to be more prevalent for lamellae that grow roughly perpendicular to the clay long axes. This may give rise to an anisotropic crystalline morphology if the clay layers exhibit a preferred orientation induced by flow.

     

Spontaneous closure of lamellar macular holes studied by optical coherence tomography

Purpose: To document and study the spontaneous closure of lamellar macular holes (LMH) by optical coherence tomography (OCT). Methods: Two women with LMH, 62 and 71 years old, respectively, were followed up with fundoscopy, fundus photography and OCT. Results: In both patients spontaneous closure of LMH was observed 11 and 21 months after baseline examination, respectively. The foveal thickness in case 1 increased from 84 μm at baseline to 162 μm at the final examination. The foveal thickness in case 2 increased from 48 μm at baseline to 148 μm at the final examination. The foveal contour was also restored in both eyes. The foveal morphology was preserved in both eyes during the follow‐up period. Conclusion: In both patients the spontaneous closure of LMH could be attributed to the shrinkage of the hole or the release of the tension on the retinal surface, which followed the complete posterior vitreous detachment and separation of epiretinal membrane from the retina.     

Corneal endothelium after deep anterior lamellar keratoplasty and penetrating keratoplasty for keratoconus: a four-year comparative study

Purpose:

To compare the status of corneal endothelium and central corneal thickness within the first four postoperative years after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) in patients with keratoconus.

Materials and Methods:

Thirty-nine eyes (Group A) which had PK and 44 eyes (Group B) which had DALK for the treatment of keratoconus were included in this retrospective study. The endothelial cell density (ECD), the mean endothelial cell area and the coefficient of variation of cell area were assessed with a non-contact specular microscope, and the central corneal thickness (CCT) was measured with an ultrasound pachymeter.

Results:

Mean ECD loss rate at two years was 36.24% in Group A and 18.12% in Group B (P<0.001). Mean ECD loss rate at four years was 47.82% in Group A and 21.62% in Group B (P<0.001). Mean annual ECD loss rate was calculated 14.12% per year in Group A and 5.78% per year in Group B. In the PK group, increase in mean CCT was 15.60% in two years and 15.03% in four years, while in the DALK group, mean CCT increased by 8.05% in two years and 9.31% in four years.

Conclusions:

As the majority of ectatic disorders such as keratoconus occur in young people, long-term endothelial cell survival following treatment with keratoplasty is essential for the long-term visual ability. Our finding that corneal endothelial cell loss in the DALK group occurs at a slower rate than in the PK group suggests DALK as a safer alternative to PK in these selected patients.     

两种深板层角膜移植术治疗圆锥角膜的比较研究

目的对比仅保留后弹力层和内皮细胞层植床的改良Anwar技术深板层角膜移植术(deep anterior lamellar keratoplasty performed with the modified Anwar technique,DALKa)和保留少量角膜基质的手工分离深板层角膜移植术(deep anterior lamellar keratoplasty performed with the manual technique,DALKm)治疗圆锥角膜的临床效果。方法对我院临床诊断明确的中晚期圆锥角膜40例42眼进行手术治疗,其中行DALKa者18眼为DALKa组,行DALKm者24眼为DALKm组。术后随访2a,对比分析术后最佳矫正视力、屈光状态和并发症情况。结果术后2a,最佳矫正视力≥0.5者DALKa组占94.4%(17/18),DALKm占54.2%(13/24),差异有统计学意义(P<0.05);两组最佳矫正视力≥1.0者分别占50.0%和25.0%,差异无统计学意义(P>0.05)。术后1a,DALKa组的近视度数和散光度数分别为(-3.08±1.13)D和(-3.00±1.02)D,DALKm组分别为(-2.63±1.02)D和(-3.33±1.17)D;术后2a,DALKa组近视度数和散光度数分别为(-3.97±1.07)D和(-2.09±1.15)D,DALKm组分别为(-2.10±0.98)D和(-3.05±1.20)D;术后1a、2a两组近视度数和散光度数差异均无统计数意义(均为P>0.05)。DALKa组术中发生后弹力层穿孔2眼,术后后弹力层皱褶4眼;DALKm组出现后弹力层皱褶、角膜炎、上皮病变及再次角膜移植者各3眼。结论相对DALKm,DALKa成功率更高,术后并发症更少,矫正视力更好,是治疗圆锥角膜的更好的术式。     

深板层角膜移植临床观察

目的 观察深板层角膜移植术的临床疗效及并发症.方法 用甘油冷保存角膜对病变角膜行深板层角膜移植术15例(15眼)并对其疗效进行观察分析.术后随访l4～18个月.结果 术后矫正视力0.08者1眼,0.12～0.25者4眼,0.3～0.5者6眼,≥0.6者4眼.1周内角膜植片透明11眼,2周内植片透明3眼,后弹力层固有皱褶角膜半透明1眼.术后1眼病毒性角膜炎复发角膜愈合成斑翳.其余未发现角膜排斥反应.结论 深板层角膜移植术为治疗角膜病变是一种有效的方法,术后视力较好、并发症较少、对供体材料条件要求较低.     

