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Biomedical subjects

B A Noble

Publications and source records attributed to B A Noble.

At least 19 recordsLinked to original sources
PubMed2006

Comparative cohort study of the outcomes of deep lamellar keratoplasty and penetrating keratoplasty for keratoconus.

AIM: To compare the outcomes and complications of deep lamellar keratoplasty (DLK) and penetrating keratoplasty (PK) for keratoconus. METHODS: A cohort of 20 consecutive PKs, for keratoconus, was compared with 20 consecutive DLKs, for keratoconus. The PKs were performed between June 2000 and July 2001, the DLKs between October 2001 and October 2002. Surgery was performed by one surgeon. Best-corrected visual acuities (BCVA), refraction and complications were recorded at the time of surgery, 6 and 12 months postoperatively. chi(2)-tests were used to compare visual acuity outcomes and independent t-tests in the analysis of astigmatism. RESULTS: Groups were comparable for age, sex, and ethnicity. All PKs were uncomplicated. Two of the DLK group had microperforations of Descemet's membrane. There was no significant difference in the proportion of patients achieving 6/9 or better between the PK and DLK groups (85 vs 78%, P=0.54). PK patients were, however, more likely than the DLKs to achieve 6/6 at 1 year; 70% (14/20) of PKs compared to 22% of (4/18) DLKs (P=0.04). Astigmatism was significantly higher in the PKs compared to the DLKs (P=0.022). There were two cases of graft rejection in the PK group, while none in the DLKs. CONCLUSIONS: This study confirms good visual results from both PK and DLK in keratoconus with similarly high percentages reaching 6/9 BCVA. DLK appears to cause less astigmatism and also has the advantage of no endothelial graft rejection. The apparent cost, however, is a reduction in the likelihood of achieving 6/6 BCVA.

Adult↗
PubMed2004

Comparison of autologous serum eye drops with conventional therapy in a randomised controlled crossover trial for ocular surface disease.

AIMS: To evaluate the efficacy of 50% autologous serum drops against conventional treatment in ocular surface disorders refractory to normal treatments in a prospective randomised crossover trial. METHOD: Patients fulfilling ophthalmological and haematological entry criteria were randomised to either 3 months of autologous serum 50% followed by 3 months of their conventional treatment, or 3 months of conventional treatment, followed by 3 months of autologous serum. Clinical assessments, including Schirmer's test, rose Bengal, and fluorescein staining, were carried out on entry and at monthly intervals. Impression cytology was performed at entry, 3 and 6 months. Grading was carried out on degrees of squamous metaplasia and goblet cell density. Subjective comfort was recorded daily using the "faces" scale. These categorical scores were converted to linear measurement using Rasch analysis. Statistical analysis was carried out using Wilcoxon's signed rank test and ANOVA. RESULTS: 16 patients were recruited with 31 eyes studied. The ocular surface diseases chiefly included Sjögren's syndrome (n = 6) and keratoconjunctivitis sicca (n = 5). Impression cytology available in 25 of 31 eyes showed significant improvement on serum treatment, p<0.02. Rasch weighted faces scores were statistically significantly better with serum, p<0.01. CONCLUSION: The results of this randomised study provide further evidence of the beneficial effects of autologous serum in severe ocular surface disorders. For most of these patients, autologous serum was superior to conventional treatment for improving ocular surface health and subjective comfort.

Adult↗
PubMed2001

Identifying the origin of single corneal cells by DNA fingerprinting: part I--implications for corneal limbal allografting.

PURPOSE: To demonstrate that the combination of impression cytology and single cell DNA fingerprinting represents a powerful tool that is suitable for detecting transplanted cells after corneal limbal allografting. METHODS: Fifty single cells were obtained by corneal impression cytology from 12 patients undergoing cataract surgery. Individual cells were isolated from samples by micromanipulation. Polymerase chain reaction and short tandem repeat profiling was used to obtain forensic standard "DNA fingerprints" from single cells. Blood samples taken at the time of impression cytology provided control "fingerprints." RESULTS: Informative DNA fingerprints were obtained from all corneal samples and 66% (33 of 50 cells) of isolated single cells. Of all fingerprints obtained, most (91%, 30 of 33 fingerprints) corneal fingerprints matched corresponding blood sample fingerprints. At least one corneal fingerprint matched the corresponding blood sample fingerprint in 83% (10 of 12 patients) of the patients in the study. CONCLUSIONS: This extremely specific single cell DNA fingerprinting system permits accurate identification of individual corneal epithelial cells, allowing very reliable determination of their origin, which will enable host and donor cells to be distinguished from each other after keratolimbal allografting procedures, even if the host and donor are the same sex or siblings. These DNA fingerprinting methods allow assessment of quality and quantity of donor cell survival, as well as survival time. The extreme sensitivity and accuracy of the technique means that should contamination occur, it would be identified, thus ensuring meaningful results.

