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Biomedical subjects

A J Bron

Publications and source records attributed to A J Bron.

At least 91 records · Page 5Linked to original sources
PubMed1989

Conjunctival involvement in cicatricial and bullous pemphigoid: a clinical and immunopathological study.

Patients with bullous pemphigoid were found to have significant ocular abnormalities. In a group of 18 patients one had conjunctival shrinkage, and 11 of 15 (73%) had positive linear direct immunofluorescence on conjunctival biopsy from a clinically uninvolved site. Our ocular findings in a group of 14 with cicatricial pemphigoid are also reported and compared with those from a control group of 20. Our findings suggest there is overlap between the pemphigoid groups and raise further questions about the pathogenicity of immunoreactants within the basement membrane zone. Bulbar conjunctival biopsy was simple and well tolerated, and the rate of immunofluorescence positivity of conjunctiva was twice that of skin in both pemphigoid groups.

Aged↗
PubMed1989

Dynamic nature of posterior subcapsular cataract.

Posterior subcapsular cataracts were studied in 10 patients (19 eyes) and were photographed at four to 12 weeks intervals by the Oxford Retroillumination Camera. Changes in the fine structure of PSC may occur in as short a time as four weeks. Posterior subcapsular cataracts are shown to be in a state of flux and are not, as might be assumed, slowly but relentlessly progressive. This could imply the existence of a repair mechanism in the lens.

Adult↗
PubMed1989

Papillo-renal syndrome. An inherited association of optic disc dysplasia and renal disease. Report and review of the literature.

A family is described in which the father and son had chronic renal disease of early onset and bilateral optic nerve dysplasia. A further son, known to have microphthalmos died of renal disease in childhood. Optic nerve changes included coloboma in the father and Handmann's optic nerve anomaly, a condition resembling the morning glory syndrome (M.G.S.), in the son. There was electrodiagnostic and visual field evidence of optic nerve dysfunction even where acuity was relatively unaffected. The son developed central serous retinopathy, a condition frequently encountered in association with optic nerve dysplasias, including M.G.S.

Adult↗
PubMed1989

Corneal changes in the dislipoproteinaemias.

The corneal changes in the hyper- and hypoproteinaemias may affect vision and/or provide a diagnostic clue to a systemic disorder. This article describes the structure and function of the major lipoprotein classes and the means by which dietary lipid is absorbed and by which exogenous and endogenous lipid is distributed to and cleared from the tissues. In hyper-beta-lipoproteinaemia, lipid arcus formation may be related to the duration and height of the raised cholesterol levels. The peripheral location of the lipid deposit is presumed to be related to peripheral trapping of low-density lipoprotein (LDL) by glycosaminoglycan binding and tight stromal packing with maintained central clearing by high-density lipoprotein (HDL), whose smaller molecular diameter should allow freer stromal diffusion. In the hypolipoproteinaemias, e.g., Tangier disease, generalised (alpha and beta) lecithin cholesterol acyltransferase (LCAT) deficiency, and alpha-LCAT deficiency (fish-eye disease), the absence or abnormality of HDL may impair clearance of endogenous and possibly exogenous stromal lipid. The hyperlipoproteinaemia that sometimes accompanies Schnyder's crystalline corneal dystrophy is thought to modify the effects of a primary failure of corneal stromal lipid metabolism.

Cornea↗
PubMed1988

Human lens nuclear colour matching and brunescence grading in vivo.

The nuclear colour of in vivo human lenses has been investigated by means of a colour matching technique, using 'Munsell' colour samples. Observations covered an extended age range, and included all degrees of nuclear pigmentation. A positive correlation was noted between increasing nuclear pigmentation and age. The colour matching data generated was used as a basis for establishing a system of nuclear brunescence grading. The system of grading consists of a Grade 0 for absence of brunescence, and Grade 1 to Grade 5 for increasing brunescence. The 'Munsell' notation for samples representing these grades are: Grade 0 (5GY 6/1), Grade 1 (5Y 7/4), Grade 2 (2.5Y 7/8), Grade 3 (7.5YR 6/8), Grade 4 (5YR 4/6), and Grade 5 (2.5YR 2.5/2). Assessments of both inter- and intra-observer variability in the use of the derived scale have shown the new colour grading system to be reliable. The measure is simple to use during biomicroscopic slit-lamp examination of the lens, and has the potential for routine clinical application as well as for use in clinical trials where detailed documentation of lens morphology is required. The new colour scale may be used either as an isolated measure, or as part of a battery of lens measures in the Oxford Clinical Cataract Classification and Grading system.

