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P Aspinall

Publications and source records attributed to P Aspinall.

At least 19 recordsLinked to original sources
PubMed2004

The development and assessment of a self-perceived quality of vision questionnaire to test pseudophakic patients.

PURPOSE: To develop and test a questionnaire to assess quality of vision in pseudophakic patients. METHODS: The problems with existing health measurement scales and the need for a new questionnaire are first discussed. Development of the new questionnaire from concept to completion is presented and all stages discussed. The questionnaire is then tested for internal consistency, reliability and validity. RESULTS: The Cronbach Alpha for internal consistency was 0.92. British Standards Institution repeatability coefficient was satisfactory at 6.6. Discriminant construct validity testing by extreme groups demonstrated excellent discrimination between patients with functionally significant posterior capsule opacification (PCO) and no significant PCO (Mann-Whitney U test, p = 0.001). CONCLUSION: The questionnaire is validated as a robust, stable measure of pseudophakic visual symptoms with a high degree of clinical utility. It should be invaluable for the many studies that compare outcomes from different forms of modern cataract surgery with implantation of different intraocular lenses.

Activities of Daily Living↗
PubMed2004

Three dimensional analysis of the lamina cribrosa in glaucoma.

BACKGROUND/AIM: Structural changes in the lamina cribrosa have been implicated in the pathogenesis of glaucomatous optic atrophy. The aim of this study was to determine a measure the surface variability of the cup floor in normal subjects and patients with glaucoma. METHODS: A sample of age matched normal subjects (NN), patients with low tension glaucoma (LTG), and primary open angle glaucoma (POAG) were included in the study. The glaucoma groups were matched for the severity of the visual field loss. Mean 10 degree topographic images of normal and glaucomatous eyes from the Heidelberg retina tomograph were imported into ERDAS image processing software where topographic analysis of the cup floor could be assessed. Each image was processed using customised spatial filters that calculated the surface depth variation in localised neighbourhood areas across each image. The local change in depth across the cup floor surface was determined and compared between the three clinical groups. RESULTS: The depth variation in the cup floor was largest in normal subjects followed by LTG and POAG. Highly statistically significant differences in surface depth variability of the cup floor existed between normal and LTG (p = 0.005), between normal and POAG (p<0.0001), and between LTG and POAG groups (p<0.0001). The variability and skewness of depth difference across the optic cup floor were also significantly different between the three clinical groups. CONCLUSION: A new parameter quantifying depth variations in the cup floor significantly discriminated between groups of normal and glaucoma patients. This new parameter may contribute to a better understanding of the pathogenesis of the glaucomatous optic nerve damage in different types of glaucoma.

Aged↗
PubMed2000

Measurement of a novel optic disc topographic parameter, "spikiness", in glaucoma.

BACKGROUND: Structural changes in the lamina cribrosa have been implicated in the pathogenesis of glaucomatous optic atrophy, but not observed. This paper presents a novel parameter of topographic variability within the optic disc, termed "spikiness", which may reflect glaucoma-related changes in the lamina. METHODS: Four age-matched groups of normal patients (n=12, mean age 64.8 years) and patients with ocular hypertension (n=14, mean age 63.1), primary open-angle glaucoma (n=11, mean age 70) and low-tension glaucoma (n=15, mean age 66.3) were recruited. Images of normal and glaucomatous eyes from the Heidelberg Retina Tomograph were imported into ERDAS image processing software where the spikiness data (30 consecutive mean surface height values across the base of the optic cup in both the vertical and horizontal meridians) were extracted in a format that facilitated further statistical analysis. RESULTS: Significant differences in topographic variability (spikiness) existed in the vertical (F=3.64, P=0.01) but not the horizontal meridian (F=1.25, P=0.3) through the optic disc. Spikiness was inversely related to Humphrey mean deviation (P<0.05), and cup-disc ratio (P<0.004) and was directly related to nerve fibre layer thickness (P<0.005). Of particular interest was the finding that the spikiness measure was the only optic disc parameter to significantly discriminate low tension glaucoma from primary open angle glaucoma. CONCLUSION: A new measure of surface variability (topography) at the floor of the optic cup has been described. The new index of spikiness may represent a measurement of lamina cribrosa fragility which has been implicated, but not previously estimated, in glaucomatous eyes.