Cell Transplantation↗
PubMed2001

Identifying the origin of single corneal cells by DNA fingerprinting: part II-- application to limbal allografting.

PURPOSE: Successful limbal allotransplantation allows regression of limbal stem cell deficiency features. Transplant survival is presumed if clinical improvement occurs. However, positive proof of surviving transplanted stem cells remains difficult. This follow-up study attempted to prove donor cell survival 5 years after limbal stem cell allograft in one woman with aniridia. METHODS: Impression cytology and single-cell DNA fingerprinting were used to investigate a previously studied patient. Corneal epithelial cells were harvested from five sites and isolated by micromanipulation. Polymerase chain reaction and short tandem repeat profiling were used to obtain forensic standard "DNA fingerprints" from single cells. (The technique is described in the preceding article, Part I.) Blood samples yielded host and donor DNA for comparison. Negative controls were performed for impression cytology and polymerase chain reaction. Simultaneous micro-scrape samples were also taken. RESULTS: Impression cytology samples permitted informative DNA fingerprints from all corneal sites and represented 76% (23/30) of tested cells. Fifty percent (15/30) of the fingerprints were "specific" but 83% (19/23) matched the host DNA fingerprint. The remaining 17% (4/23) represented contamination from various sources. Specific fingerprints were obtained in 55% (10/18) of the cells from micro-scrape samples. All samples giving sufficient information matched the host DNA fingerprint. All tested blood samples gave specific fingerprints. None of the sampled corneal cells gave a donor DNA fingerprint. CONCLUSIONS: In a single patient, no detectable long-term donor cell survival exists at 5 years. Positive identification would have provided unequivocal proof of donor cell survival. This technique gives useful information even if contamination occurs.

Aniridia↗
PubMed1999

Implantation of a black diaphragm intraocular lens for traumatic aniridia.

PURPOSE: To evaluate the suitability and safety of a black diaphragm posterior chamber intraocular lens (IOL). SETTING: Department of Ophthalmology, Leeds General Infirmary, Leeds, United Kingdom. METHODS: Seven patients who had secondary implantation of a Morcher 67G black diaphragm posterior chamber IOL were identified. All patients were men with a mean age of 42 years who had previous ocular trauma resulting in extensive loss of iris tissue (traumatic aniridia). Simultaneous penetrating keratoplasty was performed in 4 cases. Minimum follow-up was 10 months (mean 19 months). RESULTS: Best corrected visual acuity improved in 5 cases and was unchanged in 1 case. The lens was well centered in 5 cases. Two cases developed secondary glaucoma, 1 requiring trabeculectomy. One case developed infective endophthalmitis but had a visual acuity of 6/18 at last follow-up, and 1 had a vitreous and anterior chamber hemorrhage, which resolved. CONCLUSIONS: The black diaphragm posterior chamber IOL overcame aphakia in eyes with considerable loss of iris tissue and may mitigate the visually disabling effects of traumatic aniridia. Although this lens appears safe, caution should be used in its implantation until more patients with longer follow-up are studied.

Adult↗
PubMed1999

Behçet's disease: evaluation of a new instrument to measure clinical activity.

OBJECTIVE: Behçet's disease (BD) is a rare multisystem disorder characterized by vasculitis. At present, there are no laboratory markers that correlate well with the clinical activity in BD. This has led to the development of an instrument (BD Current Activity Form) to measure activity. Scoring is based on the history of new clinical features present over the preceding 4 weeks prior to assessment. Standardized questions were developed for all parts of the form. The face validity of the proforma was determined following worldwide collaboration with physicians and ophthalmologists managing patients with BD. The aim of this study was to evaluate the interobserver reliability of this form. METHODS: Nineteen patients fulfilling the International Study Group criteria for BD were randomly allocated, questioned and examined independently on the same day by five physicians experienced in BD. RESULTS: There was good agreement between the physicians' rating of oral [intraclass correlation coefficient (ICC) = 0.87] and genital (ICC = 0.95) ulceration, skin involvement (ICC = 0.62 for pustules and ICC = 0.66 for erythema nodosum), arthritis (ICC = 0.62), headache (ICC = 0.80), large vessel (kappa = 0.53), nervous system (kappa = 0.61) and eye involvement (kappa = 0.77). There was poor agreement for the question relating to the presence of bloody diarrhoea (ICC = 0.28). There was significant bias in the rating of fatigue by one of the physicians (F = 5.2, P = 0.001). CONCLUSION: Overall, this instrument has good interobserver reliability for assessing general disease activity. We therefore suggest that this proforma has a place in routine clinical monitoring of patients with BD, as well as assessing outcome in therapeutic trials.