适宜中国国情的角膜移植技术的挑战和创新

角膜盲是我国仅次于白内障的致盲性疾病,角膜供体材料匮乏造成角膜盲患者绝对数量仍在逐年上升。与欧美发达国家不同,严重的感染性角膜炎、热烧伤、化学伤和各种眼内手术引起的大泡性角膜病仍然是我国角膜移植的主要适应证。我国角膜盲的防盲面临着患者病情重、依从性差、可支付能力低和角膜供体材料严重缺乏的多重挑战。近年来,我国的角膜专科医师根据特殊的国情,发展和创新了一系列深板层移植、内皮移植、人工角膜移植和组织工程角膜异种移植的新技术,从技术层面显著提高了供体角膜材料的利用率,降低了高危移植的排斥反应。然而,由于角膜供体材料极其缺乏的瓶颈依旧,能掌握当代角膜移植新技术的角膜专科医师数量稀少,目前推动角膜捐献的立法工作和深入组织工程异种角膜材料学研究、加强国际间眼库合作迫在眉睫,适宜国情的角膜移植技术的创新和推广工作仍然任重而道远。     

自动角膜板层刀切割一个供体角膜用于两位患者

目的评估应用自动角膜板层刀切割一个供体角膜用于深板层角膜移植和角膜内皮移植的临床疗效及安全性。方法回顾性系列病例研究。应用自动角膜板层刀预先将新鲜供体角膜进行切割,将带部分基质的角膜内皮植片用于角膜内皮移植术,剩余前板层用于深板层角膜移植术。回顾性分析2010年3—8月期间在温州医学院附属眼视光医院行角膜内皮移植术的17例患者及分别来自同一供体角膜的行深板层角膜移植的17例患者。术后随访19～24个月,分别观察角膜内皮贴附情况及前板层角膜植片愈合情况。随访资料包括医学验光、前节光学相干断层扫描及角膜内皮细胞计数。手术前后视力比较采用配对t检验。结果17例角膜内皮移植患者术后角膜内皮植片均贴附良好,术后视力较术前均有提高。除1例碱烧伤患者因晶状体混浊,无法验光外,其余术后平均散光为（1．69±0．60）D。17例角膜内皮移植患者平均角膜内皮细胞计数为（2128±244）个／mm^2,平均角膜内皮植片厚度为（152±46）μm。17例前板层角膜移植患者角膜植片均透明,术后最佳矫正视力较术前提高,平均散光为（2．50±0．90）D;平均前板层角膜植片厚度为（343±39）μm。结论利用角膜板层刀将一个供体角膜用于两位患者的方法在临床实际应用中切实可行。经长期随访,角膜植片未出现明显并发症。该方法可以更充分地利用供体角膜,缓解中国供体角膜匮乏现状,意义重大。     

前部深板层角膜移植治疗偏中心角膜溃疡穿孔效果评估

目的探讨偏中心角膜溃疡发生穿孔的患者采用前部深板层角膜移植（DLKP）治疗的有效性及可行性。方法回顾性病例研究。总结观察2008年12月至2011年1月间,11例（11眼）多种原因导致的角膜溃疡穿孔、穿孔范围1．5～2．0mm且穿孔部位在瞳孔边缘到角膜缘之间的患者行深板层角膜移植术,其中2例是独眼。术后对角膜移植片透明率、视力、眼压、角膜内皮细胞数量、排斥反应、角膜新生血管以及溃疡复发等进行评估。结果随诊观察12～24个月,平均（17．5±3．7）个月。10眼角膜移植术后愈合良好（91％）,无双前房形成,角膜移植片除穿孔区混浊外余均透明,恢复正常角膜厚度;1眼下方角膜溃疡者（患有类风湿和药物过敏）术后在溃疡处出现双前房,愈合不良导致植片混浊（9％）。所有患者视力均有提高,术前视力：光感：3眼,手动：5眼,指数：2眼,0．01～0．05：1眼;术后视力：0．01～0．05：1眼,0．1～0．2：8眼,〉0．2：2眼。眼压正常。角膜内皮数为1862～2756个／mm^2,平均（2286±293）个／mm^2。未发生排斥反应,角膜溃疡无复发,未发生角膜移植片和层间新生血管化。结论深板层角膜移植是治疗偏中心小范围角膜溃疡发生穿孔患者的有效方法。     

An inadvertent usage of the deep stromal lenticule in anterior lamellar keratoplasty – An emancipator technique

Anterior lamellar keratoplasty (ALK), of late, has gained popularity because of its prolonged graft survivability as a result of reduced endothelial cell loss. A 56-year-old female with bilateral granular corneal dystrophy was taken up for ALK in the left eye. Because of unforeseen errors during the procedure, the surgeon was obliged to customize a novel technique by using a deep stromal lenticule after removal of Descemet’s membrane. Post-op visual recovery was equivalent to conventional ALK with complete epithelization of the graft. This new or adapted technique has an added advantage for surgeons to prevent forfeiture of the valuable donor tissue. In the developing world, manual dissection is still the primary technique of lamellar keratoplasty and many precious corneas get wasted because of intra-operative unintended errors of dissection and trephination. Therefore, this novel technique holds its importance in saving the precious corneal tissue, especially in developing countries, and opens a new area for exploration.