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Biomedical subjects

I H Chisholm

Publications and source records attributed to I H Chisholm.

At least 19 recordsLinked to original sources
PubMed2005

Visual functioning and quality of life in the SubFoveal Radiotherapy Study (SFRADS): SFRADS report 2.

AIMS: To determine whether or not self reported visual functioning and quality of life in patients with choroidal neovascularisation caused by age related macular degeneration (AMD) is better in those treated with 12 Gy external beam radiotherapy in comparison with untreated subjects. METHODS: A multicentre single masked randomised controlled trial of 12 Gy of external beam radiation therapy (EBRT) delivered as 6 x 2 Gy fractions to the macula of an affected eye versus observation. Patients with AMD, aged 60 years or over, in three UK hospital units, who had subfoveal CNV and a visual acuity equal to or better than 6/60 (logMAR 1.0). METHODS: Data from 199 eligible participants who were randomly assigned to 12 Gy teletherapy or observation were available for analysis. Visual function assessment, ophthalmic examination, and fundus fluorescein angiography were undertaken at baseline and at 3, 6, 12, and 24 months after study entry. To assess patient centred outcomes, subjects were asked to complete the Daily Living Tasks Dependent on Vision (DLTV) and the SF-36 questionnaires at baseline, 6, 12, and 24 months after enrolment to the study. Cross sectional and longitudinal analyses were conducted using arm of study as grouping variable. Regression analysis was employed to adjust for the effect of baseline co-variates on outcome at 12 months and 24 months. RESULTS: Both control and treated subjects had significant losses in visual functioning as seen by a progressive decline in mean scores in the four dimensions of the DLTV. There were no statistically significant differences between treatment and control subjects in any of dimensions of the DLTV at 12 months or 24 months after study entry. Regression analysis confirmed that treatment status had no effect on the change in DLTV dimensional scores. CONCLUSIONS: The small benefits noted in clinical measures of vision in treated eyes did not translate into better self reported visual functioning in patients who received treatment when compared with the control arm. These findings have implications for the design of future clinical trials and studies.

Activities of Daily Living↗
PubMed2002

Visual outcomes in the subfoveal radiotherapy study: a randomized controlled trial of teletherapy for age-related macular degeneration.

OBJECTIVE: To determine whether teletherapy with 6-mV photons can reduce visual loss in patients with subfoveal choroidal neovascularization in age-related macular degeneration. DESIGN: A multicenter, single-masked, randomized controlled trial of 12 Gy of external beam radiation therapy delivered to the macula of an affected eye vs observation only. SETTING: Three United Kingdom-based hospital units. PARTICIPANTS: Patients with age-related macular degeneration, aged 60 years and older, who had subfoveal choroidal neovascularization and a visual acuity of 20/200 (logMAR 1.0) or better. METHODS: Two hundred three patients were randomly assigned to radiotherapy or observation. Treatment was undertaken at designated radiotherapy centers, and patients assigned to the treatment group received a total dosage of 12 Gy of 6-mV photons in 6 fractions. Follow-up was scheduled at 3, 6, 12, and 24 months. After excluding protocol violators, the data from 199 patients were analyzed. MAIN OUTCOME MEASURES: The primary outcome measure was mean loss of distance visual acuity in the study eye at 12 and 24 months. Other outcome variables analyzed were near visual acuity and contrast sensitivity. The proportions of patients losing 3 or more or 6 or more lines of distance and near acuity and 0.3 or more or 0.6 or more log units of contrast sensitivity at each follow-up were also analyzed. RESULTS: At all time points, mean distance visual acuity was better in the radiotherapy-treated group than in the control group, but the differences did not reach statistical significance. At 24 months, analysis of the proportions of patients with loss of 3 or more (moderate) (P =.08) or 6 or more (severe) (P =.29) lines of distance vision showed that fewer treated patients had severe losses, but there was no statistically significant difference between groups. For near visual acuity, although there was no evidence of treatment benefit at 12 and 24 months, a significant difference in favor of treatment was present at 6 months (P =.048). When analyzed by the proportions of patients losing 3 lines of contrast sensitivity, there was a significant difference in favor of treatment at 24 months (P =.02). No adverse retinal effects were observed during the study, but transient disturbance of the precorneal tear film was noted in treated patients. CONCLUSION: The results of the present trial do not support the routine clinical use of external beam radiation therapy in subjects with subfoveal choroidal neovascularization in age-related macular degeneration.

