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Biomedical subjects

Tristan Bourcier

Publications and source records attributed to Tristan Bourcier.

13 recordsLinked to original sources
PubMed2005

Outcome of graft central thickness after penetrating keratoplasty.

OBJECTIVE: To analyze the outcome of graft central thickness after penetrating keratoplasty. DESIGN: Retrospective observational cohort study. PARTICIPANTS: Eight hundred fifty-six consecutive penetrating keratoplasties (772 patients) performed between 1992 and 2001 were analyzed and 772 were included (1 graft per patient was included). METHODS: Slit-lamp examination and ultrasound pachymetry. MAIN OUTCOME MEASURES: Slit-lamp findings, intraocular pressure, and graft central thickness were recorded. RESULTS: Patients were observed for an average of 55 months. The 36- and 60-month graft survival estimates were, respectively, 77.2% and 71.0%. The average graft central thickness in successful transplants was 655 microm at 1 week, 558 microm at 1 month, 533 microm at 6 months, 538 microm at 12 months, 558 microm at 24 months, 561 microm at 36 months, and 568 microm at 5 years. At each postoperative time point, the percentage of eyes with decreased, normal, and increased graft central thickness was significantly different according to slit-lamp findings. Of the patients with increased graft thickness, 46.2% had a simple outcome (normal intraocular pressure and normal slit-lamp findings), 28.6% experienced rejection, 15.8% experienced a graft nonimmunological event, and 9.4% experienced increased intraocular pressure. At each postoperative follow-up, subsequent graft survival was significantly lower in patients with increased graft thickness as compared with patients with normal or decreased graft thickness. When analyzing only patients with simple outcome, the relative risk of graft failure was 3.3 if graft thickness was increased at 1 month (P<0.0001). CONCLUSIONS: In conclusion, graft central thickness assessed by ultrasound pachymetry is a useful method for observing patients who have undergone penetrating keratoplasty. Even when slit-lamp examination reveals no complications, patients with an increase in graft thickness above the upper limit of normal for the postoperative time point under consideration are at greater risk of failure.

Aged↗
PubMed2005

Decreased corneal sensitivity in patients with dry eye.

PURPOSE: To explore changes in corneal sensitivity that develop in patients with dry eye and the relationship between sensibility and severity of the dry eye disease. METHODS: Experiments were performed in 44 patients with dry eye and 42 healthy individuals. Corneal sensitivity was measured with the Belmonte noncontact gas esthesiometer. Mechanical (air jets at flow rates from 0 to 200 mL/min, reaching the corneal surface at 34 degrees C), thermal (cold or warm air at subthreshold flow rates changing corneal basal temperature +/-1 degrees C), and chemical stimuli (air containing 0% to 50% CO2 at subthreshold flow rate and temperature at the cornea of 34 degrees C) were applied to the center of the cornea to determine the sensitivity threshold for each stimulus modality. The clinical state of the ocular surface was also explored, measuring the fluorescein tear break-up time, the degree of corneal staining with fluorescein and Lissamine green, and tear production with the Schirmer test. RESULTS: Both in control subjects and patients with dry eye, the corneal thresholds for mechanical, chemical, and thermal stimulation increased with age. Moreover, the thresholds for the three modalities of stimuli were significantly higher in patients with dry eye than in control subjects. In both groups, individual mechanical, chemical, and thermal thresholds correlated significantly. Also, high thresholds in patients with dry eye correlated with the intensity of fluorescein and Lissamine green corneal staining but not with the results of the Schirmer test. CONCLUSIONS: Patients with dry eye exhibit corneal hypoesthesia after mechanical, thermal, and chemical stimulation that appears to be related to damage to the corneal sensory innervation.

Adolescent↗
PubMed2004

[Cataract].

Explore the source record for details and available documents.

Aged↗
PubMed2004

Corneal keloid: clinical, ultrasonographic, and ultrastructural characteristics.

A 70-year-old man was referred to us with a 2-year, progressive, painless decrease in visual acuity in the right eye. Ocular history included extraction of a traumatic cataract with a transclerally fixated posterior chamber intraocular lens. Slitlamp examination showed a raised, white, vascularized mass covering the cornea. The lesion was removed by superficial lamellar keratectomy. Light microscopy examination confirmed the diagnosis of corneal keloid. These uncommon lesions usually develop in adults after corneal traumas, surgery, or inflammatory processes. They have also been described in children with Lowe's syndrome, Rubinstein-Taybi syndrome, and other ocular developmental disorders.

