Femtosecond laser cataract surgery: technology and clinical practice

The recent introduction of femtosecond lasers to cataract surgery has generated much interest among ophthalmologists around the world. Laser cataract surgery integrates high‐resolution anterior segment imaging systems with a femtosecond laser, allowing key steps of the procedure, including the primary and side‐port corneal incisions, the anterior capsulotomy and fragmentation of the lens nucleus, to be performed with computer‐guided laser precision. There is emerging evidence of reduced phacoemulsification time, better wound architecture and a more stable refractive result with femtosecond cataract surgery, as well as reports documenting an initial learning curve. This article will review the current state of technology and discuss our clinical experience.     

屈光手术的回顾和展望

屈光手术和眼前节成像系统的发展大大提高了手术的安全性、有效性、可预测性和稳定性。飞秒激光可用于制作角膜瓣,进行角膜基质内切割,制作角膜基质环植入隧道等。与传统激光切削模式相比,波前像差引导等个性化切削模式能提高患者术后的视觉质量。角膜胶原交联术是一种治疗圆锥角膜的全新方法。有晶状体眼人工晶状体植入术和屈光性人工晶状体置换术对于高度近视和远视的治疗有着重要的临床应用价值。现有的老视手术有助于提高患者的生活质量。本文对各种屈光手术新技术及相关的眼前节成像系统进行了评述,并展望了屈光手术未来的发展趋势,强调了解屈光手术新技术和新设备的重要性,提出应该积极稳妥地推进屈光手术新技术在临床上的应用。     

Matrix metalloproteinases in disease and repair processes in the anterior segment

The pathogenesis of many anterior segment disorders and ocular complications following surgery are secondary to the wound healing response. The extent of clinical damage observed is closely related to the amount of scarring and tissue contraction. Matrix metalloproteinases (MMPs) are a family of enzymes that play a vital role in all stages of the wound healing process. They degrade all extracellular matrix components and also have the ability to synthesize collagen and extracellular matrix members, and are therefore important in the remodeling of a wound. Overexpression of MMPs results in excessive extracellular matrix degradation, leading to tissue destruction and loss of organ function. In the case of the anterior segment, this may mean the loss of visual function. This review focuses on the role MMPs have in the development of various anterior segment disorders. The importance of MMPs in the wound healing response and its potential modulation to manipulate the scarring response is being recognized, and current developments will be described.     

A review of anterior segment dysgeneses

The anterior segment dysgeneses are an ill-defined group of ocular developmental abnormalities that share some common features and have a high prevalence of glaucoma. Current classification of what are and what are not anterior segment dysgeneses seems to vary and our knowledge of them is incomplete. As the limits of classical clinical medicine based on evaluation of signs and symptoms are reached, further advancements increasingly will come from molecular medicine and genetics. In this article we review the normal and abnormal development of the anterior segment (concentrating primarily upon neural crest derived dysgeneses), describe the various clinical entities produced and their diagnosis, and discuss the current knowledge of the genetics of these disorders. We also suggest a new approach to the classification of anterior segment dysgeneses, based upon the embryological contribution to the formation of the anterior segment of the eye.     

超高分辨率光学相干断层扫描在眼前节的应用进展

作为一项非接触、无创的组织结构成像技术,光学相干断层扫描（optical coherence tomography,OCT）系统可对眼组织高分辨率成像。最初应用于眼后节组织结构成像,随后逐渐应用于眼前节。眼前节OCT技术的发展确保眼前节组织结构精准成像。近来提出的超高分辨率OCT（ultrahigh-resolution OCT,UHR-OCT）技术,实现了对眼前节各层次组织结构超高分辨成像,并成功应用于眼前节及眼表疾病的诊治。如定量测量干眼症患者泪膜厚度值,鉴别诊断眼表鳞状上皮瘤样增生性病变,监测各类角膜炎、圆锥角膜、角膜外伤等角膜疾病的病理生理变化趋势。同时,UHR-OCT亦可协助临床工作者制定合理的眼前节手术方案,如角膜移植术,并追踪观察术后角膜组织愈合等形态学变化情况。此外,该技术加深了对眼前节组织结构生理及病理生理形态学的了解。本文主要对UHR-OCT的技术原理及在眼前节应用进展等进行综述。     

Genomics and anterior segment dysgenesis: a review

Anterior segment dysgenesis refers to a spectrum of disorders affecting structures in the anterior segment of the eye including the iris, cornea and trabecular meshwork. Approximately 50% of patients with anterior segment dysgenesis develop glaucoma. Traditional genetic methods using linkage analysis and family‐based studies have identified numerous disease‐causing genes such as PAX6, FOXC1 and PITX2. Despite these advances, phenotypic and genotypic heterogeneity pose continuing challenges to understand the mechanisms underlying the complexity of anterior segment dysgenesis disorders. Genomic methods, such as genome‐wide association studies, are potentially an effective tool to understand anterior segment dysgenesis and the individual susceptibility to the development of glaucoma. In this review, we provide the rationale, as well as the challenges, to utilizing genomic methods to examine anterior segment dysgenesis disorders.     

