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Biomedical subjects

G Renard

Publications and source records attributed to G Renard.

At least 127 records · Page 7Linked to original sources
PubMed1999

[Histological changes related to scleral buckling for treatment of retinal detachment].

Treatment of retinal detachment frequently uses biocompatible materials to obtain scleral buckling. These materials are not devoid of consequences on surrounding tissues. In 3 eyes enucleated for failure of surgical treatment using scleral buckling materials, the changes prompted by episcleral implants could be observed. The sclera underwent both an inversion of its curvature and a reduction of its thickness under the material, as well as an encapsulation of the material was observed. While a silicone sponge was used in part to encircle one of these eyes, its capsular inner surface was regular and smooth. In contrast, hydrogel implants used in the three eyes showed a peripheral fragmentation prompting in two of them a typical foreign body giant cell granulomatous reaction. Changes in scleral curvature and scleral thinning were observed reflecting the consequences of the buckling procedure. The capsule formation occurred as it does for any nonabsorbable matérial implanted in tissues. Degradation and fragmentation of the hydrogel material suscitated a granuloma in response to fragments. These hydrogel specific changes should be recognized on microscopic examination of slides of either capsule or eyes previously in contact with this implanted material. They attested of the instability of hydrogel after implantation.

Aged↗
PubMed1999

[Semi-annular pre-equatorial scleral ectasia in a patient with glaucoma and onchocerciasis].

We present the case of a glaucomatous young patient with onchocerciasis who developed a bilateral pre-equatorial scleral staphyloma with an important scleral thinness. The pathogenesis of anterior staphyloma is discussed: mechanical stress from very high ocular pressure, ocular onchocerciasis, scleral ischemia. A better understanding of scleral mechanical resistance could explain scleral thinness without any clinical scleritis.

Adult↗
PubMed1999

[Malignant melanoma on primary acquired conjunctival melanosis].

A primary acquired melanosis occurred in the right bulbar conjunctiva of a 65 year-old caucasian woman. After four years of steadiness, this lesion gave raise to a malignant conjunctival melanoma. The evolution remained under control three years after the end of the therapeutic procedures. Clinical and histopathological data are presented.

Aged↗
PubMed1998

Quantification and localization of hyaluronan in a PTFE polymer implanted in the corneal stroma.

The amount and distribution of hyaluronan in a PTFE polymer used to support an artificial cornea implanted in the rabbit cornea were determined. The findings were used to describe the polymer-corneal stroma interface and the reason for the translucence and wettability of this originally opaque and hydrophobic biomaterial. PTFE disks (6 mm in diameter, 0.2 mm thick, 50 microns in pore size) were implanted after a free-hand intralamellar dissection. The corneas were removed 15 days, 1 month, and 3 months after implantation. The hyaluronan content of pepsin-solubilized corneal stromal extracts and its distribution (7 microns cryostat sections) were investigated using an alkaline phosphatase-linked hyaluronectin assay that specifically detects nanogram amounts of hyaluronan. A PTFE polymer implant caused large, transient increases in hyaluronan density in the implanted stroma. The presence of amphiphilic hyaluronan in the polymer 15 days post implantation probably produced translucence and wettability of this opaque, hydrophobic implant despite the absence of cells. The hyaluronan density in the PTFE polymer increased considerably during the first month and then decreased to stabilize at a moderate level by the third month. These changes in hyaluronan density parallel the invasion of the polymer by inflammatory cells during the first month and the subsequent replacement of these cells by fibroblasts. The PTFE polymer is a good interface that is compatible with the native corneal stroma, and our results indicate that hyaluronan, because of its amphiphilic character, plays a major role in the polymer wettability and translucence and in the production of typical corneal extracellular matrix within the pores of the polymer.

Alkaline Phosphatase↗
PubMed1998

A second generation of artificial cornea (Biokpro II).

The properties of a new second-generation colonizable artificial cornea were evaluated in humans. The prosthesis consisted of a peripheral rim of a translucent microporous fluorocarbon polymer (expanded polytetrafluoroethylene) fused with the polymer of the central optic. The optic was made of medical-grade polydimethylsiloxane coated with polyvinylpyrrolidone. Its refractive power was 42.2 diopters and it measured 7.0 mm in diameter and 0.55 mm in thickness. The geometry of the optic was tested by high-frequency ultrasound and intraocular pressure and distensibility were measured in an artificial chamber. Prostheses were implanted in one eye of 13 humans. The average follow-up was 6 months (range 3-9 months). Most of the eyes (11/13) were clinically stable after a 7 months follow up. Seven patients had visual acuity improvements. Mean corrected final visual acuity was 20/200 (range, 20/30 to light perception). Five anatomical failures occured (two extrusions, two retroprosthetic membranes, one endophthalmitis). The new optical core, junction, and surface properties of the polymers offer many advantages, quicker colonization of the supporting skirt, and an optical core with a geometry similar to that of a normal human cornea. Epithelial cells did not migrate over the interface and optical core. It seems that formation of an epithelium over the artificial device is essential for the long-term stability of the implant.

