Neuroprotective effect of intravitreal cell‐based glucagon‐like peptide‐1 production in the optic nerve crush model

Purpose: To examine the effect of intraocularly produced glucagon‐like peptide‐1 (GLP‐1) on the survival rate of retinal ganglion cells in an optic nerve crush model. Methods: Forty‐one Sprague–Dawley rats were divided into a study group (21 animals) in which 4 beads with 3000 genetically modified cells to produce GLP‐1 were intravitreally implanted into the right eye; a saline control group (n = 12) with intravitreal saline injection; and a GLP‐1 negative bead control group (n = 8) in which 4 beads with 3000 cells without GLP‐1 production were intravitreally implanted. The right optic nerves of all animals were crushed in a standardized manner. After labeling the retinal ganglion cells by injecting 3% fluorogold into the superior colliculus, the animals were sacrificed, and the ganglion cells were counted on retinal flat mounts. Results: The retinal ganglion cell density of the right eyes was significantly higher in the study group (median: 2081 cells/mm²; range: 1182–2953 cells/mm²) than in the GLP‐1 bead negative control group (median: 1328 cells/mm²; range: 1007–2068 cells/mm²; p = 0.002) and than in the saline control group (median: 1777 cells/mm²; range: 1000–2405 cells/mm²; p = 0.07). Correspondingly, the survival rate (ratio of retinal ganglion cell density of right eye/left eye) was significantly higher in the study group (median: 0.72; range: 0.40–1.04) than in the GLP‐1 bead negative control group (median: 0.44; range: 0.36–0.68; p = 0.003) and than in the saline control group (median: 0.56; range: 0.36–0.89; p = 0.03). Conclusion: Glucagon‐like peptide‐1 produced by intravitreally implanted cell beads was associated with a higher survival rate of retinal ganglion cells after an experimental optic nerve crush in rats.     

Intraocular lens materials in the anterior chamber implantation test

The biocompatibilities of two silicones ("Homburg" and "St. Wendel" silicone) and "Perspex CQ" (Titmus Eurocon Kontaktlinsen GmbH, Aschaffenburg) were tested in rabbits' eyes using the anterior chamber implantation test. Test criteria were iris folds, corneal opacification, fibrin flocks, and iris hyperemia. All the materials proved to be sufficiently biocompatible for use in the production of intraocular lenses. The two silicones appear to cause corneal opacification more often than "Perspex CQ". "Homburg" silicone only rarely seems to cause iris folds. There are no statistically significant differences in the biocompatibility of the tested materials. Clinical observations were in agreement with the test results.     

Intraocular lenses for the correction of refraction errors. Part 1: phakic anterior chamber lenses

In this overview, the current status of intraocular lens surgery to correct refractive error is reviewed. The interventions are divided into additive surgery with intraocular lens implantation without extraction of the crystalline lens (phakic intraocular lens, PIOL) or the removal of the crystalline lens with implantation of an IOL (refractive lens exchange, RLE). Phakic IOLs are constructed as angle-supported or iris-fixated anterior chamber lenses and posterior chamber lenses that are fixated in the ciliary sulcus. The implantation of phakic IOLs has been demonstrated to be an effective, safe, predictable and stable procedure to correct higher refractive errors. Complications are rare and differ for the three types of PIOL; for anterior chamber lenses these are mainly pupil ovalization and endothelial cell loss.     

Intraocular pressure in myopic patients after Worst-Fechner anterior chamber phakic intraocular lens implantation

PURPOSE: To assess intraocular pressure measured with a Goldmann tonometer over a period of 1 year after implantation of a Worst-Fechner anterior chamber phakic intraocular lens to correct myopia of -7.00 D or more. METHODS: We performed a prospective, non-masked study of 100 patients (100 myopic eyes) who had a Worst-Fechner phakic intraocular lens implanted to correct myopia of -7.00 D or greater. Central corneal Goldmann tonometry was performed before surgery and 1, 3, 6, and 12 months after surgery. The influence of different variables was assessed. RESULTS: IOP showed a significant increase of a mean 2.1 mmHg at 3 months after surgery (P=.001). There was not a statistically significant difference between IOP before surgery and 6 months after PIOL implantation (P=.244) or 1 year after surgery (P=.845). In one eye, the lens was explanted 11 months after surgery because of the presence of ocular hypertension. No variables studied showed a statistically significant difference from before to after surgery. CONCLUSIONS: Worst-Fechner anterior chamber phakic intraocular lens implantation led to a slight transitory increase of intraocular pressure during the first 3 months after surgery, but returned to preoperative levels by 6 months after implantation.     

