Transmission electron microscopic observations of vitreous abnormalities in retinitis pigmentosa

Ultrastructural studies of six vitreous biopsy specimens obtained during cataract surgery on patients with retinitis pigmentosa showed four types of cells. These were ocular pigment epithelium, uveal melanocytes, retinal astrocytes, and macrophage-like cells. The fibrous astrocytes displayed plump cell bodies, large nuclei, and numerous intracytoplasmic filaments. The pigment epithelial cells and uveal melanocytes were round to cuboidal and were heavily pigmented. Macrophage-like cells demonstrated round cell bodies, inclusions of glycogen, and long processes extending from the cell membrane. Also identified in the vitreous material were loose pigment granules. In contrast, vitreous from the control group showed occasional macrophages and loose pigment. These findings explained the clinical observation of material within the vitreous of patients with retinitis pigmentosa.     

Histogenesis of the intravitreal membrane and secondary vitreous in the mouse

PURPOSE: The intravitreal membrane (IVM) is a membranous structure between the primary and secondary vitreous bodies in developing mammalian eyes. In this study, for the first time the histogenesis of the IVM and the relationship between the hyaloid vasculature and the IVM was characterized in newborn mice. METHODS: Eyes of mice less than 12 days old were fixed and embedded. From these, serial paraffin-embedded sections were made for lectin histochemistry, immunohistochemistry, and picrosirius red (PSR) staining, and ultrathin sections were made for transmission electron microscopy (TEM). Eight biotinylated lectins and antibodies for laminin and type IV collagen were used. RESULTS: Among the eight lectins tested, concanavalin A (Con A) agglutinin, Ricinus communis agglutinin I, and wheat germ agglutinin demonstrated strong positive staining in the IVM and vitreous fibrils of the primary and secondary vitreous bodies. They also bound to the internal limiting membrane (ILM) of the retina. At postgestational day 4, the secondary vitreous first appeared between the ILM and the vasa hyaloidea propria (VHP). Immunohistochemical staining revealed that the IVM consists of extracellular matrix components including laminin and type IV collagen, whereas PSR staining and TEM showed that collagen fibrils in the IVM are bundled and continuous with the basement membrane of hyaloid capillaries or the VHP. CONCLUSIONS: Lectin histochemistry and immunohistochemistry provided good methods for visualizing the structures of the IVM and vitreous fibrils. These results suggest that the IVM is separated from the basement membrane of the retinal ILM along with the vascular network of the VHP when the secondary vitreous begins to form.     

The use of vitreous fluorophotometry to distinguish between diabetics with and without observable retinopathy: effect of vitreous abnormalities on the measurement

Ten age-matched normals, diabetics with retinopathy, and diabetics without observable retinopathy were evaluated by vitreous fluorophotometry (VFL) using a 0.15 mm and a 0.45 fiberoptic probe in a photomultiplier system as well as a commercially available photodiode instrument to determine whether differences in intraocular sodium fluorescein levels could be detected among the three groups. Each subject was injected in the antecubital vein with 7 mg/kg of sodium fluorescein (25% solution) and measurements were taken 1 hr postinjection at 4.5 mm and 7.5 mm from the retina. The influence of choroidal fluorescein and ocular pigmentation are reduced at these locations. We found that a breakdown in the blood-ocular barrier may not be present early in the course of diabetes. Furthermore, no significant difference was found between normals and diabetics without retinopathy. Although the mean value for vitreous fluorescein was significantly higher in diabetics with retinopathy compared to normals, several of the diabetics with retinopathy had values in the normal range. These results differ from those previously reported in the literature. However, our studies took into consideration several factors not considered by other investigators, such as ocular pigmentation, choroidal fluorescence, slit width, and vitreous changes, that may have significant effects on the fluorophotometry values.     

