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Biomedical subjects

G Renard

Publications and source records attributed to G Renard.

At least 19 recordsLinked to original sources
PubMed1992

A new fluorocarbon for keratoprosthesis.

Previous studies have demonstrated the potential use of microporous, biocompatible materials to improve the long-term stability of keratoprosthesis. To determine the factors that will influence corneal tissue ingrowth into biocompatible, microporous materials, we have compared three types of fluorocarbon polymers--Impra, Gore-Tex, and Proplast--after intrastromal implantation in rabbit corneas. Despite similar physicochemical structures, a great difference was observed in histologic and ultrastructural cross sections after 4- and 8-month follow-ups. For Gore-Tex, we observed extrusion of the implant and infiltration of necrotic and inflammatory cells. All implants of Proplast also led to significant corneal damage resulting in extrusion of the material. Through the use of electron and light microscopy and image analysis, this study demonstrates the presence of cell differentiation and collagen synthesis in the pores of the Impra implant. Apart from biocompatibility, this experiment demonstrates the influence of pore size, porous microorganization, and biomechanical factors on prosthetic corneal material. Only Impra offers satisfactory interface, allowing fibroblastic cells and neocollagen synthesis into its pores, and it can become transparent.

Animals↗
PubMed1992

[Bilateral hidrocystoma of the median canthus. Apropos of a case].

Cystic lesions of the eyelids are not uncommon and are variable in nature. A case report of a 42-year-old male patient is detailed. A bilateral cystic lesion was clearly visible at both medial canthuses. Surgical resection was performed under local anesthesia, followed by histopathological study of the specimens. This revealed that these lesions were hidrocystomas, of probable eccrine origin. As many different cystic lesions may be encountered on the eyelids (dermoid cysts, epidermic cysts, cystic basal cell carcinomas...), routine histopathological study of surgically removed cystic specimens is mandatory to obtain an accurate diagnosis.

Adult↗
PubMed1992

[Pigmented seborrheic wart on the skin of the eyelid].

Pigmented tumors of the eyelid are often difficult to identify accurately, as different tumors may have the same clinical presentation. We report the case of a 84 year old female patient who noticed a black tumor of the lower eyelid, with a recent increase in size. Clinically, this lesion was an exophytic tumor of the medial part of the left lower eyelid, respecting the lacrimal punctum and involving the palpebral margin. A surgical excision was performed. Microscopic examination revealed a pigmented seborrheic keratosis, a benign tumor of the epidermis. Histopathology has a key role in the precise diagnosis of pigmented tumors of the eyelid, in which the differential diagnosis concludes sweat gland cysts, pigmented basal cell carcinoma, naevus and uncommon malignant melanoma.

Aged↗
PubMed1992

[Palpebral form of mixed tumor of the lacrimal gland. Apropos of a case].

The clinico-pathological findings in a 45-year-old male patient with a lacrimal gland tumor are reported. This tumor had a spontaneous course of about nine years before it was resected. The clinical presentation was unusual as the tumor appeared as a nodular well-circumscribed swelling of the lateral part of the left superior eyelid. Imaging techniques did not reveal any involvement of the orbital part of the lacrimal gland. However a wide supero-lateral approach was chosen to achieve monobloc resection. Histopathology showed the typical features of an encapsulated pleomorphic adenoma, with no suspicious cytologic changes. Complete resection had a total curative effect for the patient. A wide lateral approach seems to be mandatory for tumors of the lacrimal gland to avoid partial resection and local recurrences.

Eyelid Neoplasms↗
PubMed1992

[Bilateral actinic keratosis of the corneal limbus. Apropos of a case].

Keratinised tumors of the conjunctiva are not uncommon lesions. However, different pathological lesions may have a similar clinical. Actinic keratosis is one of these, it is an epithelial pre-cancerous lesion of the conjunctiva, which may become, if untreated, an invasive carcinoma. A case of bilateral lesions of this type is reported in a 61-year-old male patient who used to work outdoors, and the clinical diagnosis was followed by bilateral surgical removal of the two lesions. Histological examination study showed that the acquired modifications of the epithelium were typical of conjunctival actinic keratosis.

Conjunctival Neoplasms↗
PubMed1992

[Pilomatrixoma of the eyelid. Apropos of a case].

Primary adnexal tumors of the eyelids are quite uncommon. This diagnosis should be considered in the case of a sub-epidermal tumor. We report the case of a 25-year-old female patient presenting with a left eyelid nodular tumor, which appeared clinically as a whitish swelling of the lateral part of the eyelid, covered by normal epidermis. Ultrasonography showed a heterogeneous structure probably containing calcified areas. Complete surgical removal was performed under local anesthesia. Macroscopically, the tumor was encapsulated, with an irregular surface, and it appeared stony under section. Microscopically, it was characteristic of a pilomatrixoma, with sheets of mummified cells devoid of nuclei, either clear or basophilic, and partially calcified. Neither granulomatous reaction nor ossification were observed. This clinicopathological report recalls that pilomatrixoma may appear as a single nodular tumor of the eyelid.