Aged↗
PubMed2000

Measurement of peripapillary retinal nerve fiber layer volume in glaucoma.

PURPOSE: To measure peripapillary retinal nerve fiber layer volume in normal subjects and patients with ocular hypertension, primary open-angle glaucoma, and low-tension glaucoma. METHODS: Sixty-five subjects were classified into four groups of normal subjects and subjects with ocular hypertension, primary open-angle glaucoma, and low-tension glaucoma on the basis of intraocular pressure measurements, visual field loss, and optic disk appearance. Groups were matched for sex, age, and optic disk area. Peripapillary retinal nerve fiber layer volume measurements were made with a modification of software version 1.11 of the Heidelberg Retina Tomograph confocal scanning laser ophthalmoscope. Retinal nerve fiber layer volume measurements were taken at 0.1-mm increments from the disk margin for a global 360-degree assessment and at four predefined segments using two different reference planes. Statistical analysis was carried out using analysis of variance with Bonferroni correction. RESULTS: Retinal nerve fiber layer volume measurements showed a gradation from normal to ocular hypertension and from ocular hypertension to glaucoma groups. Mean group measurements showed statistically significant differences (P <.05) in peripapillary retinal nerve fiber layer volume for most segmental measures between the groups. Measurements with the default reference plane in the 0.0-mm to 0.1-mm and 0.1-mm to 0.2-mm increments for the superotemporal segment showed the greatest differences between groups (P <.00005). CONCLUSION: Peripapillary retinal nerve fiber layer volume measurements differ between groups of normal subjects and patients with ocular hypertension, primary open-angle glaucoma, and low-tension glaucoma. This measure offers a further method of assessment of retinal nerve fiber layer in patients with glaucoma and glaucoma suspects.

Aged↗
PubMed2000

Is cataract surgery justified in patients with age related macular degeneration? A visual function and quality of life assessment.

AIMS: To determine whether patients with age related macular degeneration (ARMD) benefit from cataract surgery in terms of visual function and quality of life measures, and to assess the impact of surgery on the progression of ARMD. METHODS: A prospective study was carried out of patients with and without ARMD undergoing cataract surgery. Data were collected from 187 patients at the Princess Alexandra Eye Pavilion, Edinburgh and the Oxford Eye Hospital, Oxford. The patients were divided into three groups: (1) a control group with ARMD and no surgery (n=41), (2) a study group of patients with ARMD who underwent cataract surgery (n=90), and (3) a second control group of patients without ocular comorbidities who underwent cataract surgery (n=56). Visual function and quality of life assessments were carried out at baseline and 3-5 months after baseline or surgery. RESULTS: There were significant improvements both in terms of quality of life and visual function measures in the study group. Benefits were greater in patients with moderate cataract irrespective of the degree of ARMD. No increased incidence in progression to the "wet" form of ARMD was found. Improvements in quality of life measures and visual function were more pronounced in patients with no ocular comorbidities. CONCLUSIONS: Patients with mild and moderate degrees of ARMD do benefit from cataract surgery and the benefits are greater in patients with moderate degrees of lens opacity. Longer follow up is required to assess the risk of increased ARMD progression.

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PubMed1999

Patients' perception of visual impairment in glaucoma: a pilot study.

BACKGROUND/AIMS: There is a paucity of useful information on the level of visual disability suffered by glaucoma patients. The aims of this study were to determine and rank the frequency of self reported visual disability in daily tasks performed by glaucoma patients; to examine the interrelation between disabilities using factor analysis; to study the relation between perceived visual difficulty and a measure of the severity of visual field loss; to develop a glaucoma specific subgroup of questions; and examine the validity and reliability of this subgroup of questions. METHODS: 63 glaucoma patients completed a questionnaire containing 62 questions covering 10 broad aspects of daily life activities using a five point answer scale. Patients were classified into three groups as having mild, moderate, and severe field loss on the basis of the perimetric results. The relation between a measure of the severity of visual field loss and subjective visual disability in the three groups was examined. RESULTS: Using factor analysis, the most frequently reported problems were grouped into the following four categories: outdoor mobility, glare and lighting conditions and activities demanding functional peripheral vision, household tasks, and personal care. These four factors accounted for 72% of the variability in the patients' questionnaire responses. With increasing severity of binocular visual field loss there was an increase in the number of self reported visual problems. A loss of confidence in performing some routine daily tasks tended to precede self reported specific visual disabilities. The factor "glare and lighting and activities demanding functional peripheral vision" was found to have a significant relation with a measure of visual field loss and was used to create a glaucoma specific subset of questions. Cronbach's alpha showed a high degree of reliability and internal consistency (alpha =0.96) in this glaucoma specific subset of questions. Furthermore, the validity of this new subset of questions was shown to be significant (r=0.037, p<0.05) for the correlation between a measure of the severity of binocular visual field loss and the mean score of the variables used in the glaucoma specific subgroup of questions. CONCLUSIONS: Outcome measures and quality of life issues need to be addressed in glaucoma. This pilot study identified common problems encountered by patients which at the present time are not assessed in routine glaucoma care. It also identified a subgroup of questions that seems to be specific for glaucoma. Further research is required if a significant impact on the quality of life of glaucoma patients is to be achieved.

