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Biomedical subjects

B Briat

Publications and source records attributed to B Briat.

At least 19 recordsLinked to original sources
PubMed1999

[Phototherapeutic keratectomy in the treatment of Groenouw's type I corneal dystrophy].

PURPOSE: This study was designed to investigate the therapeutic potential of phototherapeutic keratectomy (PTK) for the treatment of corneal granular dystrophy. PATIENTS AND METHODS: PTK was performed with the Excimed UV 200, (Summit Technology, Inc) on a series of 27 eyes of 22 patients with corneal granular dystrophy. Mean patients' age was 34.6 years. The mean follow-up period was 31 months (ranged from 6 to 52 months). The changes in best corrected visual acuity and spherical equivalent were evaluated at 6, 12, 18 and 24 months. RESULTS: All of patients achieved visual improvement. Mean preoperative best corrected visual acuity (BCVA) was 20/100 and mean postoperative BCVA was 20/30 at one year. The mean hyperopic shift caused by tissue ablation was +/- 2.8 D after one year. CONCLUSION: Corneal grafting was the standard treatment for visually disabling granular dystrophy, but PTK has significant advantages over this procedure and must now be the standard method of managing corneal granular dystrophy when intervention is required.

Adult↗
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

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

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

[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

[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↗
PubMed1997

Influence of ePTFE polymer implant permeability on the rate and density of corneal extracellular matrix synthesis.

Microporous polymers have great potential for the production of corneal keratoprosthetic devices. Keratocytes invade the pores of expanded polytetrafluoroethylene implants (ePTFE) and collagen synthesis occurs. This ePTFE becomes translucent after its implantation in the stroma of rabbit cornea. The rate and density of cell growth within this polymer depends on the implant thickness, pore size, and its placement in the cornea. We have investigated the influence of the polymer permeability on the collagen and protein contents ePTFE implants. Rabbit corneal stroma were implanted with ePTFE disks (6 mm in diameter) by intralamellar keratoplasty. The implanted polymers were removed from the stroma after 3 to 6 months. The collagen and protein contents were determined after pepsin solubilization. The collagen content of the high-permeability implant was 3.7-fold greater than that of the low-permeability implant 3 months after implantation and 2.4-fold greater after 6 months. The total protein content of the high-permeability implant was 2.5-fold greater than that of low-permeability implant at 3 months and was the same after 6 months. The collagen-to-protein ratio was 68% in the high-permeability implants, and thus similar to that of normal corneal stroma. Thus, high polymer permeability increased both the rate and density of the corneal extracellular matrix ingrowth.

Animals↗
PubMed1997

[2nd generation bio-integrated keratoprosthesis. Implantation in animals].

PURPOSE: Our goal was to evaluate a second generation biointegrable keratoprosthetic device (BioKpro II). METHODS: The device consists of a porous transparent PTFE (12 mm diameter) and a soft copolymer structure for the optical system (7 mm diameter). Intraocular pression was evaluated with a Goldmann tonometer on an artificial chamber. A lamellar dissection was carried out 3 mm radially for 360 degrees creating a pocket to accommodate the skirt. The soft optic (42.5 D; 500 microns thick) was positioned through a hole (6 mm in diameter) trephined in the central cornea. A 360 degrees peritomy was performed and conjunctiva was placed in front of the prosthesis, sutured and was opened 15 days post implantation. 14 rabbits were implanted and were allowed to heal for three months. RESULTS: We are able to measure the intraocular pressure by Goldmann tonometer on an artificial chamber. We did not observed epithelialisation on the hydrophilic optical surface (14/14). Aseptic necrosis in direct contact between cornea and the soft optical system was observed when conjunctiva was not effective (4/14). As observed with the first generation devices, conjunctiva or buccal mucosa is needed to avoid local necrosis. In other cases no adverse reactions were observed after implantation. DISCUSSION: The geometry and biomechanical properties of the BioKpro II is closed to that of the human cornea. The junction between the optical and the flange was bound by polymeric interpenetration and prosthesis dislocation was not seen under pressure over 1000 mmHg. CONCLUSION: Second generation biointegrable keratoprostheses (BioKpro II) can be implanted successfully. Further tests will determine if surface modifications designed to promote epithelial cell attachment on the optical system could prevent ulceration at the junction between the fluorocarbon and the core.

Animals↗
PubMed1997

[Computerized video-keratoscopic analysis and cataract surgery by phacoemulsification. Predictive calculation of the power of the intraocular implant].

PURPOSE: The authors present the results of a prospective study of 125 consecutive cases of phacoemulsification, performed by a single surgeon, to assess the benefit of computerised videokeratoscopy for the improvement of the predictive calculation of the power of intraocular lenses (IOL). METHODS: Preoperative keratometry was determined by means of 3 concurrent techniques, including automated kerato-refractometry (AKR 2000, Nidek) and videokeratoscopy by TMS-1 (Tomey) and CAS-1 (EyeSys). The results of the IOL calculation by these 3 methods was compared postoperatively to the power of the actual IOL yielding emmetropia as calculated by the optical method based on the postop, refraction at the various time-points. RESULTS: Simulated values obtained with videokeratoscopy significantly reduced the refractive error at 1 postop, week (p = 0.001), one month (p = 0.002) and 3 months (p = 0.002) for the CAS1 and at 3 months (p = 0.002) for the TMS1, as compared to values obtained with conventional automated keratometry. The refractive error was significantly reduced with the CAS1 at one month (p = 0.001) and 3 months (p = 0.019) as compared to TMS1. CONCLUSION: The determination of the anterior curvature of the entrance pupil by videokeratoscopy significantly improves the predictive calculation of the IOL power.

