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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
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.

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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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PubMed1979

Senile disciform macular degeneration: features indicating suitability for photocoagulation.

During a 1-year period 398 new patients were seen with disciform macular degeneration (530 eyes). The lesions were studied retrospectively, and those in which the neovascular tissue did not underlie the fovea, and therefore were treatable, were identified. The following conclusions were drawn: (1) Treatment is possible in most patients with good acuity and few with poor acuity. (2) Treatment is possible in a large proportion of patients with a short history and few with a long history of visual loss. (3) As many as 50% of all patients with senile disciform macular degeneration may be amenable to treatment if seen early enough in the course of their disease. (4) Over one-third of eyes with lesions that are untreated have a visual acuity of 6/60 or better 3 years after the onset of symptoms. (5) If a controlled trial proves that treatment is beneficial, these results emphasise the need for rapid referral and show that these patients will generate a large additional clinical load.

Humans↗
PubMed1977

Senile disciform macular degeneration in the second eye.

Development of senile disciform degeneration in the second eye was studied in a group of 104 patients over a period of up to five years. 12 to 15% of these patients develop disciform degeneration in the other eye each year. Patients with large and confluent drusen, especially if combined with accumulation of dye on fluorescein angiogram, were at greatest risk of developing disciform degeneration in the second eye.

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