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Biomedical subjects

G Renard

Publications and source records attributed to G Renard.

At least 181 records · Page 10Linked to original sources
PubMed1993

Comparative study of a collagen corneal shield and a subconjunctival injection at the end of cataract surgery.

To compare the effectiveness of subconjunctival injections and collagen shields in delivering anti-inflammatory agents and antibiotics after cataract surgery, we conducted a prospective study of 61 patients. They were randomly assigned to three groups: subconjunctival injection of gentamicin and dexamethasone; the same route plus a collagen shield without drug; collagen shield soaked in gentamicin and dexamethasone. All subjects had a manual extracapsular cataract extraction with posterior chamber intraocular lens implantation. Eyes were evaluated at the end of surgery and 24 hours later. The collagen shield achieved a progressive effect on pain and a decrease in conjunctival redness after 24 hours. The occurrence of folds in Descemet's membrane was less frequent and aqueous flare less severe than when subconjunctival injections were used. No adverse effect was reported. We conclude that the collagen shield could be a safe, better, noninvasive technique because of its double action of bandage and enhancement of drug penetration.

Aged↗
PubMed1993

Residual cornea and the degenerate eye of the cryptophthalmic Typhlotriton spelaeus.

The cave-dwelling Typhlotriton spelaeus larvas live in daylight. The larvas undergo a metamorphosis when the thyroxin level (T3 and T4) increases. They leave aquatic life for terrestrial and subterranean aphotic life. The larval eyes are normal and show good vision response to tests. On the contrary, in the oldest larva and the adult, the eyes are small with poor vision or no vision at all. The lens can disappear but in any case the eyelids grow over the eye. The retinal degeneration takes place during and after metamorphosis. The admitted statement that "after metamorphosis . . . the developing lids close over the eye and invade the cornea" is not confirmed concerning the invasion, because it is now evident that the eyelids separate spatially from the residual cornea. Consequently, the fibroblasts of the eyelids are not able to invade the corneal stroma. In fact, the periocular tissues do not invade the cornea but invade the eyelids' tissues. We are able to confirm that the development of the larval eyes is complete and apparently normal. After metamorphosis, the eyes decrease in size. The cornea "sinks" with the eye into orbit tissues. The eyelids cover the eye and are themselves replaced by a supraocular skin. This fits the description of the human cryptophthalmia. We also demonstrate that even in the degenerate eye the residual cornea retains the main structure of a normal salamander cornea. The preservation of the endothelium and of the Descemet membrane is exceptional in blind cave-dwelling vertebrates because in the other degenerate corneas the edema of the stroma depends on the spatial disjunction of the underepithelial stroma and the supraendothelial stroma. Perhaps, the very advanced development of the eye and the late start of the degenerative processes could explain the relative preservation of the cornea. Thus, the arguments put forward tend to prove that the thyroxinic metamorphosis sets off the growth and fusion of the eyelids but that the eye degeneration is related to hereditary processes.

Animals↗
PubMed1993

[Keratoprosthesis with biocolonizable support].

Keratoprosthesis consists in replacing the central cornea with an optical system. The optic requires a support which was usually located in front of or behind the cornea. In our opinion microporous materials can hold the prosthesis in place and prevent melting and leakage. The prosthesis is implanted in a single procedure. The optical core is made of clinical quality PMMA. The core is 5 mm in diameter and 2.5 mm long. To promote tissue stability, 9 mm of a new microporous fluorocarbon (200 microns thick and 80 microns pore size) is used. The material becomes transparent and wettable after implantation in the human cornea as confirmed by experimental investigation. The material of the flange is initially hydrophobic and maintains the depth of the anterior chamber without leakage. We present our results concerning the 10 consecutive cases. The average follow-up is 11 months (range; 6 to 17 months). The surgical indication was 4 cases of corneal burns, 3 cases of pseudopemphigus, 1 trachoma, and 2 cases of corneal edema. Visual acuity was 20/60 (range: 20/400 to 20/30). Anatomic failures occurred in 2 cases in the first two months. We observed one traumatic dislocation of the optic system and one extrusion in the first week after error of manipulation of the polymer. The 5 mm optical diameter of the keratoprosthesis allows a visual field of about 120 degrees.