Adult↗
PubMed1998

Confocal microscopy of cystic disorders of the corneal epithelium.

OBJECTIVE: This study aimed to describe the morphology of cystic disorders of the corneal epithelium by confocal microscopy. DESIGN: The study design was a prospective evaluation of confocal microscopic images of patients with cystic corneal disorders. PARTICIPANTS: Thirteen patients (19 eyes) were included. The corneal disorders included four patients with corneal decompensation (Fuchs' dystrophy), five patients with epithelial basement membrane dystrophy (e.g., Cogan's microcystic and map-dot dystrophies), one patient with Meesmann's dystrophy, and three patients with recurrent erosion syndrome of unknown etiology. Confocal images of diseased corneas were compared with those of ten normal control eyes (ten subjects). INTERVENTION: All patients were examined by slit-lamp biomicroscopic analysis and confocal microscopic analysis (Tomey, Erlangen-Temmenlohe, Germany). Image analysis was used to identify the corneal epithelial structures correlated with the corresponding pathology. MAIN OUTCOMES MEASURES: Confocal microscopy was used to assess the size, shape, light scatter, and reflection of the cysts. RESULTS: Slit-lamp examination results showed corneal epithelial cystic lesions in all cases. Confocal microscopy was able to identify cystic lesions in 9 (69.2%) of 13 patients. Of the four patients in whom lesions could not be found by confocal microscopy, three had recurrent erosion syndrome and the other one had epithelial basement membrane dystrophy. The confocal images were compatible with the clinical and histologic pictures of the disease. Normal control eyes did not show any epithelial lesion, either by biomicroscopy or confocal microscopy. CONCLUSIONS: Confocal microscopy provides an in vivo evaluation of cystic epithelial corneal lesions. This study shows that confocal microscopy is suitable for examining cystic lesions of the corneal epithelium. Nevertheless, it is not as sensitive as biomicroscopy in detecting cystic lesions in certain corneal conditions.

Corneal Diseases↗
PubMed1998

Encapsulation of scleral buckling materials. A study of sixty specimens.

OBJECTIVE: The purpose of the study was to obtain information on the encapsulation of two nonabsorbable biomaterials (silicone and hydrogel) used as explants in scleral buckling in retinal detachment surgery. DESIGN: The study design was a histopathologic study on a cohort of capsule fractions and complete eyes. PARTICIPANTS: Fifty-nine patients participated in this study, in which 60 specimens, including 37 hydrogel and 21 silicone capsule specimens as well as 2 whole eyes, were gathered. There were no control subjects. INTERVENTION: The capsule specimens were obtained from eyes operated on previously for scleral buckling for retinal detachment. The two whole eyes were enucleated. All specimens were studied with routine optic microscopy. MAIN OUTCOME MEASURES: Patient characteristics, type of scleral buckling, and number of operations performed were analyzed. Histologically, the capsular structure, its interface with the explant, and its different components also were studied. Remnants of the buckling material also were investigated. RESULTS: There were 45 male and 14 female patients, with a mean age of 49 years. Histologically, capsule specimens had a fibrous matrix with fibroblasts and few inflammatory cells. Eighteen (48.6%) of 37 hydrogel capsule specimens displayed hydrogel fragments surrounded by a foreign body giant cell granuloma in 16 cases. CONCLUSION: Nonabsorbable materials undergo encapsulation after implantation on the eye surface. Giant cell granuloma was observed in some hydrogel capsule specimens in relation to hydrogel fragmentation. The exact origin of this fragmentation remains unknown.

Adolescent↗
PubMed1998

Toxicity of Xylocaine to rabbit corneal endothelium.

PURPOSE: To assess the toxicity of lidocaine hydrochloride (Xylocaine) to the corneal endothelium. SETTING: Department of Ophthalmology, Hôtel-Dieu Hospital, Paris, France. METHODS: Rabbit corneas were excised and the endothelium was exposed to balanced salt solution (BSS), Xylocaine 1%, or Xylocaine 5% (5 corneas/group) for 20 minutes. The endothelium was then stained with trypan blue and alizarin red, and 5 photomicrographs were taken of each cornea at a standard magnification and analyzed with a digital imaging system (Biocom 200). RESULTS: Xylocaine solutions produced changes in endothelial cell morphology, but there was no cell staining with trypan blue. Corneas exposed to Xylocaine 5% had more marked cell alterations. Small areas of cells were lost from all 15 corneas, mainly at the periphery, but the differences among the 3 groups of corneas were not significant. CONCLUSION: Exposure of rabbit corneal endothelium to Xylocaine solutions in vitro was not associated with trypan blue staining of endothelial cells.

