圆锥角膜的诊断

圆锥角膜是一种常见的角膜扩张性疾病 ,在屈光手术就诊者中发病率尤高 ,是许多屈光手术的禁忌证。及早发现圆锥角膜 ,是进行有效防治的基础 ,现就目前圆锥角膜的诊断方法进行了简要论述。     

视觉敏感期后弱视的可塑性研究进展

弱视是视觉发育相关性疾病。视觉发育敏感期是弱视发生的危险期,也是逆转弱视的最佳时机。然而,越来越多的研究证实人类视觉系统在敏感期后仍存在不同程度的可塑性,这对于很多在年幼时贻误了治疗在年长时才被确诊的弱视患者的治疗具有很重要的指导意义,并为探讨弱视的发生及防治提供理论依据。笔者就有关弱视患者在视觉敏感期后是否具有可塑性的研究进展进行综述。     

选择性激光小梁成形术治疗开角型青光眼的研究进展

激光用于青光眼的治疗已有近35a的历史。近年来,选择性激光小梁成形术(SLT)以其安全、有效降眼压、并发症少等优点逐渐成为开角型青光眼的首选治疗。选择性激光小梁成形术是治疗开角型青光眼的一种新型激光手术,它应用倍频Q-开关、波长532nm的Nd:YAG激光,选择性作用于色素性小梁组织达到降低眼压目的。与氩激光小梁成形术(argonlasertrabeculoplasty,ALT)相比,两者降眼压效果相似,但是相对于ALT对小梁网的凝固性损伤,SLT选择性作用于色素性小梁细胞,无凝固性损伤,对小梁网组织轻微破坏,是一种安全且可重复治疗的手段。     

Iron metabolism in the eye: A review

This review article covers all aspects of iron metabolism, which include studies of iron levels within the eye and the processes used to maintain normal levels of iron in ocular tissues. In addition, the involvement of iron in ocular pathology is explored. In each section there is a short introduction to a specific metabolic process responsible for iron homeostasis, which for the most part has been studied in non-ocular tissues. This is followed by a summary of our current knowledge of the process in ocular tissues.     

Retinal contrast loss with non-monofocal IOLs

Non-monofocal IOLs are designed to give simultaneously sharp images of distant and near objects. This is achieved by means of different focal distances for various portions of the light reaching the eye. As a result, for any given object, one part of the light will be properly focused, while another part is out of focus. This results in a sharp image superposed on a blurred image, causing contrast loss. The retinal contrast loss as a function of spatial frequency is derived in this paper.     

Rod-cone interactions in night-blinding disease

When rods are dark-adapted they reduce cone flicker sensitivity as though a low-pass filter had been inserted in the visual pathway. This process is exaggerated in certain individuals and accounts for their complaint of night blindness, though ordinary clinical testing shows no abnormality. This rod-cone interaction occurs in the ERG and is absent in disease of the outer retina, which argues that the pathway involved is via the horizontal cell feedback onto the cones. Various anomalies of rod-cone interaction can be seen in retinitis pigmentosa. These suggest that it is the rod dark current which is responsible for inhibiting cones. The implications for the pathophysiology of retinitis pigmentosa are discussed.     

The effect of volition on the horizontal forced-vergence fixation disparity curve

An anomalous horizontal forced-vergence fixation disparity curve in the shape of the letters V or U is presented. This phenomenon is associated with an increase in eso fixation disparity with base-out prism. This response is shown to be related to instructional set. Intrusion of voluntary vergence is suggested as the most likely basis for this effect.     

Malignant melanoma of the choroid in a naevus of Ota.

A rare case of choroidal malignant melanoma in a naevus of Ota is described. This is the first reported case from Asia outside the Japanese population. This case illustrates the need for close observation of all pigmented lesions of the eye.     

Botulinum Toxin for Lower Lid Entropion Correction

This prospective clinical study was designed to evaluate the efficacy of botulinum toxin for temporary treatment of senile and congenital lower lid entropion. Seventeen patients with senile entropion and three children with congenital entropion were treated with botulinum toxin injection into the preseptal orbicularis muscle of lower lid. This resulted in transient relieve of the condition, which lasted for a period of 8–26 weeks. This technique is easy and effective for senile entropion as well as certain cases of congenital entropion.     

A new in vitro corneal preparation to study epithelial wound healing.

Corneal epithelial wound healing is an important process necessary for maintenance of visual integrity. Corneal epithelial wound healing occurs by cellular migration and proliferation. However, the molecular basis of reepithelialization is not known. To investigate individual molecular contributions to the wound healing process, an in vitro corneal preparation comparable to the in vivo condition is needed. This investigation developed a new whole mount in vitro rabbit cornea preparation and studied epithelial wound healing rates for epithelial and subepithelial wounds. The wound closure rates obtained in this study for epithelial and subepithelial wound healing (52 +/- 14 microns/hr and 38 +/- 7 microns/hr, respectively) are comparable to in vivo rates of wound healing determined by other laboratories for rabbits. This preparation, achieved by functionally separating the epithelial and endothelial sides of the cornea, allows application of agents to the cornea in a manner that approximates the in vivo condition. This in vitro system is promising for future studies designed to investigate corneal wound healing while reducing potential ocular discomfort associated with in vivo corneal wounding.     

