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Biomedical subjects

S Tuft

Publications and source records attributed to S Tuft.

15 recordsLinked to original sources
PubMed2001

Visual outcome following posterior capsule rupture during cataract surgery.

AIM: To determine the relative risk of a poor visual outcome following posterior capsule rupture during cataract surgery. METHODS: Prospective data were collected on consecutive eyes undergoing cataract extraction. The patient's age, preoperative visual acuity, ocular comorbidity, grade of surgeon, and operative complications were documented. The best spectacle corrected visual acuity was recorded at discharge from the hospital service. RESULTS: From a total of 1533 cases, 1420 (92.6%) eyes had complete follow up data. Posterior capsule rupture occurred in 59 (4.1%) cases. Eyes with posterior capsule rupture were 3.8 times more likely to have a final best spectacle corrected visual acuity less than 6/12. CONCLUSIONS: Eyes having posterior capsule rupture during cataract surgery have a significant risk of reduced visual acuity.

Clinical Competence↗
PubMed2001

Computer modelling of a cataract waiting list.

AIM: To compare three different strategies for determining admission dates for patients awaiting cataract extraction after scoring for visual impairment. METHODS: 357 patients attending for assessment for cataract surgery were scored for visual impairment. These scores were used as a basis for ranking patients into three impairment strata. A computer simulation was used to compare 3 years' operation of different admission strategies-a first come first served booking system, a triage booking system, and a waiting list system in which admissions were strictly ordered according to priority stratum. Differences in priority weighted delays before treatment were analysed. RESULTS: Both the triage system and the priority based waiting list system gave considerable reduction in priority weighted delay compared with a first come first served admission policy. The percentage reduction achieved (30%-60%) is strongly influenced by the number of weeks fully booked when the booking systems are introduced. The priority weighted delay of the triage system, where booking decisions were made at the time of the outpatient assessment, was consistently and substantially outperformed by the priority based waiting list system where the decision to allocate an admission date was delayed as long as possible. CONCLUSIONS: There is considerable scope for reducing delays to high priority patients if simple rules are used to determine admission dates. Using these rules, booking patients at the time of the outpatient assessment gives substantially less benefit in terms of reducing delays to high priority patients than if the decision about the admission date is deferred.

Cataract Extraction↗
PubMed1999

The mathematical modelling of cell kinetics in corneal epithelial wound healing.

This paper considers the comparison of experimental spatial and temporal data of mitotic rates measured during corneal epithelial wound healing (CEWH) of a rat model with the predictions of a computer modelling framework. We begin by briefly showing that previous models, used in the study of corneal epithelial wound healing speeds, are inadequate for the study of cell kinetics. We proceed to formulate a new modelling framework more suited to such a study. This framework is simulated in its simplest form, and the results from this motivate a new realisation of the modelling framework, including a caricature of age structuring. Finally, a model with a simple representation of juxtacrine signalling is considered. The final model captures many, though not all, of the trends of the experimental data. This paper thus lays a foundation for the modelling of the cell kinetics of corneal epithelial wound healing, and yields valuable insight regarding the important mechanisms a model should consider in order to reproduce the observed experimental trends.

Animals↗
PubMed1997

Outcome of acanthamoeba keratitis treated with polyhexamethyl biguanide and propamidine.

OBJECTIVE: This study investigates the clinical outcome of Acanthamoeba keratitis treated with polyhexamethyl biguanide (PHMB) and propamidine isethionate (Brolene). DESIGN: A retrospective review of all patients treated for Acanthamoeba keratitis between September 1992 and February 1995 was carried out. All patients were treated with PHMB 0.02% and propamidine 0.1% hourly for 3 days, the frequency reduced to four to six times daily according to clinical response. MAIN OUTCOME MEASURES: Age, gender, result of laboratory investigation, duration of disease before diagnosis, visual acuity (VA) pretreatment and post-treatment, need for keratoplasty, and presence of adverse reaction were measured. RESULTS: One hundred eleven cases were identified in 105 patients (60 male, 45 female; mean age, 32). Ninety-two percent of infections were in contact lens wearers. The clinical diagnosis was confirmed by corneal culture or histopathology in 64 cases (57.7%). The diagnosis was made "early" (within 28 days) in 65 cases (58.6%). Twenty-one (18.9%) were "intermediate" (28 days-2 months) and 20 (18%) were "late" (> 2 months) diagnoses. Overall post-treatment VA was 6/12 or better in the majority (88/111, 79.3%) of cases, and 18 (16.2%) had VA of 6/36 or worse. The VA of > or = 6/12 was achieved by 90.8% of the early, 71.4% of the intermediate, and 65% of the late groups. Clinical relapses occurred in 19 patients on reducing the therapy. Treatment toxicity was never serious and consisted only of stinging or superficial punctate keratopathy. Keratoplasty was indicated in only ten patients, and disease activity was controlled adequately in all patients before grafting. CONCLUSIONS: Combined treatment with PHMB and propamidine is well tolerated, nontoxic, and effective. Typically, visual outcome is favorable and the requirement for keratoplasty reduced markedly.

Acanthamoeba↗
PubMed1993

Limbal transplantation in the management of chronic contact-lens-associated epitheliopathy.

