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Biomedical subjects

A Ringvold

Publications and source records attributed to A Ringvold.

At least 55 records · Page 3Linked to original sources
PubMed1991

Pseudo-exfoliation, IOP and glaucoma.

On the basis of a glaucoma survey in a total population greater than or equal to 65 years of age, the IOP in eyes with and without pseudo-exfoliation (PE) has been compared. The average IOP was 22.2 mmHg in eyes with PE versus 17.4 in eyes without. The corresponding averages in eyes without glaucomatous damage were 18.6 and 17.1 mmHg, and in eyes with glaucoma 31.5 and 25.5 mmHg. The IOP elevation connected with the PE process was 4.8, 1.5, and 6.0 mmHg in the total, normal and glaucomatous population, respectively. The IOP frequency distribution curves of these 3 groups were compared. The right shift of the distribution curves of the PE groups was more pronounced at high pressure levels. The PE process seems to elevate the IOP particularly in eyes with a high IOP, which is in correspondence with hydrodynamical laws. At a certain IOP, the probability of having glaucomatous damage was higher in eyes with PE than in those without, indicating an increased vulnerability of PE eyes to an elevated IOP. PE may be a glaucoma risk factor also on its own, i.e. independent of the pressure elevation connected with this syndrome.

Aged↗
PubMed1990

Culture of iris tissue from human eyes with and without pseudoexfoliation.

Samples of iris tissue were removed from human eyes with and without pseudoexfoliation syndrome and maintained in vitro for several weeks. The samples were cultured on tissue culture plastic as well as on biological basement membranes. The morphology of the cultures was examined by phase contrast-, scanning electron-, and transmission electron microscopy. Out-growth of cells with similar shapes was observed from normal iris as well as from pathological tissue on both type of substrate. In sections the outgrowing cells formed multilayered structures. In these areas the individual cells were separated by spaces containing extracellular material. The PE positive specimens revealed typical PE aggregates both within the native tissue and between the outgrown cells. Production of viable cell cultures from human eyes with pseudoexfoliation may facilitate the search for morphological and biochemical abnormalities in this syndrome.

Anterior Eye Segment↗
PubMed1990

Pseudo-exfoliation pattern on posterior IOL.

Extracapsular cataract extraction with posterior chamber lens implantation was performed in a 75-year-old man. Eight months later PE syndrome had developed with a distinct peripheral band on the anterior surface of the pseudophacos. This case clearly shows that the peripheral band is added to the lens surface from outside, and is not derived from the lens epithelium.

Aged↗
PubMed1989

Lateral cell connections at the inner segment level of human parafoveal photoreceptors.

Cytoplasmic processes on macular rod inner segments are described both in torn, fractured, and sectioned human tissue specimens. Longitudinal rows of villi are present along the inner segment's proximal part in fractured and sectioned tissue. Some villi were obviously abutting neighbouring cells. It is concluded that these processes undoubtedly represent a new type of cell extension different from calycal, pigment-epithelial, and Muller basket processes.

Fovea Centralis↗
PubMed1989

Electrophoretic study of proteins associated with pseudo-exfoliation syndrome.

Lens capsule and aqueous humour from cataractous eyes with and without pseudo-exfoliation syndrome have been studied by SDS-PAGE electrophoresis. Four cataractous lenses with and four without pseudo-exfoliation were used. The pseudo-exfoliation positive capsule revealed two polypeptides not present in the control material, and accordingly, these components were regarded to be pseudo-exfoliation specific. The molecular weight of the respective polypeptides was estimated to be 14,400 and 16,300. No marked differences were found between the pseudo-exfoliation positive and negative aqueous humours.

Aqueous Humor↗
PubMed1988

The calcium and magnesium content of the human lens and aqueous humour. A study in patients with hypocalcemic and senile cataract.

Previous observations of raised calcium content in mature senile cataract are confirmed in the present study. Also human hypocalcemic cataract showed increased amounts of calcium in accordance with previous observations in animals. On the other hand, the magnesium content of the lens was not influenced by cataract development. The calcium aqueous/serum ratio was similar in all examined groups (normal, hypocalcemic-, incipient-, and mature senile cataract), whereas the corresponding magnesium ratio was elevated in the cataract patients. This observation may indicate a possible connection between magnesium metabolism and the development of cataract.

Aqueous Humor↗
PubMed1988

Outpatient anterior chamber lens implantation.

