CYP1B1基因缺失小鼠眼前房角组织结构的观察

目的 研究细胞色素P450 181(CYP1B1)基因对小鼠眼前房角组织结构的影响.方法 实验研究.采用成年CYP1B1基因缺失小鼠模型,以同龄C57BL/6J小鼠为对照.通过塑料包埋切片技术,用光学显微镜和透射电子显微镜观察两组小鼠眼前房角组织的形态和超微结构.结果 C57BL/6J小鼠眼前房角组织发育正常;CYP1B1因缺失小鼠存在不同程度的房水引流系统发育畸形,表现为小梁网发育不良,网眼狭窄,小梁细胞结构变异,有时可见小梁柱间有异常存在的均质膜,Schlemm管狭窄或缺失,虹膜突从虹膜根直达全部小梁网.这些异常改变在CYP1B1基因缺失小鼠眼前房角内呈局灶性分布.结论 CYP1B1基因在房角的发育过程中有重要作用,其缺失可导致小梁网、Schlemm管、虹膜突等房水滤过道的结构异常,可能影响房水引流系统的代谢和功能.     

Light and electron microscopy of the anterior chamber angle structures following surgical disinsertion of the ciliary muscle in the cynomolgus monkey.

Light and electron microscopic studies were done on 11 cynomolgus monkey eyes which had undergone total iris removal followed by surgical disinsertion of the ciliary muscle from the scleral spur 4.7 to 14.4 months earlier. Anterior chamber perfusion to measure gross outflow facility had been performed one to nine times postoperatively. Over most of the circumference in most eyes (1) the ciliary muscle had been retrodisplaced from the scleral spur and had reattached to the sclera more posteriorly; (2) ciliary muscle, trabecular meshwork, and Schlemm's canal appeared normal. A cyclodialysis cleft was never seen. Fixation of some eyes in the in vivo and in vitro presence of pilocarpine demonstrated the contractibility of the retrodisplaced muscle. In isolated areas where the ciliary body had been surgically cut, scar tissue of varying thickness connected scleral spur, sclera, ciliary body, zonule, and lens capsule, but did not infiltrate trabecular meshwork or Schlemm's canal. In such sectors, plasma cell-like cells replaced trabecular endothelial cells and were also present in the scar tissue, ciliary muscle, and surrounding vessel walls in the scar and sclera. In sectors of two eyes, a previously existing trabecular operculum extended posteriorly and completely covered the meshwork. The meshwork in these sectors was poorly perfused by aqueous humor, and electron-dense deposits were present beneath the inner wall of Schlemm's canal. Four totally iridectomized and two unoperated eyes from these monkeys were also examined; ciliary muscle, trabecular meshwork, and Schlemm's canal appeared normal in all, despite the numerous anterior chamber perfusions.     

Effects of intracameral Na2EDTA and EGTA on aqueous outflow routes in the monkey eye

Intracameral perfusion with 4 to 6 mM Na2EDTA or 4 mM EGTA for 40 to 80 min caused a very large increase in gross outflow facility. This effect was partly reversible when followed by perfusion with mock aqueous humor. Eyes perfused with Na2EDTA were studied morphologically. In the trabecular meshwork the cells separated due to a splitting of the cell junctions. A distention of the cribriform meshwork, a wash-out of extracellular material , and a disintegration of the denuded trabecular cores were also noticed. The inner wall of Schlemm's canal protruded in a "balloonlike" manner into the lumen of the canal and showed frank ruptures, especially after prolonged perfusion times. The conventional outflow pathways beyond Schlemm's canal showed no abnormalities. In the uveoscleral outflow routes the anterior and middle part of the ciliary muscle demonstrated very wide intermuscular clefts and many degenerated muscle fibers. The posterior third of the muscle was normal. So were the ciliary epithelium, the choroid, and the retina. The pupillary sphincter also showed degeneration. The corneal endothelial cells separated, starting at the apical junctional complex.     