Posterior Segment Complications of Laser in situ Keratomileusis (LASIK)

Laser in situ keratomileusis (LASIK) is the most common surgical procedure for treatment of refractive errors worldwide. Most of its complications are related to the refractive outcome or to corneal and anterior segment injury and wound healing. We review published posterior segment complications of LASIK, current clinical and experimental hypotheses explaining the occurrence of these events, and their management and outcome. Vitreoretinal complications after LASIK are very rare, and a cause-effect relationship between LASIK and reported posterior segment complications has not been proven.     

斜视手术后屈光状态的变化

斜视是指任何一眼视轴偏离的临床现象,可因双眼单视异常或控制眼球运动的神经肌肉异常或各类机械性限制引起。手术治疗是斜视矫正的重要方法,最初人们的关注点只在眼位,但随着对手术患者逐渐深入地观察及随访,有研究发现斜视手术可能改变眼球原本的屈光状态。本文从斜视手术后受术者屈光状态、眼球参数的改变、其可能的发生机制以及影响因素等作一综述,希望能对斜视手术有更为全面的认识,同时为确定术后验光配镜的理想时间提供依据。     

Anterior segment and external ocular disorders associated with human immunodeficiency virus disease

The eye is a common site for complications of human immunodeficiency virus (HIV) infection. Although cytomegalovirus retinitis remains the most prevalent of the blinding ocular disorders that can occur in individuals with the acquired immunodeficiency syndrome (AIDS), several important HIV-associated disorders may involve the anterior segment, ocular surface, and adnexae. Some of these entities, such as Kaposi sarcoma, were well described, but uncommon, before the HIV epidemic. Others, like microsporidial keratoconjunctivitis, have presentations that differ between affected individuals with HIV disease and those from the general population who are immunocompetent. The treatment of many of these diseases is challenging because of host immunodeficiency. Survival after the diagnosis of AIDS has increased among individuals with HIV disease because of more effective antiretroviral therapies and improved prophylaxis against, and treatment of, opportunistic infections. This longer survival may lead to an increased prevalence of anterior segment and external ocular disorders. In addition, the evaluation and management of disorders such as blepharitis and dry eye, which were previously overshadowed by more severe, blinding disorders, may demand increased attention, as the general health of this population improves. Not all individuals infected with HIV receive potent antiretroviral therapy, however, because of socioeconomic or other factors, and others will be intolerant of these drugs or experience drug failure. Ophthalmologists must, therefore, still be aware of the ocular findings that develop in the setting of severe immunosuppression. This article reviews the spectrum of HIV-associated anterior segment and external ocular disorders, with recommendations for their evaluation and management.     

Wavefront analysis and Zernike polynomial decomposition for evaluation of corneal optical quality

Wavefront-guided excimer laser refractive surgery and new customized intraocular lens and contact lens designs are major clinical applications of corneal wavefront analysis. Other therapeutic applications include corneal disorders, conventional excimer laser refractive surgery, incisional techniques and cataract surgery, corneal transplantation, intrastromal corneal ring segment implantation, and crosslinking therapy. Basic data regarding corneal wavefront aberrations, such as distribution in the population and changes with aging, are essential for understanding the nature of each aberration and correcting it. Corneal aberrometry also improved our comprehension of the optical effects of the aforementioned topics while helping us assess the success of the procedures. Zernike polynomials are representations of the higher- and lower-order aberrations of the cornea, allowing a mathematical approach to their determination. Polynomials are used to model individual components of the wavefront in familiar terms. This article reviews the current knowledge of the wavefront aberrations of the human cornea and analyzes studies in the fields of anterior segment surgery and/or therapy, diseases, and optical quality in the context of this knowledge.     

