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Biomedical subjects

T Olsen

Publications and source records attributed to T Olsen.

At least 109 records · Page 6Linked to original sources
PubMed1980

Endothelial morphology related to disease activity in human corneas.

Twenty normal and four groups of pathological corneas with the diagnoses aphakia, macula after herpetic keratitis. Fuchs' endothelial dystrophy and graft rejection were stained with trypane blue and alizarin red. The morphology of the endothelium was described in terms of cell density, coefficient of variation for cell area, percentage of hexagonal cells, percentage of joint meetings of more than three cells, nuclei per cell and nuclear shape. The groups of aphakia, keratitis, Fuchs' dystrophy and graft rejection were considered to represent increasing degrees of endothelial disease activity at the time of evaluation. The only parameter showing consistent variation with disease activity was the percentage of joint meetings of more than three cells.

Adolescent↗
PubMed1980

On the significance of a low endothelial cell density in Fuchs' endothelial dystrophy. A specular microscopic study.

In order to verify a low endothelial cell density is a primary event in Fuch's endothelial dystrophy, a specular microscopic examination was attempted in 20 patients with Fuchs' dystrophy. Most of these patients had previously undergone cataract extraction. In five patients only, was it possible in places to observe endothelial cellular outline to such an extent that the cell density could be estimated. The resulting estimates ranged from 715 to 2380 cells/mm2 and were not, as a group, found to be lower than in a control group of aphakic subjects. This finding is evidence against the view that Fuchs' endothelial dystrophy is a low cell density syndrome.

Adult↗
PubMed1980

Changes in the corneal endothelium after acute anterior uveitis as seen with the specular microscope.

In order to investigate whether inflammation of the anterior uveal tract is accompanied by a loss of endothelial cells, 13 patients with previous unilateral attacks of anterior uveitis were photographed with the non-contact specular microscope. All patients had shown an increased thickness or frank oedema of the cornea during the acute phase of the inflammation. As compared to the healthy eye, only two patients (15%) showed endothelial cell densities on the affected side which were lower than was to be expected from the normal difference between counts from left and right eye in a control population of 36 subjects. The two patients with detectable cell loss also showed defects in the specular reflex, the significance of which is discussed.

Acute Disease↗
PubMed1980

The endothelial cell damage in acute glaucoma. On the corneal thickness response to intraocular pressure.

In order to assess a possible damage to the corneal endothelium during pressure induced abnormal hydration of the cornea, 23 patients with a previous attack of unilateral acute glaucoma were photographed with a specular microscope. As compared to the healthy side, the endothelium of the affected side showed a mean decrease in cell density of 23.1%, range --4.8 to 68% (P less than 0.001). In retrospect this cell loss was found to correlate significantly to the increase in corneal thickness measured during the acute attack on first day of admission. At present examination mean central corneal thickness was identical in the affected and unaffected eye. A large variation was, however, found in the intraocular pressure of the previously attacked eye. If the subject inter-eye difference in intraocular pressure was related to the inter-eye difference in corneal thickness is significant negative correlation appeared. It is concluded that the intraocular pressure has a dual effect on the corneal hydration: if the endothelium is intact, the intraocular pressure decreases corneal thickness, whereas an increase is seen only if the endothelium is acutely damaged.

Acute Disease↗
PubMed1980

Corneal thickness and endothelial damage after intracapsular cataract extraction.

In a prospective study corneal thickness and specular microscopic findings of corneal endothelium are reported in 37 patients undergoing intracapsular cataract extraction. Central endothelial cell loss was estimated six months after the operation and was found to correlate significantly to the immediate post-operative increase in central corneal thickness. A subgroup of patients showing slight endothelial dystrophy prior to the operation showed a significantly higher increase in corneal thickness fourth day after the operation. Six months after the operation a significant residual increase in corneal thickness was found for this group, while the rest of the patients had returned to near pre-operative levels. No correlation was found between cell loss and residual corneal thickness increase at this time. Six months after the operation a vertical difference in cell density was found. This difference could be correlated to the age of the patient, presumably indicating a less complete redistribution of the cell population in older patients.

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

Corneal thickness and endothelial damage after intraocular lens implantation.

The corneal thickness and the specular appearance of the corneal endothelium are reported in 100 patients with unilateral intraocular lens implantation. Post-operative time ranged from one to 42 months. An average central endothelial cell loss of uncomplicated cases of 46%, range 1 to 83%, with no correlation with time after the operation was found. A significantly higher cell loss was found in cases with technical complications, shallow anterior chamber or increased intraocular pressure post-operatively. No correlation was found between the corneal thickness and the endothelial cell loss. In two patients, however, with a cell density below 500 cells/mm2, a slight increase in corneal thickness was noted. Thirty patients presented a guttate endothelium. Irrespective of the occurrence of surgical complications the presence of a guttate endothelium was found to be a major determinant of the corneal thickness increase and could be ascribed as a cause of persistent corneal swelling in six of twelve patients with elevated corneal thickness. The progression of guttate changes occurred independently of the cell loss.

Aged↗
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↗
PubMed1979

Non-contact specular microscopy of human corneal endothelium.

The non-contact specular microscope enables a large area of the corneal endothelium to be examined and photographed without any risk of traumatizing the anterior surface of cornea. This non-contact technique is described in detail. Standard deviation of the relative difference between two independent estimates of central endothelial density from 24 eyes was 3.7%. Standard deviation of the relative difference between counts from left and right eyes from 57 subjects was 4.7%. A significant negative correlation between age and endothelial cell density was found (r = -0.59, P less than 0.001, n = 76). The interindividual variation in cell densities was found to be larger in the old age group, indicating that cell loss during aging varies among different individuals.