Recent advances in Toll‐like receptors and anterior uveitis

Uveitis involves acute, recurrent or chronic inflammation of the uvea, and occurs when the normal state of ocular immune privilege has broken down. Accumulating evidence implicates the role of microbial triggers in the development of various forms of immune‐mediated uveitis in addition to its causative role in infectious uveitis. Toll‐like receptors (TLRs) are the most important pattern‐recognition receptors of the innate immune system that recognize pathogen‐associated molecular patterns of microbes. Activation of TLRs by pathogen‐associated molecular patterns leads to the induction of an inflammatory cascade and activation of both innate and adaptive arms of the immune response. TLRs have been implicated in the pathogenesis of various inflammatory diseases, including uveitis. This review provides an update on recent progress in TLR research and uveitis, specifically summarizing new evidence for the role of TLRs in anterior uveitis. There have been important observations from studies involving human ocular tissue, clinical uveitis and from experimental animal models of uveitis, such as endotoxin‐induced uveitis. The ‘Toll rush’ has certainly gained momentum, and future advances in this field have the potential for selectively targeting the TLR pathway and ultimately translating into better therapies for patients with sight‐threatening uveitis.     

Effect of age on anterior chamber angle configuration in Asians determined by anterior segment optical coherence tomography; clinic‐based study

Acta Ophthalmol. 2010: 88: e205–e210

Abstract.

Purpose: To evaluate the distribution of anterior chamber angle (ACA) parameters and to assess association of these parameters with age in Asian subjects. Methods: Four hundred and thirty‐nine consecutive Korean subjects aged from 30 to 89 were enrolled from a university clinic. All participants were scanned using anterior segment optical coherence tomography (AS‐OCT, Visante, version 2.0). We measured ACA parameters such as anterior chamber depth (ACD), angle opening distance at 500 and 750 μm (AOD_500,750), angle recess area at 500 and 750 μm (ARA_500,750), trabecular iris space area at 500 and 750 μm (TISA_500,750), and determined age‐related changes in these parameters with use of a linear mixed effect model that adjusted for gender, axial length, intraocular pressure, and keratometry data. Slopes of ACA parameters as a function of age were determined. For various AS‐OCT parameters, the normalized slope was calculated by dividing the slope by the mean value. Results: All analysed ACA parameters decreased with age in both nasal and temporal quadrants. Axial length and keratometry data were significant covariates for ACA changes. The slopes of ACD were ?0.02396 mm/year, AOD₅₀₀, ARA₅₀₀, and TISA₅₀₀ measured at the temporal angle were ?0.00634 mm/year, ?0.0019 mm²/year, and ?0.00177 mm²/year, respectively. There was no age‐dependent difference in central corneal thickness (p value; 0.4597) Based on the normalized slopes, the AOD showed the steepest slope at both temporal and nasal sectors. Conclusion: All ACA parameters assessed by AS‐OCT, which accounted for other ocular biometric parameters, showed significant negative slopes with increasing age. These results should be considered when assessing changes in the anterior chamber over time.     

Intraocular concentrations of gatifloxacin and moxifloxacin in the anterior chamber via diffusion through the cornea using collagen shields

PURPOSE: To evaluate the penetration of gatifloxacin and moxifloxacin into the anterior chamber, and any adverse reaction to the cornea, using collagen shields presoaked in oversaturated solutions of the antibiotics. METHODS: Collagen shields, presoaked for 10 minutes in an oversaturated solution of gatifloxacin or moxifloxacin, were placed on the surface of each of the corneas of 15 rabbits for a total of 30 eyes (15 in each group). The antibiotics were prepared by dissolving the powder form of the antibiotics in a solution until no further particulate could be further dissolved. Aqueous humor samples were taken 3.5 and 6 hours later. RESULTS: The initial concentrations of gatifloxacin and moxifloxacin were 5.43 +/- 0.16 mg/mL and 3.14 +/- 0.22 mg/mL, respectively. The average concentration of gatifloxacin in the anterior chamber was higher than that of moxifloxacin at the 3.5-hour sample (6.32 +/- 2.67 microg/mL versus 3.55 +/- 3.5 microg/mL, P = 0.0034). The concentrations of both antibiotics, although decreased, remained relatively high at the 6-hour sample (1.39 +/- 1.13 microg/mL versus 0.816 +/- 0.6 microg/mL at 6 hours, respectively, P = 0.22). No obvious clinical or histologic signs of toxicity were noticed in either group. CONCLUSION: Gatifloxacin and moxifloxacin showed good penetration into the anterior chamber with no obvious adverse reaction to the cornea. The concentrations in the anterior chamber exceeded the minimal inhibitory concentration (MIC) 90 of most organisms responsible for postoperative endophthalmitis (POE).     