Ab interno trabeculectomy: development of a novel device (Trabectome) and surgery for open-angle glaucoma

PURPOSE: To design an instrument to selectively remove trabecular meshwork and Schlemm's canal inner wall (SCIW), and demonstrate its effectiveness by histologic analysis of treated cadaveric human tissue. METHODS: The design parameters of the instrument were the ability to permanently remove a segment of trabecular meshwork and Schlemm's canal inner wall without causing damage to surrounding tissue, and to allow use with standard anterior segment surgical techniques and equipment via an ab interno approach. Treatment was applied to 20 segments of human corneoscleral rims. The treated areas were examined using a confocal microscope and compared with matching areas in untreated controls and simulated goniotomy. RESULTS: The resultant instrument system surgically removes the trabecular meshwork and Schlemm's canal inner wall from an anterior chamber approach. It consists of a disposable surgical handpiece with irrigation, aspiration, and electrocautery to focally ablate the target tissues. The attached console includes a high-frequency (550 KHz) electrosurgical generator and irrigation/aspiration controlled by a foot pedal. Histologic examination of specimens treated with the Trabectome displayed disruption of the trabecular meshwork and Schlemm's canal inner wall without damage to surrounding structures. The specimens treated by simulated goniotomy displayed significant damage to the outer wall of Schlemm's canal and the surrounding sclera. The controls showed no disruption or damage to any tissues. CONCLUSIONS: The Trabectome system is designed for performing trabeculectomy via an ab interno approach. It successfully removed sections of trabecular meshwork and Schlemm's canal inner wall with less injury to the adjacent tissue compared with goniotomy knife in vitro. Theoretically, this procedure should provide direct access of aqueous humor to Schlemm's canal.     

原发性开角型青光眼非穿透小梁手术患者深层巩膜瓣及小梁膜的病理学观察

目的 研究原发性开角型青光眼患者(POAG)非穿透小梁手术的解剖学基础,探讨POAG患者房水外流的阻力部位及其病理改变。方法 选择行非穿透小梁手术的POAG患者12例(18只眼),取术中切除的深层巩膜瓣及撕除的外层小梁膜进行光镜、扫描电镜及透射电镜观察。结果 光镜观察标本见：深层巩膜瓣前端为少许深层角膜基质,并可见Schlemm管外壁单层内皮细胞。扫描电镜观察见：深层巩膜瓣内侧可见被打开的Schlemm管管腔和狭长的积液管开口;撕除膜小粱面可见角巩膜小粱的网状结构,排列致密,网眼较小,近管腔侧呈致密的板状结构。透射电镜观察见：Schlemm管外壁周围散在高电子密度物质;撕除膜包括Schlemm管内壁,邻管组织(内皮网)和部分角巩膜小梁,邻管组织细胞减少,细胞外基质增多,可见大量致密斑块沉积;角巩膜小粱网胶原板层结构增厚,弹力纤维增多,细胞体积增大,尤以细胞核增大明显。晚期患者的角巩膜小梁网内有致密斑块沉积,阻塞了小梁间隙。结论 非穿透小梁手术的深层巩膜瓣包括Schlemm管外壁,撕除膜包括邻管组织和部分角巩膜小梁。邻管组织和部分角巩膜小梁是POAG患者房水外流的主要阻力部位,同时Schlemm管外壁也是其重要构成部分。     

The role of the actomyosin system in regulating trabecular fluid outflow

Abnormally high resistance to aqueous humor drainage via the trabecular meshwork and Schlemm's canal is highly correlated with the development of primary open-angle glaucoma. Contractility of the actomyosin system in the trabecular cells or inner wall endothelium of Schlemm's canal is an important factor in the regulation of outflow resistance. Cytoskeletal agents, affecting F-actin integrity or actomyosin contractility, or gene therapies, employing overexpression of caldesmon or Rho-A inhibition, can decrease outflow resistance in the drainage pathway. In this review, we discuss the mechanisms underlying these and similar effects on trabecular outflow resistance in living animals and/or in cultured ocular anterior segments from enucleated animal or human eyes.     

