SEARCH · Search PubMed

Results for “Trabecular Meshwork”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,099 records · Page 61Linked to original sources

PubMed1994

Anterior chamber angle vascularization in Sturge-Weber syndrome. Report of a case.

The case of a 20-year-old woman with a left-sided facial hemangioma and a homolateral glaucoma is reported, complete with the histology of a trabeculectomy specimen. Her left eye had an episcleral hemangioma and goniodysgenetic features in the anterior chamber angle, while the intraocular pressure was measured to be 45 mmHg. The left optic disc showed a large cupping and the left visual field was constricted. The right eye had no glaucomatous changes. Histological examination of the trabeculectomy specimen by both light and electron microscopy showed multiple congenital anomalies. There was a cluster of blood vessels in the trabecular meshwork. Abnormal accumulations of fine granular extracellular matrixes were observed in both the juxtacanalicular connective tissue and around the vascular structures. The lumen of Schlemm's canal was subdivided into three or four parts with few giant vacuole structures. The endothelial cells lining the inner wall of Schlemm's canal contained a well-formed basal lamina with many villi projecting into the lumen. These findings suggest that the multiple anomalies observed in the trabecular tissue may contribute to the manifestation of glaucoma in Sturge-Weber syndrome.

Adult↗

PubMed1988

The effect of some treatment variables on the results of trabeculoplasty.

One hundred nineteen eyes of 99 patients were prospectively followed up for 12 to 21 (mean, 17) months. Laser powers used were lower than those originally proposed by other physicians and ranged from 500 to 800 mW. The postoperative pressure reduction was statistically significant in each power group. The pressure reduction was statistically significantly dependent on the grade of pigmentation on the trabecular meshwork. The quality of the visible burn effect or placement of burns did not have any impact on the postoperative pressure reduction.

Aged↗

PubMed1995

Immunocytochemical localization of prostaglandin E2 receptor subtypes in porcine ocular tissues. I. Uveal tissues.

Polyclonal antibodies were raised against 15-residue sequences in the carboxyl terminal region of mouse EP1, EP2, and EP3 subtypes. The selected sequences are well conserved in different species. Using the antibodies, the localization of the receptor subtypes in porcine uveal tissues was investigated by immunoperoxidase reaction (by light microscopy) and immunogold labeling (by electron microscopy). EP1 immunoreactivity was found in ciliary nonpigmented epithelium and iris muscles (both sphincter and dilator). EP2 was localized to ciliary nonpigmented epithelium and muscle, iris sphincter muscle, and trabecular meshwork. EP3 immunoreactivity was detected in all uveal tissues examined.

Amino Acid Sequence↗

PubMed1984

Anatomical classification of the developmental glaucomas.

With the use of observations in 250 cases of childhood glaucoma, defects were classified anatomically according to the three major anterior chamber structures affected: the trabecular meshwork, the iris, and the cornea. The classification should do much to facilitate communication in the area of the developmental glaucomas and provide standardization of terminology to allow collaborative study of these rare diseases.

Adolescent↗

PubMed1987

A common pathway for developmental glaucomas.

In a clinicopathologic study of ten patients, utilizing a modified trabeculectomy technique for acquisition of histologic specimens, a high insertion of the iris was observed in four types of developmental glaucoma. A survey of the literature revealed additional developmental disorders with this abnormality of the anterior chamber angle. The common defect is believed to arise from a developmental arrest during the third trimester of gestation of tissues derived from cranial neural crest cells. The mechanism by which this developmental defect leads to aqueous outflow obstruction may, in some cases, be a paradoxical collapse of the trabecular meshwork and Schlemm's canal in response to contraction of the ciliary musculature, while other patients may have additional developmental abnormalities in the aqueous outflow system as the possible mechanism of glaucoma.

Adolescent↗

PubMed1983

Why is intraocular pressure elevated in chronic simple glaucoma? Anatomical considerations.

