Improved biometry of the anterior eye segment

In this paper, a method is presented to evaluate the true values of several optical parameters of the anterior eye segment. These are: the thicknesses of the cornea and lens, the depth of the anterior chamber and the anterior and posterior curvatures of the cornea and lens. First, a photo is taken of each patient's eye with a Topcon SL-45 Scheimpflug camera. There are two effects distorting the photo. As the film plane and the object plane are perpendicular to each other, the imaging scale is not constant over the photo, a phenomenon which is called the camera distortion. As the light passes through different refractive media on its way from the inner structures of the eye to the camera, the rays of light are refracted, which is called the refractive distortion of the eye. Following these distortions, the proportions on the photo do not correspond to those in the human eye. The intention of this paper is to calculate the true optical parameters of the anterior eye segment. The seeming optical parameters are taken from the photo and the path of light from a point in the film plane through the camera and the refracting surfaces into the eye is constructed by ray tracing. A set of representative points calculated according to ray tracing provides a basis to evaluate the true optical parameters. This work is done using a Basic program, that accepts the seeming parameters from the photo as input values and provides the true values as output. The adjectives seeming and true added to the optical parameters indicate a value correlating with a distorted photo and a value that was corrected by the theory. The two terms were chosen by mnemonic reasons, although another pair of adjectives such as distorted and corrected might have been of higher precision. For an average adult human eye the optical parameters from the photo were compared with the calculated ones. A phantom eye with well-known optical parameters was constructed and photos were taken from this eye to verify the calculations.     

Effect of inflammation on antibiotic penetration into the anterior segment of the rat eye

Bacterial infections were established in the right cornea of rats. Animals infected with Staphylococcus aureus were given cephradine intravenously (IV) (40 mg/kg) or topically (50 mg/ml) to both eyes. Animals infected with Pseudomonas aeruginosa were given gentamicin sulfate IV (40 mg/kg) or topically (10 mg/ml). Antibiotic concentrations in cornea and aqueous humor were measured for 4 hrs following dosing using bioassay and radioimmunoassay. In general, infection significantly increased the concentrations obtained soon after dosing. Topically applied cephradine passed through infected eyes more quickly than through normal eyes. Of the pharmacokinetic parameters derived, the permeability of the corneal epithelium to gentamicin in the rat more closely agrees with reported human values than does the rabbit, while the coefficient of elimination from aqueous in the rat is considerably greater than that for either humans or rabbits. This suggests that there are both advantages and disadvantages in using the rat for therapeutic studies of ocular disease.     

超声乳化术对眼前节结构和功能的影响

超声乳化术已经成为了目前治疗老年性白内障的主要手术方式。随着超声乳化术的广泛应用,该种术式对于眼前节结构和功能影响的研究也层出不穷。本文回顾了近几年来国内外这方面的相关文献,阐述了超声乳化术对眼前节结构和功能的影响。     

Therapy of herpetic diseases of the anterior eye segment

Clinico-virologic investigations and the availability of the new antiviral drug Acyclovir have changed our therapeutic approach to deep herpetic diseases. Treatment of the symptoms alone with steroids should now be avoided. Basic treatment should consist of optimal dosages of Acyclovir. However, additional steroid therapy is still necessary. Significant progress in the treatment of dendritic keratitis is to be expected as soon as high-titer interferon preparations become commercially available. Treatment of dendritic keratitis with a combination of a modern antiviral drug and high-titer interferon will reduce the average time the corneal epithelium takes to heal from the present 6 days to 3 days. While considerable progress has been made in the treatment of herpes, no more than a step in the right direction has been taken with herpes zoster varicellosus virus, owing to its greater resistance to Acyclovir.     

Mist delivery of eye medication to the anterior segment

PURPOSE: To compare the mydriatic efficacies of mist and drop delivery of tropicamide 1.0%. DESIGN: Randomized, masked, active, controlled clinical trial. METHODS: One hundred subjects were randomized to receive small-volume (6 microl) mist administration of tropicamide 1.0% in one eye and either nothing or a conventional drop (30 microl) of the same solution in the fellow eye. RESULTS: Comparing misted eyes with untreated eyes in the same subjects, the mean maximal increase in pupil diameter in the misted eyes was 2.02 mm and was 0.25 mm in the fellow eyes. The difference is statistically significant (P 相似文献   

磁共振成像技术在眼前节的应用

随着磁共振成像(MRI)技术的发展,其对眼部药物代谢、眼内结构、血一房水屏障及房水循环等的研究应用逐渐增多,显示出其非损伤、实时、动态等优点.本文就MRI及其造影剂在眼前节的显像特点和应用进行综述.     

眼前节毒性综合征原因的探讨

目的 探讨眼科显微手术后眼前节毒性综合征(toxic anterior segment syndrome,TASS)发生的原因.方法 报道2008年10月至2010年4月发生TASS 4例,进行回顾性分析,随诊12月至2年.探讨术后TASS的形成原因.结果 4例TASS病例出现在4例不同的眼科显微手术患者.术后分析,1例患者可能是术后球结膜下注射的庆大霉素误入眼内导致.1例患者可能是视网膜镜经戊二醛熏蒸后,未冲洗干净引起.另2例无明显的致病因素.4例保守治疗效果欠佳,2例最终形成大泡性角膜病变.结论 TASS是眼内显微手术比较少见的并发症,发生原因主要与眼科手术器械残留的消毒药物、术中眼前房内使用的药物、前房内灌注及术后眼局部用药等有关.TASS保守治疗效果欠佳,预防是关键.