Adult↗
PubMed1991

[Mucoepidermoid carcinoma of the conjunctiva with intraocular invasion. Apropos of a case].

One case of mucoepidermoid carcinoma of the conjunctiva with intraocular invasion is described. Review of literature retrieve 15 cases of conjunctival localisation of mucoepidermoid carcinoma. These tumors appear to be locally aggressive, they all invade the intraocular or intraorbital structures. They require always a radical surgery with wide excision. Histopathologically, histochemical stains for glycoproteins confirm the diagnosis with admixture of squamous and mucus secreting cells.

Aged↗
PubMed1991

[Damage to the corneal endothelium caused by radial keratotomy].

In our experimental study on 53 rabbits we compared the amount of corneal endothelial damage caused by radial keratotomy (RK) referred to (1) the number of incisions (4, 8, or 16), (2) the postoperative interval (0 h, 48 h) and (3) the direction of the incision [centripetal (cp), centrifugal (cf)]. The endothelial damage was quantified by means of the Janus green photometry technique. Morphological changes were evaluated by scanning electron microscopy (SEM). Depending on the group examined, we found endothelial damage extending over 3-7% of an analysed surface of 64 mm2. One perforation caused endothelial damage of up to 17% of the surface examined. Increasing the number of incisions from 4 to 8 or 16 resulted in a statistically significant increase in the amount of endothelial damage (4.2%, 5.1%, 5.8%; P less than 0.05). At 0 h it was significantly higher than after 48 h (5.5%, 4.6%; P less than 0.05). The direction of the incision had no statistically significant influence in our study (zp: 5.2%, zf: 4.9%). The morphological changes in the rabbit corneal endothelium examined directly after the RK procedure were ruptures in the cell membranes, loss of cells, and posterior corneal protrusions beneath the incisions. After 48 h, we found fewer damaged cells and no denuded Descemet's membranes, but larger polymorphy of the cells and a numerical increase in the microvilli of the cells surrounding the damaged cells. Our results support the crucial argument against RK: the alteration and destabilization of healthy corneal tissue up to the endothelium.

Animals↗
PubMed1991

Biocompatibility of a refractive intracorneal PMMA ring.

Intrastromal ring (ISR) implantation is a promising concept in refractive corneal surgery. In theory, it has two main advantages: eccentric corneal surgery and reversibility after ISR explanation. We present our first experimental data on histobiocompatibility after implantation of a 0.2/1.0 mm vaulted polymethylmethacrylate (PMMA) ISR of 7.5 mm diameter with a specially designed "puzzle lock" using a suction-guided stromal channelling device. Ninety-six rabbit eyes were implanted and enucleated after a 24-h to 8-month follow-up to be period and processed for histology (n = 51), scanning electron microscopy (n = 30) and transmission electron microscopy (n = 9). In this study, the histological data are reported. Two main histopathological phases of stromal reaction were observed: (1) up to 3 months: mild inflammation, mostly mononuclear cell reaction with some macrophages; (2) over 3 months: moderate fibrosis surrounding the ISR filling irregularities of the stromal channel. Mild scarring and rare circumscribed vascularization occurred at the sutured peripheral insertion site of the ISR. Persistent epithelial atrophy without erosion or ulceration was regularly observed over the bulging shoulder of the ISR. There was no significant endothelial surgical trauma due to ISR placement. Major complications occurred in 11 cases (11.5%): stromal abscess starting from the incision (n = 8) and massive neovascularization (n = 3). However, the incidence of complications regressed with improved surgical technique. In conclusion, there is good middle-term tolerance of the PMMA ring with a transparent central cornea.

Animals↗
PubMed1991

Surgical management of corneal perforation with expanded polytetrafluoroethylene (Gore-Tex).

We report a series of six patients with spontaneous corneal perforations successfully treated with a temporary graft of expanded polytetrafluoroethylene (Gore-Tex) until a definitive penetrating keratoplasty could be performed. Two other patients had a paralimbic perforation treated with an artificial lamellar Gore-Tex graft. No infection or extrusion developed, and the artificial graft kept the anterior chamber tight in all cases. Gore-Tex appears to be a safe and effective material for use in treating acute central and peripheral corneal perforation.

Adult↗
PubMed1990

[Combined operation of glaucoma and cataract. Comparison between 2 operative techniques].