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PubMed1997

Pulsatile ocular blood flow in untreated diabetic retinopathy.

PURPOSE: To measure the pulsatile component of total ocular blood flow in patients with untreated diabetic retinopathy. SUBJECTS AND METHODS: An adapted pneumotonometer attached to a slit-lamp biomicroscope. 82 age-matched subjects divided into 4 groups: non-diabetic controls (n = 22); diabetics with no clinical retinopathy (n = 20); background diabetic retinopathy (n = 20); pre-proliferative/proliferative diabetic retinopathy (n = 20). RESULTS: The mean pulsatile ocular blood flow values were found to be increased in all grades of diabetic retinopathy (no retinopathy 818 microl/min, background 1015 microl/min, pre-proliferative/proliferative 1097 microl/min) compared to the control group (644 microl/min). These pulsatile ocular blood flow values were significantly higher (p<0.05) in the background and pre-proliferative/proliferative retinopathy groups compared to controls. Pulse volume and pulse amplitude were also higher in the diabetic subjects. Mean arterial blood pressure did not differ across the groups studied. CONCLUSION: Pulsatile ocular blood flow was found to be higher in diabetics compared to controls and appears to increase as the severity of retinopathy progresses. Such a hyperdynamic circulation may contribute to the pathogenesis of diabetic eye disease.

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PubMed1997

Color Doppler imaging in untreated high- and normal-pressure open-angle glaucoma.

PURPOSE: To evaluate ocular blood flow velocity indices in untreated primary open-angle glaucoma (POAG) and normal pressure glaucoma (NPG). METHODS: Twenty-five untreated patients with NPG, 23 untreated patients with POAG, and 26 age-matched normal control subjects underwent color Doppler imaging for the measurement of blood flow velocity in the central retinal and ophthalmic arteries. Neither the patients nor the control subjects were using systemic beta-blockers or calcium channel blockers. After log transformation of non-normal data, group differences were compared with a one-way analysis of variance followed by unpaired t-test with the Bonferroni correction. Statistical significance was set at P < 0.05. RESULTS: The central retinal artery end diastolic velocity was significantly lower in patients with POAG than in normal subjects. The ophthalmic artery peak systolic velocity (PSV) was significantly greater in patients with POAG than in those with NPG and normal subjects. The resistance index (RI) of both the ophthalmic and central retinal arteries was significantly greater in patients with POAG than in normal subjects, and the central retinal artery RI was significantly greater in those with NPG than in normal subjects. Systemic pulse pressure and systolic blood pressure were significantly greater in patients with POAG compared with normal subjects. Multiple regression analysis showed a significant relation between ophthalmic artery PSV and intraocular pressure (but not with any of the cardiovascular parameters) in the POAG group. Chi-square analysis found significantly more systemic vascular disease in patients with NPG and POAG compared with that of normal subjects. CONCLUSIONS: There was an increased resistance to blood flow in the central retinal artery of untreated patients with NPG and POAG and also in the ophthalmic artery of patients with POAG. The ophthalmic artery peak systolic velocity was elevated in untreated patients with POAG. Altered ocular circulation (with different patterns of presentation) appears to be common to patients with NPG and patients with POAG.

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PubMed1995

Measurement of ocular blood flow velocity using colour Doppler imaging in low tension glaucoma.