Aged↗
PubMed2004

Early bacterial keratitis after laser-assisted subepithelial keratectomy.

We report a case of bacterial keratitis that occurred after laser-assisted subepithelial keratectomy. The patient presented with a decrease in visual acuity and pain 2 days after the procedure. Culture was positive for Staphylococcus haemolyticus. The infiltrate slowly resolved with topical antibiotics, and the best corrected visual acuity improved to 20/20. Although bacterial keratitis occurs rarely after refractive surgery, patients should be informed of the potential risk for visual loss caused by this infection.

Adult↗
PubMed2004

Culture-proven herpetic keratitis after penetrating keratoplasty in patients with no previous history of herpes disease.

OBJECTIVE: To report three cases of herpetic infection in recipients of organ-cultured donor corneas among 586 consecutive corneal transplantation procedures. METHODS: Three patients with no history of symptomatic herpes infection underwent corneal transplantation for keratoconus (2 patients) and Fuchs dystrophy (1 patient). Two patients developed keratouveitis and primary graft failure. The third patient developed dendritic keratitis in the graft. Culture of corneal scrapings and the patient's bandage contact lens were positive for herpes simplex virus type 1 (HSV-1). Donor and recipient sera were tested for HSV serology by EIA. Recipient corneal buttons were studied by means of transmission electron microscopy and immunohistochemistry. The three HSV-1 strains were genotyped by sequencing part of a variable antigenic domain of glycoprotein B (gB). RESULTS: None of the donor corneas showed endothelial cell necrosis after organ culture. All keratoplasties performed with the three mate donor corneas had an uncomplicated course. All three donor sera were positive for HSV. Preoperative recipient sera were positive for HSV. Analysis of the recipient corneal buttons showed no evidence of herpetic infection. Sequence analysis revealed three different gB genotypes. CONCLUSION: Ascertaining that a postoperative herpetic infection in a corneal transplant originates from the donor tissue is still difficult. Although some features of the reported cases suggest donor-to-host transmission of herpes simplex virus, the recipients could have been the source of the virus.

Adult↗
PubMed2004

[Amniotic membrane transplantation for the treatment severe acanthamoeba keratitis].

BACKGROUND: It is now possible to treat ocular surface disorders by means of amniotic membrane transplantation. We performed a study to determine the efficacy of this technique in the treatment of severe Acanthamoeba keratitis. METHODS: We studied six patients with severe, painful, nonhealing Acanthamoeba keratitis who underwent one or two amniotic membrane transplantation procedures between February 2001 and January 2003. Histopathological analysis of the corneal buttons was performed in four cases. RESULTS: Eight amniotic membrane transplantation procedures were performed. The mean length of follow-up was 14 (range 3-21) months. The mean interval between institution of medical treatment and the procedure was 3.6 months. All patients had progressive stromal lesions caused by an inflammatory reaction. Complete reepithelialization occurred in four cases, and partial healing in two cases. Ocular inflammation and tissue destruction were decreased in all cases, pain was lessened in five cases, and corneal neovascularization was decreased in four cases. No postoperative complications were observed. Amniotic membrane was observed under dysplastic corneal epithelium on histologic examination. INTERPRETATION: Amniotic membrane transplantation may be a safe and effective treatment of severe Acanthamoeba keratitis, particularly during the inflammation phase. It may permit penetrating keratoplasty to be delayed.

Acanthamoeba Keratitis↗
PubMed2003

Characterization and functionality of CXCR4 chemokine receptor and SDF-1 in human corneal fibroblasts.

