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Biomedical subjects

F E Kruse

Publications and source records attributed to F E Kruse.

At least 55 records · Page 3Linked to original sources
PubMed1998

[Location of the fovea at the fundus in relation to the optic nerve head].

BACKGROUND: Exact determination of the location of the fovea may be difficult, especially in patients suffering from macular pathology. The purpose of this study was to evaluate whether the distance between the optic nerve head and fovea in healthy eyes may be helpful in such patients. PATIENTS AND METHODS: We measured the distance between the center of the optic nerve head and the fovea in 165 healthy eyes in a horizontal and vertical direction. Results were correlated to the refractive status. RESULTS: There was a relatively high deviation between all eyes for the distance between the optic disc and the fovea (15.5 +/- 1.2 degrees [12.8 to 21.3 degrees]). There was a significant relationship between this distance and the refraction (r = 0.353, P < 0.001). Intraindividual deviation between the right and left eyes showed a markedly lower variance (0.67 +/- 0.49 degree [0.05 to 2.3 degrees]). CONCLUSION: The distance between the optic nerve head and the fovea does not allow for meaningful determination of the location of the fovea in eyes in which morphological changes have occurred. However, knowledge of this distance from the other eye of the same patient is helpful.

Adult↗
PubMed1998

In vivo fluorescence microscopy of corneal neovascularization.

PURPOSE: The purpose of our study establish an animal model to study the microcirculation in corneal neovascularization in the living animal atraumatically. METHODS: Corneal neovascularization was induced in New Zealand white rabbits by a standard micropocket assay utilizing pellets with 250 ng basic fibroblast growth factor. Anesthesia consisted of intramuscular injections of ketamine and xylazine. Intravital microscopy was performed without preparation of the cornea. Rhodamine 6G was used as fluorescent dye to stain leukocytes. Fluorescein-isothiocyanate-dextran served as plasma marker. Microcirculation analysis was done off-line by digital video imaging with special analysis software and included the following parameters: vessel diameters, blood velocity, and differentiation of leukocytes according to their interaction with endothelium into free-floating. rolling and sticking leukocytes. RESULTS: Vessel diameters in venular trunk vessels showed diameters of 54.0 +/- 13.3 microns with 1.1 +/- 0.5 mm/s flow; 29.4 +/- 16.3% of all leukocytes were attached to the vascular wall. The number of sticking leukocytes was found to be 17.8 +/- 36.0 cells/mm endothelial surface. Values are given for arteriolar trunk and branch as well as venular branch vessels. CONCLUSIONS: This method for in vivo microscopic observation and quantification of the vasculature of the ocular surface seems to be suitable for evaluation of microhemodynamic and leukocyte measurements in mature neovascular vessels. It allows atraumatic experiments without corneal preparation procedures which disturb the microcirculation. The results concerning microhemodynamics and adherence of leukocytes are in a range comparable to other microcirculation studies. This new model could provide insight into the pathophysiology of microcirculatory disorders of the anterior eye segment, e.g. during angiogenesis.

Animals↗
PubMed1998

Thalidomide inhibits corneal angiogenesis induced by vascular endothelial growth factor.

BACKGROUND: Ocular diseases caused by neovascularization are among the leading causes of blindness. No specific pharmacological treatment is available. Among potential drugs, thalidomide deserves special interest since a wide body of clinical experience exists. However, its antiangiogenic effect is controversial. We therefore investigated the effect of thalidomide on corneal angiogenesis induced by vascular endothelial growth factor (VEGF), which has a special role among angiogenic growth factors. METHODS: Corneal neovascularization was induced in NZW rabbits by an intrastromal pellet loaded with 500 or 750 ng VEGF. Animals received two daily feedings of 200 mg/kg thalidomide. RESULTS: Significant inhibition of corneal angiogenesis (P < 0.0001) was caused by the teratogenic dose of thalidomide after the 5th day of treatment and persisted for more than 16 days. No obvious side effects were recorded. CONCLUSIONS: Thalidomide has a significant antiangiogenic effect against VEGF-induced neovasclar growth. Together with earlier findings this observation indicates that the drug inhibits two angiogenic pathways which are mediated through integrin adhesion molecules.

Administration, Oral↗
PubMed1998

Macular function testing in a German pedigree with North Carolina macular dystrophy.

BACKGROUND: Our purpose was to investigate central visual function in North Carolina macular dystrophy (MCDR1). A German family with genetically proven MCDR1 was followed for more than 20 years. METHODS: In addition to routine clinical examinations, static and kinetic fundus perimetry was performed with the scanning laser ophthalmoscope. The center of fixation was determined. RESULTS: Visual acuity was 0.6 or better in all but one eye of seven members of this family and did not markedly change during follow-up. Fundus examination confirmed that the fixation was at the nasal edge of the central scar in five affected eyes with reduced stability of fixation. One eye had a prominent gliotic membrane, and fixation was within this area. CONCLUSIONS: Patients had nearly normal visual acuity even though they presented with deep central scotomas and a shift of the center of fixation away from the fovea. Because MCDR1 has good long-term functional prognosis, there might be an early transdifferentiation of the new locus of fixation.