Aged↗
PubMed1997

[Rigid endoscope with Gradient-index lenses. Preliminary studies].

PURPOSE: Endoscopes for use in ophthalmology can be manufactured in dimensions smaller than 0.89 mm. MATERIALS: Gradient-index lenses that give a higher resolution than fiber bundles can be miniaturized down to 0.35 mm. RESULTS: We used this new endoscope in 6 eyes of 6 patients during anterior segment surgery. Preliminary clinical experience has demonstrated the usefulness and practical application of this new instrument. CONCLUSION: The clear views the instrument provides of the ciliary sulcus and ciliary body behind the iris make it useful in secondary posterior chamber intraocular lens implantation, retroprosthetic membrane behind keratoprosthesis, Molteno valve, and in endolaser photocoagulation.

Aged↗
PubMed1997

[A new material for intraocular implant].

PURPOSE: The aim of our study was to evaluate a new fluorocarbon (Teflon AF), used as a coating of poly-methylmethacrylate intraocular lenses. Teflon AF can be dissolved in special solvents (liquid fluorocarbons). It is the first amorphous and transparent form of teflon. MATERIALS AND METHODS: The coating was performed and the surface quality of the teflon-coated lenses was evaluated by scanning electron microscopy. Twenty teflon-coated and 10 uncoated lenses were implanted in rabbit eyes after phacoemulsification. They were compared concerning the presence of iris-lens synechias and the number of deposits on the lens' surfaces. An in vitro static touch model was used to compare endothelial damage produced by the 2 kinds of intraocular lenses. The results from this model were quantitatively analyzed, using the BIOCOM 200 image-processing system. RESULTS: The teflon group had no iris-lens synechias and the control group had 2 extensive synechias. There were significantly fewer deposits on the surfaces of teflon-coated lenses on days 30 and 60 post-operatively (P < 0.0001) than on the control lenses. Teflon-coated lenses produced significantly less endothelial damage than did control lenses (P < 0.0001). CONCLUSIONS: Teflon AF presents an anti-adhesive effect that increases the biocompatibility of polymethylmethacrylate lenses and reduces endothelial damage during their intraocular insertion.

Animals↗
PubMed1997

[Uncommon corneal hydrops. Apropos of a case].

We report a case of corneal hydrops in a young patient with unremarkable ophthalmologic history or intercurrent identified pathology. Different etiologies of corneal hydrops are discussed.

Adult↗
PubMed1996

[Corneal abscess: therapeutic attitude based on microbiological testing].

PURPOSE: Bacterial corneal ulcers can affect the integrity of the eye and need therefore to be treated following strict rules. The authors present a prospective study on 15 bacterial corneal ulcers for which the initial treatment with topical fortified antibiotics was guided according to the results of Gram stain. MATERIAL AND METHODS: Gram positive cocci ulcers were treated with vancomycine (5 cases), Gram negative rod ulcers with gentamycine and ticarcilline (2 cases), and the association of these 3 antibiotics was used when no bacteria was found (8 cases). RESULTS: The results of the Gram stain and the culture were consistent in all the cases. Mean healing time was statistically significantly shorter when an infectious agent was found on Gram stain (13 days) than when not (23 days). CONCLUSION: These results suggest that the prognosis of bacterial corneal ulcers is enhanced when infectious agents are recovered and that the strategy of initiating an antibiotic therapy adapted to the gram stain results appears reliable and efficient. The successful outcome of this approach needs a perfect collaboration with the microbiologist.

Abscess↗
PubMed1994

[Temporomandibular ankylosis in children: apropos of 30 cases].

Temporomandibular joint ankylosis in children is responsible for facial growth disorder. A series of 30 cases is presented. Patients are aged from 3 months to 15 years (mean = 7.6 years). Infection is the most frequent etiology. Recurrence rate is higher in bilateral cases. Early surgical treatment followed by meconotherapy led us to 93% satisfactory results.

Adolescent↗
PubMed1977

The low temperature magnetic circular dichroism spectra of iron-sulphur proteins. I. Oxidised rubredoxin.

Variable temperature magnetic circular dichroism spectra have been measured on oxidised Clostridium pasteurianum rubredoxin. Evidence has been obtained for the presence of two one-electron charge-transfer transitions, sulphur to ferric ion, in the region 15 000 to 28 000 cm-1. The first moment of the lower energy band is consistent with it being the orbital transition t1 non-bonding sulphur orbital, to the 2 e ferric d-orbital. The magnitude of the spin-orbit coupling constant in the lower excited state has been determined and shown to be small compared with the axial distortion. The splitting of the low energy band observed in the absorption spectrum can therefore be equated directly with the axial distortion of the lowest excited charge-transfer state. Finally, the potential utility of making saturation experiments at very low temperatures has been examined.

Circular Dichroism↗