Anesthetics, Local↗
PubMed1998

In vivo study of a fluorocarbon polymer-coated intraocular lens in a rabbit model.

PURPOSE: To evaluate the biocompatibility in rabbit eyes of poly(methyl methacrylate) (PMMA) intraocular lenses (IOLs) that were surface modified using Teflon AF. SETTING: Hôtel-Dieu Hospital, Paris Cedex, France. METHODS: The IOLs were coated with Teflon AF, an amorphous, transparent, and highly hydrophobic fluorocarbon polymer, by immersing them in Teflon AF 5% and evaporating the solvent (C8F18). The surface quality of the Teflon-coated IOLs was evaluated by scanning electron microscopy (SEM). Teflon-coated (n = 20) and control PMMA (n = 10) IOLs were implanted in rabbit eyes. The presence of iris-IOL synechias and the number of deposits on the IOL surfaces were clinically evaluated in both groups to assess the antiadhesive effect of Teflon AF. The Teflon-coated IOLs were removed, their surfaces were evaluated by SEM, and their elemental composition was checked by EDXA and Raman spectrometry. RESULTS: The PMMA IOLs were completely coated with Teflon AF. The Teflon group had no iris-IOL synechias and the control group, two extensive synechias. There were significantly fewer deposits on the surfaces of Teflon-coated IOLs than on the control IOLs 30 and 60 days postoperatively (P < .0001). Scanning electron microscopy showed lens epithelium proliferation and spindle-shaped cells on the surfaces of the PMMA IOLs and cell deposits on the irregular regions of the Teflon-coated IOLs. White-yellow spots were present on the surfaces of both IOL types. The elemental composition of Teflon-coated IOLs was stable. CONCLUSION: Teflon AF had an antiadhesive effect that increased the biocompatibility of PMMA IOLs in vivo.

Adhesiveness↗
PubMed1998

A prospective randomized trial of topical soluble 0.1% indomethacin versus 0.1% diclofenac versus placebo for the control of pain following excimer laser photorefractive keratectomy.

BACKGROUND AND OBJECTIVE: To compare the safety and efficacy of topical nonsteroidal antiinflammatory drugs (NSAIDs) for the control of pain after excimer laser photorefractive keratectomy (PRK). PATIENTS AND METHODS: One hundred twenty informed patients were enrolled in a double-masked, randomized, comparative study and assigned to either 0.1% indomethacin, 0.1% diclofenac, or placebo treatment. Subjective postoperative pain, symptoms, re-epithelialization rate, and systemic medications were monitored for 2 days following photoablation. RESULTS: Compared with the placebo, 0.1% indomethacin solution significantly reduced pain on the day of surgery (D0) (P < .05), whereas 0.1% diclofenac did not reach a significant level (P = .46). At D0, analgesic intake by the oral route was significantly greater in the placebo group (P < .05). Severe photophobia was significantly less frequent in the group treated with 0.1% indomethacin (P < .05). Corneal wound healing was significantly delayed in the patients treated with 0.1% diclofenac at D2 as compared with other groups (P = .04). CONCLUSION: Topical 0.1% indomethacin solution helps control the pain induced by excimer laser photoablation of the cornea without any detrimental effect to the corneal epithelial wound healing.

Administration, Topical↗
PubMed1998

[Choroid melanoma associated with 2 other primary malignant lesions. Apropos of a case].

A case of choroidal melanoma associated to two other primitive malignancies is reported. The patient, a 65-year-old woman had an amelanotic choroidal tumor of her left eye. In her clinical history was found a previously treated kidney carcinoma eight years ago. A choroidal metastasis was therefore diagnosed. After radiation therapy, an initial regression was observed. Fifteen months later, the tumor grew again. Enucleation was performed, and histopathology concluded on choroidal malignant melanoma. Three years later, a mammal carcinoma was discovered and treated by mammectomy. Her ophthalmologic and general status remained normal until now. Amelanotic choroidal tumors are difficult to diagnose. Regular follow-up can lead to a change in the diagnosis. The occurrence of multiple cancers is still not fully understood.

Aged↗
PubMed1998

[Biocompatibility of a porous alumina orbital implant. Preliminary results of an animal experiment].

PURPOSE: Evaluation of clinical tolerance and scanning electron microscopy study of the bio-colonisation of a porous ceramical alumina implant after evisceration of the rabbit. Preliminary results. METHODS: Sixteen white New Zealand rabbits were eviscerated. A porous hydroxyde alumina ball was implanted in the opened sclera and explanted 15, 30, and 90 days after implantation. Clinical tolerance was assessed and implant tissular ingrowth was analyzed by scanning electron microscopy. RESULTS: One infection was observed and there was no conjunctival breakdown. Fibrovascular ingrowth occurred as soon as 15 days after implantation, and was full at one month. CONCLUSION: Porous alumina implant orbital tissue tolerance and fast fibrovascular ingrowth in the rabbit socket suggest promising result in the human anophthalmic socket.