Hyaluronan synthase immunoreactivity in the anterior segment of the primate eye

The anterior segment of human and cynomologus monkey eyes was investigated for the presence of hyaluronan (HA) synthesizing cells using a polyclonal antibody against the enzyme HA synthase (HAS). In the chamber angle region the most intense staining was seen in the cell membranes of the corneal endothelium and in monkey eyes in the cells covering the posterior extension of the cornea (the operculum). The trabecular meshwork cells of the uveal and inner corneoscleral lamellae were also intensely stained. On the other hand, no staining was observed in the trabecular cells of the outer corneoscleral and the cribriform meshwork. The cell membranes of the inner wall endothelium of Schlemm's canal were labelled only at their luminal surface.In the iris stroma and the trabeculum ciliare (the ciliary body band), labelled cells were also found, whereas the connective tissue of the ciliary muscle and the muscle itself did not contain HAS-positive cells. In the ciliary processes immunoreactivity was seen in the non-pigmented epithelial cells (NPE) covering the anterior tips of the processes, suggesting that HA found in the aqueous humor is produced by these cells. The pars plana NPE showed the most intense staining in the cells directly adjacent to the ora serrata region. The hyalocytes found in the neighborhood of the pars plana also showed intense HAS immunoreactivity. It is likely that both hyalocytes and NPE cells of the posterior pars plana release HA into the vitreous.The study was supported by grants from Deutsche Forschungsgemeinschaft, Bonn, Bad Godesberg (Dr 124/6-1)     

Effect of repeated anterior chamber perfusion on intraocular pressure and total outflow facility in the cynomolgus monkey

Total outflow facility was determined by two-level constant pressure perfusion of the anterior chamber in surgically virgin, aniridic, and ciliary muscle disinserted cynomolgus monkey eyes 6 to 13 times at 1- to 2-month intervals over periods of 8 to 24 months. Facility decreased approximately 15 to 20% between consecutive thirds of the perfusion history, independent of eye type. The facility decreases were too large to be explained by decreased uveoscleral facility or pseudofacility, and were not mediated by the iris, ciliary muscle, or gonioscopically or ultrastructurally apparent chamber angle alterations. They most probably reflected functional alterations in the trabecular meshwork/inner wall of Schlemm's canal. Intraocular pressure as measured by applanation tonometry did not increase progressively, most probably due to a decreased rate of aqueous humor formation.     

A case of Rubinstein-Taybi syndrome suspected with goniodysgenetic glaucoma

We reported a case of Rubinstein-Taybi syndrome suspected in association with goniodysgenetic glaucoma, and studied using light and electron microscopy the anterior chamber angle tissues obtained surgically by trabeculectomy. The patient was 31-year old male, who had a systemic appearance of Rubinstein-Taybi syndrome with dwarfism, mental retardation, antimongoloid slant, flat-broad based thumbs, low set ears, high arched plate except for whorl of dermatographism. In addition to these malformations, goniodysgenetic glaucoma was also present which is characterized by underdevelopment of the angle recess and invisible ciliary body band in gonioscopic examination. The histopathological studies of the specimens revealed the presence of a compact tissue filled with a large amount of collagen fibers with few cells in the juxta-canalicular tissue of Schlemm's canal. There were 3 to 4 layers of trabecular sheets of corneoscleral meshwork at the anterior chamber side of the compact tissue. We conclude that the presence of the compact tissue under Schlemm's canal represents goniodysgenesis, underdevelopment of the trabecular meshwork, which is the primary cause of the glaucoma in this case.     