Behcet Syndrome↗
PubMed1997

Do transplanted corneal limbal stem cells survive in vivo long-term? Possible techniques to detect donor cell survival by polymerase chain reaction with the amelogenin gene and Y-specific probes.

PURPOSE: To investigate donor cell survival following corneal limbal stem cell grafting, which is based on the corneal stem cell model. METHODS: We describe the use of the amelogenin gene probe with the polymerase chain reaction (PCR) to detect surviving donor cells and report preliminary studies using Y-specific DNA probes. RESULTS AND CONCLUSIONS: DNA polymorphisms have a detection limit of 10%. The SRY 'Y-specific' probe has a theoretical detection limit of 1 cell in 10,000. The techniques were applied to investigate survival of male donor cells in an aniridic female patient 2 1/2 years following limbal stem cell grafts. We speculate that low levels of donor-derived cells may still be present. We discuss the advantages and disadvantages of the two approaches, which may have future clinical and experimental application.

Amelogenin↗
PubMed1996

Early-onset posterior polymorphous dystrophy.

We report an unusual case of posterior polymorphous dystrophy in which corneal failure began within a few weeks of birth. Histopathologic findings included the presence of abnormal corneal endothelial cells with many microvilli on the surface. Descemet membrane was severely attenuated, and there was a thick posterior collagenous layer consisting of numerous fibroblast-like cells in a fibrillar extracellular matrix; ultrastructural immunocytochemistry showed this to contain tenascin, fibronectin, and collagen type I. Few histopathologic data on this disease at such an early age have been available, and to our knowledge, the composition of Descemet membrane has not been examined before. The microvilli-covered cells are shown to be present from the outset of the disease, not just in long-standing cases as in previous reports; changes in Descemet membrane may influence disease evolution.

Age of Onset↗
PubMed1995

Factors affecting visual outcome in children following uniocular traumatic cataract.

The correction of paediatric traumatic aphakia remains a controversial topic. This study examines retrospectively the visual outcome in 32 children with uniocular traumatic cataracts. Fifteen received intraocular lens implants following lensectomy, and 17 received aphakic contact lenses. Age range was 2-14 1/2 years at the time of injury. The maximum follow-up time was 13 years. Twenty-four children obtained a good visual result (6/5 to 6/18). These were equally divided between those receiving intraocular lens implants and those with contact lenses. Factors adversely affecting visual outcome are discussed. These include complex trauma, delay in referral for lensectomy, inadequate postoperative correction of aphakia, contact lens difficulties and problems with occlusion therapy. Although aphakic correction with intraocular lens implants may require several subsequent surgical procedures such as capsulotomy, we advise early lensectomy and intraocular lens implantation where possible, particularly in young children with traumatic cataracts. This eliminates contact-lens-associated problems and maximises the chance of good visual outcome and retention of stereoscopic vision.

Adolescent↗
PubMed1994

Retinal and optic disc neovascularization in leukaemia.

We report a case of chronic myeloid leukaemia initially presenting with a vitreous haemorrhage associated with bilateral retinal and optic disc neovascularization. The literature is briefly reviewed and the probable reasons for the observed microcirculatory disturbances are discussed.

Aged↗
PubMed1994

Aggressive management of an epidemic of chronic pseudophakic endophthalmitis: results and literature survey.

Six cases of chronic endophthalmitis following extracapsular cataract extraction and lens implantation are reviewed. All were referred for tertiary management by one surgeon over a period of just over 2 years. In two of the cases coagulase negative staphylococci were isolated and in three Propionibacterium spp were retrieved. In the remaining case a mixed growth of coagulase negative staphylococci and Propionibacterium acnes was cultured. The surgical management, microbiological results, and eventual visual outcome are discussed. To our knowledge, this is the first documented outbreak of chronic pseudophakic endophthalmitis with commensal organisms from a single centre.

Aged↗
PubMed1994

A comparative study of the elastic properties of continuous tear curvilinear capsulorhexis versus capsulorhexis produced by radiofrequency endodiathermy.

Capsulorhexis using radio-frequency endodiathermy may confer some advantages over continuous tear curvilinear capsulorhexis (CTCC) in certain clinical situations. It is unclear whether a capsulorhexis produced in this fashion has the clinically advantageous elasticity and resistance to tearing that a CTCC has been demonstrated to have. To investigate this, a test of capsular elasticity was carried out on pairs of eyes obtained from an eye bank, 42 eyes of 21 patients in total, using modified digital vernier calipers. One eye of each pair had a CTCC, the other a diathermy capsulorhexis (DC). The elasticity of the capsule in both groups was expressed by comparing the circumference of the capsulotomy at rest with its circumference at rupture. The mean capsular elasticity of the CTCC group was significantly greater than that of the DC group (p << 0.001). The capsular edge in both groups was examined using scanning electron microscopy, and the difference in morphology appears to be the source of the difference in elasticity.

Adolescent↗