玻璃体消融术治疗玻璃体混浊的临床分析

目的 探讨玻璃体混浊患者行玻璃体激光消融术的临床效果及安全性.方法 对2016-07到2017-02在我院门诊诊断为玻璃体轻中度混浊30例30眼患者进行回顾性分析,所有患者术前均作眼压、视力、眼部黑白B超及眼底照相并且放瞳眼底检查,排除活动性视网膜病变.选择混浊物在晶体后2-3mm及视网膜前3-4mm并且混浊物偏离视神经及黄斑的患者.采用Uhra Q∶YAG激光仪治疗,2.0-5.0mj的能量单脉冲准确聚焦在混浊物上进行激射,每次不超过500点.结果 每次术后1月复查视力、眼压、黑白B超及眼底.疗效显著的术后第1个月有15眼(占50％),2月有18眼(占60.0％),好转的术后第1月12眼(占40％),术后2个月11眼(占36.6％),无效的术后第1个月3眼(其中1例为Weiss环,2例为膜状混浊)(占10％),2个月1眼(占3.4％为膜状混浊).术后第1个月总有效率占90％,无效率占10％.术后2月总有效率占96.6％,无效率占3.4％.无视网膜脱离及损伤,外伤性白内障,虹膜睫状体炎等并发症发生.结论 YAG激光玻璃体消融术治疗玻璃体混浊,疗效较好、简单、经济、安全,能够消除或减轻玻璃体混浊带来的视觉不适,同时由于本次治疗病例样本较少,观察时间较短,还需要更多病例及更长时间的观察.     

全反式维甲酸诱导的Cx43基因在RB细胞中的过表达及其对RB生长的抑制作用

背景诱导细胞间隙连接蛋白（＆）基因在瘤细胞中过表达是全反式维甲酸（ATRA）抑制肿瘤细胞生长的重要机制。我们先前的研究已证实,ATRA抑制视网膜母细胞瘤（RB）细胞增生、分化作用的机制与诱导Cx43过表达有关,但药物作用位点及其对在体肿瘤组织生长的影响尚未明确。目的研究ATRA对RB细胞中Cx43基因及其蛋白表达的影响,探讨其作用机制。方法用无水乙醇将ATRA溶解并配制成浓度为1×10^-2mol／L的溶液,使用前再用细胞培养液配制成不同浓度ATRA液。用含体积分数10％热灭活胎牛血清（FBS）的RPMI-1640培养液常规培养人RB细胞株HXO—RB44,将1×10^5-×10“和1×10^-2mol／L的ATRA分别加至培养基中,分别于添加后2、4、6d采集细胞,分别采用Westernblot法和逆转录PCR法检测细胞中Cx43蛋白及mRNA的表达变化。选取15只BALB／c裸鼠,将RB细胞悬液1恤l（含5×10^5个细胞）进行裸鼠右眼前房注射,建立裸鼠眼前房RB模型。将造模成功的11只裸鼠随机分为空白对照组、阴性对照组和1X10。mol／LATRA组,阴性对照组和1×10^-5mol／LATRA组裸鼠分别行0．5％无水乙醇的生理盐水或1×10^-5mol／LATRA前房注射,每3天1次,共注射3周,裂隙灯显微镜下观察各组裸鼠肿瘤生长情况;实验结束时摘除实验眼,用苏木精-伊红染色法进行组织病理学检查。结果Westernblot法检测结果显示,随ATRA作用时间的延长,各组Cx43蛋白表达量（Acx43／AGPDH）均逐渐增加,总体比较差异有统计学意义（F时间=71．31,P=0．00;F分组7．66,P=0．00）;药物作用后2d1×10^-5mol／LATRA组、作用后4d1×10^-6mol／LATRA组、作用后6d1×10^-7mol／LATRA组Cx43蛋白表达量均明显高于空白对照组,差异均有统计学意义（t=3．34,P〈0．叭;t=2．33,P〈0．05;t=3．12,P〈0．01）。逆转录PCR检测结果显示,随ATRA作用时间的延长,各组Cx43 m     

A new technique for separation of posterior vitreous in vitreous surgery

To describe a new and effective technique, hydroseparation, for use in detaching the posterior cortical vitreous from the retina by the simple injection of fluid into the subhyaloid space. This technique was used in 7 eyes of 6 patients with diabetic retinopathy who had limited posterior vitreous detachment. Following core vitrectomy, a 32 gauge cannula was inserted into the subhyaloid space and a balanced salt solution (BSS) was injected. The injected fluid spread easily to the periphery, causing the vitreous cortex to be smoothly separated, except for areas with firm vitreoretinal adhesion. In those areas, we also used microscissors to separate the tissue. No iatrogenic retinal break occurred in any case. This simple technique, which exerts minimal traction force on the retina, was safe and useful for inducing posterior vitreous detachment in patients with diabetes.     