Aging↗
PubMed1988

Inter-observer and intra-observer variability of the Oxford clinical cataract classification and grading system.

Intra-observer (within observers) and inter-observer (between observers) variability of the Oxford Clinical Cataract Classification and Grading System were studied. Twenty cataracts were examined and scored independently by four observers. On a separate occasion two of the observers repeated the assessments of the same cataracts in the absence of information from the initial observations. The chance corrected and weighted kappa statistics for observer agreement, both for inter-observer and intra-observer variability demonstrated satisfactory repeatability of the cataract grading system. The overall intra-observer mean weighted kappa was kappa w = +0.68 (range SE kappa = 0.012-0.052) and the overall inter-observer mean weighted kappa was kappa w = +0.55 (range SE kappa = 0.011-0.043).

Cataract↗
PubMed1988

Eyelid secretions and the prevention and production of disease.

Tears are necessary for the continued health of the ocular surface. Normal constituents include water, mucin, and lipids, electrolytes, non-electrolytes, and proteins. Lacrimal secretion is under cholinergic control and modulated by sympathetic adrenergic, peptidergic (VIP) and humoral influences; the meibomian glands are innervated, but the goblet cells are not. Retinoids are important for ocular health and prealbumin may be a carrier for vitamin A in the tears to supply corneal epithelium with its requirements. Changes in tear constituents may cause certain ocular disorders. In dry eyes increased osmolarity is thought to cause surface ocular damage but the presence of granulocytes and inflammatory mediators such as prostaglandins and super-oxide may contribute to inflammatory events in this and other external diseases.

Animals↗
PubMed1988

Mucosal involvement in bullous and cicatricial pemphigoid. A clinical and immunopathological study.

Thirty-six patients with bullous pemphigoid (BP) and 15 with cicatricial pemphigoid (CP) were studied for evidence of mucosal involvement both clinically and by direct immunofluorescence. Twenty-one patients with BP and all those with CP had lesions of the mucous membranes. Eighteen patients with BP and 14 patients with CP had involvement of the oral mucosa. Lesions of the eyes, nose, pharynx, vulva and urethra also occurred in both groups. The lesions tended to be more widespread in CP patients. Twenty-one patients with BP and 14 with CP were examined by an ophthalmologist. Fine scarring of the tarsal conjunctiva was found in both groups, but also in elderly controls. However, symblepharon occurred in one patient with BP as well as in three patients with CP, but was not seen in a group of 20 controls. Direct immunofluorescence (IF) studies showed linear deposition of IgG or C3 or both in the basement membrane zone of the skin, oral mucosa and conjunctival mucosa in both groups. The frequency of positive immunofluorescence was higher in the conjunctiva than in the lip mucosa or skin in both BP and CP patients. The significance of these findings and the relationship between BP and CP is discussed.

Aged↗
PubMed1988

Central compaction in the process of lens growth as indicated by lamellar cataract.

The lens growth through life is the net result of surface accretion partially offset by central compaction. Compaction has previously been shown to affect the cortex. The present study examines compaction in the nucleus by measuring the change in dimensions of congenital lamellar cataract with time and by comparing the different dimensions of dominantly inherited lamellar cataract in individuals of different ages in the same family. It is now shown that compaction affects the nucleus at a decreasing rate with increasing age and that the rate of compaction of lamellar cataracts is faster the greater diameter of the affected lamella. It is concluded that compaction of lens fibres towards the centre of the lens affects all regions of the cortex and nucleus in youth and that the compaction becomes largely or completely confined to the cortex in middle age and beyond. The shape of the lamellar cataract changes from a lenticular shape in youth to a rounded shape with increasing age. This accounts for the development of the peripheral divergence of the zones of discontinuity of the cortex, which allows the lens to remain emmetropic with increasing age in spite of changes in surface curvature.

Adolescent↗
PubMed1988

Keratoconus.

Keratoconus is a bilateral disorder of corneal shape which may be sporadic or genetically determined. Early corneal thinning suggests that a functional loss of structural elements is a primary event in the disease. Tensile strength of the cornea is reduced and is expressed by signs of rupture and scarring in Bowman's layer, scarring in the substantia propria, and rupture of Descemet's membrane. The overall stretching of the cornea results in an increase in curvature while an increased area of the corneal surfaces probably determines the onset and form of Fleischer's ring and the occurrence of endothelial polymegathism. Biochemical studies have shown an increase in collagenolysis and of reduceable collagen cross-links, but there is inconsistent evidence of altered solubility or of hydroxyproline or proteoglycan content. Of recent interest is the characterization of proteoglycan bridges along and between corneal collagen fibrils in keratoconus and the apparent loss of keratan sulphate demonstrated by electron-histochemical and x-ray diffraction techniques. The manner in which this could interfere with corneal strength is discussed.

