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Biomedical subjects

A B Laursen

Publications and source records attributed to A B Laursen.

15 recordsLinked to original sources
PubMed1988

Modified grid pattern treatment of diabetic perifoveal edema by orange dye laser photocoagulation.

Diabetic perifoveal edema is a potentially dangerous condition. A consecutive series of 58 diabetic eyes with fluorescein angiographically verified perifoveal edema and decreasing visual acuity and/or metamorphopsia was treated by orange dye laser photocoagulation in a perifoveal grid pattern. Observation periods ranged from 3 to 74 weeks (median 23.5 weeks). Post-treatment fluorescein angiography showed 51 dry foveas, 5 had discrete residual edemata and 2 were not controlled by fluorescein angiography, but were clinically dry. Metamorphopsia decreased simultaneously in most patients. Two eyes deteriorated more than 2 lines on the Snellen chart. Both developed chronic maculopathy, maybe induced by treatment. Except for these two, we found only minor changes in visual acuities and central visual fields. We find the method to be a relatively safe procedure to dry up diabetic foveal edema.

Adult↗
PubMed1986

Visualized cyclodialysis--an additional option in glaucoma surgery.

Visualized cyclodialysis was carried out in 16 consecutive cases of operation-demanding glaucoma, where trabeculectomy was considered inexpedient. In 9 cases simultaneous cataract extraction was carried out. At follow-up 2-34 months (median = 15) post-operatively, the IOP had decreased from a median value of 32 mmHg (range 21-44) to a median value of 17 mmHg (range 7-28) in 15 out of 16 eyes. The 16th eye had to be eviscerated because of pain before and after an inefficient cyclodialysis. Five eyes were reoperated upon. Essential complications were 2 cases of central visual field impairment and 1 case of arteriovenous occlusion after cyclodialysis revision. We find visualized cyclodialysis a useful procedure for aphakic glaucoma as well as for re-operations. Frequent post-operative examinations are necessary for 1-2 months post-operatively.

Aged↗
PubMed1980

Human senile cataract. Light- and electron-microscopic studies of the morphology of the anterior lens structures, with special reference of anterior capsular/subcapsular opacity.

Light- and electron-microscopic studies of human senile cataractous lenses with and without biomicroscopically detectable anterior capsular/subcapsular opacity (ACSCO) revealed the main difference between the two types of cataract to be in the subepithelial cortex, where ACSCO lenses showed disintegrating cortex fibres, fibres of the deep cortical type and even in some cases collapsed fibres. These findings were considered to be associated with the decomposition and disappearance of the superficial cortex in ACSCO lenses. Numerous mitochondria in the epithelium of ACSCO lenses point towards a high oxidative metabolism, which may facilitate active transport across the epithelium. No difference in capsular surface morphology between cataractous lenses with and without ACSCO was found by scanning electron microscopy. Transmission electron microscopy showed in both categories of lenses granular inclusions in the capsules, most pronounced in totally opaque lenses. Large intercellular vacuoles were seen in the anterior part of the epithelium, both light- and electron-microscopically in both categories. Consequently, these ultrastructural changes do not seem to form part of the biomicroscopical picture of ACSCO. Based on our study, we prefer the term: ASCO (anterior subcapsular opacity) in place of ACSCO, the latter term having been used by us previously.

Age Factors↗
PubMed1980

Human senile cataract and Na-K ATP'ase activity in the anterior lens structures with special reference to anterior capsular/subcapsular opacity.

Location and in vitro determination of Na-K ATP'ase activity in the anterior structures of individual human lenses with senile cataract are reported, with special reference to anterior capsular/subcapsular opacity (ACSCO). Histochemically, ATP'ase reaction products were found exclusively in the epithelium. Even totally opaque lenses showed strong positive reactions. Biochemically, increasing ratios of Na+/K+ concentrations in the assay medium resulted in an increase in enzyme activity to a limited degree, whereafter the activity remained stable. We cannot decide whether the Na-K ATP'ase activity of the anterior lens structures is unchanged in relation to ACSCO as indicated by our figures. For there are methodological problems, although our analytical error, expressed as the variation coefficient for slaughterhouse pig lenses, seems to be one of the lowest so far reported in the literature on interindividual, non-pooled material.

Aged↗
PubMed1979

Variations of lens thickness in relation to biomicroscopic types of human senile cataract.

The results are reported of 38 ultrasonographic in vivo mensurations of intraindividual differences in axial thickness between a cataractous lens in one eye and a biomicroscopically clear or slightly cataractous lens (incipient deep cortical opacity) in the other. Obviously intumescent cataractous lenses were excluded. In general, the cataractous lens was thinner than the contralateral clear or slightly cataractous lens. Large decreases in lens thickness appeared in lenses with the capsule-near opacities of posterior subcapsular cataract (PSC) + anterior capsular/subcapsular opacity (ACSCO). PSC was more closely correlated to lens thinning than was ACSCO. Nuclear cataract very often occurred in thin lenses, but did not appear to cause lens thinning per se. Deep cortical opacity was not associated with lens thinning. The present results contributed to our argumentation that the decrease in lens thickness is due to a leak of lens material through the "lens membrane" beside a possible cessation of growth of the lens fibres.

