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Biomedical subjects

N Ehlers

Publications and source records attributed to N Ehlers.

At least 109 records · Page 6Linked to original sources
PubMed1982

Post-operative thickness and endothelial cell density in cultivated, cryopreserved human corneal grafts.

Seventeen corneas obtained 2-72 h post mortem, from donors aged 17-78 years, were cultivated for 24 h, cryopreserved, thawed, cultivated for another 24 h and grafted. One year post-operatively 12 of the 17 grafts were clear. In 10 of these 12 cases the visual acuity was greater than or equal to 0.33. One primary graft failure occurred, while 4 primarily clear grafts became cloudy due to glaucoma (2), phthisis bulbi (1) and herpetic reinfection (1). One year after the transplantations the central thickness of the clear grafts was 0.51 mm, and the endothelial cell density was 1028 cells/mm2, corresponding to 32% of the cell density before cryopreservation. This endothelial cell loss was not correlated to donor age or to the time between the death of the donor and the primary cultivation.

Adolescent↗
PubMed1982

No increase in arteriolosclerotic retinopathy or activity in tests for circulating immune complexes 5 years after vasectomy.

On the basis of studies in monkeys, the hypothesis has been proposed that vasectomy induces the formation of circulating immune complexes (CICs), which--via activation of the complement system--may result in immune injury of the endothelium and thereby exacerbate atherosclerosis; the same mechanism has been suggested to cause retinal arteriolar changes in vasectomized men. We compared 46 men, 5 years after vasectomy, with 46 age-matched control subjects and found no difference in the distribution of arteriolosclerotic retinopathy gradings evaluated by ophthalmoscopy and fundus photography. Blood samples from the two groups were collected and handled identically, and no significant difference in activity was found in four different tests for CICs and two tests for split products of complement factor C3. Thus, the results do not support the hypothesis that changes mediated by CICs occur in vessels after human vasectomy.

Adult↗
PubMed1981

Corneal graft rejection probably mediated by antibodies.

A clinical and laboratory analysis of a rejection episode is presented. A clear graft in a non-vascularized cornea from 1975 was rejected when the contralateral eye was grafted in 1979. Clinically this case was unique by showing no endothelial rejection line and no precipitates and, as seen after successful treatment, no endothelial cell loss. A test for direct cell mediated lympholysis (DCML) was negative while antibody dependent cell mediated cytotoxicity (ADCC) was positive at time of rejection, and negative three months later. This case suggests that humoral factors may be involved in corneal graft rejection.

ABO Blood-Group System↗
PubMed1981

Fresh and cultured corneal grafts compared by post-operative thickness and endothelial cell density.

Thirty-nine corneas were removed within 6 h post mortem and stored in a moist chamber at 4 degrees C before grafting. The mean donor age was 33 years and the average time between death and grafting was 11 h. Thirty cadaver corneas were selected after trypane blue staining and cultured at 31 degrees C for 24 h before grafting. The mean donor age was 61 years and the mean time between death and culture was 18 h. During the first 10 postoperative days fresh grafts were thinner than cultured grafts. One year after the transplantation the two groups did not differ significantly in regard to the clinical result, corneal thickness, or endothelial cell loss. This indicates that corneas from old donors with extended post mortem time can be used for transplantation after individual evaluation and corneal culture.

Adult↗
PubMed1981

Aqueous humour and plasma amino acids in tapeto-retinal degenerations.

The concentration of 18 amino acids and related compounds has been determined in plasma and aqueous humour in 17 patients with tapeto-retinal degenerations, among them 10 patients with retinitis pigmentosa. When compared with a previously obtained reference series of 40 patients abnormal aqueous concentrations (Caq) were found for taurine, glutamine, glutamic acid, proline, glycine, alpha-ANBA and cystine. As regards the plasma concentrations (Cpl) only glutamic acid and alpha-ANBA showed abnormal values. Several of the substances showing abnormal concentrations are possible neurotransmittors or inhibitors. The results suggest that aqueous humour analysis will be a useful way of studying retinal degenerations.