100 outpatient and 143 inpatient intracapsular cataract extractions with anterior chamber lens implantation were examined 6 months post-operatively. 74 (74%) in the former and 107 (75%) in the latter achieved visual acuity greater than or equal to 0.5. Excluding non-surgical pathology, 93% in the outpatient group and 98% in the inpatient group had a visual acuity greater than or equal to 0.5 (P = 0.12). There were no significant differences in post-operative complications except for the incidence of cystoid macular edema. Six (6%) of the outpatient and 1 (0.7%) of the inpatient procedures had cystoid macular edema that resulted in a visual acuity below 0.5 (P = 0.02).

Ambulatory Surgical Procedures↗
PubMed1988

The Middle-Norway eye-screening study. I. Epidemiology of the pseudo-exfoliation syndrome.

This is the first population-based PE prevalence study allowing comparison of observations from different geographical areas. The prevalence of the PE syndrome for persons above 64 years of age was found to be 10.2, 21.0 and 19.6% in three municipalities lying distinctly apart. Of 343 married couples the man was PE-positive in 36, the woman in 34, and both in 12 cases. One of the 12 couples was excluded because the spouses were cousins. The observed number of 11 couples is significantly higher (P = 0.022) than expected assuming independent occurrence of PE syndrome. Two homozygote pairs of twins were found in this material, both of them discordant for the presence of PE syndrome. This fact along with the discrepancy between observed and expected numbers of PE positivity in both spouses may indicate environmental influence on the distribution of the syndrome.

Aged↗
PubMed1987

The occurrence of simple and capsular glaucoma in Middle-Norway.

The records of all patients with simple and capsular glaucoma who visited our clinic in the period from 1.1.1972 to 31.12.1982, and who were alive at the 31.12.82, have been evaluated. In the population older than 49 years 0.54% had simple and 0.74% had capsular glaucoma, equally distributed on men and women. In average near 60% had capsular glaucoma, with great variation in different municipalities. Highest figures were found in a belt reaching from the coast into the inland. Both simple and capsular glaucoma showed increasing occurrence till 75-80 years, thereafter the curves decline.

Demography↗
PubMed1986

Hypotony and retinal detachment.

The present work has been based on the assumption that the decreased intraocular pressure in eyes with retinal detachment is due to an abnormal posterior aqueous outflow, in addition to the normal anterior pathways. Subretinal fluid may leak out either through the peri-optic connective tissue or across the retinal pigment epithelium. In order to test the validity of these alternatives against clinical observations, a fluid dynamic model has been developed to calculate intraocular pressure-drop versus detached area in both cases. In contrast to the choroidal alternative, the numerical results from the peri-optic route exhibit qualitative agreement with clinical observations. It is concluded that both clinical and theoretical findings lend support to the hypothesis that the intraocular pressure-drop in eyes with retinal detachment is due to drainage of subretinal fluid via the peri-optic tissue.

Aqueous Humor↗
PubMed1986

Glaucomatocyclitic crises (Posner-Schlossman syndrome). A case report.

A white man aged 40 suffering from glaucomatocyclitic crises, was treated with trabeculectomy during an acute attack. The tissue specimen showed numerous mononuclear cells in the trabecular interspaces. The hypertensive attacks are supposed more to be due to blockage of the aqueous outflow pathway by these cells, and less to increased aqueous formation.

Adult↗
PubMed1985

Scanning and transmission electron microscopy of Müller cells isolated from rabbit retina.

Proteolytic enzymes were applied in the dissociation of rabbit retina to obtain isolated Müller cells. Both trypsin and papain were used, and in some cases the trypsinization was shortly interrupted by tissue fixation before it was continued. Scanning electron microscopy mostly confirmed the previous descriptions of these cells, which were based on different techniques. In addition, some new cell extensions were observed that derived from the nuclear region. The papain procedure ensured the best cell preservation with a free surface and limited contaminant material attached. Roughly 90% of the cells excluded trypan blue. It is concluded that these cells should be preferred for biochemical studies, because their cytology also turned out to be intact as judged from electron microscopic sections.

Animals↗
PubMed1985

Idiopathic haemochromatosis and eye symptoms. A case report.

A 61-year-old man with idiopathic haemochromatosis and eye symptoms is described. The examination showed microaneurysms scattered over the bulbar conjunctiva, and some discrete pigmentations in the superficial tissue in the perilimbal area. Each cornea revealed a light brown, ellipsoid opacity with the longest diameter horizontally, seemingly being located in the corneal epithelium and/or the anterior part of the stroma. A corneal biopsy was examined by light and electron microscopy. Two different types of granules were found mainly located to the Bowman's membrane. X-ray microanalysis showed no detectable amounts of iron, but high concentrations of phosphorus and calcium, and in addition magnesium in one type of the granules. Treatment with EDTA improved the vision considerably.

Conjunctiva↗