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Biomedical subjects

S Kohnen

Publications and source records attributed to S Kohnen.

9 recordsLinked to original sources
PubMed2000

Light-induced damage of the retina through slit-lamp photography.

BACKGROUND: I report on two patients who suffered severe loss of visual acuity after slit-lamp photography of the anterior eye segment. METHODS: Both patients were pseudophakic and pictures were taken to document the degree of posterior capsule opacification via retroillumination with dilated pupils. Both patients had excellent visual acuity at the time of photography was taken and experienced reduction of to hand movement afterwards. A Zeiss 75 SL device was used for the slit-lamp photography. In cooperation with Carl Zeiss Jena the slit lamp was investigated. RESULTS: Ophthalmoscopy and angiography after photography discovered a central macular defect, similar to a photocoagulation. The visual acuity did not recover. CONCLUSION: Under certain circumstances slit-lamp photography of the anterior eye segment can lead to severe light-induced damage of the retina.

Aged↗
PubMed2000

Postoperative refractive error resulting from incorrectly labeled intraocular lens power.

Postoperative refractive errors after intraocular lens (IOL) implantation can be caused by different reasons. The most likely is incorrect IOL calculation resulting from incorrect measurements of the eye. However, other explanations must also be taken into account. The surgeon in the operating theater should make sure that the correct IOL was chosen. The IOL package should also contain the correct IOL cartridge. When unsealed IOL packages are used, an IOL cartridge from 1 package can be mistakenly placed in another package. Finally, incorrect IOL labeling by the manufacturer can occur. In this case, the optical power of an explanted IOL was not identical to the IOL power printed on the company's label. Even with the highest quality control throughout the IOL manufacturing process, the surgeon should keep in mind the possibility of a mislabeled IOL.

Device Removal↗
PubMed2000

Cataract extraction with multifocal intraocular lens implantation: clinical, functional, and quality-of-life outcomes. Multicenter clinical trial in Germany and Austria.

PURPOSE: To compare bilateral implantation of a multifocal intraocular lens (IOL) versus a monofocal lens with respect to visual function, patient satisfaction, and quality of life. SETTING: Seven clinical sites in Germany and 1 site in Austria. METHODS: A prospective randomized masked clinical trial included 124 randomly assigned bilateral pseudophakic individuals, 64 of whom had bilateral implantation of an Array(R) foldable multifocal IOL (model SA-40N, Allergan) and 60 of whom had bilateral implantation of an AMO(R)PhacoFlex II(R) silicone monofocal IOL (model SI-40NB). Clinical data included binocular uncorrected and corrected distance and near visual acuities, complications, adverse events, and reports of halos and glare. Quality-of-life data were collected on 3 occasions using the modified Cataract TyPE Specification instrument. The functional status of the 2 groups was compared from baseline to final postoperative interview. RESULTS: Three months after surgery, a higher proportion in the Array group achieved a Jaeger value of J3 (20/40 Snellen) or better uncorrected binocular near visual acuity and 0.5 (20/40) or better distance-corrected binocular near visual acuity than in the monofocal groups (97% versus 68% and 95% versus 59%, respectively; P <.001). A higher proportion in the multifocal group achieved both 0.5 (20/40) and J3 or better uncorrected binocular distance and near visual acuities (97% versus 66%; P <.001). Those in the Array group were more likely than those in the monofocal group to never wear glasses overall (41% versus 12%; P <.001). Multifocal patients rated their vision without glasses better overall, at near and at intermediate distances (P <.05), and demonstrated better visual function for near tasks and social activities. CONCLUSIONS: Those who had bilateral implantation of the Array multifocal IOL obtained better uncorrected and distance-corrected near visual acuities and reported better overall vision, less limitation in visual function, and less spectacle dependency than patients with bilateral monofocal IOLs.

Aged↗
PubMed2000

Effects of propofol on endothelial cells subjected to a peroxynitrite donor (SIN-1).

We investigated the effect of propofol on endothelial cells subjected to the peroxynitrite (ONOO-) donor 3-morpholino sydnonimine (SIN-1). Cells were incubated overnight with 0.5, 1.0 or 2.0 mM SIN-1, with or without 10-3 M propofol (Diprivan). Cytotoxicity, assessed by measuring the release of pre-incorporated 51Cr, increased when the concentration of SIN-1 increased, and was significantly decreased by 10-3 M propofol (90%, 78% and 28% of protection against 0.5, 1.0 and 2.0 mM SIN-1, respectively). Cell protection against 1 mM SIN-1 was tested with 0.03-1.0 mM propofol and this was compared to tyrosine, a target molecule for peroxynitrite. Propofol protected cells in a dose-dependent manner (r = 0.98; p < 0.001) and was as effective as tyrosine. Finally, using high-performance liquid chromatography, we demonstrated that propofol reacted with ONOO- more rapidly than did tyrosine, inhibiting nitrotyrosine formation. In the absence of propofol, 3.5 mM ONOO- with 1 mM tyrosine yielded 39.6% nitrotyrosine, but nitrotyrosine was not produced when 5 mM propofol was added. We conclude that propofol protects endothelial cells against the toxicity of ONOO-. The anti-oxidant properties of propofol can be partially attributed to its scavenging effect on peroxynitrite, a property that might be relevant in pathological situations involving a significant contribution of peroxynitrite to tissue damage.