Adolescent↗
PubMed1997

[Inhibition of neovascularization of the eye by dietary factors exemplified by isoflavonoids].

UNLABELLED: Chronic malignant diseases with neovascularization sometimes seem to improve when an exclusively plant-based diet is followed. In order to identify antiangiogenic substances in such diets, inhibitory factors such as genistein were isolated. We investigated the antiangiogenic substance genistein with regard to the possibility of an inhibitory effect on corneal angiogenesis in vivo. METHODS: Corneal neovascularization was experimentally induced in NZW rabbits by the use of methylcellulose discs loaded with 250 ng basic fibroblast growth factor (bFGF). Blood vessels grew from the limbus towards the pellet and were quantified under the microscope. Genistein was injected subconjunctivally (0.04 mg genistein/day). RESULTS: All eyes which received genistein subconjunctivally showed a statistically significant reduction of blood vessels at the limbus (from 63 +/- 40 vessels to 36 +/- 11 vessels; P = 0.001). Vascularized areas in the eyes treated with genistein also decreased, from 21.4 +/- 6.7 mm2 to 10.4 +/- 5.0 mm2 (P < 0.0001). CONCLUSION: Our results show that components of a plant-based diet, such as genistein, inhibit ocular neovascularization in vivo. The genistein level rises significantly in human urine following ingestion of soy products, for example. Therefore, certain vegetarian diets could have a positive effect on ocular diseases characterized by progressive neovascularization.

Animals↗
PubMed1997

[Endogenous porphyrins for photodynamic therapy of cataracts in vitro].

UNLABELLED: Photodynamic therapy is based on accumulation of a photosensitizing substance in tissues and excitement by light of a suitable wavelength. Because of high levels of locally absorbed energy this process may also enable the selective destruction of proliferating lens epithelial cells. Delta-aminolaevulinic acid (ALA) is a natural precursor of hemoglobin. An accumulation of porphyrin derivates occurs following ingestion of ALA, of which one, protoporphyrin IX (P IX), is a potent photosensitizer. METHODS: Bovine lens epithelial cells were removed from the anterior lens capsule and cultivated in Waymouth/Ham's F12 (1:2) with 10% serum. Cells of an epithelial tumor cell line were cultivated. Cultures were incubated with various concentrations of ALA and irradiated with an argon-pulsed dye laser (630 nm). RESULTS: Fluorescence typical for porphyrin was detectable following incubation with 200 micrograms/ml ALA. Irradiation of such cultures with 10 J/cm2 resulted in death of the cells; 75% of the cells were lethally damaged at 3 J/cm2. Addition of P IX to the medium at a concentration of 50 micrograms/ml resulted in cell death at the low energy of 1 J/cm2. No lethal effect was observed following laser treatment without addition of ALA or P IX. DISCUSSION: Our results show for the first time that photodynamic destruction of lens epithelial cells can be achieved by a photosensitizer, which is the product of cellular metabolism.

Aminolevulinic Acid↗
PubMed1997

[Detection of glaucomatous nerve fiber damage. Laser polarimetry in comparison with equivalent visual field loss].

PATIENTS AND METHODS: A total of 45 eyes of 45 patients were equally divided into three age-matched groups (controls, glaucoma, suspected glaucoma). All patients were examined using laser polarimetry and automated visual field testing. We compared the agreement of the location of visual field defects with changes in the nerve fiber layer. In addition we calculated the change in NFLT along a peripapillary circle at four different distances of the optic disc margin. RESULTS: The localization of nerve fiber defects corresponds to the localization of the visual field defect exactly in eight of 15 eyes and roughly in another five. Six of the eyes suspected of having glaucoma showed pathological results with the nerve fiber analyzer (NFA) although visual fields were normal. There was a significant difference for NFLT change towards the periphery between the three groups. CONCLUSION: While the NFA does not always allow a definite correlation between morphological defects and resulting functional impairment, a decrease in the NFLT with increasing distance from the optic disc margin seems helpful for clinical classification. The value of this new method has yet to be proven in longitudinal clinical studies.

Adult↗
PubMed1997

Stem cells, wound healing, growth factors, and angiogenesis in the cornea.

