Search PubMed⌕ Search

Biomedical subjects

N Ehlers

Publications and source records attributed to N Ehlers.

At least 73 records · Page 4Linked to original sources
PubMed1991

A clinical comparison of optical and ultrasonic pachometry.

Central corneal thickness (CCT) of normal and oedematous corneae was measured in a study comparing a modified Haag-Streit optical pachometer and an ultrasonic pachometer (Teknar Ophthasonic, preset velocity 1630 m/s). Sixty-eight patients were examined before and after cataract extraction with implantation of an anterior chamber lens. Mean values of CCT before operation were 531 +/- 4.9 (SEM) micron by optical pachometry and 524 +/- 4.7 microns when measured by ultrasound (not significantly different). On the first post-operative day the values were 618 +/- 8.4 and 602 +/- 7.6 microns for optical and ultrasonic measurements, respectively (significantly different, 2P less than 0.001). Correlation analysis showed a high dependence between the methods with coefficients of correlation being 0.955 before and 0.958 after the operation. Linear regression analysis revealed small, but significant differences between the techniques. The difference between the two methods increased with increasing corneal hydration, whereas it could not be ascribed to sex, age, or intraocular pressure. It is concluded that for clinical purposes optical and ultrasonic pachometry techniques are comparable.

Aged↗
PubMed1990

Effect of near normoglycemia for 5 years on progression of early diabetic retinopathy and renal involvement.

The effect of strict metabolic control for 5 years on renal function and retinal morphology was estimated in 24 insulin-dependent diabetic individuals (age 29 +/- 8 years, diabetes duration 10 +/- 6 years) with albustix negative urine and minimal or no background retinopathy before the study. They were randomized to conventional insulin treatment (CIT) or continuous subcutaneous insulin infusion (CSII) with a portable pump. During CSII treatment the metabolic status was significantly improved. HbA1c fell from 8.9 +/- 2.0 to 7.4 +/- 1.3% (p less than 0.01) whereas HbA1c was unchanged during CIT treatment. The mean value of urinary albumin excretion (UAE) was not statistically significantly changed (from 12 +/- 10 mg/24 h to 13 +/- 5 mg/24 h in CSII patients and from 14 +/- 12 to 11 +/- 6 mg/24 h in CIT patients (p greater than 0.1). On the other hand, the elevated GFR values were significantly reduced in both CSII and CIT patients, 129 +/- 17 to 120 +/- 9 and 129 +/- 18 to 119 +/- 12 ml/min.1,73m2, respectively (p less than 0.05). Both the number of microaneurysms, haemorrhages and exudates tended to increase mor in CIT patients than in CSII patients during the 5 year study period, but the differences did not reach statistically significance (p greater than 0.1). Pump treatment did not induce proliferations or "cotton wool" exudates. We conclude that no statistically significantly differences between GFR values, UAE rates, and progression of background retinopathy was observed between normoalbuminuric IDDM patients treated for 5 years with CIT and CSII, respectively. However, due to the size of the material a type II error must be taken into consideration.

Adult↗
PubMed1989

[Control of refraction in cataract surgery].

The optical problems associated with cataract surgery are reviewed and methods to control the refractive state of the eye after the operation are presented. The clinical benefit of a calculation of intraocular lens (IOL) power from measurements of corneal curvature and eye length is demonstrated in a series of operated patients from two Danish eye departments. It is concluded, that the postoperative refraction can be controlled with a reasonable accuracy. Large and unexpected deviations in the postoperative refraction are avoided in this way, and in a number of cases it is possible to reduce the need for spectacles after the operation.

Cataract Extraction↗
PubMed1989

Exogenous, ocular, and systemic factors associated with keratitic ulceration.