Effects of alpha-chymotrypsin on the outflow routes for aqueous humor

The anterior chamber was perfused with alpha-chymotrypsin, 50 micrograms ml-1, in mock aqueous humor in cynomolgus monkeys. The enzyme caused a marked rise in outflow facility and had clear effects on the structure of the outflow routes for aqueous humor. The intertrabecular spaces in the iridocorneal chamber angle were wider than normal, the openings in the uveal and corneoscleral meshwork appeared enlarged, there was ballooning of the juxtacanalicular region and the inner wall of Schlemm's canal into the canal and also splitting of the inner wall of the canal. The trabecular cells appeared relaxed with most of the cell processes retracted, some broken. There were discontinuities in the cell membrane and blebs. Parts of the trabecular beams were denuded. Two days after the enzyme treatment the facility was in the normal range, no splits in the inner wall of Schlemm's canal we observed but many of the other changes in structure remained. The number of invaginations in the inner wall of Schlemm's canal was markedly reduced after 2-18 days. A second and third perfusion with alpha-chymotrypsin caused a rise in outflow facility similar to the first. Some morphological changes remained 163 days after enzyme treatment. Pilocarpine a few days after alpha-chymotrypsin treatment caused a marked increase in outflow facility. The results suggest that alpha-chymotrypsin affects the glycoproteins of the cell membrane and as a result causes disorganization of the cytoskeleton, loss of loose adhesions and breaks of cell processes. The rapid recovery of the resistance to outflow was probably due to healing of the splits in the inner wall of Schlemm's canal; a marked reduction in the number of cells with invaginations suggests that in addition there may have been a reduction in the number of transcellular pores in the inner wall of Schlemm's canal.     

The effects of a new type of laser on fixed tissue of the angle of the anterior chamber in the monkey eye (author's transl)]

Segments of fixed tissue of the chamber angle of the monkey eye are irradiated with a neodymium (YAG-) q-spoiled laser at a pulse duration of 50 ns, a pulse energy of 200 mJ and an optic distance of 15 mm. Perforating injuries are observed between the anterior chamber and Schlemm's canal. When an acute angle of the laser beam relative to the cornea is chosen, the application point must be at the anterior part of the trabecular meshwork, close to the cornea, to open the canal of Schlemm. An impact further back toward the iris would create cyclodialysis.     

Long-term effects of Q-switched ruby laser on monkey anterior chamber angle

In an attempt to clarify whether pulsed lasers might be able to cause permanent fistulas from the anterior chamber to the interior of the canal of Schlemm, slightly suprathreshold, low energy, small diameter Q-switched ruby laser pulses were applied to the trabecular meshwork of nine eyes of six rhesus monkeys. Clinical examinations during the next 2 months disclosed no adverse effect on the cornea, iris, lens, or retina. There was transient mild inflammation in five eyes. Intraocular pressure was not changed significantly; the facility determined by perfusion of the anterior chambers at 2 months was normal. Light microscopy and scanning electron microscopy show localized trabecular lesions; some are slightly indented, but there is no persistent penetration to Schlemm's canal. Endothelial cells, confluent with those of the cornea, cover the inner (anterior chamber) surface of the lesions. Cross-sections through the center of a lesion show that trabecular meshwork and Schlemm's canal have been obliterated by the treatment and healing; these changes are similar to those previously seen after argon laser monkey trabecular treatment. In the untreated areas, between pulsed laser application sites, trabecular meshwork and Schlemm's canal are normal by light microscopic and scanning electron microscopic examination. Any effect on IOP from this particular type of pulsed laser treatment of the trabecular meshwork is probably not due to trabeculopuncture and flow of fluid through the fistula.     

Histopathological Study of Trabeculum after Excimer Laser Trabeculectomy ab Interno

Purpose: To study the clinical manifestations and histopathologic changes of trabeculum after excimer laser trabeculectomy ab interno ( ELT),and to investigate the mechanisms of ELT in reducing intraocular pressure. Methods : ELT was performed on ten rabbit eyes and postoperative responses were documented. Corneoscleral tissue samples were harvested consecutively each week until the 5th postoperative week and these samples were examined under light and electrical microscopy. Results : Mild stimulation signs were present postoperatively in nine of ten eyes, but no serious complications were experienced. Obvious inflammation was observed in one rabbit eye as a result of iris damage during the surgical manipulations. Local fractures on the trabecular meshwork and openings into Schlemm‘ s canal were detected in all tissue samples under light microscope. Mitochondria were found to be turgescent and dilated like vacuoles and endoplasmic reticula were found to be dilated under electrical microscope in the early postoperative period. Later, all trabecular cells returned normal and no fibroblast cells were ever detected. Conclusions : Permanent openings through trabecular meshwork into the inner wall of Schlemm‘s canal can be created with ELT. The outflow resistance of aqueous humor can be reduced with these openings and intraocular pressure can be controlled thereafter. Eye Science 2001; 17:11 - 15.     

