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Biomedical subjects

C J Macewen

Publications and source records attributed to C J Macewen.

8 recordsLinked to original sources
PubMed2006

Can we predict which patients are at risk of having an ungradeable digital image for screening for diabetic retinopathy?

PURPOSE: We aimed to determine the reasons for, and variables which predicted, ungradeable retinal photographs during screening patients for diabetic retinopathy. MATERIALS AND METHODS: Age, duration of diabetes, visual acuity, and HbA1c were recorded. Following dark adaptation, a single 45 degrees nonmydriatic photograph was taken of each fundus. The pupils were then dilated and the photograph repeated. Using slit lamp biomicroscopy, lenticular changes (LOCS III), and fundus appearance were recorded. RESULTS: In ungradeable photographs the fovea could not be visualised in 98% of cases of images from nonmydriatic photography, and in 88% if mydriasis was used. Poor definition in the nonmydriatic image was associated with a subsequent ungradeable mydriatic photograph (P=0.001), however, the positive predictive value was poor (34%). Age, posterior subcapsular cataract, and near vision predicted ungradeable status of nonmydriatic photographs (P<0.001, P=0.004, P=0.006, respectively; regression analysis). Nuclear colour and poor definition of the nonmydriatic photograph predicted ungradeable status of mydriatic photographs (P=0.006 & P=0.001, respectively). CONCLUSION: Inability to visualise the fovea is the commonest cause of an ungradeable image from digital retinal photography. Age and posterior subcapsular cataract were best predictors of ungradeable status of nonmydriatic fundus photographs. Nuclear colour was the strongest predictor for ungradeable mydriatic photography.

Adolescent↗
PubMed2005

Endoscopic-assisted probing for congenital nasolacrimal duct obstruction.

PURPOSE: To determine the success rate of initial probing in children with congenital nasolacrimal duct obstruction (CNLDO) at different ages using nasal endoscopy, and to identify the anatomical sites of blockage within the drainage system. METHODS: A total of 87 eyes from 67 consecutive children with CNLDO underwent endoscopic nasolacrimal duct (NLD) probing under general anaesthetic. Patients who had had previous probings were excluded from the study. Diagnosis was based on history of epiphora since birth or shortly after, and fluorescein dye disappearance test (FDDT). Cure was judged as complete or near-complete remission of symptoms and signs and a normal FDDT. RESULTS: The age range was 12-91 months (mean 32.3 months). The success rates of probing were: 100% (58/58) for atresia and stenosis at the lower NLD, 100% (13/13) for punctal stenosis, 55.6% (5/9) for functional epiphora, and 0% (0/7) for canalicular and upper NLD obstruction. Age was not found to significantly affect the outcome of probing, whereas site did. Obstruction at canalicular or upper NLD level became more common with increasing age. CONCLUSION: Probing of the nasolacrimal system using the endoscopic approach allows direct visualisation of the distal nasolacrimal duct, which facilitates diagnosis of the anomaly at this site. More complex proximal anomalies became increasingly prevalent in older children, which accounted for the poorer results with increasing age. Site of obstruction has a greater bearing on outcome than patient age.

Age Factors↗
PubMed2005

Optometric and ophthalmic contact in elderly hip fracture patients with visual impairment.

AIM: To describe previous contact with optometry and ophthalmic services in a group of elderly patients with and without visual impairment (VI) who had fallen and sustained a fractured neck of femur. METHOD: A cross sectional study of 537 patients aged 65 and over who had undergone hip fracture surgery in four Scottish centres (Glasgow, Ayr, Dundee and Fife). All patients had an in-depth optometric history, ophthalmic history and examination. RESULTS: Three hundred and ninety-three (79%) patients reported optometric contact in the 3 years preceding surgery and 107 (21%) patients had not seen an optometrist for more than 3 years. In the latter group, 64 had VI, which was due to uncorrected refractive error in 17 (27%) and untreated cataract in 20 (31%). VI (best binocular visual acuity of 6/18 or less) was found in 239 (46%) patients. A past ophthalmic history was present in 257 (50%) patients. Only 39 (16%) patients with VI were under ophthalmic care at the time of the study. CONCLUSIONS: There was significantly poor optometric and ophthalmic contact in patients who had VI and had fallen and sustained hip fracture. A proportion of the VI (66%) was due to uncorrected refractive error and untreated cataract. Public health providers should be made aware of the fact that current optometric and ophthalmic care pathways are not accessed by this group of elderly patients with VI and at risk of falling.

