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Results for “Tenon Capsule”

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PubMed1998

Synergistic effect of electric pulses and bleomycin on cultured rabbit subconjunctival fibroblasts.

BACKGROUND: The combined effect of electric pulses (EP) and antiproliferative agents on the proliferation of rabbit Tenon's capsule fibroblasts was investigated. METHODS: Rabbit Tenon's capsule fibroblasts were cultured. Some of these cells were exposed to various intensities of EP alone (500-2500 V/cm). Other cells were then exposed for 30 min to an antiproliferative agent: bleomycin (BLM; 0.0005-50 mumol/l), mitomycin C (MMC; 0.0005-50 mumol/l), 5-fluorouracil (5-FU; 0.05-5000 mumol/l), or streptomycin (SM; 0.0005-50 mumol/l) with or without EP (2000 V/cm, 99 mus, eight pulses). Cell proliferation was assessed by cell counting on day 3 and by a 3H-thymidine uptake assay. DNA fragmentation was assessed by flow-cytometric analysis and agarose gel electrophoresis. RESULTS: A significant reduction in the cell number was observed only at 2500 V/cm (P < 0.05). BLM, MMC and 5-FU treatment inhibited cell proliferation in a dose-dependent manner either with or without EP (ID50: BLM alone, 0.029 mumol/l; BLM and EP, 0.00022 mumol/l; MMC alone, 41.6 mumol/l; MMC and EP, 27.5 mumol/l; 5-FU alone, 1045 mumol/l; 5-FU and EP, 690.2 mumol/l; P < 0.05). EP treatment induced an inhibitory effect of BLM on cell proliferation which was 100 times more prominent than BLM alone (0.0005 mumol/l of BLM alone 103.4 +/- 4.4%, 0.0005 mumol/l of BLM and EP 26.0 +/- 4.4%; P = 0.021). BLM treatment with EP also augmented the apoptotic-like DNA fragmentation in both a flow-cytometric DNA histogram and agarose gel-electrophoresis. CONCLUSION: EP treatment enhanced the inhibitory effect of BLM on the cell proliferation of Tenon's capsule fibroblasts of rabbits. The combination of electric pulses and antiproliferative drug treatments may therefore reduce the necessary dose of antiproliferative agents in filtering surgery.

Animals↗

PubMed2005

[Effects of latanoprost eye drops on the proliferation of human Tenon's fibroblasts in tissue culture].

OBJECTIVE: To observe whether there is a direct effect of latanoprost eye drops on the proliferation of cultured human Tenon's capsule fibroblasts (HTCFs) in vitro. METHODS: Human Tenon's capsule fibroblasts were cultured in vitro. Latanoprost eye drops was serially diluted in order to make nine concentrations ranging from 5.00 microg/ml, 0.50 microg/ml, 0.05 microg/ml to 5 x 10(-8) microg/ml. Fibroblasts growth was evaluated with MTT assay. Morphological changes were observed under phase contrast microscope. RESULTS: Majority of cultured human Tenon's capsule fibroblasts was dead at the concentration of Latanoprost (5 microg/ml), the A values were significantly decreased (P < 0.01). There were no significant changes of the A values (P > 0.05) in lower concentration (under 0.05 microg/ml) compared with control. there was no statistical difference in proliferation of HTCFs after latanoprost treatment for 24 hours, 48 hours, 72 hours. CONCLUSIONS: Latanoprost has the toxic effect on the fibroblast at higher concentrations, but there is no influence on the proliferation of HTCFs at the lower concentrations.

Antihypertensive Agents↗

PubMed2000

Enhanced short-term plasmid transfection of filtration surgery tissues.