Ultrastructural analysis of 400 trabeculectomy specimens of glaucomatous eye revealed three types of extracellular deposits within the cribriform layer of the trabecular meshwork. One of these derives from the sheath of the subendothelial elastic-like fibres. Tissue culture and ultrahistochemical studies led to the assumption that these deposits contain glycoproteins, probably secreted by the cribriform layer cells.

Animals↗

PubMed1997

Age-related changes in trabecular cells in vitro.

The changes in the morphology and the amounts of selected extracellular matrix proteins in serially passaged porcine trabecular cells cultured from young animals (age range, 4-6 months) were investigated. After 4 weeks incubation, trabecular cells in primary confluent cultures had a flattened elongated profile, whereas the cells in secondary or tertiary cultures, after an additional 4 to 8 weeks incubation, respectively, were epithelioid in shape. Time-lapse micrography of the passaged cells revealed membrane ruffling at the cell periphery, but sparse cell movement. No mitotic events took place in either the secondary or tertiary cultures for 24 hr prior to harvesting the cells. No remarkable differences were observed in the total polypeptide profile of primary, secondary or tertiary cells analysed by SDS gel electrophoresis and silver staining. However, laser densitometry of immunoblots treated with antibodies against type VI collagen, thrombospondin, fibronectin, and laminin demonstrated that, compared to primary cultures of trabecular cells, the amount of type VI collagen was elevated 20.5-fold in tertiary cultures, thrombospondin 6-fold, and fibronectin 5-fold, but laminin was not detectable. Because aging trabecular cells in vitro exhibit specific biochemical characteristics that are comparable to those known to occur in the human trabecular meshwork in vivo, the present method provides a model for the investigation of age-related changes in this tissue at the cellular level under defined and controlled conditions.

Aging↗

PubMed2004

[Aqueous humor dynamics].

Intraocular pressure is mainly controlled by the rate of aqueous humor production and the resistance to its outflow. Aqueous humor formation is the result of fast unidirectional secretion and slow contradirectional reabsorption. The most striking evidence of endogenous regulation of the ciliary epithelial secretion is provided by the observation of the circadian rhythm. Aqueous humor formation is mainly controlled by the interaction of inhibiting alpha(2)-adrenoreceptors and stimulating beta-adrenoceptors. The role of the central nervous system in the regulation of this process remains unclear and the precise mechanism of outflow regulation is not fully understood. The aqueous humor passes into the anterior chamber and leaves the eye by two routes: the direct outflow pathway through the trabecular meshwork or the indirect outflow pathway through the ciliary muscle. Further biochemical, biological and pharmacological investigations are necessary to determine the fundamental process of aqueous humor formation, outflow and regulation.

Absorption↗

PubMed1986

Clinical signs of the pseudoexfoliation syndrome.

Pseudoexfoliation syndrome (PXS) is a common cause of glaucoma throughout the world. It is most commonly diagnosed after the observation of pseudoexfoliation material (PXM) on the anterior lens surface. However, there are numerous clinical signs of PXS that should alert the examiner to search carefully for PXM on the anterior lens surface. These include pupillary ruff defects, iris sphincter transillumination, a characteristic whorl-like pattern of particulate pigment deposition on the iris sphincter, particulate pigment deposition on the peripheral iris and trabecular meshwork, and exfoliation material on the zonules and ciliary body. Accuracy of diagnosis is important for purposes of treatment, prognosis, and basic research in he mechanisms of glaucoma, particularly tissue culture.

Anterior Chamber↗

PubMed1981

Pathophysiology of glaucoma in uveitis.

Glaucoma secondary to uveitis may occur by any one or by a combination of several different pathophysiological mechanisms. These include acute angle-closure due to iris bombé caused by posterior synechiae; chronic angle-closure due to peripheral anterior synechiae; and open angle glaucoma due to obstruction and/or inflammation of the trabecular meshwork. Secretory hypotony may mask impairment of outflow, while steroids used to treat the uveitis may further complicate the situation by causing a rise in intraocular pressure. Careful delineation of the pathophysiology involved is the cornerstone of successful management.

