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Biomedical subjects

A C Bird

Publications and source records attributed to A C Bird.

At least 217 records · Page 12Linked to original sources
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.

Aged↗
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.

Aged↗
PubMed1990

No evidence for linkage between late onset autosomal dominant retinitis pigmentosa and chromosome 3 locus D3S47 (C17): evidence for genetic heterogeneity.

Retinitis pigmentosa is an inherited form of blindness caused by progressive retinal degeneration. P. McWilliam et al. (1989, Genomics 5: 619-622) demonstrated close genetic linkage between autosomal dominant retinitis pigmentosa (ADRP) and locus D3S47 (C17) in a single early onset pedigree. The marker C17 maps to the long arm of chromosome 3. Clinically, the disease phenotype has been subdivided into at least two forms on the basis of age of onset, as well as electrodiagnostic criteria. We demonstrate that C17 is unlinked in a late onset pedigree, indicating that the phenotypic variation seen reflects underlying genetic heterogeneity.

Chromosomes, Human, Pair 3↗
PubMed1990

Adult vitelliform macular dystrophy.

Adult vitelliform macular dystrophy was first described by Gass as giving rise to bilateral, round or oval, yellow, symmetrical, subretinal lesions typically one-third to one-half disc diameter in size. Although Gass proposed that this was an autosomal dominant disease, doubt has been expressed as to whether or not it is heritable. We investigated the families of 12 patients who presented to our clinic with foveal lesions typical of adult vitelliform macular dystrophy and found familial involvement compatible with an autosomal dominant inheritance in ten, although it has not been conclusively proven in all families. In the remaining two patients, no familial involvement was detected, but in neither family were both parents available for examination so that autosomal dominant inheritance could not be ruled out. Over half (14/25) the patients with abnormal fundi were asymptomatic, and most had good visual acuity. However, two had visual acuities of less than 6/18 in both eyes. We conclude that adult vitelliform macular dystrophy is an autosomal dominant disorder, and the term would be best reserved for foveal lesions similar to that described by Gass with a dominant pattern of inheritance.

Adult↗
PubMed1990

Bilaterality of drusen.

The characteristics of drusen in 81 patients with bilateral drusen as a manifestation of age related disease were analysed for symmetry between the two eyes. It was found that there was close concordance with respect to drusen size, number, density, and fluorescence which was greater than would have been expected by chance alone. This finding implies that drusen may result from metabolic malfunction specific to the patient rather than the non-specific result of aging.

Aged↗
PubMed1990

Aging changes in Bruch's membrane. A histochemical and morphologic study.

Using histochemical staining techniques and electron microscopy, the authors have examined the histochemical properties and ultrastructure of Bruch's membrane in 30 human eyes with an age range of 1 to 95 years. The results analyzed in three age groups (0-30 years, 31-60 years, and older than 60 years) show that there is a progressive accumulation of lipids in Bruch's membrane with relation to age. Differences were found in the specific types of lipids in individual eyes. Five eyes stained for neutral lipids alone, four stained predominantly for phospholipids, and nine stained intensely for both neutral lipids and phospholipids. The deposits were associated with the progressive destruction of the native architecture of Bruch's membrane but no correlation was identified between specific inclusions in Bruch's membrane with a particular lipid. These results are significant to age-related macular disease (ARMD), and the lipid rich barrier in Bruch's membrane is implicated as a cause of photoreceptor dysfunction and pigment epithelial detachment.

Adolescent↗
PubMed1990

Long-term effect of acetazolamide in a patient with retinitis pigmentosa.

The authors studied the therapeutic effect of acetazolamide on a patient with autosomal dominant retinitis pigmentosa complicated by retinal edema. In addition to reduction of macular edema and some improvement of central vision, they found an unexpected progressive increase in extrafoveal retinal sensitivity with prolonged medication. It is proposed that the therapeutic effect is mediated by alteration of retinal pigment epithelial function and that disturbed polarity is restored to a more normal state.