Information on type and frequency of empirically observed exogenous, ocular, and systemic predisposing factors for keratitic ulceration is important for clinical identification of groups at risk and may form a basis for planning experimental studies on the pathogenesis of ulceration. Therefore a retrospective study comprising 104 patients with 25 herpetic and 79 non-herpetic corneal ulcerations was performed. Patients with herpetic ulcerations were mainly males and were younger than patients with non-herpetic corneal ulceration. Keratoplasty and steroid treatment was found as frequent co-existing predisposing factors in the herpetic group. In the non-herpetic group an exogenous factor was found in 56%, an ocular factor in 56%, and a systemic predisposing factor in 46% of the patients. In only 2.5% of these patients was there found no predisposing factor. Pathogenetic mechanisms of predisposing factors for non-herpetic corneal ulceration is discussed.

Adolescent↗
PubMed1989

Some metabolic changes during human corneal organ culture.

In order to evaluate the changes in medium composition during closed system corneal organ culture at 30 degrees C, pH, pO2, glucose and lactate was measured 1 to 7, 14 and 28 days after incubation of a total of 49 human corneas. During organ culture pO2 decreased from 17.3 kPa to 8.8 kPa at day 28. The average oxygen consumption was initially 0.16 mumole/h/cm2, but decreased rapidly to an average of 0.04 mumole/h/cm2 during the first weeks of incubation. The glucose concentration fell from 5.1 mM to 0.25 mM after 28 days, and the lactate concentration rose from 2.5 mM to 11 mM. The concentration changes were for both substances highest during the first 14 days of organ culture. The pH fell from 7.36 to 6.64 after 28 days. These findings indicate that the cultured human cornea predominantly metabolizes glucose anaerobically, and that the metabolic activity decreases during incubation. The limiting metabolic factors for prolonging the culture period seem to be development of severe acidosis and glucose depletion in the medium.

Adult↗
PubMed1989

Long-term visual results in eyes cured for retinoblastoma by radiation.

Twenty-four eyes from 18 patients cured for retinoblastoma by radiation on an average 12 years previously, were re-examined with respect to visual performance. The macular functions, i.e. visual acuity, colour vision and contrast sensitivity demonstrated performances predictable from tumour localization and radiation dose to the macula. The rod functions, i.e. visual field and dark adaptation were found to be relatively resistant to the radiation treatment. A special problem encountered in two-eyed patients was the unavoidable amblyopia due to unequal handicaps in the two eyes at the vulnerable age.

Adolescent↗
PubMed1988

Predictive value of flow cytometric DNA-analysis on fresh retinoblastoma tissue.

The cellular DNA content and the distribution of tumour cells in different phases of the cell cycles has been analysed in 8 consecutive enucleated eyes with retinoblastoma. All tumours had abnormal ploidy levels. The analysis did not reveal any specific pattern in 2 tumours which had metastasized compared to 6 local tumours. The flow cytometric analysis alone or in combination with histopathology appeared not to improve the classification of large retinoblastomas.

Child, Preschool↗
PubMed1988

Evaluation of penetrating keratoplasty in keratoconus. Nine years follow-up.

Penetrating keratoplasty was done in 104 cases with keratoconus. The donor material were preserved either as a whole eye in moist chamber at 4 degrees C, or as a corneoscleral segment in MK-medium at 4 degrees C, or in a tissue culture. The post-operative observation time varied between 6 months and 9 years. The visual acuity was found to be better than before surgery in 96%, unchanged in 3%, and worse in 1% of the cases. The average visual acuity was found to be after 6 months 0.25 +/- SD 0.2 and after 7 years 0.65 +/- SD 0.23. The post-operative spherical error of refraction was found to be -3.26 +/- SD 3.5 D, and the post-surgical astigmatism -2.6 +/- SD 1.9 D.

Adolescent↗
PubMed1988

Evaluation of keratoplasty in cases of post-inflammatory corneal opacity with vascularization.

Penetrating keratoplasty was performed in 106 cases of post-inflammatory corneal opacity with vascularization. Donor material obtained post mortem was preserved in a moist chamber, MK-medium at 4 degrees C or in culture medium at room temperature. 55.7% of patients gained a useful vision after keratoplasty. The post-operative spherical error of refraction was found to be -1.4 +/- 3.6 D and the astigmatic error of refraction -3.3 +/- 2.0 D. The post-operative visual acuity was found to be 0.2 +/- 0.2. The ocular pathology associated with keratoplasty is discussed.