Adrenal Cortex Hormones↗

PubMedDate not supplied

Goniotomy vs trabeculotomy.

Goniotomy is a safe effective procedure in isolated trabeculodysgenesis occurring in children under the age of two years, and is preferred by the authors in all such cases when visibility allows. It may also be effective for varying periods of time in Sturge-Weber syndrome, Aniridia, Axenfeld's syndrome, and Lowe's syndrome when these occur in infancy. Trabeculotomy is generally preferred in children with trabeculodysgenesis over the age of three years, in situations where corneal clouding prevents adequate visualization of the trabecular meshwork, and in patients with aniridia. In the latter group, although goniotomy can be effective, its success rate is low. The absence of iris covering the lens does increase the risk of lenticular injury and, therefore, trabeculotomy is usually chosen.

Adult↗

PubMed1980

[Histopathological aspects of the surgical treatment of congenital glaucoma].

Two tissue specimens obtained by trabeculectomy from infant eyes with different reactive changes in their chamber angles due to previous trabeculotomies are described and discussed. Both eyes had been operated on glaucoma for several times. In the first case, the trabeculotomy had resulted in the formation of laminar scar tissue with hyalinized and atrophic trabecular sheets. In the second case, however, the original trabecular meshwork was completely transformed to a fibrocellular scar tissue. These different structural changes in the chamber angle region may support the hypothesis that such tissue reactions are not only the result of the antiglaucoma procedure adopted, but are also caused by surgical wounds.

Female↗

PubMed1986

Pilocarpine-induced movement of the trabecular mesh.

From geometrical considerations of the trabecular meshwork, ciliary muscle contraction has been predicted to produce an inward movement of the mesh. Goniophotographs taken under carefully controlled conditions before and after topical administration of pilocarpine showed a change in angle between cornea and mesh that is consistent with the predicted change.

Ciliary Body↗

PubMed2004

Viscocanalostomy in rhesus monkeys.

OBJECTIVE: To examine structural changes and aqueous humor outflow after viscocanalostomy in live normal monkey eyes. METHODS: Viscocanalostomy surgery was performed in 1 eye of each of 4 rhesus monkeys. Outflow facility was determined before and after surgery. All eyes were fixed and examined by light and/or electron microscopy 36 or 63 days postoperatively. RESULTS: Schlemm canal was replaced by scar tissue at the surgical site. The juxtacanalicular zone contained homogeneous material, probably high-molecular-weight 1.4% sodium hyaluronate. The sclera external to Schlemm canal was overhydrated, and remains of a scleral lake were present in 1 animal. Multiple defects were present in the endothelial lining of Schlemm canal inner and outer wall. Fine fibrillar material and sheath-derived plaque material partly bridged the defects. Along the inner wall, aggregations of thrombocytes covered some defects in the endothelial lining of the canal. At 90 degrees to 180 degrees from the surgical site, small and fewer breaks in the inner wall were seen. Postsurgery outflow facility (n = 2) was approximately 30% higher in the treated eye than in the contralateral control, corrected bilaterally for presurgery baseline. CONCLUSIONS: The most likely explanations for the increase in outflow facility in monkeys after viscocanalostomy are focal disruptions of the inner wall endothelium of Schlemm canal and disorganization of the juxtacanalicular zone, resulting in direct communication of juxtacanalicular zone extracellular spaces with the lumen of Schlemm canal. The continuous presence of sodium hyaluronate might prevent repair of these defects by interfering with thrombocyte function. CLINICAL RELEVANCE: In nonhuman primates, viscocanalostomy appears to decrease outflow resistance through persisting focal disruption of the inner wall endothelium and opening of the juxtacanalicular or cribriform region of the trabecular meshwork, the tissue most affected by pathologic changes in primary open-angle glaucoma in humans.

Animals↗

PubMed1989

Pulsed neodymium-YAG laser trabeculotomy: energy requirements and replicability.