PURPOSE: To quantify and localize plasmid transfection of filtration surgery tissues using two delivery techniques. METHODS: Full-thickness filtering procedures were performed on eyes of New Zealand albino rabbits. In 10 eyes, naked plasmid DNA in saline was either injected beneath Tenon's capsule at the filtration site or absorbed into a collagen shield that was then placed external to the sclerostomy and under the Tenon's capsule. Forty-eight hours after surgery, levels of the reporter gene, chloramphenicol acetyltransferase (CAT) were measured in samples of ocular tissues. In two additional eyes, the ss-galactosidase (ss-GAL:) reporter gene expression was localized histologically. RESULTS: Injection of plasmid DNA in saline vehicle into the filtration bleb produced readily detectable CAT activity in bleb tissue (conjunctiva, Tenon's capsule, and sclera) whereas CAT activity was nearly undetectable in samples of the cornea, iris-ciliary body, and tissues located opposite the bleb site. Delivery of the plasmid DNA into the bleb through a collagen shield increased CAT activity 30-fold over injection of plasmid in saline (2711 +/- 567 mU/mg versus 92 +/- 38 mU/mg). ss-Gal activity was imaged only in the region of the bleb, and microscopic examination showed ss-Gal activity localized to Tenon's capsule fibroblasts, with minimal ss-Gal activity observed in inflammatory cells or scleral fibroblasts. CONCLUSIONS: Transfection of filtration tissues is enhanced by absorption of naked DNA into a collagen shield. Furthermore, transfection is localized to the fibroblasts and inflammatory cells of the filtration bleb site. Gene therapy using naked plasmid DNA and a simple collagen shield delivery vehicle may be useful for regulating wound healing after glaucoma surgery.

Animals↗

PubMed2001

Small incision trabeculectomy: experiences with this new procedure for glaucoma surgery in Indian eyes.

PURPOSE: The purpose of this study was to evaluate the potential advantages and disadvantages, success rate and complications of this new procedure for glaucoma surgery, which includes the formation of a filtration fistula without any dissection of the Tenon's capsule; as an alternative to trabeculectomy with or without pharmacological wound modulation. METHODS: Small Incision Trabeculectomy avoiding Tenon's capsule was performed in 40 glaucomatous eyes through a 2.5 mm limbal incision and intraocular pressure was monitored serially over a period of 12 months. RESULTS: The mean postoperative intraocular pressure (16.60+/-5.93 mmHg) at 12 months follow-up was significantly lower than the mean preoperative IOP (30.20+/-10.70 mmHg). Thirty-six eyes (90%) had IOP less than 22 mmHg without antiglaucoma medications at the end of the 12-month follow-up. Blebs were pale and diffusely elevated. No serious complications were encountered. CONCLUSION: This new technique is a low-cost and safe alternative to conventional trabeculectomy that effectively reduces intraocular pressure. The use of a small 2.5 mm incision which obviates the dissection of the Tenon's capsule and subsequent subconjunctival fibrosis, the absence of requirement of any sophisticated instruments, and the absence of any major complications which are encountered with the use of anti-metabolites entails that this procedure be performed more often in glaucomatous eyes needing filtration surgery.

Adult↗

PubMed2001

Spontaneous subconjunctival orbital fat prolapse: report of three cases.

Spontaneous subconjunctival orbital fat prolapse is an uncommon but benign entity. It is seldom discussed in the literature, and is sometimes confused with other ocular surface tumors, such as dermolipoma. We present 3 cases, two of which are bilateral, the other being unilateral. Two cases underwent surgical excision due to ocular irritation, and the pathology proved mature adipose tissue compatible with the diagnosis. Computed tomography (CT) was available for 1 case and revealed a fat-compatible radiolucent mass continuous with the intraconal fat. Some other reports have presumed that the intraconal fat was prolapsed from a dehiscence of Tenon's capsule. However, according to our surgical findings, we suggest that the possible weak point for intraconal orbital fat prolapse is between the regions where the rectus muscle tendons penetrate into Tenon's capsule. The fat just bulges anteriorly, but not penetrates the Tenon's capsule and the intermuscular septum.

Aged↗

PubMed2005

[Modulation of cell proliferation and collagen synthesis of porcine Tenon's fibroblasts by extracts of lens and vitreous with treatment of dexamethasone].