Acetazolamide↗
PubMed1990

[Drusen and their significance in age related macular degeneration].

In 81 patients with bilateral drusen and 150 patients with unilateral disciform lesions drusen were analyzed with respect to number, size, density and early and late angiographic behavior. In patients with bilateral drusen excellent symmetry was observed for all parameters. Drusen in fellow eyes of patients with avascular pigment epithelium detachments were larger, more confluent and less fluorescent than drusen in fellow eyes of patients with choroidal neovascularization. These results reveal drusen as products of specific metabolic failures of the pigment epithelium rather than unspecific aging changes. These metabolic failures result in specific individual patterns of drusen, which predispose to the development of specific complications of age-related macular degeneration.

Fluorescein Angiography↗
PubMed1990

A histopathologic study of a choroideremia carrier.

We have examined eyes from a heterozygote (carrier) of choroideremia, an X-linked disease. Gross examination revealed irregular pigmentation at the level of the retinal pigment epithelium (RPE) except at the posterior pole, and islands of well defined depigmentation of 1-4 mm in diameter in the midperiphery. The optic nerve and retinal blood vessels appeared normal, and there was minimal pigment migration into the retina. Histopathologic examination showed normal photoreceptors in the posterior and anterior fundus, but the outer segments were short or absent in much of the equatorial region. Little gliosis was noted in areas of retinal atrophy. The RPE was abnormal, with irregular thickness and pigmentation associated with variable lipofuscin content from one RPE cell to another, as shown by fluorescence microscopy. There were areas of profound atrophy in the equatorial region, with abrupt transitions between relatively normal RPE and photoreceptors, and retina devoid of RPE and photoreceptors. Bruch's membrane was thickened to a greater extent than is common in age-related change. The choriocapillaris was normal in areas with normal photoreceptors, except for widening of the intercapillary pillars. In those regions with abnormal photoreceptors, choroidal capillaries were fewer in number, had reduced luminal diameter, and fenestrae were sparse. In some areas of intense atrophy, there were no choroidal capillaries. The findings are compatible with the primary defect residing in the RPE. The Lyon hypothesis of X-chromosome inactivation and mosaicism could explain the irregularity of change and areas of intense atrophy, but abrupt demarcation between grossly abnormal, and relatively well preserved retina also occurs in hemizygotes (affected males).

Aged↗
PubMed1990

Linkage to D3S47 (C17) in one large autosomal dominant retinitis pigmentosa family and exclusion in another: confirmation of genetic heterogeneity.

Recently Dryja and his co-workers observed a mutation in the 23d codon of the rhodopsin gene in a proportion of autosomal dominant retinitis pigmentosa (ADRP) patients. Linkage analysis with a rhodopsin-linked probe C17 (D3S47) was carried out in two large British ADRP families, one with diffuse-type (D-type) RP and the other with regional-type (R-type) RP. Significantly positive lod scores (lod score maximum [Zmax] = +5.58 at recombination fraction [theta] = .0) were obtained between C17 and our D-type ADRP family showing complete penetrance. Sequence and oligonucleotide analysis has, however, shown that no point mutation at the 23d codon exists in affected individuals in our complete-penetrance pedigree, indicating that another rhodopsin mutation is probably responsible for ADRP in this family. Significantly negative lod scores (Z less than -2 at theta = .045) were, however, obtained between C17 and our R-type family which showed incomplete penetrance. Previous results presented by this laboratory also showed no linkage between C17 and another large British R-type ADRP family with incomplete penetrance. This confirms genetic heterogeneity. Some types of ADRP are being caused by different mutations in the rhodopsin locus (3q21-24) or another tightly linked gene in this region, while other types of ADRP are the result of mutations elsewhere in the genome.

Base Sequence↗
PubMed1989

The risk of fellow eye visual loss with unilateral retinal pigment epithelial tears.