溴芬酸钠滴眼液在眼科中的临床应用

非甾体抗炎滴眼液常用于眼表、眼前段及眼术后炎症的抗炎镇痛治疗。作为新一代非甾体抗炎药,溴芬酸钠因其独特的化学结构,使其既是一种强效抗炎药,又是一种可渗透到眼部组织中的亲脂分子,从而增加作用的持续时间。溴芬酸钠滴眼液作为一种抗炎药,在治疗白内障和屈光手术后眼部疼痛及炎症方面有着广泛的全球安全记录。目前,学者还开发出溴芬酸钠滴眼液除了抗炎、镇痛外的其他眼科应用,发现溴芬酸钠滴眼液具有强效、安全且便利的特点。本文归纳了溴芬酸钠滴眼液在眼科中的应用进展及前景,以期为今后的临床治疗提供新思路。     

有晶状体眼前房角固定型人工晶状体植入术的进展

有晶状体眼前房角固定型人工晶状体植入术是近年来发展起来的矫正高度和超高度近视的一项新技术，随着晶状体材料的改良和临床经验的积累，这种屈光手术逐渐显示出了安全、有效、预测性好、可逆性、保留调节功能和对角膜内皮损伤小等优点。因此，在未来的几年里，前房角固定型人工晶状体植入术作为一种屈光手术将会扩大它的临床应用范围。就该手术的历史、人工晶状体的设计、手术适应证与禁忌证、手术技术、并发症及其防治等方面进行综述。     

ArcScan Insight 100超高频数字超声扫描仪在眼科临床中的应用

ArcScan Insight 100 VHF数字超声扫描仪是一种新型眼部超声测量仪,可对眼前节进行检查和测量,可用于角膜屈光手术前后的筛查和随访、ICL植入术术前眼前节参数的测量、拱高的预测和术后观测、圆锥角膜的早期筛查及青光眼、白内障、眼外伤等检查诊断,兼具超声生物显微镜(UBM)检查范围广、光学相干断层扫描(OCT)操作简便的特点,具有广泛的临床应用前景。本文就ArcScan Insight 100 VHF数字超声扫描仪的测量原理、使用方法、测量参数及临床应用新进展进行综述。     

Practical Applications of Anterior Segment Optical Coherence Tomography Imaging Following Corneal Surgery

Anterior segment optical coherence tomography (AS-OCT) has recently emerged as an important modality for imaging of the cornea. Since its introduction less than a decade ago, it has been clinically used for the diagnosis and management of an expanding number of corneal conditions. In this review, we will discuss the applications of anterior segment optical coherence tomography after corneal surgery, focusing on penetrating and lamellar keratoplasty, keratoprosthesis, intracorneal ring segments, collagen cross-linking and refractive surgery. Anterior segment optical coherence tomography is useful in evaluating outcomes, detecting adverse events, determining prognosis, guiding management decisions, and surgical planning.     

New diagnostic methods for imaging the anterior segment of the eye to enable treatment modalities selection

New diagnostic instruments for imaging the anterior segment of the eye have been developed using the corneal topographer, wavefront sensor, and anterior segment optical coherence tomography (OCT). Data obtained from these instruments can be used to choose treatment modalities by providing information that is complementary to slit-lamp examination and visual acuity measurements. Zernike vector analysis was used to evaluate the corneal higher-order aberrations to quantify the effects of the corneal shape on the optical quality of the eye. The analyses showed the optical characteristics of the anterior and posterior surfaces of the cornea in patients with keratoconus or pellucid marginal corneal degeneration. The association between the deterioration of optical quality during rigid gas-permeable contact lens wear in patients with keratoconus and the residual coma due to posterior corneal shape was suggested by the findings made with this method. Zernike vector analyses also revealed the differences in the ocular higher-order aberrations between conventional Laser in situ keratomileusis (LASIK) and custom LASIK. Serial measurements of the ocular higher-order aberrations by a wavefront sensor enabled us to evaluate the effects of tear fluid dynamics on the optical quality of the eye. The findings clarified the characteristics of serial alterations of higher-order aberrations in normal eyes, dry eye with tear deficiency and dry eye with tear evaporation. The effects of internal lubricating agents on the soft contact lenses were also evaluated objectively. In addition, these results suggest that the effects of serial fluctuations in the ocular higher-order aberrations on refractive surgery should be considered. To observe the cornea at the cellular level with anterior segment OCT, a prototype machine of full-field OCT was developed. This made it possible to show epithelial edema in human donor corneas as well as the alterations in the epithelial layer and stromal layer associated with intraocular pressure elevation in ex vivo porcine eyes. An OCT-based corneal topographer was developed using a three-dimensional anterior segment OCT with the swept-source principle. Corneal topographic analyses of the anterior and posterior surfaces either in eyes with keratoconus or following keratoplasty was possible even in where it was difficult for conventional corneal topographers to analyze accurately. Also, OCT-based corneal topographer analyzed the host and donor cornea separately following Descemet stripping automated endothelial keratoplasty by recognizing the host-graft interface. The results from these new diagnostic methods for imaging the anterior segment of eye will be useful for the diagnosis of corneal disorders and the planning of treatment by evaluating the effects of corneal topographic abnormalities and tear fluid dynamics on visual function, by observing the abnormalities of the corneal tissue at the cellular level, and by showing corneal topography in diseased corneas more accurately and non-invasively.     