Accidental Falls↗
PubMed2004

Prevalence of diabetic eye disease in Tayside, Scotland (P-DETS) study: methodology.

AIMS: To describe the use of a validated diabetes register for sampling frame generation and assessment of the representative nature of participants in a fieldwork study of diabetic eye disease. METHODS: We performed an observational, cross-sectional fieldwork study of diabetic retinal disease using reference standard eye examination. We sampled the entire diabetic population using the Diabetes Audit and Research in Tayside Study (DARTS) diabetes register. RESULTS: The study population comprised 4825 diabetic patients aged over 16 years registered with one of 166 general practitioners (GPs) in 41 practices in Tayside in October 1999. This represented 61.1% of the Tayside diabetic population (7903). A total of 586 (66%; 95% confidence interval 63, 70) patients were examined from a sampling frame of 882 living patients registered with a Tayside GP. Demographic and disease parameters recorded on the DARTS patient register allowed comparison between participants and non-participants. CONCLUSIONS: This study shows the clear benefit of using a complete diabetic population as a sampling frame. This allows potential selection bias and external validity to be evaluated using routine data sources. Studies performed and reported in this way will aid the critical appraisal process.

Adult↗
PubMed2003

Using human reliability analysis to detect surgical error in endoscopic DCR surgery.

The aim of this study was to describe the nature of active skill-based errors occurring in endoscopic dacrocystorhinostomy (DCR) surgery. A human reliability analysis methodology was used to assess surgical error from observational capture data. Twelve endoscopic DCR operations performed by three different surgical trainees were video recorded. The steps (subtasks) of each operation were carefully analysed and common errors were documented. Specific errors that resulted in trauma to the nasal mucosa were noted. Execution errors were common, with errors of grasping being most frequent (67% of all execution errors). Most of these involved the Blakesley forceps. In total, there were 69 mucosal trauma hits. Inserting instruments into or withdrawing them from the nasal cavity with too much force or speed caused more than half of these. Incising with too much force resulting in 'overshoot' caused 34% of mucosal trauma. Trainee ENT surgeons should take particular care when inserting or withdrawing instruments from the nasal cavity and also when performing lacrimal sac or nasal mucosa incisions. Performance of these tasks with too much force was identified as a common and potentially avoidable cause of mucosal trauma. Further research is needed into the design and use of endoscopic sinus surgery instruments with the aim of avoiding the errors that were encountered.

Dacryocystorhinostomy↗
PubMed1989

Eye injuries: a prospective survey of 5671 cases.

5671 patients with injuries presenting to a busy eye casualty department were examined prospectively to determine the incidence, aetiology, and severity of the injury. Of these cases 69.9% occurred at work, 18.3% during leisure and domestic activities (excluding recognised sport), 2.3% during sport, and 1.9% were due to assaults; contact lens injury occurred in a further 2.3%, and the cause was unknown in 5.3%. One hundred and two (1.8%) patients required admission to hospital, and of their injuries 13.7% occurred at work, 22.6% during leisure and domestic activities, 42.2% at sport, 18.6% during assault, and 2.9% from an unknown cause. Children under 10 years of age accounted for 4% of the total patients presenting, but for more than 18% of those admitted and 26% of ocular penetrations. 98.3% of all injuries involved periorbital or superficial ocular structures only. The remainder involved intraocular structures. The majority of serious injuries were contusional. There was only one case of intraocular foreign body. This indicates that, while most injuries still occur in the workplace, sport and leisure activities account for the majority of serious injuries. While most injuries do not threaten sight, they do so disproportionately in children.

Accidents, Occupational↗