OBJECTIVE: To demonstrate the effects of lens extract (LE), vitreous extract (VE) and dexamethasone on the modulating of the proliferation and collagen synthesis of Tenon's capsule fibroblast. METHODS: Cell proliferation and collagen synthesis of Tenon's fibroblast were measured using MTT and reverse transcription polymerase chain reaction techniques in the presence or absence of LE, VE, or dexamethasone, respectively. RESULTS: The growth of Tenon's fibroblasts was stimulated by LE and VE in dose and time-dependent manners. Dexamethasone significantly inhibited the proliferation of the cells either in the presence or absence of LE and VE. Similarly, LE and VE significantly stimulated the collagen synthesis of the cells. However, dexamethasone showed no significant effect on the LE or VE-enhanced collagen synthesis of the cells. CONCLUSION: These results suggested that there might be some ingredients in LE or VE that could stimulate the cell proliferation and collagen synthesis of Tenon's capsule fibroblasts. These ingredients, if released, may affect the success rate of filtration surgery for glaucoma. The application of glucocorticoid itself might not be sufficient to retard the scar formation following the filtering surgery in refractory glaucoma after cataract surgery or vitrectomy.

Animals↗

PubMed2006

Matrix metalloproteinase-9 expression in pterygium.

PURPOSE: To assess matrix metalloproteinase (MMP)-9 expression in pterygium lesion. METHODS: A prospective randomized clinical trial was done to evaluate the expression of matrix metalloproteinase in normal and in primary or recurrent pterygia in Tenon's capsule by immunohistochemical analysis and a computerized image analysis system. The data were submitted to statistical analysis. RESULTS: Matrix metalloproteinase expression showed no difference in normal Tenon's capsule and in primary or recurrent pterygia. CONCLUSION: The similar expression of the matrix metalloproteinase in normal Tenon's capsule and in primary or recurrent pterygia allowed us to conclude that matrix metalloproteinase is not implicated in the genesis or the recurrence of pterygium lesion.

Adult↗

PubMed1991

A simple method of conjunctival dissection for Gunderson flaps.

In this study we describe a method for simplifying the often frustrating and time-consuming task of dissecting conjunctiva from underlying Tenon's capsule during Gunderson flap procedures. Using gentian violet marks as a guide, a needle and two pairs of scissors are used in series to separate superior bulbar conjunctiva from the superficial layers of Tenon's capsule along a series of semimeridians. The techniques provides the surgeon with important landmarks, reduces the risk of inadvertent buttonholing, and minimizes conjunctival retraction caused by uneven dissection of Tenon's capsule.

Conjunctiva↗

PubMed1975

Unintentional filtration after cataract surgery.

The eyes of an 81-year-old man were obtained three and ten days after intracapsular extractions had been made through limbal incisions under limbal-based flaps of conjunctiva and Tenon's capsule. The wounds were closed with 7-0 chromic collagen. Before death from bronchopneumonia, the patient developed bilateral filtrations in association with violent coughing spells. In both specimens, the healing processes of the conjunctiva and Tenon's capsule were advanced, confining the escaping aqueous humor to the subepithelial tissues of the flap. In contrast, the stromal wounds were still inert in accordance with our earlier observations that these wounds are precariously weak during the first two weeks after surgery. In cataract surgery, flaps including both conjunctiva and Tenon's capsule should be prepared and closed to support the slower healing stromal wound. Prevention of filtrations is not a simple matter of using many sutures. This patient's eyes demonstrated that improperly placed or too tightly tied sutures may be directly responsible for leaking wounds.

Aged↗

PubMed1991

Bone implants after enucleation.

A method of preparing antigen-free cancellous bone for use as an orbital implant is described together with the surgical technique for its use in enucleation. The results of 52 patients with follow-up spanning 10 years is reported. In the first four years, five implants had to be removed, all due to infection following breakdown of Tenon's capsule in the early postoperative period. However, with more careful closure of Tenon's capsule, there have been no extrusions during the last six years.