Adolescent↗
PubMed1981

A-beta-lipoproteinaemia. Ocular involvement in a Danish case.

A-beta-lipoproteinaemia in a Danish woman is reported. The ocular involvement comprised pigmentary retinopathy, anisocoria and reduced corneal sensibility. Serum concentrations of vitamin A and retinol-binding protein (RBP) were low, but were normalized after vitamin treatment. Serum concentration of carotene was low, and not altered by treatment. The retinopathy progressed over a 2 1/2 year period in spite of controlled serum vitamin A and RBP concentrations. The possible role of vitamin A in the development of retinopathy is discussed.

Abetalipoproteinemia↗
PubMed1980

Enucleation in children.

In adults enucleation is usually considered a rather simple operation. By contrast the removal of an eye of a child is often a difficult task. We describe an effective technique which makes this surgical intervention a safe and trouble-free procedure.

Age Factors↗
PubMed1980

On the optical measurement of a corneal thickness. I. Optical principle and sources of error.

The optical principle for the estimation of corneal thickness with a commonly employed method is considered. The theoretical relationship between the apparent and true corneal thickness is described in a simple manner. Based on the theoretical results it could be confirmed that physiological variations in refractive index and radius of the cornea induce an insignificant error in the corneal thickness estimate. The theoretical relationship between apparent and true corneal thickness was compared to the performance of two commercially available pachometers (Haag-Streit and Zeiss). The actual reading of the pachometers was found to be lower than the theoretical reading by a non-linear error amounting to about 0.010 and 0.100 mm at a true corneal thickness of 0.50 and 1.00 mm, respectively.

Anthropometry↗
PubMed1980

Influence of tranexamic acid and acetylsalicylic acid on the thickness of the normal cornea.

In a masked cross-over study ten normal subjects were treated with tranexamic acid and acetylsalicylic acid one g three times daily for seven days. The central corneal thickness. was found to increase in response to acetylsalicylic acid and to decrease in response to tranexamic acid. This finding provides evidence for the involvement of the fibrinolytic system in the regulation of the normal corneal thickness. The endothelial morphology, as seen with the specular microscope, was unchanged during treatment with either drug.

Adult↗
PubMed1980

On the optical measurement of corneal thickness. II. The measuring conditions and sources of error.

The optical measurement of corneal thickness based on oblique viewing of the optical section of the cornea is complicated by the finite width of the incident slit beam. In this report the theoretical and practical aspects of the effect of the slit width on the thickness reading are analysed. In practice, it was not possible to make slit-width independent thickness readings which were reproducible from one observer to another. In addition, the observed slit-width error was found to vary from one patient to another. The lack of reproducible estimate of the corneal thickness is attributed to difficulties associated with an exact definition of the edges of the visible bands of the optical section, which are determined by biological properties of the cornea as well as perceptive properties of the observer. Although inter-observer errors up to 0.02 mm were found, the intra-observer error amounted to only 0.005-0.006 mm (SD) between consecutive readings. Presumably this high intra-observer reproducibility is the result of the auxiliary pin-lights used. Changes in corneal thickness, measured by the same observer, can therefore be determined with great accuracy.

Adult↗
PubMed1980

Ocular complications to diabetes and their treatment.

Ocular complications to diabetes may be described as early or late, the late ones being by far the most important. Early complications are the frequently occuring transitory changes in refraction, and the more serious but rarely occuring diabetes cataract both possibly related to an overloading of the carbohydrate metabolism of the lens with accumulation of sorbitol. Oculomotor palsies (often III-nerve) and optic neuropathy may also occur. The pathogenesis of these lesions are unknown. Late complications comprise diabetic retinopathy (non-proliferative with or without maculopathy and proliferative), vitreous hemorrhage, vitreous membranes, traction detachment of the retina, hemorrhagic secondary glaucoma and a possible accelerating effect on senile cataract, and retinal vascular sclerosis. The treatment of the above mentioned complications is discussed, emphasis particularly being given to the retinopathy.