Ocular findings in lissencephaly.

PURPOSE: To report our retrospective study of 20 cases with lissencephaly and describe ocular and visual abnormalities associated with this disorder. METHODS: Patients with lissencephaly were identified and classified into classic (type I) or cobblestone (type 2) lissencephaly on the basis of a review of clinical records and neuroimaging studies. Only patients examined by an ophthalmologist were included in the study. RESULTS: Only 1 patient had a normal ocular examination. Ocular abnormalities included optic nerve hypoplasia and atrophy, retinal dysplasia, retinal nonattachment, macular hypoplasia, anterior segment malformation, and strabismus. CONCLUSIONS: Ocular abnormalities in classic (type 1) lissencephaly are less severe. Central, steady, and maintained fixation may be present despite the presence of optic nerve hypoplasia, optic atrophy, macular hypoplasia, strabismus, or refractive errors. Retinal and anterior segment abnormalities were observed only in cobblestone (type 2) lissencephaly. These patients often have severe visual impairment because of retinal or cortical disease.     

Toxic anterior segment syndrome: A review

Toxic anterior segment syndrome is a surgical complication characterized by a noninfectious anterior chamber inflammatory reaction having multiple etiologies. The clinical signs (prominent limbus-to-limbus corneal edema, anterior chamber inflammation) and symptoms (decreased visual acuity, discomfort) generally occur within the first 12-48 hours after intraocular surgery. Most patients achieve good clinical and visual outcomes when there is a prompt clinical diagnosis and adequate treatment. We review the literature on toxic anterior segment syndrome, emphasizing its etiology, pathophysiology, and clinical and surgical management, as well as prognosis and sequelae. Our goal is to reduce the frequency of toxic anterior segment syndrome by highlighting the importance of prevention, early recognition, and distinguishing toxic anterior segment syndrome from infectious endophthalmitis.     

Ultra High-Resolution Anterior Segment Optical Coherence Tomography in the Diagnosis and Management of Ocular Surface Squamous Neoplasia

The development of optical coherence tomography (OCT) technology has helped to usher in a new era of in vivo diagnostic imaging of the eye. The utilization of OCT for imaging of the anterior segment and ocular surface has evolved from time-domain devices to spectral-domain devices with greater penetrance and resolution, providing novel images of anterior segment pathology to assist in diagnosis and management of disease. Ocular surface squamous neoplasia (OSSN) is one such pathology that has proven demonstrable by certain anterior segment OCT machines, specifically the newer devices capable of performing ultra high-resolution OCT (UHR-OCT). Distinctive features of OSSN on high resolution OCT allow for diagnosis and differentiation from other ocular surface pathologies. Subtle findings on these images help to characterize the OSSN lesions beyond what is apparent with the clinical examination, providing guidance for clinical management. The purpose of this review is to examine the published literature on the utilization of UHR-OCT for the diagnosis and management of OSSN, as well as to report novel uses of this technology and potential directions for its future development.     

Retinal complications of phakic intraocular lenses

High myopia has always been a challenge for refractive correction. Current laser surgical techniques, however, fall short of correcting high refractive errors due to lack of predictability, regression, corneal ectasia, and introduction of high order optical aberration. Phakic intraocular lenses (IOL) have been proposed as an effective refractive surgical procedure for the correction of severe myopia, but, despite recent advances in implant material technology and design, their concept is still under clinical investigation. Most of the concern regarding the complications of phakic IOLs focuses on the anterior segment of the eye. This review examines the posterior segment complications associated with phakic IOL implantation, evaluates possible pathogenetic mechanisms and discusses posterior segment complications, prevention and management.