Adolescent↗

PubMed2006

Expression of bone morphogenetic proteins (BMPs), their receptors, and activins in normal and scarred conjunctiva: role of BMP-6 and activin-A in conjunctival scarring?

Bone morphogenetic proteins (BMPs) and activins are multifunctional growth factors, which also affect wound healing and tissue fibrosis. To determine their putative role in conjunctival wound healing and scarring, we investigated the expression of various BMPs, BMP receptors, and activins in normal and scarred human conjunctival tissue and in cultured human Tenon's capsule fibroblasts on the mRNA and protein level. Messenger RNA expression of BMP-2, BMP-3, BMP-4, BMP-5, BMP-6, BMP-7, the BMP receptors type I (BMPR-IA, BMPR-IB) and II (BMPR-II), and of activin A and B was investigated by semi-quantitative RT-PCR in normal conjunctival specimens and in scarred filtering blebs as well as in cultured Tenon's capsule fibroblasts obtained from patients with primary open-angle glaucoma (POAG), pseudoexfoliation (PEX) glaucoma and cataract. Immunohistochemistry was used to study the protein expression of BMP-2, BMP-4, BMP-6, BMP-7, and activin A in normal and scarred conjunctival tissue as well as in cultured Tenon's capsule fibroblasts. BMP-2, BMP-3, BMP-4, BMP-6, BMP-7, all BMP receptors, and activin A were expressed on the mRNA and protein level in conjunctival biopsies without showing any differences between groups of patients. The mRNA and protein expression of both BMP-6 and activin A was found to be significantly increased in scar tissue compared with normal conjunctiva and could be immunolocalized to epithelial cells, vascular endothelia, stromal fibroblasts, and macrophage-like cells. However, no significant increase in receptor gene expression was observed in scar tissue. With the exception of BMP-7, all growth factors and receptors were also expressed in cultured Tenon's fibroblasts without showing any differences between cultures derived from normal and scarred conjunctival specimens. These findings suggest various BMPs and activin A as components of the conjunctival cytokine meshwork regulating tissue homeostasis and wound healing and provide evidence that alterations in the expression of BMP-6 and activin A, in particular, are associated with conjunctival scarring. Modulation of BMP/activin activities may, therefore, be explored as new approaches for managing postoperative conjunctival scarring responses in glaucoma patients.

Activins↗

PubMed1988

A simplified scleral graft technique for covering an exposed orbital implant.

A simplified method of covering an exposed orbital implant is presented. Donor sclera is placed between Tenon's capsule and the spherical implant without dissecting any tissue planes between the conjunctiva and Tenon's capsule. Technical manipulations and bleeding are thereby minimized. Preplaced absorbable sutures in the periphery of the graft are externalized and tied to the anterior surface of the conjunctiva.

Adolescent↗

PubMed2003

Matrix metalloproteinase inhibition modulates fibroblast-mediated matrix contraction and collagen production in vitro.

PURPOSE: To investigate the effect of matrix metalloproteinase (MMP) inhibition on fibroblast-mediated matrix contraction and production. METHODS: Free-floating fibroblast-populated type I collagen lattices were prepared with human Tenon's capsule fibroblasts. Lattice areas were photographed and digitally analyzed to indicate the degree of lattice contraction. Quantitative competitive reverse transcription-polymerase chain reaction (QCRT-PCR) and enzyme-linked immunosorbent assay (ELISA) were used to quantify mRNA and protein respectively for MMP-1, -2, and -3 by fibroblasts during lattice contraction. Gelatin zymography demonstrated activity of MMPs released into the conditioned medium of contracting lattices. Concentrations of the broad-spectrum MMP inhibitors ilomastat, CellTech (Slough, UK), and BB-94 were added to the contracting fibroblast-populated collagen lattices. Secreted C-terminal propeptide of type I collagen was measured in conditioned medium of contracting lattices by ELISA. Fibroblast proliferation in the presence of concentrations of ilomastat was measured by using the reagent water-soluble tetrazolium-1 (WST-1). RESULTS: During contraction of type I collagen lattices, Tenon's capsule fibroblasts expressed MMP-1, -2, and -3 mRNA and protein. Zymography demonstrated the release of four gelatinolytic species into the conditioned medium of contracting lattices (57, 72, 91, and 100 kDa). Inclusion of MMP inhibitors in the zymogram-developing buffer reduced the proteolytic activity of the detected bands. MMP inhibition (1-100 microM) significantly reduced fibroblast-mediated collagen lattice contraction (P < 0.05), and this effect was found to be reversible. Ilomastat also significantly inhibited production of collagen in a dose-dependent manner (P < 0.05). No effect on fibroblast proliferation was found in the presence of ilomastat. CONCLUSIONS: MMPs are produced during Tenon's capsule fibroblast-mediated collagen lattice contraction. Broad-spectrum MMP inhibition significantly reduced matrix contraction and production without cell toxicity. Future clinical use of MMP inhibitors may be possible, because MMP inhibition significantly reduces fibroblast functions associated with contractile scarring.