Cataract↗
PubMed1979

Studies on the handling of retinotoxic doses of iodate in rabbits.

Accumulation of iodate in eye tissues and fluids as a possible explanation of the retinotoxic effect of iodate has been studied by intravenous injection of NaIO3(30 mg/kg), 125IO-3 and 131I- in rabbits. 125IO-3 was determined in fluids and tissue extracts by precipitation with BaCl2 after addition of KIO3. 125IO-3 was rapidly broken down in blood (T 1/2 = 14 min.). 125IO-3 was not present in aqueous humour, vitreous or extracts from retina, choroid + pigmentary epithelium or liver. Concentrations of 125I were comparable in blood, choroid + pigmentary epithelium and liver tissue while in vitreous and aqueous humour low concentrations of 125I were found which, however, increased gradually during 5 hrs after injection to reach levels comparable with blood levels of 125I. Retina had a low concentration of 125I. The ratio 125I/131I (R) in blood decreases during the first 60 min. after injection followed by a slow rise. R in retina, choroid + pigmentary epithelium and liver was the same as in blood at the same time after injection. During the first 80 min. after injection R was higher in vitreous than in blood while it was lower in aqueous humour than in blood. At longer times after injection R was identical in the three fluids. The investigation has been supplemented with whole body scintigraphy of rabbits injected with NaIO3(30 mg/kg) and 131IO-3 or 131I-. The reduction kinetics of IO-3 to I- by some body fluids, tissues, cystein and glutathione was also studied. It is concluded that the retinotoxic effect of iodate is not due to accumulation of IO-3 in eye tissues, but more likely to damage to biochemical mechanisms involved in the reduction of IO-3 to I-.

Adipose Tissue↗
PubMed1979

Early postoperative changes in graft thickness after penetrating keratoplasty. Influence of host corneal disorder on time course.

In 172 patients the thickness of the corneal graft was followed with frequent measurements during the first 14 days after operation. Three different graft thickness time courses were observed. Patients with keratitis, stromal dystrophy and corrosion or mechanical lesion showed a secondary rise in graft thickness on the 6th postoperative day, while patients with keratoconus and those treated with tranexamic acid showed no rise on the 6th day. Patients with Fuchs' dystrophy differed from the other groups in not reaching the maximal thickness until the 3rd postoperative day. The possible correlation of these three time courses with changes in the fibrinolytic system is discussed.

Age Factors↗
PubMed1979

HLA types in corneal diseases.

Evaluation of the results of HLA typing of 187 patients grouped into herpetic keratitis (37), non-herpetic keratitis (43), keratoconus (42), endothelial dystrophy (23), stromal dystrophy (13), lues (5), and injuries (24), failed to show convincing deviations in any of the groups from a normal control series (2900 persons). Yet, as for the herpes group, a rise in B5 must strongly be suspected. The data are presented and possible implications are discussed.

Corneal Diseases↗
PubMed1979

Corneal transplantation and HLA histocompatibility. A preliminary communication.

A series of 222 cases of 7 mm penetrating corneal grafts were analysed with respect to the influence of HLA compatibility. The degree of compatibility was random as no matching was done (HLA types unknown at time of operation). Consequently, most of the cases showed 3 or 4 incompatibilities. The series was divided into seven diagnostic groups (keratoconus, herpetic keratitis, non-herpetic keratitis, stromal dystrophy, endothelial dystrophy, mechanical lesion and corrosion). In all groups there was a tendency towards better results among the compatible transplantation, but only when considering the entire series could statistical significance be demonstrated. The groups of 0--2 incompatibilities showed fewer rejection episodes or opaque grafts than the groups of 3 or 4 incompatibilities (chi 2 = 9.20, P less than 0.005). Comparing only the frequency of opaque grafts among the two groups the correlation was less significant (chi 2 = 3.66, P similar to 0.05).

Corneal Diseases↗