To identify the magnitude of risk of fellow-eye visual loss, we reviewed the records of 43 patients with unilateral central visual loss caused by a tear of detached retinal pigment epithelium seen in our institution over a period of one to 13 years. Loss of vision because of complications of age-related macular disease occurred in 16 of 43 patients (37%) in the first year, seven of 23 patients (30%) in the second year, and eight of 16 patients (50%) in the third year. An additional five patients lost visual acuity between the third and eighth years of follow-up. The cumulative risk of loss of visual acuity was 37% in one year, 59% in two years, and 80% in three years. Visual loss occurred in 29 of the 36 eyes as a result of a complication of retinal pigment epithelial detachment. The magnitude of risk to the fellow eye was greater than has been documented in unselected age-related macular degeneration.

Aged↗
PubMed1989

Sorsby's fundus dystrophy. A clinical study.

A survey was undertaken of a family known to have Sorsby's fundus dystrophy. Fifty members were reviewed, and 14 were found to be affected. Many of Sorsby's original conclusions were confirmed, including the pattern of inheritance and age of visual loss. Yellow material was present at the level of Bruch's membrane early in the course of the disease. However, the earliest phenotypic marker was delayed filling of the choriocapillaris. Abnormalities of choroidal perfusion became more profound and extended centrifugally with time. The loss of central vision was commonly due to atrophy of the outer retina and choroid. Subretinal neovascularization was a rare occurrence. The homology between this dystrophy and age-related macular disease underlines the importance of the clinical findings in this family.

Adult↗
PubMed1989

Sorsby's fundus dystrophy. A light and electron microscopic study.

The light and electron microscopic changes in both eyes of a patient with Sorsby's fundus dystrophy are reported. The most striking finding was a 30-microns thick deposit present within Bruch's membrane that stained positive for lipids. The deposit has several unique features when compared with those found in other retinal dystrophies and in aged eyes. In addition, there was gross loss of the outer retina, the retinal pigment epithelium was discontinuous, and there was atrophy of the choriocapillaris. These findings are discussed in relation to the published clinical observations of other members of this pedigree.

Choroid↗
PubMed1989

Acute macular neuroretinopathy.

Acute macular neuroretinopathy is a rare, unilateral, or bilateral condition of abrupt onset causing parafoveal scotomata and occasionally reduced visual acuity. The features are described in five new cases, and the evolution of the lesions described over a period of 9 months to 9 years. One patient was studied by fine matrix perimetry, which indicated a generalized elevation of thresholds at the macula early in the disorder, together with parafoveal scotomata. The thresholds improved over several months, and the scotomata became less dense. In another case, the scotomata were still present at 9 years, although at this time they were less dense. The condition appears to mainly affect young women, and in this group there is a high incidence of a recent immunologic disturbance suggesting an immune-based etiology.

Adult↗
PubMed1989

Laser treatment of retinal angiomatosis.

We have treated 26 retinal angiomas of less than 4.5 mm in size in 15 eyes using repeated applications of contiguous argon blue green laser burns. All except one of the angiomas regressed without a massive exudative response of treatment. Haemorrhage occurred in two cases but only affected the visual outcome in one eye. Traction retinal detachment persisted in 50% of the large angiomas, despite regression of the tumour.

Adult↗
PubMed1989

Monitoring of patients taking canthaxanthin and carotene: an electroretinographic and ophthalmological survey.

1. Patients who have taken canthaxanthin and beta-carotene to avert phototoxicity have been monitored by electroretinographic testing. 2. Patients took the compounds only during the summer months, but were monitored for more than 1 year to determine if seasonal changes in the ERG were visible. 3. The characteristic refractile retinal crystals reduced during the winter. 4. The scotopic b-wave amplitude increased during the winter, whether evoked by red or blue flashes. 5. No other ERG parameter altered. 6. Changes noted in 3 and 4 above are reversible. 7. A dose/ERG-amplitude response relationship was established, but no correlation between blood level or total cumulative dose and b-wave amplitude could be found. 8. It is suggested that the Müller cells concentrate canthaxanthin and this is the mechanism which affects the ERG.

Aged↗