Spontaneous breakage of intracorneal ring segments (ICRS) 8 years after implantation

We present a case of spontaneous in situ breakage of intracorneal ring segments (ICRSs) 8?years after their implantation in a patient with keratoconus. The patient presented to our clinic with a red and painful right eye that had not improved despite topical steroids and antibiotics. The decision was made to explant the broken ICRSs from the cornea and send them for laboratory analyses, by which manufacturer defects were excluded. It is noteworthy that corneal curvature re-steepening was observed 4?months after ICRS removal despite the performance of crosslinking (CXL) 1?year prior to ICRS implantation.     

圆锥角膜基质环植入术的研究进展

角膜基质环植入术(ICRS)是一种用于治疗轻中度圆锥角膜的手术方法。ICRS是通过植入基质环,使中央角膜扁平化,弧长缩短,角膜曲率半径增大,屈光力降低,从而改善角膜前突导致的轴性近视眼与不规则散光。ICRS具有微创性、安全性、有效性、可逆性且并发症少等优点,其中长期疗效较佳。本文中笔者就ICRS的发展史、适应症、手术方法、手术疗效的影响因素、术后处理及疗效的评估等方面进行阐述。     

Using an Ultrasound Elasticity Microscope to Map Three-Dimensional Strain in a Porcine Cornea

An ultrasound elasticity microscope was used to map 3-D strain volume in an ex vivo porcine cornea to illustrate its ability to measure the mechanical properties of this tissue. Mechanical properties of the cornea play an important role in its function and, therefore, also in ophthalmic diseases such as kerataconus and corneal ectasia. The ultrasound elasticity microscope combines a tightly focused high-frequency transducer with confocal scanning to produce high-quality speckle over the entire volume of tissue. This system and the analysis were able to generate volume maps of compressional strain in all three directions for porcine corneal tissue, more information than any previous study has reported. Strain volume maps indicated features of the cornea and mechanical behavior as expected. These results constitute a step toward better understanding of corneal mechanics and better treatment of corneal diseases.     

Association of Lysyl oxidase (LOX) Polymorphisms with the Risk of Keratoconus in an Iranian Population

Background: Keratoconus is a connective tissue-related eye disease with unknown etiology that causes the loss of visual acuity. Lysyl oxidase (LOX) is an amine oxidase that catalyzes the covalent cross-link of collagens and elastin in the extracellular environment, thus determining the mechanical properties of connective tissue. The current study aimed to investigate the possible associations between two LOX polymorphisms, rs1800449 and rs2288393, and susceptibility to keratoconus.

Methods: A total of 262 Iranian subjects including 112 patients with keratoconus and 150 healthy individuals as controls were recruited. Genotyping for the LOX variants was performed using allele-specific PCR.

Results: A significant difference was found between two groups regarding allelic and genotyping distribution of LOX polymorphism at position rs1800449 G>A. The frequency of AA and GA?+?AA genotypes were increased in patients compared to controls (17% versus 8% and 62.5% versus 50%, respectively), showing a statistically significant difference (OR?=?2.827, 95% CI: 1.251–6.391, p?=?0.012). The A allele was associated with an increased risk for keratoconus, with the frequency of 39.9% and 29% in patients and controls, respectively (OR?=?1.614, 95% CI: 1.119–2.326, p?=?0.011). Furthermore, the haplotype analysis revealed that the rs1800449G/rs2288393C is a protective factor against keratoconus (OR?=?0.425, 95% CI?=?0.296–0.609, p?=?0.001). Conversely, the +473A/rs2288393C (OR?=?3.703, 95% CI?=?2.230–6.149, p?=?0.001) and +473G/rs2288393G (OR?=?15.48, 95% CI?=?3.805–63.03, p?=?0.001) haplotypes were identified as risk factors for keratoconus.

Conclusion: Our study demonstrated that the LOX rs1800449 genotypes (AA and GA?+?AA) and allele (A) appears to confer risk for susceptibility to keratoconus.     

Pilot study of transepithelial， very high fluence accelerated corneal collagen cross-linking in primary keratoconus

Objective Evaluate the safety and effectiveness of transepithelial, very high fluence accelerated corneal collagen cross-linking （A-CXL） in primary keratoconus. Methods Self-control study. Thirteen primary keratoconus eyes of 13 patients were treated with transepthelial, very high fluence A-CXL with a UVA intensity of 45 mW/cm2, an irradiation time of 2 min 40 s, and a total energy of 7.2 J/cm2. Routine ophthalmologic examination, UCVA, BCVA, refractive error, corneal keratometry, anterior and posterior elevation （AE and PE）, index of vertical asymmetry （IVA）, minimum corneal thickness （CT）, compensated intraocular pressure （IOPcc）, endothelial cell density （ECD） were evaluated pre-operatively and 7-day, 1-month, 3-month, 6-month, 12-month post-operatively. Results The UCVA （F=6.111, P＜0.01） and BCVA （F=9.734, P＜0.01） showed a statistically significant improvement by 12-month post-operatively. The decrease in spherical lens （F=5.871, P＜0.05）, steeper K-value （F=19.651, P＜0.05）, Kmax （F=3.253, P＜0.05）, AE （F=23.958, P＜0.01）, PE （F=20.832, P＜0.01） and IVA （F=4.068, P＜0.05） were statistically significant. CT （F=4.180, P＞0.05）, ECD （F=1.812, P＞0.05） and IOPcc （F=0.332, P＞0.05） were without significant change. Conclusion Transepithelial, very high fluence A-CXL is safe and effective in treating primary keratoconus.     