The purpose of this study was to compare the velocity of blood flow and vascular resistance measured by colour Doppler imaging in the ophthalmic and central retinal arteries in 34 eyes of 34 patients (mean age 68.1 years) with low tension glaucoma (LTG) and 17 eyes of 17 age-matched normal controls (mean age 65.2 years). The Acuson 128 machine (using a 7.5 MHz probe) was used to measure peak systolic velocity (PSV), end-diastolic velocity (EDV) and resistive index (RI). The EDV of the ophthalmic artery (OA) in the LTG was significantly (p = 0.04) less than in the normal control group. There was a significant (p = 0.02) increase in the vascular RI of both the OA and central retinal artery in the LTG group compared with the normal controls. The OA RI increased with age (r = 0.61, p = 0.0001), and the OA EDV decreased with age (r = -0.50, p = 0.003), in the LTG group but not in the normal control group. The results suggest an increased resistance to blood flow in the ophthalmic and central retinal arteries of LTG patients.

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PubMed1994

When a vulnerable patient absconds.

This case-study examines the nurse's role when a patient at risk absconds. It highlights possible weaknesses in the system for dealing with absconding patients who are so cognitively and emotionally impaired, that they may present a danger to themselves. The issues of patient identification and stigmatization are raised along with the possible conflict this may cause in psychiatric nurses. Recommendations for care at ward level are made, including asking the vulnerable patient to wear an identity bracelet and the instigation of a prepared action plan which involves engaging the help of outside agencies should a patient abscond.

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PubMed1992

Low contrast visual acuity changes in human immuno-deficiency virus (HIV) infection.

A pilot study of low contrast visual acuity testing using Regan Charts has been undertaken in 34 patients seropositive for Human Immuno-Deficiency Virus and 20 normal control subjects. Low contrast visual acuities of the HIV (+) patients both with and without HIV retinopathy were found to be significantly lower than the age-matched controls (p < 0.01). This finding is probably attributable to pathology related to HIV in the visual pathways/Central Nervous System. Lowest contrast Chart (Chart C) was found to be a useful diagnostic tool for HIV retinopathy and presumed neuropathy.

Adult↗
PubMed1992

The effect of anticonvulsants on cognitive functioning following a probable encephalitic illness.

A 54-year-old man developed an acute encephalitic illness and subsequently suffered from marked memory difficulties. Considerable improvement with anticonvulsant therapy was demonstrated using a ward-based observation programme and serial neuropsychological assessments. The case report highlights the prominent role played by epileptic activity in determining the severity of the patient's amnesia.

Carbamazepine↗
PubMed1984

Clinical inferences and decisions--II. Decision trees, receiver operator curves and subjective probability.

In patient management, clinical decisions follow a logical sequence which can be formally expressed as a decision tree in which the uncertainties associated with each alternative outcome may be made explicit using Bayes' theorem. Where test data is used in the formulation of a decision, the uncertainty associated with the information it conveys may be modified by changing the pass/fail criterion to alter the false positive and false negative error rate. Classical procedures based on information theory are described to illustrate how this may be achieved for any test. When hard data is not available to permit such an approach, the clinician must rely on his own past experience or that of a colleague. Several methods are available for quantifying such experience by estimating subjective probabilities associated with an action or test result. Two simple methods are described for deriving subjective probabilities for subsequent use within a Bayesian decision model.

Bayes Theorem↗
PubMed1983

Clinical inferences and decisions--I. Diagnosis and Bayes' theorem.

Clinical decisions are based upon inferences derived from test evidence where data is collected as a means of hypothesis testing. In medicine, the initial expectation of a clinical state is rarely expressed in the classical scientific language of a null hypothesis where alternative outcomes are assumed to be equally probable, because clinical experience reinforces the maxim that common events occur commonly. The collection of test evidence in clinical practice, therefore, is directed towards overturning prior likelihoods for a clinically pathological state which are far from mere chance expectations. The extent to which any test evidence can modify such prior expectations not only depends on its relevance to the clinical state in question (i.e. the hypothesis) but also is largely influenced by the inherent error rates in the test itself. Clinical decision models should reflect these facts. Using examples from the field of ophthalmology, this paper presents a normative model using Bayes' theorem of conditional probabilities which provides a rational framework upon which to base or appraise clinical decisions. Parts II and III of the series will expand this clinical application of decision theory to show how it may be used in the absence of hard test evidence and also where a different emphasis or utility may be placed on false positive or false negative errors.

Bayes Theorem↗