The fate of anterior chamber flurescein in the monkey eye. 1. The anterior chamber outflow pathways.

As defined by freeze-dry tissue techniques, there are two distinct routes by which fluorescein leaves the anterior chamber of the living rhesus monkey eye. I. The conventional pathway: Within five minutes of the initiation of fluorescein perfusion through the anterior chamber, the conventional pathway filled. Tracer passed through the trabecular meshwork into Schlemm's canal, and flowed back within scleral and episcleral venous derivatives to enter large veins in the extraocular muscles. II. The uveo-vortex pathway: Fluorescein rapidly moved into the iris stroma and into the anterior part of the ciliary body. The anterior chamber border of the ciliary body is little more than a sparse mesh from which fluorescein entered directly into the substance of the anterior ciliary muscle. Fluorescein penetrated blood vessels in the iris stroma and in the anterior ciliary body from where it could be traced posteriorly to the equatorial choroid and vortex veins. The specific sequential tissue distribution of fluorescein strongly supports the existence of a uveo-vortex pathway for aqueous outflow.     

Posterior chamber intraocular lens in the anterior chamber

BACKGROUND: The choice of design for intraocular lenses (IOLs) mainly depends on the selected location for the implant. HISTORY AND SIGNS: We report the case of dislocation of a foldable open-loop posterior chamber IOL into the anterior chamber during retinal detachment surgery. After several vitreoretinal interventions visual acuity was hand movements. THERAPY AND OUTCOME: The IOL remained in the anterior chamber without complications such as IOP rise or endothelial decompensation for several years. CONCLUSIONS: Foldable open-loop posterior chamber IOLs can be left in suitable anterior chambers for years without complications such as rise of intraocular pressure or corneal endothelial damage. Repeated measurements of endothelial cell density can provide an informative basis for the operative removal of this lens.     

不同类型急性闭角型青光眼行晶状体超声乳化吸出术后眼压控制率比较

目的比较不同类型急性闭角型青光眼行晶状体超声乳化吸出术后的眼压控制率及其与前房角改变的关系。设计回顾性病例系列。研究对象急性闭角型青光眼合并白内障以晶状体超声乳化治疗病例173例173眼。方法2005年1月,2007年6月,安溪明仁眼科医院的上述患者173例,通过超声生物显微镜（UBM）检查确定其前房角关闭类型为单纯瞳孔阻滞型（52．0％,90／173）、非瞳孔阻滞型（17．9％,31／173）、混合机制型（30．1％,5／173）。行超声乳化白内障吸除联合折叠型人工晶状体植人术,随访48W;通过UBM对比术前、术后前房深度、前房角变化以及眼压变化。主要指标眼压、前房角开放程度、并发症情况。结果手术后8W三种类型急性闭角型青光眼其眼压控制率分别为单纯瞳孔阻滞型88．9％（64／72）、非瞳孔阻滞型52．0％（13／25）、混合机制型83．4％（35／42）,差异有统计学意义（x^2=7．13,P=0．022）;随访48W时分别为54．2％（13／24）、33．3％（3／9）、35．8％（5／14）,差异有统计学意义（x^2=12．56,p=0．003）。手术中及术后并发症发生率与同期单纯白内障超声乳化手术相当。48W时前房角开放率（UBM检查）分别为单纯瞳孔阻滞型66．7％（16／24）、非瞳孔阻滞型33-3％（3／9）、混合机制型33．3％（4／12）。结论急性闭角型青光眼患者行晶状体超声乳化吸出术其眼压控制有效率依次为单纯瞳孔阻滞型、混合机制型、非瞳孔阻滞型;眼压控制率与前房角开放程度有关。