Guide to the clinical assessment of on-eye wettability of rigid gas permeable lenses

The number of rigid gas permeable (RGP) contact lens materials is increasing rapidly. One of the most critical issues for acceptance of new materials is lens wettability. This paper describes techniques for assessing lens wetting characteristics while the lenses are worn on the eye, and relates each observation to the lens material properties or patient tear characteristics. This method of lens wetting assessment is intended to aid the practitioner in determining the optimal lens material for a patient, based upon assessment of the interactions inherent in the lens-eye system.     

A local mechanism for differential velocity detection

Differential velocity detection in the fovea was used to probe the properties of a local motion mechanism. Human observers can detect differences in velocity of less than 5% even for a 200 msec target duration. This precision is not based on variations in the distance traversed by the target or in the total target duration. The relevant timing signal for velocity is the detection of a difference in stimulus onset time at spatially separate points. This onset asynchrony detection is shown to be very precise for small spatial separations. Discontinuous stimuli (apparent motion) are adequate substitutes for continuous motion in velocity judgments provided that the spatial interval between target presentations is less than 20 min arc.     

Pay for performance: is it ethical?

Since the advent of pay for performance in medicine, there has been an intense debate about its efficacy and enforceability. This article examines some philosophical and psychological aspects of pay for performance. The very concept of pay for performance is inimical to the Hippocratic oath; it operates in direct conflict with powerful ideals such as altruism and concern for community. These ideals traditionally serve as powerful motivators for physicians. Physicians have just begun to incorporate and enhance the autonomy model. This is designed to help patients and physicians make decisions leading to positive outcomes. Pay for performance threatens to reintroduce an incurable power imbalance between patients and clinicians. Research from the corporate world suggests that hardwiring the thought processes of pay for performance into health-care delivery may lead to a culture of hyper-productivity. This can lead to addictive behavior and ethical abuse.     

Research status of photodynamic therapy for corneal neovascularization

Pathological corneal neovascularization is an important reason of visual impairment. Research outcomes showed that angiogenesis mechanism is similar in all the tissues of the body and photodynamic therapy demostrate a useful effect in blocking tumor and choroidal neovascularization. This method is currently being tried for the treatment of corneal neovascularization. This paper will review the research status of photodynamic therapy in corneal neovascularization using various photosensitizers.     

Botulinum toxin for lower lid entropion correction

This prospective clinical study was designed to evaluate the efficacy of botulinum toxin for temporary treatment of senile and congenital lower lid entropion. Seventeen patients with senile entropion and three children with congenital entropion were treated with botulinum toxin injection into the preseptal orbicularis muscle of lower lid. This resulted in transient relieve of the condition, which lasted for a period of 8-26 weeks. This technique is easy and effective for senile entropion as well as certain cases of congenital entropion.     

Objective evaluation of sensorial and sensorimotorial status in esotropia: their importance in surgical prognosis.

Appropriate use of base-out prisms may be useful objective test for detecting persistence of normal binocular vision (4-dioptre prism test). By prolonged observation of prismatic correction of an esotropic patient one may infer the presence of an anomalous sensorial status. This can be done when the prismatic correction is compensated for by an increase of the angle of esotropia (prism adaptation test). The increase in the angle of esotropia induced by base-out prisms, here called anomalous movements, is probably related to a type of anomalous movement fusional in nature. When anomalous movements are present, it is important to realise how powerfully they have developed. This may be inferred by determining what amount of prism overcorrection of the esotropic angle the patient is capable of compensating for (progressive prism compensation test). This has important implications for surgery. It has been statistically demonstrated that esotropia with strong anomalous movements tends to respond less effectively to surgery than esotropia without or with weak anomalous movements.     

Anterior "lenticonus" in exfoliation syndrome

Presence of exfoliation syndrome (XFS) is associated with an increased risk of complications during cataract surgery. This risk is, in part, dependent on the severity of XFS. We describe a central bulge ("lenticonus") in the anterior lens capsule of some eyes with XFS. This finding is associated with very fragile zonules and a high risk for intraoperative zonular dialysis.     

Lacrimal canaliculitis as a cause of recurrent conjunctivitis

BackgroundBacterial conjunctivitis is routinely managed by optometrists. This case report describes a case of lacrimal canaliculitis, which is a cause for nonresolving conjunctivitis and is commonly misdiagnosed.Case ReportA 48-year-old man presented with a 5-month history of chronic conjunctivitis in the right eye. This was diagnosed as bacterial in etiology but had a short-lived response to various topical antibiotics. Examination found signs of canaliculitis, and Actinomyces israelii was cultured from the discharge. This was treated successfully by canaliculotomy with curettage followed by a postoperative course of phenoxymethylpenicillin.ConclusionsIt is important to consider the diagnosis of lacrimal canaliculitis in any patient with chronic or recurrent conjunctivitis. Greater awareness of this condition would prevent misdiagnosis and delays in referral for definitive treatment.     

A novel suture technique in stellate corneal lacerations

A novel suture technique for regular stellate corneal lacerations, called a star-shaped suture is described. The suturing begins from inside any of the wound lips in a clockwise direction. Suture placement proceeds in a counterclockwise direction by the adjacent wound limb, while the suture passes are all in clockwise direction. Finally, a star-shaped suture is achieved with the knot self-buried in the corneal stroma at the initial entry site. This is a continuous suture, of which tractional forces direct to the center of the wound providing good apical apposition for stellate lacerations. This suture technique can be an alternative for the reconstruction of stellate corneal lacerations.