We describe the clinical management of 6 patients who developed a chronic corneal epitheliopathy 1-18 years after commencing soft contact lens wear. All had a history of exposure to thiomersal in contact lens fluids. The corneal changes were characterised by epithelial haze and superficial stromal vascularisation which extended from the limbus towards the visual axis. Five patients were observed for a minimum of 18 months after stopping contact lens wear before undergoing limbal transplantation. A good result was obtained in 1 patient who had worn a contact lens in one eye only. Recurrent epithelial changes were observed on the recipient eyes of the remaining patients who had previously worn contact lenses bilaterally, and in 1 patient epithelial haze also developed adjacent to the donor site in the previously clinically normal donor eye. All 5 patients experienced an improvement in symptoms post-operatively but in 2 patients the visual acuity later deteriorated because of epithelial irregularity. The sixth patient has not had surgery. We conclude that limbal stem cell dysfunction in chronic contact-lens-associated epitheliopathy may be subclinical and that autograft transplantation in bilaterally exposed patients may fail to restore the epithelial phenotype of the host eye whilst jeopardising the epithelial integrity of the donor eye by depleting its stem cell reserve.

Adolescent↗
PubMed1992

The detection of IgE-secreting cells in the peripheral blood of patients with atopic dermatitis.

We report, for the first time, the identification of IgE-secreting cells in human peripheral blood with an ELISA plaque assay that detects the fingerprint of individual IgE-secreting cells. No IgE-secreting cells could be detected in the blood of normal individuals (IgE, less than 100 IU/ml) or atopic patients (IgE, less than 1000 IU/ml), but in patients with atopic dermatitis (AD) whose IgE was greater than 2000 IU/ml, there was an average of 49 +/- 9 IgE-secreting cells per 10(6) peripheral blood mononuclear cells (PBMNCs). The rate of IgE production per cell per day from the PBMNCs of patients with AD varied from 0.051 to 0.628 IU/ml, and the number of IgE-secreting cells was positively correlated with the serum-IgE levels of these subjects (r = 0.74; p less than 0.001) and the amount of IgE detected in the culture supernatant (r = 0.085; p less than 0.02). Secretion of IgE by these cells could be completely inhibited (96.2% +/- 3%) by the addition of 75 micrograms of cyclohexamide to the cultures. Preformed intracellular IgE comprised 10% of the IgE detected in the supernatants of 7-day cultures. PBMNCs from patients with AD depleted of monocytes by adherence and T cells by E rosetting, all contained some detectable IgE-secreting cells, whereas isolated T cells and monocytes did not, supporting the view that cells secreting IgE that were detected were indeed B cells.

Antibody-Producing Cells↗
PubMed1992

Surgically induced necrotising sclerokeratitis (SINS)--precipitating factors and response to treatment.

The clinical features, treatment, and visual outcome of 52 eyes from 43 patients who developed scleritis following surgery were reviewed. In all patients the scleral inflammation developed adjacent to a surgical wound. Ninety six per cent had necrotising disease and 23% also had evidence of secondary posterior scleritis. Many different types of ocular surgery were implicated and the majority (75%) of the patients had two or more surgical procedures before the onset of the scleritis. Although cataract extraction through a limbal incision resulted in the largest subgroup, scleritis also followed glaucoma, strabismus, and retinal detachment surgery. The latent period between surgery and the appearance of inflammation was short (mean 9 months) except for a small group in whom scleritis occurred many years after squint surgery. Sixty three per cent of patients had evidence of a systemic disease. Early diagnosis and aggressive medical treatment significantly improved the visual outcome. The precipitating factors, pathogenesis, and course of this condition are discussed.

Adult↗
PubMed1990

Characterization of the fluorescence spectra produced by excimer laser irradiation of the cornea.

The epithelium and stroma of bovine and human corneas were exposed to both ablative and subablative levels of 193-nm excimer laser radiation and the spectra of the induced fluorescence recorded. Two broad peaks in the emission spectra were observed, at 310 nm and 460 nm, with a difference in the relative height of these peaks between epithelium and stroma. The lower cut-off for fluorescence (260 nm) was similar for both tissues. Time-resolved measurements showed that fluorescence occurs on the nanosecond time scale, and an estimate gives the quantum yield for photons emitted in the 260-350-nm range as approximately 1 X 10(-5). The significance of these results in the evaluation of the safety of surgery with an argon fluoride excimer laser is discussed.

Animals↗
PubMed1989

Assessment of corneal wound repair in vitro.

The time course for the closure of linear wounds produced in cultured cell monolayers following either mechanical debridement or excimer laser photoablation were compared. Wounds were produced in the central zone of a confluent layer of bovine corneal epithelial cells, keratocytes, or endothelial cells, and the residual area of the wound measured at regular intervals. Differences in the rate of wound closure between cell types were demonstrated. For epithelial cells the rate of resurfacing after mechanical or excimer laser damage was similar; for keratocytes there was a lag period before cell slide began after laser injury, but the subsequent rate of resurfacing was then similar to mechanical wounds; only for endothelial layers was a significantly reduced rate of closure observed after photoablation as compared to mechanical wounding. In this model of wound healing it appears that it is the mechanism of removal of the extracellular matrix formed by endothelial cells that produces the major difference in the rate of wound closure between mechanical injury or photoablation.

Animals↗
PubMed1988

Infectious crystalline keratopathy.

Crystalline deposits developed in the anterior third of the stroma in a 60-year-old woman. The deposits resolved only after aggressive treatment with intravenously given penicillin and topical erythromycin and vancomycin hydrochloride. Review of reported cases indicated that infectious crystalline keratopathy is caused by chronic colonization of the stroma by bacteria, usually streptococci of the viridans group. Local tissue trauma, concomitant use of topical corticosteroids, an intact overlying epithelium and use of a bandage-type soft contact lens are factors in the development of the infection. Patients with crystalline formations in this setting should undergo early lamellar biopsy for histologic examination, culture and sensitivity testing, followed by aggressive therapy with appropriate antibiotics.

Administration, Topical↗