Age Factors↗
PubMed1977

Relative contents of sodium, potassium, water and dry matter in human senile cataractous lenses in relation to anterior capsular/subcapsular opacity.

In 49 human senile cataractous lenses the sodium and potassium concentrations of the lens water as well as the water and dry weight percentages were examined. It was found justifiable to classify the lenses into three categories on the basis of correlated biomicroscopic and biochemical findings: 1. Immature cataractous lenses without anterior capsular/subcapsular opacity (ac-sco) were characterized by low CNaL+, high CKL+ and low sums of CNaL++CKL+. 2. Immature cataractous lenses with ac-sco were characterized by intermediate value of CNaL+ and CKL+, as well as high sums of CNAL++CKL+. 3. Totally opaque lenses (these lenses had 80-100% of ac-sco) were characterized by high CNaL+, low CKL+, high sums of CNaL++CKL+, high water, and low dry weight percentages. It was found that in immature cataractous lenses increasing extension of ac-sco was correlated to increasing CNAL+ and increasing ratios of CNAL+/CNAA+ as well as to decreasing CKL+ and decreasing ratios of CKL+/CKA+. The sums of CNaL++CKA+ increased. There was a correlation of the extent of ac=sco to the water and dry weight percentages of the immature senile cataractous lenses with ac-sco, viz. a negative correlation for water and a positive one for the dry weight. However, these latter two correlations may be due to chance significances, the level of significance being only greater than P greater than 0.02 in both instances. Lenses which were estimated to have larger than or equal to 30% of ac-sco were found to be more opaque than lenses with less than or equal to 25% of ac-sco.

Aged↗
PubMed1976

Concentrations of some ribonucleotides, L-lactate, and pyruvate in human senile cataractous lenses with special reference to anterior capsular/subcapsular opacity.

The concentrations of some ribonucleoside tri- and diphosphates, adenosine-5'-monophosphate, L-lactate and pyruvate were determined in human senile cataractous lenses removed during cataract operations. Pyruvate concentrations were found to be negligible (median = 56 mumol/kg lens wet weight) in 15 human senile cataractous lenses. On the basis of correlations between the biomicroscopic appearances of the senile cataractous lenses (N = 80) and the concentrations and ratios of the metabolites in question, the following classification was found to be justified: 1. Immature cataractous lenses without anterior capsular/subcapsular opacity: high levels of ribonucleoside triphosphates (RTP), high sums of RTP, ribonucleoside diphosphates (RDP), and adenosine 5'-monophosphate (AMP) as well as high levels of L-lactate and high ratios of L-lactate in the lens/L-lactate in the aqueous. 2. Immature cataractous lenses with anterior capsular/subcapsular opacity; intermediate levels of RTP, intermediate values for the sums of RTP, RDP, and AMP, high L-lactate levels, and intermediate values of the ratios of L-lactate in the lens/L-lactate in the aqueous. 3. Totally opaque lenses, which all had extensive anterior capsular/subcapsular opacity; low values for the concentrations of lens RTP, for the sums of RTP, RDP and AMP, and for lens L-lactate. Low ratios of L-lactate in the lens/L-lactate in the aqueous.

Adenosine Diphosphate↗
PubMed1975

Concentrations of some metabolites in the aqueous humour of human senile cataractous eyes.

Glucose, pyruvate, l-lactate, and citrate concentrations of the aqueous humour were examined in 51 patients aged 54-87 years with senile cataracts, and in one patient with a clear lens. Furthermore, the ratios of glucose in aqueous/glucose in plasma and citrate in aqueous/citrate in plasma were investigated. Among the parameters recorded, age dependence could only be demonstrated for glucose concentrations in the aqueous humour, as this parameter decreases with increasing age. However, a chance significance because of multipleignificance tests cannot be left out of account in this material. The parameters in question are unfit for an evaluation of possible changes in the energy metabolism of the lens in relation to cataract development because no significant differences were found between concentrations and ratios in different clinical types of cataract. Also, considerable ranges of variation were recorded.

Age Factors↗
PubMed1975

Glucose, pyruvate, L-lactate, and citrate concentrations in the aqueous humour of fasting rabbits in relation to age.

Results are reported of determinations of glucose, pyruvate, l-lactate and citrate concentrations in aqueous humour from 42 fasting albino rabbits aged from 8 months to 9 years. The glucose concentrations decreased significantly with increasing age. The pyruvate and l-lactate concentrations as well as the ratios of l-lactate/pyruvate did not change significantly with age. However, the pyruvate concentrations were higher and the l-lactate/pyruvate ratios were lower in the 2-year-old rabbits than in the others. The citrate concentrations were found to rise with increasing age. Because of wide ranges of variation between individuals of the same age groups, the parameters in question have limited value in the evaluation of the energy metabolism of the anterior eye segment.

Age Factors↗