Cell Division↗

PubMed1992

Pigment-containing cells in extraocular tissues of the primate.

In the present study pigment-containing (PC) cells, localized in extraocular tissues of man and the cynomolgus monkey, were investigated to establish their localization, nature and relationships with the autonomic nervous system. In the orbit of man as well as the cynomolgus monkey three localizations of PC cells were detected: (1) Tenon's capsule along the ciliary arteries at the level of the entrance of the arteries into the eyeball, (2) Tenon's capsule along the ciliary nerves at the level of the entrance into the eyeball, and (3) the sclera around the ciliary arteries and nerves. Moreover in the orbit of the cynomolgus monkey PC cells were found along and around the accessory lateral rectus muscle. Histological, histochemical and electron microscopical studies led to the conclusions that PC cells are similar in nature to melanocytes and do not have neuronal properties. In contrast to the melanocytes in the anterior segment of the eye in both man and monkey, melanocytes in the extraocular tissues are not innervated either adrenergically or cholinergically.

Animals↗

PubMed1995

Modification of the scleral openings to reduce tissue breakdown and exposure after hydroxyapatite implantations.

We compared the incidence of exposure of the hydroxyapatite implant after evisceration according to the position of scleral windows which allow rapid fibrovascularization into the implant. Three patients (10%) developed tissue breakdown and exposure of the hydroxyapatite, out of 30 patients who had external scleral windows located in a position just anterior to the insertion of each of the rectus muscles, whereas no patient developed exposure, out of 24 patients who had internal scleral windows located in a position just position just posterior to the insertion of each of the rectus muscles. Internal windows sealed with rectus muscles could prevent direct contact between implant and the overlying Tenon's capsule and conjunctiva. These findings seem to indicate that the rough spicular surface of the hydroxyapatite irritates and erodes the overlying Tenon's capsule and conjunctiva.

Biocompatible Materials↗

PubMed1989

Paracellular permeability of corneal and conjunctival epithelia.

The paracellular permeability of normal rabbit cornea and conjunctiva was studied in vivo and in vitro. After intravenous administration, horseradish peroxidase was found to percolate to the intercellular space of conjunctival epithelia and was restricted by the tight junctions of the superficial epithelium. Only minimal tracer was present in the limbus and cornea. The difference between corneal and conjunctival paracellular pathways was further compared in vitro by tissue perfusion studies using various tracers from subepithelial space to apical surface. The intact full-thickness cornea was permeable to mannitol (MW 182) but not to inulin or dextran. The conjunctiva was permeable to mannitol, inulin and FITC-dextran (MW 20,000). The quantitative permeability to 3H-mannitol (X10(-8) cm/sec) of adult rabbit cornea was 0.12 +/- 0.02, which is about 55-fold and 50-fold lower than that of conjunctiva (6.78 +/- 0.21) and peritoneum (6.12 +/- 0.63), respectively. Removal of the corneal epithelium increased the permeability 40-fold; however, removal of the endothelium had little effect on the solute permeation. When both corneal epithelium and endothelium were debrided, the bare stroma became edematous and the permeability increased 70-fold. The permeability of 1-week-old rabbit cornea was 1.32 +/- 0.18, which decreased to 0.46 +/- 0.06 in 2-week-old rabbits, and became similar to the adult level at 4 weeks of age. When Tenon's capsule was included in the perfusion, the conjunctival permeability decreased 2.5-fold. With the apposition of bare corneal stroma to the conjunctiva and Tenon's capsule, the permeability decreased further (4-fold).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1997