Adolescent↗
PubMed1988

The influence of donor age and post mortem time on corneal graft survival and thickness when employing banked donor material (A five-year follow-up).

Sixty-three consecutive corneal transplantations employing banked donor material were grouped according to donor age and post mortem time, respectively, and followed at regular controls for 5 years. Twenty-six cases (38% belonging to a risk group i.e. had earlier had corneal transplantation(s) and/or vascularized corneas) with a mean donor age of 55.8 years were compared with 37 cases (35% at risk) with a mean donor age of 75.7 years. The five-year graft survival was 72.0% in the first group and 86.3% in the second group, however, the difference was statistically insignificant. In 27 cases (26% at risk) with a mean post mortem time of 17.4 h a five-year graft survival of 81.0% was found compared with 80.3% for 36 cases (44% at risk) with a mean post mortem time of 40.5 hours. No difference in graft thickness was demonstrated between any of the groups, and in all cases with surviving grafts normal values for corneal thickness were achieved. It is concluded that neither donor age nor post mortem time are limiting factors when selecting donor material for organ culture and corneal grafting.

Adolescent↗
PubMed1988

Pathology and pathomechanisms of epithelial microcystic and basement membrane abnormalities of the cornea.

Four patients with 'microcystic epithelial abnormality' were studied. Photographs demonstrated biomicroscopically visible alterations taking place over months. The histopathology comprising intraepithelial basement membrane abnormalities and intraepithelial cysts is described at the light and electron microscopical level. The biomicroscopically grey-white microcysts correspond in size to the basement membrane abnormalities. The histopathologically described cysts are much smaller. The pathogenetic mechanisms are discussed and it is suggested that breaks in the normal basement membrane are a more likely initial event than a speculative 'primary cellular dystrophy or degeneration'. Cells grow beneath the basement membrane and lift it up into the epithelium. A subsequent intraepithelial synthesis of basement membrane material may account for part of the ultrastructural appearance. The epithelial cysts were found exclusively beneath the basement membrane. They are thought to reflect the cellular maturation which is altered by the inserted membrane. It is suggested that the cysts pass through stages of maturation, which account for the observed difference in appearance.

Adult↗
PubMed1988

Histopathological changes in an intraocular retinoblastoma-like tumour following photodynamic therapy.

The histopathological effect of photodynamic therapy (PDT) was investigated in an intraocular retinoblastoma-like tumour in vivo. Eighty-two tumours were studied by light microscopy and 8 by electron microscopy. Damage of the vascular endothelium with dilation of the organelles was evident 1 h after treatment, followed by leakage of the blood vessels, tissue hemorrhages, and vascular collapse. Histopathological examination showed an overall pattern of shrinkage of the cytoplasm and pycnosis of the nuclei in most of the tumour cells 3-5 days after treatment. The tumour recurrence often developed from the periphery of the tumours and in a few cases from small islets of viable tissue. Use of high doses of Photofrin II or light energy was associated with damage in the light irradiated area both to the conjunctiva or cornea in the form of leucocyte infiltration or ulcers, and to the retina, which often developed edema and appeared severely disorganized, with damage of the photoreceptors.

Animals↗
PubMed1988

Radial keratotomy for pseudophakic myopia.

Cataract extraction with implantation of a standard power IOL occasionally gives rise to considerable post-operative myopia. When operation of the second eye is indicated, the question may arise whether the patient should be made strongly myopic in both eyes, be made anisometropic, or have the already implanted IOL exchanged for a weaker one. We report here on 3 patients made isometropic and low-grade myopic after radial keratotomy in the myopic pseudophakic eye followed by cataract extraction and implantation of an IOL of predicted power in the second eye.

Aged↗