Adult↗
PubMed1979

Variations in endothelial morphology of normal corneas and after cataract extraction. A specular microscopic study.

The central corneal endothelium of 22 normal subjects and 11 unilateral aphakic subjects was photographed with the non-contact specular microscope. The aphakic patients had undergone intracapsular cataract extraction one to four years previously. Endothelial cell densities were estimated. All cells which had been counted were then grouped according to their number of neighbours. The percentages of cells having 4, 5, 6, 7, or 8 neighbours were means +/- SD): 0.4 +/- 0.8; 18.0 +/- 3.4; 64.1 +/- 6.5; 15.9 +/- 2.6 and 0.9 +/- 0.8 per cent, respectively in the normal eyes, and 0.8 +/- 1.3; 20.9 +/- 3.7; 57.4 +/- 5.6; 19.6 +/- 3.9 and 1.4 +/- 1.2 per cent in the aphakic group, respectively. The frequency of cells having 5, 6, or 7 neighbours were significantly different in the two groups. Cells with 9 or 10 neighbours were not seen in the normal group but occurred in 2 and 1 of the aphakic eyes, respectively. In the normal group the frequency of hexagonal cells was found to correlate to the cell density (r = 0.46, 2P less than 0.01) and age (r = -0.40,2P less than 0.05).

Adolescent↗
PubMed1979

Optical principles for estimation of endothelial cell density with the non-contact specular microscope.

In non-contact specular microscopy of corneal endothelium, endothelial cell density is overestimated due to the angle of observation and the curvature of cornea. On the basis of theoretical considerations, it is concluded that if the angle of observation is kept at a small value the curvature of cornea contributes only insignificantly to this overestimation, the major determinant being the angle of observation. When an angle of 46 degrees is chosen between slit illumination and optical axis of the microscope it is calculated that estimates of endothelial cells should be multiplied with a factor of 0.959 to correct for the angle effect. Six eye were photographed with both a contact and non-contact specular microscope and endothelial cell density estimated. Mean observed difference in cell counts was +5.5% without correction and +1.2% with correction for angle effect. 95% confidence limits for the difference with correction were -3.7 and +6.0% respectively showing that estimates of endothelial cell density obtained with the non-contact specular microscope agree closely with those obtained by contact specular microscopy when corrected for angle of observation.

Cell Count↗
PubMed1979

The specular microscopic appearance of corneal graft endothelium during an acute rejection episode. A case report.

The specular microscopic appearance of a graft endothelium during a successfully treated acute endothelial rejection episode is reported. Coinciding with the increased thickness of the graft great disturbance in cellular morphology was observed. Individual cells were seen to appear swollen or to show bright intracellular areas. Also abnormalities with respect to cellular intersections were seen with the occurrence of junctional complexes at which more than three cells met. The significance of these abnormalities is discussed. The morphological changes subsided gradually as the graft cleared and the thickness decreased. This study examplifies the value of the non-contact specular microscopic technique which enables a thorough study of the diseased corneal endothelium without traumatizing the cornea and interfering with subsequent specular microscopic examinations.

Cell Count↗
PubMed1979

Free T4, free T3 and free reverse T3 in dialysates of serum. The influence of electrolytes and pH with special reference to the physiological range.

The influence of electrolyte composition and pH of buffer on free T4, free rT3, and free T3 concentrations in serum dialysates has been evaluated, using an equilibrium dialysis method with subsequent direct radioimmunoassay estimations of the dialysate. Cl-, HCO3- and H+ were found to be the important ions which at concentrations similar to those occurring in vivo decreased the protein binding of all three hormones in serum, T3 being much less sensitive to these changes than T4 and rT3. The possible influence of pathological concentrations of electrolytes in serum on estimated free thyroid hormone concentrations is discussed. Because the effect of in vivo changes in serum Cl-, HCO3- and H+ on free thyroid hormone concentrations to a certain extent tend to counteract each other, it is concluded that electrolyte and pH disturbances only to a minor extent can affect measurements on free T4, free rT3 and free T3 concentrations in serum obtained by an equilibrium dialysis method.

Blood↗
PubMed1978

Low serum triiodothyronine and high serum reverse triiodothyronine in old age: an effect of disease not age.

Serum concentrations of T4, T3, T3, free T4, free T3, and TSH were determined in four groups of adult subjects: group A, 27 healthy young volunteers (aged 18-29 yr); group B, 24 carefully selected healthy elderly subjects (aged 70-90 yr); group C, 41 subjects living at a municipal nursing home for the elderly (aged 70-90 yr); and group D, 35 hospitalized patients (aged 70-90 yr). Identical levels of iodothyronines in serum were found in the young and in the elderly healthy subjects. Moderate and severe disease induced alterations in iodothyronine concentrations in serum comparable to those reported earlier. Serum T3 and free T3 levels were low and serum rT3 levels were high in groups C and D subjects; serum free T4 was elevated in group D, while serum T4 was low. Serum TSH was lower in the healthy elderly subjects than in the young subjects. Serum TSH was higher in the elderly sick subjects (groups C and D) than in the healthy subjects (group B). We conclude that advanced age per se is not accompanied by alterations in free or total serum iodothyronine levels.

Adolescent↗