兔眼玻璃体腔植入维甲酸缓释系统防治增殖性玻璃体视网膜病变的药效学研究

目的　探讨全反式维甲酸 (atRA)缓释系统玻璃体腔植入对实验性增殖性玻璃体视网膜病变 (PVR)的预防作用。方法　采用中轴部玻璃体切除联合成纤维细胞注入术构建兔PVR模型。术中 3组兔眼玻璃体腔均分别植入不同含量的atRA缓释系统 :B组缓释系统atRA含量为 42 0 μg ,C组缓释系统atRA含量为 650 μg ,D组缓释系统atRA含量为 1 0 70 μg ;设空白对照两组 :A组不植入atRA缓释系统 ,E组玻璃体腔植入空白atRA缓释系统。植入后共观察 8周 ,每周抽取玻璃体腔液进行atRA含量检测。 8周后行组织病理学检查。结果　术后 8周 ,植入atRA含量 650 μg和 1 0 70 μg缓释系统组 ,兔眼PVR程度低于其他各组 ,经统计学分析差异有显著意义 (P <0 0 5) ,组织病理学检查未见眼内毒性反应。结论　atRA缓释系统玻璃体腔给药方便、安全。atRA抑制PVR能力与玻璃体腔药物浓度相关 ,atRA含量为 650 μg和 1 0 70 μg缓释系统植入玻璃体腔可有效预防术后PVR发生 ,而atRA含量为 42 0 μg缓释系统植入玻璃体腔仅能抑制和延缓PVR发生     

Quantitation of hemodynamic function during developmental vascular regression in the mouse eye

PURPOSE: Ultrasound biomicroscopy (UBM) utilizes frequencies higher than conventional diagnostic ultrasound and can noninvasively provide anatomic and functional information about mouse ocular structures in vivo at high resolution. Vascular development can also be assessed with high-frequency Doppler imaging, which permits detection and characterization of ocular blood flow not detectable at lower, conventional Doppler frequencies. METHODS: The eyes of CD-1 mice were examined daily from the day of birth to postnatal day (P)16. Hyaloid vascular system anatomy was imaged with UBM and microcomputed tomography (microCT). Blood flow velocity was also measured with Doppler UBM imaging in the hyaloid artery, vasa hyaloidea propria, tunica vasculosa lentis, and retina. RESULTS: In the mouse, the hyaloid vasculature degenerated from a well-defined structure at birth by progressive loss of branches. Hyaloid regression coincided with a progressive decrease in blood velocity detected in the hyaloid vascular structures, which is thought to be one of the major triggering factors of the regression in these vessels. At P13, no further blood flow was detected in the CD-1 mouse hyaloid vasculature. An inverse relationship was also shown between peak blood velocity in the lens and retina. CONCLUSIONS: UBM imaging provides a valuable means of rapidly and noninvasively characterizing ocular development in vivo. MicroCT scans have also provided intralumenal images of hyaloid vascular structure. This is the first study of vascular structure and function during the dynamic process of hyaloid vascular regression during mouse neonatal eye development and the first three-dimensional images of the complex hyaloid vascular structure.     

Postnatal thyroid hormone supplementation rescues developmental abnormalities induced by congenital-neonatal hypothyroidism in the rat retina

Thyroid hormones (TH) play a key role in central nervous system development. We have studied the influence of congenital and neonatal hypothyroidism on retinal development and the effects of postnatal TH supplementation. An experimental model was set up using Wistar rats by inducing chemical thyroidectomy during gestation and suckling. Eyes from control (CG) and TH-depleted (THDG) groups of animals were obtained at postnatal days 10 and 25. In the THDG, there was a significant reduction in the retinal thickness and layering, retinal volume, cell number and nuclear volumes in all layers. A third group of rats, made hypothyroid during the gestational and neonatal period and then supplemented with TH (THSG), showed a recovery of both the retinal thickness [at P25: 188.5 +/- 9.2 microm (THSG) vs. 175.8 +/- 16.1 microm (THDG), p < 0.001, and 210.8 +/- 8.9 (CG)] and total retinal cell number [at P25: 6.9 x 10(6) (THSG) vs. 3.7 x 10(6) (THDG) cells, p < 0.001, and 5.3 x 10(6) cells (CG)]. Light and electron microscopy studies confirmed that TH deprivation altered the organization of the retina, which was mostly normalized by hormone administration. Our data show that TH regulates intrinsic mechanisms for controlling retinal cytoarchitecture and layering, and that alterations in retinal maturation induced by congenital-neonatal TH deficiency can be at least partially rescued by early hormonal treatment in vivo.