Single exposures to antiproliferatives: long-term effects on ocular fibroblast wound-healing behavior.

PURPOSE: To determine the long-term effects of single, 5-minute exposures to 5-fluorouracil (5FU) and mitomycin-C (MMC) on Tenon's capsule fibroblast migration, growth factor production, growth factor receptor expression, and extracellular matrix (ECM) production. METHODS: Monolayer cultures and the overlying growth medium of Tenon's capsule fibroblasts exposed to 5FU (0.25 to 25 mg/ml) or MMC (0.001 to 0.1 mg/ml) were harvested up to 48 days after treatment. The expression of growth factors and growth factor receptors, including transforming growth factor beta (TGFbeta), basic fibroblast growth factor (bFGF), and epidermal growth factor (EGF), and ECM molecules (collagen type I, collagen type III, and fibronectin) were quantitated at the mRNA and protein levels. The ability of fibroblasts exposed to 5FU and MMC to migrate to fetal calf serum was also investigated up to 48 days after treatment. RESULTS: Control cultures were found to produce the growth factors TGFbeta and bFGF but not EGF. Exposure to 5FU or MMC resulted in an initial significant increase (P < 0.05) in the production of TGFbeta and bFGF, with levels then decreasing toward those of controls. Cells exposed to 5FU or MMC exhibited an initial significant decrease (P < 0.05) in the number of TGFbeta, bFGF, and EGF growth factor receptors, with subsequent recovery toward control levels by day 48 after treatment. Both 5FU and MMC caused a significant reduction (P < 0.05) in collagen type I and fibronectin production compared to controls throughout the 48-day culture period. The production of collagen type III was initially elevated (P < 0.05) compared to controls after exposure to 5FU or MMC, production then decreasing toward control levels over the remainder of the 48-day culture period. The migration of cells exposed to 5FU or MMC was significantly reduced (P < 0.05) compared to controls up to 48 days after treatment; these cells exhibited a partial recovery of migratory ability throughout this period. CONCLUSIONS: Fibroblasts whose growth was arrested using single, short exposures to 5FU or MMC appear to be capable of performing several crucial aspects of wound healing, including the expression of growth factors and receptors and ECM molecules and the ability to migrate. These findings may help explain why in some patients treated with antiproliferatives, glaucoma filtration surgery fails because of scarring.

Antimetabolites↗

PubMed2002

Tenon's traction sutures: an aid for trabeculectomy and aqueous drainage device implantation.

PURPOSE: To describe a surgical technique to improve visualization and surgical access for trabeculectomy and implantation of aqueous drainage devices. MATERIALS AND METHODS: After the corneal traction suture (6-0 polygalactin; S-29 needle) is placed, a second suture is passed through Tenon's capsule alone, either at the anterior edge of a limbus-based conjunctival flap for trabeculectomy or at the incisional edge of a fornix-based conjunctival flap for drainage implant surgery. RESULTS: The incision for limbus-based peritomies must be posterior enough to take advantage of the posterior thickening of Tenon's capsule when placing the traction suture. The use of traction sutures enhances visualization and limbal surgical access for trabeculectomy. They also enhance posterior ocular surface visualization and aid placement of scleral fixation sutures for securing the explants of aqueous drainage devices. CONCLUSIONS: Tenon's traction sutures are an aid to visualization and to surgical access during glaucoma filtering surgery.

Connective Tissue↗