Anesthetics, Intravenous↗
PubMed1999

Peroxynitrite reacts with biological nitrogen-containing cyclic molecules by a radical pathway, as demonstrated by ultraweak luminescence coupled with ESR technique.

Ultraweak luminescence (uwCL) was coupled with electron spin resonance to study the reactions of 3 heterocyclic compounds (tryptophan, serotonin and imidazole) with peroxynitrite at pH 8.7. Tryptophan and serotonin reacted with emission of a flash peak of light (5 s) followed by a long-living light emission of +/- 80 s. Addition of the spin trap 4-POBN at different intervals, after the beginning of reaction revealed that a short-living free radical was produced in the case of serotonin and imidazole, but that with tryptophan, the initial radical rearranged into a relatively long-living radical, which was still formed when 4-POBN was added after 55 s (decreasing phase of uwCL).

Electron Spin Resonance Spectroscopy↗
PubMed1996

First results of cataract surgery and implantation of negative power intraocular lenses in highly myopic eyes.

OBJECTIVES: To determine whether cataract surgery in highly myopic eyes should be considered high-risk surgery and whether exact intraocular lenses (IOLs) should be implanted if negative power is required. SITE: Klinik Dardenne, Bonn-Bad Godesberg, Germany. METHOD: We retrospectively studied 32 eyes of 27 highly myopic patients who had cataract surgery and posterior chamber IOL implantation. Intraocular lens power varied from -1.0 to -8.0 diopters (D), and eye length varied from 31.0 mm to more than 35.0 mm. Follow-up ranged from 6 to 36 months. Patients were analyzed for postoperative visual acuity and for intraoperative and postoperative complications. RESULTS: No patients experienced intraoperative complications. Posterior capsule opacification, which occurred in 14 eyes, was the only postoperative complication in the anterior or posterior segments. Ninety-four percent of eyes achieved improved best corrected visual acuity, and 69% of eyes were within 1.0 D of the refractive target. CONCLUSIONS: Cataract surgery can be performed in highly myopic eyes without intraoperative complications. A posterior chamber IOL should be implanted for postoperative refraction and intraocular stability, even if negative lens power is required.

Adult↗
PubMed1996

Visual function in pseudophakic eyes with poly(methyl methacrylate), silicone, and acrylic intraocular lenses.

PURPOSE: To evaluate the quality of visual function after cataract surgery and intraocular lens (IOL) implantation with three lens materials. SETTING: Klinik Dardenne, Bonn Bad Godesberg, Germany. METHODS: In a prospective, randomized study, 55 patients having uncomplicated phacoemulsification received IOLs made of three materials: 16 received acrylic IOLs, 20 received silicone IOLs, and 19 received poly(methyl methacrylate) (PMMA) IOLs. Pseudophakic patients with accompanying eye diseases were excluded. Visual acuity, glare sensitivity, contrast sensitivity, and mesopic acuity were evaluated 6 weeks postoperatively. RESULTS: Postoperatively, best corrected visual acuity was excellent in all three lens groups. Acuity under bright light conditions and contrast sensitivity were low in all groups; mesopic acuity was extremely low in 73% of patients. Glare and contrast sensitivity were significantly better with PMMA and acrylic IOLs. CONCLUSION: The visual quality achieved in pseudophakic eyes with three different lens materials was lower than expected. The results of individual visual function tests were better for PMMA and acrylic IOLs than for silicone IOLs.

Acrylates↗
PubMed1993

[Refsum syndrome in a pair of monozygotic twins].

We report the case of a pair of twins with the ophthalmological and functional findings of Refsum syndrome. The twins were monozygotic twin brothers whose ophthalmological symptoms were noticed when they were in their forties. The diagnosis in the first brother led to a search for findings in the second. It was possible to attribute the non-specific subjective complaints to this as yet unknown syndrome. No causal therapy can be offered the patients. However, knowledge of the biochemical basis of the disease makes it possible to treat it by means of diet. In patients with retinopathia pigmentosa, an attempt should be made to identify Refsum syndrome if neurological symptoms are found in addition.

Adult↗