Asociación entre polimorfismos de los genes POLG y XRCC1 y aparición de queratocono entre pacientes egipcios

BackgroundKeratoconus is a progressive disorder distinguished by thinning of the corneal tissue and bulging forward into a cone-shaped fashion. Yet its etiology, which is multifactorial, despite intensive research remains elusive. Corneal exposure a reactive oxygen species causing oxidative DNA damage has been reported to be associated with KC and therefore suggesting that DNA base excision repair mechanism might lie behind the pathogenesis of the disease.MethodsWe studied the association of three variants in two BER genes (XRCC1 and POLG) and QC occurrence in a cohort of patients from Egypt. Genotyping of the three variants was performed using PCR and restriction enzymes analysis.ResultsWe observed that A allele and A/A genotype of the c.1196A>G variant in the XRCC1 gene were significantly associated with increased KC occurrence while the G allele was associated with decreased KC occurrence. Similarly, the A/A genotype of the c.–1370T>A polymorphism in the POLG gene and the A allele were associated with increased occurrence of KC, while T/A genotype and the T allele were accompanied with decreased occurrence of KC. On the other hand, no association was observed between the c.580C>T variant in the XRCC1 gene and KC occurrence among the studied group of patients.ConclusionOur results suggest that c.1196A>G variant of the XRCC1 and c.–1370T>A variant of the POLG gene may be involved in KC pathogenesis and might be considered as a genetic risk factors of the disease among Egyptian population.     

Corneal ectasia after photorefractive keratectomy

Background Corneal ectasia after photorefractive keratectomy (PRK) has only been occasionally reported, and its incidence has not been assessed. Methods In a retrospective, non-comparative case series, incidence of corneal ectasia was evaluated in a personal consecutive 6453-case series of myopic PRK with a minimum follow-up of 18 months. Features and prognosis were evaluated in all patients with ectasia after PRK (in both personal and referred cases). Results Ectasia was detected in three eyes of two patients (patients 1 and 2) 3 years and 1 year after PRK performed elsewhere. In addition, in the personal PRK series, two eyes of two patients (patients 3 and 4) developed corneal ectasia 5 months after surgery (incidence: 0.03%). Pre-operatively, forme fruste keratoconus was present in patients 1, 3 and 4; keratoconus in the fellow eye in patient 2; pachymetry <500 micron in patients 2 and 3. In patient 1, rigid contact lenses were prescribed, and in patient 2 deep anterior lamellar keratoplasty was needed; in patients 3 and 4, low induced astigmatism resulted, requiring driving spectacles in patient 3. Conclusions PRK induced corneal ectasia in predisposed eyes, even after low myopic ablations. Forme fruste keratoconus and keratoconus in the fellow eye were the main pre-operative findings. Prognosis varies according to severity. The author has no financial or proprietary interest in any product or technique mentioned. The author has full control of all primary data, and agrees to allow Graefes Archive for Clinical and Experimental Ophthalmology to review the data upon request.     

亚临床期与进展期圆锥角膜地形图的比较

目的探讨圆锥角膜患者角膜地形图的特点，以期早期发现圆锥角膜患者。方法5例（8只眼）亚临床期圆锥角膜患者，14例（20只眼）进展期圆锥角膜患者。检查项目：（1）角膜地形图形态，（2）角膜中央层屈光力，（3）角膜屈光度的变化范围，（4）角膜曲率，（5）角膜表面规则指数。结果亚临床期的患者中，角膜地形图主要表现为蝶形，且多为非对称性，进展期的患者主要表现为乳头形、卵圆形及球形，角膜中央屈光度，距角膜中央I—S值有差异。结论角膜地形图检查可以早期发现圆锥角膜。     

表面角膜镜片术治疗有中央视区瘢痕的圆锥角膜

应用自制的表面角膜镜片对５例已有中央视区瘢痕的中晚期圆锥角膜者施行表面角膜镜片术，术中对４例行前房穿刺，降低眼压，以便充分地压平角膜圆锥，减低近视。结果：术后表面镜片上皮在３￣６天内完全再生，经过平均１１个月的随访，术后裸眼视力较术前提高１￣５行，平均３行。矫正视力较术前提高４￣７行，平均５行。近视较术前减少５￣１５．５Ｄ，平均１１．０Ｄ。讨论：根据本组５例的手术治疗结果，证实对于中央视区有较薄瘢