Short pulsed laser trabeculotomy has been shown to reduce intraocular pressure in patients with primary open angle glaucoma. This study seeks to determine the energy levels required to produce a fistula into the canal of Schlemm for four different Q-switched neodymium-YAG lasers. The laser was fired at fixed human trabecular meshwork specimens at a range of energy settings for each laser and the characteristics and replicability of the lesions produced were analysed. Energy levels between 3 and 5 mJ were sufficient to produce fistulae into the canal of Schlemm with an approximately 50% success rate for each instrument.

Humans↗

PubMed1996

Neodymium:YAG laser lens ablation in a rabbit model.

PURPOSE: To assess the safety of neodymium:YAG (Nd:YAG) laser lens ablation in a rabbit model prior to human investigation. METHODS: The Nd:YAG laser lens ablation probe was inserted into the anterior chamber of 14 New Zealand white rabbit eyes and Nd:YAG laser lens ablation was simulated, exposing the eyes to energy significantly higher than that used in previous experimental Nd:YAG lens ablation of the human crystalline lens. After the procedure, the rabbits were killed at 1 hour, 1 day, or 1 week and the eyes evaluated by specular microscopy, ultrasonic pachymetry, and light microscopy. RESULTS: There was no statistically significant difference in the postoperative endothelial cell counts or ultrasonic pachymetry of study eyes and control (unoperated) eyes. Light microscopy revealed no apparent damage to the cornea, trabecular meshwork, or retina of the study eyes. CONCLUSIONS: the Nd:YAG laser lens ablation device appears to be a safe method of cataract removal in this animal model. Further study is needed to determine the safety and efficacy of this device for cataract removal in humans.

Animals↗

PubMed2002

Neovascularization in the anterior segment of the rabbit eye by experimental anterior ischemia.

PURPOSE: To investigate the effects of anterior ischemia accompanied by neither retinal nor choroidal ischemia on the anterior segment of the eye. METHODS: Both long posterior ciliary arteries in the right eye of 14 rabbits were directly cauterized with an electric coagulator. The eyes were enucleated 1, 2, 4, 7, 9 or 14 days after cauterization, then fixed with 4% paraformaldehyde. Semi-thin sections were studied by light microscopy. Several sections were stained with Griffonia simplicifolia lectin, which bound specifically to mammalian vascular endothelium. Other specimens were examined immunohistochemically for vascular endothelial growth factor (VEGF) protein. The tissue specimens of the first postoperative day were studied for expression of VEGF mRNA by in situ hybridization. RESULTS: Atrophy of the iris and ciliary body was seen after the second postoperative day. Corneal neovascularization appeared after 7 days. Neovascularization on the anterior surface of the iris and in the trabecular meshwork was detected after the ninth postoperative day. The proliferative tissues with newly formed vessels obstructed the iridocorneal angle 14 days after the treatment. There was no histological change in either the retina or choroid. Immunohistochemically, VEGF protein was detected in the epithelial and vascular cells of the iris on the first and fourth postoperative day. Expression of VEGF mRNA was detected in the epithelial cells of the ciliary body on the day following the treatment. CONCLUSIONS: Anterior segment ischemia, when unaccompanied by retinal ischemia, causes neovascularization in the cornea, iris and trabecular tissue.

Animals↗

PubMed2000

Malignant melanoma of the conjunctiva with intraocular extension.

Intraocular extension of a malignant melanoma of the conjunctiva is a rare entity. A 75-year-old woman underwent repeated surgery after receiving the diagnosis of a multilocular recurrent malignant melanoma arising from a primary acquired melanosis. Treatment included 2 lamellar sclerokeratectomies and percutaneous radiotherapy. Five years after initial surgery, intraocular extension of the melanoma was observed, and enucleation was performed. Findings from histopathological examination revealed a malignant melanoma occupying part of the ciliary body, the trabecular meshwork, and the iris. Eyes with recurrent malignant melanoma of the conjunctiva should be carefully monitored for intraocular extension. Deep excision of conjunctival melanoma, including lamellar sclerokeratectomy, may abolish the natural barrier against intraocular extension of malignant melanomas of the conjunctiva.

Aged↗