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PubMed1995

Immunophenotyping in presumed ocular histoplasmosis like retinopathy.

Four cases of presumed ocular histoplasmosis like retinopathy are presented. A detailed immunological assessment was carried out on the patients and a control group: lymphocyte immunophenotyping; flow cytometric analysis; HLA typing and T cell receptor variable region (TCR V region) expression were assessed. Analysis of TCR V region expression revealed no significant preferential expression. HLA typing also failed to reveal any links. All lymphocyte markers analysed were unremarkable, with the exception of CD38 which was significantly raised compared with controls (p < 0.01). This finding was confirmed by the use of two different CD38-specific monoclonal antibodies. The raised CD38 in our cases was shown to be persistent when the patients were retested after an interval of several months. Significantly, this may correlate with poor T cell function, as in Common Variable Immunodeficiency, making these patients more susceptible to various stimuli.

ADP-ribosyl Cyclase↗
PubMed1994

Bilateral macular drusen in age-related macular degeneration. Prognosis and risk factors.

BACKGROUND: In patients with unilateral visual loss related to age-related macular disease, the risk of visual loss in the second eye is documented as being between 7% and 10% per year. The risk is uncertain in those with good vision with each eye and bilateral macular drusen. METHODS: In a prospective study, 126 patients with bilateral drusen were reviewed annually for up to 3 years. Serial fundus photographs and fluorescein angiograms were analyzed independently by two readers in a masked fashion using a standardized grading scheme, including size, number, density, and fluorescence angiographic behavior of drusen. RESULTS: New lesions occurred in one or both eyes of 17 (13.5%) of the 126 patients. The cumulative incidence of exudative or nonexudative lesions was 8.55% at 1 year, at 2 years 16.37%, and 23.52% at 3 years for patients older than 65 years of age. Significant risk factors included the degree of confluence of drusen within 1600 microns of the center of the fovea (P = 0.023), focal hyperpigmentation (P = 0.004), slow choroidal filling (P = 0.023), and focal extrafoveal areas of atrophy of the retinal pigment epithelium (P = 0.042). CONCLUSIONS: The results give an estimate for the incidence of complicating lesions in patients with bilateral drusen and identify those features indicating higher than average risk of visual loss.

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PubMed1993

Age-related Bruch's membrane change: a clinical study of the relative role of heredity and environment.

For many years there has been controversy concerning the role of genetic influences in the pathogenesis of age-related macular disease. It is widely believed that the lesions causing visual loss occur in response to age-related changes in Bruch's membrane which are recognised clinically as drusen. In this study the density, size, and confluence of drusen as shown on colour photographs were compared in eyes of 50 spouses and 53 sibling pairs ascertained during a prospective study of age-related macular disease. Concordance between pairs of drusen--number, size, and density-were determined by kappa statistic and chi 2 test for trend. Drusen were absent in one sibling and 26 spouses of patients. There was a trend towards concordance of drusen characteristics between siblings but not between spouses, although the difference achieved 5% significance only for the number and density of drusen in the central macula. The difference of concordance between the probands and spouses and the probands and siblings was significant for all characteristics. These findings support the belief that genetic factors influence age-related changes in Bruch's membrane. They also imply that environmental factors are less important or alternatively that the environmental variation between households included in our study was not great enough to be evident.

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PubMed1992

Evolution of age-related macular degeneration with choroidal perfusion abnormality.