Aluminum Oxide↗
PubMed1998

[Artificial trabeculum (MESH). Clinical and histological study in the rabbit].

PURPOSE: Designed to avoid postoperative hypotony that often occurs after trabeculectomy and to maintain long lasting filtration, the MESH is a thin porous expended polytetrafluoroethylene (ePTFE) implant that mimics the physiological meshwork. The aim of this study is to assess the tolerance, biocompatibility and effectiveness of this device during 6 months in the rabbit. MATERIAL AND METHODS: We used an ePTFE with about 5 microns pore size (Zytex). The head of the implant is 3,0 mm wide and 1,5 mm long and fits in the anterior chamber. The tail is 2,0 mm wide and 3,0 mm long and fits in the subconjunctival space. The MESH is 250 microns thick. 24 Dutch pigmented rabbits were selected because their dark pigmented iris contrasts with the ePTFE implant giving a better visualization. All the animals were cared for in accordance with ARVO resolutions. Surgery was performed on the right eye by the same surgeon (P.H.), the left eye serving as control for IOP measurements. The animals were distributed in 3 groups: one with MESH alone (MESH), one with MESH and Mitomycin C (MMC), one with MESH and 5-FU (5-FU). Follow-up was performed every week (W) during 6 months including IOP measurement, slit lamp observation, photography and bleb assessment. Histological study was done at POD 0, 15, 30, 90 and 180 one eye in each group. Student t test and alternate Welch t test were used for statistics. RESULTS: Filtering bleb: no bleb was visible before W3. A bleb was found between W3 and W6, decreasing between W6 and W9 with no more change after W10. The MESH implant: no change appears in the color of the MESH during the study. Some iris pigments or synechiae were seen in some cases. No extrusion occurred. Intraocular pressure: IOP was lower than in the control eye. The statistical analysis showed a significant lower pressure for the MESH alone at W5 (p = 0.0069), for the 5-FU group at W1 (p = 0.0326), W2 (p = 0.0488), W4 (p = 0.0312). With Mitomycine C we found very significant results at W1 (p = 0.0073), W2 (p = 0.0136), W4 (p = 0.0497), W9 and W11 (p = 0.0174). After W12 the groups were joined and IOP was significantly decreased at W17 (p = 0.0376) and W23 (p = 0.0462). Histology confirmed the correct position of the MESH, its biocompatibility and its ability to drain aqueous humor even if there is colonization of the pores by fibroblast-like cells. CONCLUSION: The present study has shown that the filtering bleb appeared after 3 weeks without major hypotony. The material was integrated only in the intrascleral tunnel and was stable. After 6 months the Mesh was well tolerated. The new concept has a simple surgical technique, less invasive than trabeculectomy and required less surgical time. This technique reduced IOP and produced long survival blebs in rabbits. This device appears suitable for the surgical treatment of open angle glaucoma.

Animals↗
PubMed1998

[Reis-Buckler dystrophy: therapeutic photo-ablation with the excimer laser].

PURPOSE: Reis-Buckler's corneal dystrophy consist of superficial reticulated opacities with recurring attacks of corneal erosion. Lamellar and penetrating keratoplasties were the traditional surgical means of improving recurrent erosions and vision but the dystrophy recurs following surgery. Phototherapeutic keratectomy (PTK) is now the standard method of managing this anterior corneal disease when intervention is required. MATERIAL AND METHODS: We have treated ten eyes with Reis-Buckler's dystrophy using Excimer laser PTK. RESULTS: All of patients achieved visual improvement (preoperative corrected visual acuity: average 0.3 +/- 0.2 SD, postoperative at one month 0.6 +/- 0.3 SD and 0.7 +/- 0.2 SD at one year. The refractive shift changed from a spherical equivalent of -0.92 D to a postoperative refraction of +1.80 D at one month and +1.65 D at one year.

Adult↗
PubMed1998

[Pseudotumor-like superficial conjunctival foreign body].

Pseudo-tumoral presentation of a superficial conjunctival foreign body. A 4-year-old girl was seen in consultation for an apparent conjunctival tumor of the inner canthus of the right eye. With a soft traction, the tumor was detached of the conjunctiva, as it represented in fact a foreign body. Histopathology helped to diagnose that the foreign body was made of textile fiber. Superficial conjunctival foreign bodies may sometimes appear difficult to identify primarily especially in children.

Child, Preschool↗