Biomechanical Phenomena↗
PubMed1987

An estimate of the human lens epithelial cell size in vivo.

There are few previous estimates of the size of the human lens epithelium. In this study the lens epithelium is measured by specular reflex photography with a macro camera. The results are corrected for cornea magnification. One hundred subjects were studied ranging in age from 11 to 75 and including 20 diabetics and 18 subjects with cataract. The results show a range of epithelial cell diameters from 8-21 microns with 97% of the measurements lying in the 9-17 microns range. Pleomorphism is marked. The mean cell size was 12.7 microns. Large differences exist in mean cell size between individuals, but no correlation was found with age, diabetes or cataract.

Adolescent↗
PubMed1987

The objective assessment of cataract.

The objective assessment of cataract is central to any epidemiological or therapeutic study of cataract. The objective methods consist of: 1: A resolution target projection ophthalmoscope (Acuity scope) for the estimation of potential visual acuity. 2: The Oxford Clinical Cataract Classification and Grading System, which records and quantifies the features of the lens that are visible at the slit-lamp microscope. This system is essential since photographic methods cannot define the morphology of cataract. 3: Two photographic methods; slit-lamp photography and retro-illumination photography are needed to give a comprehensive statement about the amount of cataract. The negatives are measured by computerised image analysis systems.

Cataract↗
PubMed1987

An estimate of the size and shape of the human lens fibre in vivo.

The size and shape of the lens fibres were estimated by specular reflex photography. The fibres were measured in three separate regions. Peripheral fibres have a mean width of 10.2 micron, the central fibres 11.9 micron, and the central fibres with suture 15.8 micron. Measurements were made of the taper (becoming narrower towards the suture) and flare (becoming wider towards the suture). The peripheral fibres have a mean taper of 0.3 micron per 100 micron. The central fibres have a mean flare of 0.6 micron per 100 micron, and the central fibres with suture have a mean flare of 2.4 micron per 100 micron. These differences are highly significant (p less than 10(-6]. From these measurements the overall shape of the average lens fibre was estimated. This fibre tapers as it passes forward from the equator to the peripheral extent of the lens sutures and then flares increasingly as the junction with the lens suture is approached. A mean increase in peripheral lens fibre width with age at 0.028 micron per year was demonstrated. This is significant (p = 0.042). No difference in fibre width was found in diabetics and non-diabetics.

Adolescent↗
PubMed1987

Perinuclear lens retrodots: a role for ascorbate in cataractogenesis.

Lens retrodots are round, oblong, or oval features in the perinuclear zone of the adult lens after the fifth decade of life and associated with cataract. Retrodots were found in 47 out of 121 eyes with cataract (39%) in the present series. They show birefringence in vivo and in vitro, and chemical studies suggest that they contain calcium oxalate. It is proposed that ascorbic acid, which is abundant in the normal human lens, is the most likely source for this oxalate. Ascorbic acid is thought to have a protective role against oxidative stress in the lens and other parts of the eye, and its level is known to be reduced in senile cataract. The presence of the retrodots may identify lenses which have been exposed to oxidative stress and are less capable of resisting oxidative damage.

Adult↗
PubMed1987

Congenital deficiency of meibomian glands.

A 16-year-old girl presented with contact lens intolerance. She was found to have a marked deficiency of meibomian glands in the upper lids and almost total absence in the lower lids. Evidence of tear film instability was found and attributed to deficient lid oil production. A daily wear soft contact lens was later fitted and tolerated.

Adolescent↗
PubMed1986

The Oxford Clinical Cataract Classification and Grading System.

A composite slit-lamp based system for the clinical classification and grading of cataract is described. Cataract features are classified morphologically, and individual features are graded by comparison with standard diagrams mounted adjacent to the slit-lamp. Attention has been paid to relevant aspects of measurement theory, with equal interval steps between the grades. The image degrading effect of the cataract is assessed using a 'resolution target projection ophthalmoscope'. The method may be used in conjunction with photographic and image analysing techniques.

Cataract↗