The integrity of the corneal epithelium is, among other factors, dependent on the function of corneal stem cells which serve as proliferative reserve. The concept that corneal stem cells are located in the basal limbal epithelium has been further strengthened by experimental evidence. Furthermore, the usefulness of surgical treatment for bilateral stem cell malfunction by means of limbal allograft transplantation has been confirmed. The field of growth factor interactions has further been expanded by the meaning such factors have for the paracrine cross-signaling between the various corneal cell populations, especially epithelium and stroma. This review focuses on the progress that has been made in the field of corneal cell biology in the context of stem cells, wound healing, and corneal angiogenesis.

Animals↗
PubMed1997

Scanning laser fundus perimetry before laser photocoagulation of well defined choroidal neovascularisation.

AIM: To assess the centre of fixation before laser photocoagulation of well defined juxtafoveal or extrafoveal choroidal neovascularisation (CNV) secondary to age related macular degeneration (AMD), and to better predict visual function after treatment using scanning laser ophthalmoscope (SLO) fundus perimetry. METHODS: 19 consecutive eyes with juxtafoveal or extrafoveal CNV were examined by fundus perimetry before and after laser treatment with documentation of the fixation point using the SLO. The stability of fixation was defined as standard deviation around the mean fixation point. Overlays of fluorescein angiographic pictures and fundus perimetry were obtained using image analysis software. RESULTS: Fundus perimetry allowed accurate determination of the centre of fixation. Overlays demonstrated the precise geographic relation of the angiographically detectable foveal margin of the CNV and the centre of fixation. Thereby, prediction of the visual outcome with regard to reading ability was facilitated. Stability of fixation did not change significantly after treatment. CONCLUSIONS: Fundus perimetry using the SLO was helpful in patients who underwent laser treatment for juxtafoveal or extrafoveal CNV secondary to AMD and may aid the pretreatment counselling of such patients.

Aged↗
PubMed1996

Comparison between serum-free and fibroblast-cocultured single-cell clonal culture systems: evidence showing that epithelial anti-apoptotic activity is present in 3T3 fibroblast-conditioned media.

PURPOSE: To compare the supporting mechanism between the serum-free and the fibroblast-cocultured single-cell clonal culture systems. METHODS: Clonal growth, measured by colony forming efficiency (CFE) and size, was compared between rabbit corneal and limbal epithelial cells in a previously-established serum-free MCDB medium supplemented with growth factors, and in a coculture system with a feeder layer of mitomycin C-treated mouse 3T3 fibroblasts grown in the MCDB or DMEM medium plus 20% fetal bovine serum (FBS). RESULTS: Limbal epithelial cells in the serum-free MCDB medium had a significantly lower CFE than corneal epithelial cells (p < 0.001), suggesting that this system promoted more clonal growth of corneal progenitor cells. In contrast, with cocultured 3T3 fibroblasts limbal CFE was significantly increased (p < 0.001), while corneal CFE was not changed, indicating that the 3T3 system promoted more clonal growth of limbal progenitor cells. Addition of 20% FBS in the MCDB medium cocultured with 3T3 fibroblasts significantly promoted both limbal and corneal CFEs (p < 0.001). For both cultures, switching the serum-containing MCDB medium to the serum-containing DMEM medium produced clonal growth only with cocultured fibroblasts. This epithelial growth-promoting activity was not present on the cell surface or in the extracellular matrix, but present in pre-centrifuged and prefiltered 3T3 fibroblast-conditioned media. Both growth-promoting and anti-apoptotic activities were present in fibroblast-derived serum-free conditioned media. In the presence of this anti-apoptotic activity, serum addition promoted clonal growth, and the expression of cornea-type K3 keratin in limbal colonies was negative using AE-5 monoclonal antibody. CONCLUSIONS: Further purification and characterization of this fibroblast-derived anti-apoptotic survival factor will facilitate understanding of the mechanism by which epithelial stem cells are regulated via epithelial-mesenchymal interactions.

3T3 Cells↗
PubMed1996

Fundus-controlled examination of reading in eyes with macular pathology.

The ability to read is an important parameter for the optical rehabilitation of visually handicapped patients. For the choice of the best therapy, more detailed knowledge of the physiology of reading is required. We evaluated reading velocity as well as the number of saccades in and against the direction of reading for reading plates with different character sizes (10 steps from a letter height of 3-0.25 degrees) using the scanning laser ophthalmoscope in 20 healthy eyes and 30 eyes with central and paracentral scotomas. The number of characters read during each fixation increased with decreasing size of characters from 3.2 to 4.4 in normals. However, the reading velocity decreased from 14 to 11 digits/s when digits became very small. In patients' eyes the greatest reading velocity was reached at 6.1 digits/s for a 1 degree size, and the maximal number of digits read during one rest phase was 3.2 for a 0.75 degree size. In patients we observed a high number of saccades against the reading direction and different loci of fixation. Fundus-controlled examination allows for new insights into the physiology and pathophysiology of reading. Loss of the central visual field leads to an increase in the number of saccades because the number of digits perceived during each fixation decreases. The high number of regressions may be caused by the typical shift of the center of fixation following paracentral scotoma. Saccades directed toward the scotoma have to be corrected due to failure of exact positioning.