Prolonged choroidal filling on fluorescein angiography in age-related macular degeneration is thought to indicate diffuse thickening of Bruch's membrane. To test the importance of this clinical sign, we reviewed the evolution of disease in eyes of patients with good visual acuity and a readable transit phase of fluorescein angiography at the time of recruitment into a longitudinal study of age-related macular degeneration. Ninety-six eyes satisfied these criteria. Of the 32 eyes with prolonged choroidal filling, 12 (38%) lost two or more lines, of visual acuity by two years, whereas only nine of 64 (14%) eyes with normal choroidal filling did so. The difference was caused by the higher incidence of geographic atrophy in the first group. The proportion of eyes that developed subretinal neovascularization was the same in the two groups, and no pigment epithelial detachments occurred. These findings indicate that this clinical sign has implications concerning visual prognosis in age-related macular degeneration.

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PubMed1992

Controlled trial of laser photocoagulation of pigment epithelial detachments in the elderly: 4 year review.

Patients who were enrolled in a controlled treatment trial of laser grid photocoagulation for retinal pigment epithelial detachment as part of age-related maculopathy were reviewed 4 years after entry into the trial. The data imply that the original conclusion that this form of treatment did not improve the visual prognosis at 18 months was also justified at 4 years. It has become clear that lesions with evidence of subpigment epithelial new vessels were included in the trial. In a retrospective study the lesions were separated into those in which there was evidence of subretinal neovascularisation and those in which no such evidence existed. A difference was identified in the behaviour of the treated and untreated lesions designated avascular in that the treated eyes had a poorer visual outcome. These cases accounted for the different behaviour between two management groups in the initial study such that the original conclusion that grid photocoagulation of avascular pigment epithelial detachments in the elderly does not improve the visual prognosis is justified.

Humans↗
PubMed1992

Detection of subpigment epithelial neovascularisation in cases of retinal pigment epithelial detachments: a review of the Moorfields treatment trial.

The entry angiograms of 42 eyes with detachment of the retinal pigment epithelium in a treatment trial of laser photocoagulation were reviewed in a masked fashion by three observers in order to assess the possible presence of subpigment epithelial neovascularisation. Vascularity or avascularity was designated with reference to a list of clues believed to imply the presence of subpigment epithelial neovascularisation. As a predictor of outcome the initial assessment achieved a sensitivity and specificity of 77% and 82% respectively. Despite notable parity of the degree of sensitivity and specificity among the three observers, full agreement on the initial assessments was reached in only 23 eyes (55%), 10 with vascular and 13 with avascular outcome. Of these, only one eye which developed new vessels after 4 years had an outcome which differed from that predicted by classification of the entry angiograms.

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PubMed1990

Choroidal perfusion abnormality with age-related Bruch's membrane change.

Observation of patients with Sorsby's fundus dystrophy has shown that a prolonged choroidal filling phase on fluorescein angiography may indicate the presence of diffuse thickening of Bruch's membrane. We analyzed fluorescein angiography transit photographs in 100 eyes of 100 consecutive patients with age-related changes at the level of Bruch's membrane. Of these, 26 eyes had evidence of a prolonged choroidal filling phase during the initial dye transit. We suggest that this may represent a clinical correlate of diffuse thickening of Bruch's membrane, and that the two features are causally related.

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PubMed1990

Drusen as risk factors in age-related macular disease.

In a study of 150 consecutive patients with age-related macular disease and unilateral visual loss, the drusen in the better eye were analyzed for size, number, density, and fluorescein angiographic appearance, and these characteristics were compared with the type of the lesion causing visual loss in the contralateral eye. In the fellow eye of an eye with avascular detachment of the retinal pigment epithelium, the drusen were more densely packed, larger, and less fluorescent than in the fellow eye of an eye with primary neovascularization. The characteristics of drusen in fellow eyes of those eyes with pigment epithelial detachments and evidence of subpigment epithelial new vessels were intermediate between the other two groups. Because there is significant symmetry of drusen between fellow eyes, these data imply that the characteristics of drusen are important in the determination of the form of the lesion complicating age-related macular disease.

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