Sites of breakdown of the blood-aqueous barrier after paracentesis of the rhesus monkey eye.

Sites of breakdown of the blood-aqueous barrier following rapid paracentesis have been investigated in rhesus monkeys with two independent procedures. (1) The entrance of fluorescein into the anterior and posterior chambers following paracentesis was studied in vivo in normal eyes, in eyes with laser-induced experimental glaucoma, and in totally iridectomized eyes. (2) Scanning electron microscopy was used to study the ciliary body and trabecular meshwork regions in normal eyes and paracentetic eyes. These investigations show that the ciliary body, particularly the anterior pars plicata region, is a source of secondary aqueous humor protein. In addition, the study shows reflux of blood into Schlemm's canal and plasma movement across the inner wall into the anterior chamber.     

The canine eye: the vessels of aqueous drainage.

Lumenal castings of canine vessels of aqueous drainage, prepared by microvascular injection of room-temperature vulcanizing silicone or Batson's methacrylate corrosion compound No. 17, were viewed with a stereo dissecting microscope and by scanning electron microscopy. The pathways for aqueous drainage in the dog appear to extend radially from the interstices of the filtering meshwork, through the deep intrascleral venous plexus, to the midscleral venous circle of Hovius, which also serves choroidal venous drainage. Venous blood mixed with aqueous humor may egress the globe from the venous plexus of Hovius via the anterior ciliary vein or posterior vortex veins. The canine pathways of aqueous drainage are distinguished from those in the primate by the absence of Schlemm's canal and the intrascleral mergence of drainage routes for aqueous humor and uveal venous blood.     

Anterior and posterior axial lens displacement and human aqueous outflow facility

We studied the effect of anterior and posterior axial crystalline lens displacement (and thereby ciliary tone) on the aqueous humor outflow facility in enucleated human eyes. After attaching a reversible footplate plunger to the anterior lens capsule with cyanoacrylate, the lens was placed in one of three positions: "neutral baseline," posterior displacement (2.5 mm), or anterior displacement (2.0 mm). In seven pairs of eyes, the mean "neutral baseline" was not statistically different from the control eye, but anterior lens displacement decreased outflow facility "C" by 0.14 (36%) (P less than 0.0001), and posterior displacement increased "C" by 0.18 (50%) (P less than 0.01). Anterior or posterior lens displacement after complete ciliary body detachment produced no effect on outflow facility in two pairs. Histologic correlation studies demonstrated narrowing of the intertrabecular spaces and Schlemm's canal in the eyes fixed in anterior lens displacement, and widening of the same structures in the eyes fixed in posterior lens displacement. The lens-zonular-ciliotrabecular force vectors are responsible for the compression or decompression of the meshwork and Schlemm's canal in this model, with compression decreasing, and decompression increasing aqueous humor outflow facility.     

Non-penetrating filtering surgery: concept, technique and results

Recently, many discussions occurred concerning non-penetrating filtering surgery. Viscocanalostomy and deep sclerectomy with external trabeculectomy are the most practiced techniques. Their goal is to reduce intraocular pressure by enhancing the natural aqueous outflow, while reducing its resistance. Both techniques involve the removal of a deep scleral flap, the external wall of Schlemm's canal and corneal stroma behind the anterior trabecular meshwork and Descemet membrane, thus creating a scleral lake, where the aqueous humor remains until it is absorbed in many different ways. In viscocanalostomy, a high-molecular viscoelastic substance is injected into the ostia of Schlemm's canal in order to enlarge it and its collectors channels. In deep sclerectomy with external trabeculectomy, the inner wall of Schlemm's canal is removed with adjacent trabecular layers. Studies, both retrospective and prospective, demonstrated similar tensional results when compared to classical trabeculectomy, with fewer complications and better visual recovery after non-penetrating procedure. The aim of this study is to expose the non-penetrating surgery techniques, mechanism of action and results based on the analysis of published literature.