PURPOSE: The aim of this study was to investigate whether cultured human corneal fibroblasts express functional chemokine CXCR4 receptors on their cell surface and to determine the presence of its specific ligand, SDF-1 (CXCL12), in human corneal fibroblasts. METHODS: Human corneal fibroblast cultures were obtained using human donor corneas. CXCR4 receptors were characterized using binding studies and autoradiography with [125I]SDF-1. The functionality of CXCR4 receptors was assessed by intracellular calcium measurement using a dynamic imaging microscopy system. CXCR4 and SDF-1 mRNA were detected in human corneal fibroblasts using reverse transcriptase polymerase chain reaction (RT-PCR). The CXCR4 protein was detected by western blot analysis. RESULTS: [125I]SDF-1 specifically bound to cultured corneal fibroblasts with a KD value of 8.3+/-1.2 nM. The presence of CXCR4 was confirmed by autoradiography of the radioligand on slices of corneal stroma. SDF-1 induced a rapid and transient intracellular calcium increase in cultured corneal fibroblasts that was blocked by the specific antagonist bicyclam. Moreover, a 48 kDa protein was detected by western blot analysis of corneal fibroblast extracts, using a specific CXCR4 polyclonal antibody. RT-PCR showed the expression of both CXCR4 and SDF-1 mRNAs in human corneal fibroblasts. CONCLUSIONS: These results indicate for the first time that cultured human corneal fibroblasts express the chemokine receptors CXCR4 and its ligand SDF-1. This latter might exert physiological effects on the cornea and could be involved in pathological conditions such as corneal angiogenesis.

Autoradiography↗
PubMed2003

Late bacterial keratitis after implantation of intrastromal corneal ring segments.

We report a case of bacterial keratitis that occurred after implantation of intrastromal corneal ring segments (Intacs). The patient presented with decreased vision, inflammation, and stromal infiltrates localized at the extremity of an Intacs channel 3 months after surgery. Culture were positive for Clostridium perfringens and Staphylococcus epidermidis. The infiltrates progressed despite treatment with topical fortified and systemic antibiotics. The Intacs were removed. The keratitis slowly resolved, and the patient recovered a best corrected visual acuity of 20/20.

Adult↗
PubMed2003

Candida parapsilosis keratitis.

PURPOSE: To present clinical, microbiologic, and histopathologic features of keratitis due to Candida parapsilosis. METHODS: Clinicomicrobiologic evaluation of four patients (four eyes) with culture-proven C. parapsilosis keratitis. The patients were evaluated for symptoms, visual acuity, clinical observations, microbiologic examination of corneal scrapings, and pathologic examination of corneal buttons. RESULTS: Three cases were observed after penetrating keratoplasty, and one case occurred after inhalation of corticosteroids. Clinical presentation of C. parapsilosis keratitis showed a great diversity. There was one case of crystalline keratopathy and three cases of suppurative corneal infiltrate. Histopathology of corneal buttons showed interlamellar accumulations of yeast. Medical treatment included topical amphotericin B and systemic triazoles. Penetrating keratoplasty was required in three patients. CONCLUSION: Risk factors for C. parapsilosis keratitis may include corticosteroid use and prior corneal transplantation. The prognosis of C. parapsilosis keratitis with antifungal and surgical therapy may vary from good visual outcome to intraocular extension with phthisis bulbi.

Aged↗
PubMed2002

Expression of neurotensin receptors in human corneal keratocytes.

PURPOSE: The purpose of the study was to investigate whether cultured human keratocytes express the neurotensin receptors (NTR1, NTR2, and NTR3), to determine the presence of neurotensin (NT) in keratocytes, and to assess the influence of NT on these cells. METHODS: Human keratocytes were cultured in medium treated with various concentrations (10(-7)-10(-9) M) of JMV449 (a weakly degradable NT agonist). Cell proliferation and viability were analyzed by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxy-methoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay. Apoptosis was studied by nucleus labeling with a fluorescent dye and cold light fluorometry. NT, NTR1, NTR2, and NTR3 mRNA were detected in human keratocytes by means of reverse transcriptase-polymerase chain reaction (RT-PCR). NTR1 protein was detected by Western blot analysis. Functionality of NTR1 was assessed by intracellular calcium ([Ca2+]i) measurement with a dynamic imaging microscopy system. RESULTS: RT-PCR and Western blot analysis showed the expression of the NTR1 (mRNA and protein) and NTR3 mRNA in human corneal keratocytes. NT and NTR2 mRNA were undetectable. JMV449 induced a rapid and transient [Ca2+]i increase in human corneal keratocytes that was blocked by the specific antagonist SR48692. JMV449 significantly increased cell proliferation and viability after 72, 96, and 120 hours of culture, with a maximum effect at 10(-7) M (P < 0.005). Finally, JMV449 decreased keratocyte apoptosis, whatever the concentration used (P < 0.005). CONCLUSIONS: These results indicate that cultured human keratocytes express NTR1 and NTR3 and that NT may exert physiological effects on cornea such as regulation of keratocyte proliferation and apoptosis.

Apoptosis↗