Adult↗
PubMed1995

Static fundus perimetry using the scanning laser ophthalmoscope with an automated threshold strategy.

PURPOSE: The purpose of this study was to develop software that allows the performance of routine static threshold perimetry using the scanning laser ophthalmoscope (SLO) and the comparison of the results with conventional computerized cupola perimetry. The original software does not allow performance of static threshold perimetry within a reasonable examination time. METHODS: Static perimetry was performed in random order on 50 healthy eyes using our SLO staircase threshold perimetry technique and the Octopus 500 (program 38). We compared the relative sensitivities for each of 25 corresponding visual field locations. RESULTS: Mean sensitivity in the SLO perimetry amounted to 32.7 dB (range 25-37 dB) while it was 28.7 dB in the Octopus. For all test locations the SLO showed higher dB values on average. The mean difference between both methods was 3.7 +/- 0.8 dB (range 1.4-5.8 dB) when the test locations at the blind spot were excluded (linear regression between the two methods: r = 0.843, P < 0.0001). The mean time interval between two stimulus presentations was 2.5 s with the SLO perimetry. CONCLUSION: With the Heidelberg software, automated static threshold perimetry using the SLO is possible within reasonably short examination times. The mean time interval between two test point presentations is about one tenth of that necessary using the original Rodenstock software. There is a systematic difference between SLO and Octopus fields of about 4 dB which was not very much influenced by the stimulus locations.

Adult↗
PubMed1995

Stability of fixation: results of fundus-controlled examination using the scanning laser ophthalmoscope.

We evaluated the stability of fixation in 38 healthy eyes (N), 30 eyes with macular degeneration (AMD) and 20 eyes with juvenile macular dystrophy (JMD) during our newly developed automated full-threshold static perimetry using the scanning laser ophthalmoscope (SLO). The point of fixation was recorded for each stimulus presentation. After the examination, the mean fixation point (MFP) as well as the standard deviation from the MFP, the examination time, and the reaction time were evaluated. Healthy eyes did not show a mean SD of more than 0.7 degree from the center of gravity of fixation with one exception. There was only poor correlation between age and deviation from the MFP (r = 0.09 for N; r = 0.18 for AMD; and r = 0.18 for JMD), whereas the correlation between visual acuity (VA) and deviation from the MFP was slightly better (r = 0.22 for N; r = 0.34 for AMD; and r = 0.52; P < 0.02 for JMD). Eyes with functional impairment mostly showed instable fixation (deviation, > 3 degrees), which was observed even in two patients with only slightly diminished VA of 20/25. However, stable fixation was observed in isolated cases even when VA was reduced to 20/100. The deviation of fixation was more pronounced horizontally than vertically in normals (0.40 degree:0.31 degree) and in patients suffering from AMD (0.88 degree:0.68 degree), whereas eyes with macular dystrophy did not show this phenomenon (0.82 degree:0.82 degree). The results demonstrate that there is the possibility of stable fixation even in eyes with a decrease in VA due to morphological changes in the macula.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

[Possibilities for imaging the retinal nerve fiber layer with the scanning laser ophthalmoscope].

BACKGROUND: Documentation of the retinal nerve fiber layer using red free light is not established as a routine method. The reasons for this are the difficulties involved in taking the pictures and developing them, especially in glaucoma patients, and the need for maximum pupil dilation. The scanning laser ophthalmoscope (SLO) allows fast and easy documentation of the fundus with the possibility of simultaneous image control during the examination. PATIENTS AND METHODS: Nerve fiber layer images of 48 eyes of 25 patients taken with the argon blue light of the SLO were compared to conventional photographs of the nerve fiber layer with red-free light. In addition, we compared documentation of the nerve fiber layer using argon-blue or argon-green light in the SLO. RESULTS: The nerve fiber layer images obtained with the SLO were of good quality for all 48 eyes included in the study, whereas with conventional photography we could not obtain images in 9 eyes. There was a high correlation between the two methods in the detection of localized damage or zones with diffuse nerve fiber atrophy for the 39 eyes documented with both methods, and there was better image quality in some using the SLO. The use of blue light permits the nerve fiber layer to be seen more easily than with green light. CONCLUSIONS: The SLO allows nerve fiber bundle defects or diffuse atrophy to be detected similar to conventional fundus photographs using red free light sources. There is no further need to dilate the pupil maximally due to the confocal principle and the scanning technique. The smaller angle of view of the SLO requires fixation movements of the patient being examined for the detection of beginning peripheral nerve fiber bundle defects.

Adult↗