Biocompatible Materials↗
PubMed1993

[Cataract surgery in patients with myopia].

Cataract surgery in myopic eyes can be difficult. We present a retrospective study of 97 myopic eyes, with axial length of at least 26 mm. All eyes, extracapsular extraction with or without intraocular posterior chamber lens. Mean follow up is 14 months, and 54% of cases have a 1 year follow up. In only one case did a retinal break without retinal detachment appear after surgery, that was successfully treated with argon laser photocoagulation. A longer follow up of our cases will be necessary to estimate long term complications of cataract extraction in myopic eyes.

Adult↗
PubMed1993

[Indications for penetrating keratoplasty. A retrospective study of 2,962 cases over 11 years].

The authors report the course of penetrating keratoplasty (PK) in a series of 3,012 grafts performed at the Hôtel-Dieu de Paris Ophthalmology Department from 1980 to 1991; 2,962 cas (98.5%) could be analysed and were divided into 17 etiologic groups. In the literature, Aphakic Bullous Keratopathy (ABK) and Pseudophakic Bullous Keratopathy (PBK) are usually considered to be the most frequent PK indication. In our series, they came in third place overall with 281 cases (9.5%). Their incidence showed a constant increase over the study period, and they became the most frequent indication in 1991 (21.4% versus 6.8% in 1980). Keratoconus was the most frequent surgical indication with 813 cases (27.6%). This high percentage has been reported by other research groups. We explain our findings by a bias in the choice of corneal recipient candidates due to a tendency of the surgical team to give available donor corneas to patients with statistically higher chances of functional success. We also notice that corneal herpes sequelae, classically the leading cause of PK in the seventies, became the second indication overall and showed a decreasing tendency between 1980 and 1991. Finally, non herpetic leucomas (8.9%), graft failures (8.6%), and Fuchs dystrophy (8.3%) showed a constant PK indication rate throughout the study period.

Corneal Diseases↗
PubMed1993

[Perforated and pre-perforated ulcer in rheumatoid polyarthritis].

The authors report a case about relapsing corneal ulceration in a patient with rheumatoid arthritis. Treatment of such perforated and preperforated corneal ulcers is a difficult task. The poor visual outcome of an emergency penetrating keratoplasty leads to the use of other methods (conjunctival flaps, corneal graft, keratopatch, tissue adhesive). This case report stresses the importance of preserving the anatomy of the eye allowing in a record time the performance of corneal graft. The use of immunosuppressive drugs is also discussed because of the existence of a rheumatoid arthritis with eye involvement.

Arthritis, Rheumatoid↗
PubMed1993

[Invasive carcinoma of the conjunctivo-corneal limbus. Apropos of a case].

The limbus is an elective site of epithelial malignancies, mostly represented by precarcinomatous lesions. An 83-year-old female patient was operated for an exophytic tumor of the limbus. Histological examination showed an invasive squamous carcinoma. As the excision was not complete, complementary radiation therapy (45 Gy) was applied with a good short-term result. This case report emphasizes the value of early diagnosis and treatment of limbal tumors at the stage of precancerous lesions.

Aged↗
PubMed1993

[Conjunctival cyst of the inferior fornix. Apropos of a case].

Conjunctival cystic lesions are not uncommon and may arise anywhere in the conjunctiva, although the inferior fornix is one of the most frequent sites. We report the case of a 5 year-old-male black patient who underwent surgical excision of an unusually large conjunctival cyst of the inferior left fornix. The histopathological study showed that the cyst border was lined by a conjunctival epithelium, consistent with a conjunctival inclusion cyst.

Child, Preschool↗
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↗