In this retrospective study of combined surgery we compared patients who underwent Trabeculectomy (Trab.) + Intracapsular cataract extraction (EIC) +/- Intraocular lens (IOL) with patients who underwent Trabeculectomy + Extracapsular cataract extraction (EEC) +/- IOL. All the patients presented with primary open angle glaucoma with a senile cataract. Each group studied included 20 eyes. After 24 months we confirmed that the mean postoperative intraocular pressure (IOP) showed a decrease of 7.4 mmHg in the first group (EIC + Trab.) and 5.46 mmHg in the second group (EEC + Trab.) of patients. A statistically significant difference was observed between the two groups (p less than 0.05). On the basis of IOP the 1st group showed a success rate of 85% after an average period of 23.55 months (6-43 months). The 2nd group presented a success rate of 90% after an average period of 18.3 months (4-37 months). The mean visual acuity after 24 months improved in the 1st group from 0.10 to 0.50 and in the second group from 0.13 to 0.50. Seventy percent of the eyes recovered a visual acuity greater than or equal to 0.4 in each of the two groups. In both groups of patients, surgery allowed a reduction in the prescription of drugs. We therefore verified that, in the first group, combined surgery allowed us to more effectively control the IOP while achieving a greater improvement in visual acuity. However, it must be stressed that intracapsular cataract extraction is associated with a higher complication rate.

Aged↗
PubMed1990

[Treatment of dry eye by temporary punctum plug. Comparison with a control group].

35 patients with chronic dry eye were treated with punctum plug on one side only. The other side was a control: after simulation dilatation, the patient underwent a simulation insertion. This is an open study in which only the patient ignored the reality of treatment. The study was prospective. 28 females and 7 males were enrolled in this study. The age' average was 53. The follow-up average is 5.3 months. The etiologies were: idiopathic dry eye: 10 cases, Sjögren's syndrome: 11 cases, drug induced dry eye: 6 cases, filamentous keratitis: 4 cases. Other: 4 cases. Enrollment criteria were: functional symptomatology not answering to topical therapy (physiological serum drops) associated with one or more of the following items: positive Rose Bengal staining and/or Schirmer lower than 5 mm in 5 min and/or filamentary keratitis. Subjective improvement is significantly better after closing the two puncta on the same side (77%) than the other side (placebo) (17%) (p less than 0.001). This difference is also demonstrated for the improvement of Rose Bengal staining (p = 0.068) and for Schirmer's test (p = 0.002). These results demonstrated the effectiveness of this therapy versus placebo. Results after closing the 2 puncta on the same side are better than after closing one punctum.

Adolescent↗
PubMed1990

[Complications of punctum plug in the symptomatic treatment of dry eye].

76 patients with dry eyes were treated by mechanical obstruction of lacrymal puncta. The sex ratio is: 62 females and 14 males. The age average was 55, ranging from 12 to 88. The etiologies were: Sjögren's syndrome: 16 cases (21%); filamentous kerato-conjonctivitis sicca: 12 cases (15%); anxiolytical and anti-depressant treatments: 10 cases (13%); complicated viral kerato-conjonctivitis: 4 cases (5%); post radiotherapy dry syndrome: 3 cases (4%); idiopathic and various etiologies: 31 cases (40%). The 149 plugs are completely made of hydrophobic silicone; 20 had a barb inclined on the neck axis. Insertion was achieved after tropical anesthesia in 90% of the cases. 121 plugs (81%) did not lead to any anatomical complication (the average duration remaining on time interval of implantation per plug was of 5 months). Functional tolerance depends on the quality of plug-punctum adjustment. Plug protrusion is the main cause of intolerance and disappearance. The complications were: rupture of punctum during dilation: 1%; suppurative canaliculitis: 1.3%; disappearance: 16%; epiphora: 22%. No intra-canalicular migration was observed. We check canalicular permeability in 26 cases, after loss or removal: che was normal 23 times (average time-interval: 5 months). We had 3 cases of canalicular stenosis after 4 months, 5 months and 18 months of intubation.

Adolescent↗
PubMed1990

[Toxicity of ethylene oxide on the crystalline lense in an occupational milieu. Difficulty of epidemiologic surveys of cataract].

Ethylene oxide is a sterilizing gas for heat-sensitive materials. Eight cases of subcapsular cataract were attributed to this compound from 1982 to 1985. This epidemiological study was conducted in 55 persons to determine the prevalence of lens opacities and cataracts in workers exposed to this gas. The 21 persons of more than 45 years of age were then compared to 16 non-exposed persons matched for age and gender. Lens opacities (independently of visual acuity) were observed in 19 of the 55 exposed. Among exposed and non-exposed persons of more than 45 years of age, there were no significantly differences with regard to the following characteristics of lens opacities: prevalence (13 in the 21 exposed; 10 in the 16 non-exposed), distribution of the localisations, morphology and importance of the cortical opacities. No link was found between the characteristics of the lens opacities and the characteristics of the exposure: habitual exposure and accidental overexposures. For cataracts, defined by the association of lens opacities and a visual acuity less than 20/25 (this loss not being attributable to another cause), their prevalence differed significantly (p less than 0.05) between the exposed (6 of 21) and the non-exposed (0 of 16). There was no relation between their existence and accidental overexposures. The risk of lens opacification by ethylene oxide, established in cases of massive exposures as previously described, could also exist during chronic exposure to low concentrations, but is to be confirmed by other studies. It could be explained by saturation of the protective mechanisms against alkylating action of this product. This study prompted us to discuss the epidemiological difficulties in studies of cataracts.

Animals↗