Biomedical subjects

R Krott

Publications and source records attributed to R Krott.

21 records · Page 2Linked to original sources

PubMed1997

Plasminogen in proliferative vitreoretinal disorders.

OBJECTIVE: Intravitreal fibrin formation is a frequent observation after vitrectomy performed for a variety of vitreoretinal disorders including proliferative vitreoretinopathy (PVR), proliferative diabetic retinopathy (PDR), and endophthalmitis. Plasminogen activators (PA) have been used for the management of this postoperative complication. This approach requires the presence of plasminogen, the substrate for PA mediated fibrinolysis, in the vitreal cavity. METHODS: Quantification of plasminogen in the vitreous of 60 patients with PVR, PDR, and macular pucker was performed by streptokinase mediated activation using a chromogenic substrate. The presence of immunoreactive plasminogen was confirmed by immunoblot analysis of vitreal proteins and immunocytochemistry of surgically removed epiretinal membranes. RESULTS: Plasminogen levels were dramatically increased in the vitreous of PVR and PDR patients compared with macular pucker patients and normal controls. Staining for plasminogen in epiretinal membranes was confined to the extracellular matrix. Predominant staining of perivascular areas in PDR specimens indicated that breakdown of the blood-retinal barrier is an important source of intravitreal plasminogen in that condition. CONCLUSION: Plasminogen may play a role in traction membrane formation in PVR and PDR. Our biochemical analysis of presurgical vitreous indicates that there may be abundant substrate for PA mediated fibrinolysis in the vitreous cavity after vitrectomy.

Eye Diseases↗

PubMed1996

[Effects of fluorescein and indocyanine green angiography on subsequent dark adaptation and the electroretinogram].

BACKGROUND: In clinical practice the electroretinogram (ERG) usually should not be recorded immediately after conventional fluorescein angiography (FLA), because of the bleaching effects of strong light exposure on the course of dark adaptation and on the ERG. Currently it is not known, if indocyaningreen (ICG) angiography using the Heidelberg Retina Angiograph (HRA) has similar effects on the outer retina and if therefore the ERG should also not be recorded after ICG angiography. METHODS: Eight patients with different retinal diseases were examined. After 5 minutes of light adaptation to 160 cd/m2, Ganzfeld ERGs were repeatedly recorded using DTL electrodes during a 30 minutes dark period with a flash luminance of 0.1 cds/.m2. After this dark adaptation period a standardized ERG was recorded according to the ISCEV recommendations. This procedure was followed either by ICG angiography using the HRA or by conventional fluorescein angiography using the Canon CF 60 fundus camera. Within an interval of 5 minutes the above mentioned ERG procedure was repeated. RESULTS: ICG angiography using the HRA did neither affect the course of dark adaptation as measured by increasing b-wave amplitudes during the 30 minutes dark adaptation period, nor the values for each response of the Ganzfeld standard ERG. FLA did neither affect b-wave responses to dim stimuli, nor to stronger stimuli in the scotopic range. However, the course of dark adaptation was significantly prolonged after FLA. The maximum b-wave was not affected. CONCLUSIONS: ICG angiography using the HRA could be performed prior to the recording of the ERG, without any effect on the ERG. In contrast conventional FLA must be performed after ERG recordings, in order not to alter the electrophysiological responses.

Adult↗

PubMed1995

Indocyanine green videoangiography of angioid streaks.

PURPOSE: The fluorescein angiographic features of angioid streaks are variable, and angioid streaks and their main complication, choroidal neovascularization, can sometimes be difficult to visualize in the presence of diffuse pigment migration, diffuse atrophy of the retinal pigment epithelium, or hemorrhage. The objective of the present investigation was to define the indocyanine green angiographic features of angioid streaks and to compare them with findings on fluorescein angiography. METHODS: For this prospective study, we recruited 22 consecutive patients, 21 of whom had angioid streaks and one who had typical peau d'orange appearance of the fundus. Complete ophthalmologic examination, fluorescein angiography, and indocyanine green videoangiography by the means of scanning laser ophthalmoscope were performed on all patients. RESULTS: In 21 patients with angioid streaks and in one patient with peau d'orange appearance of the fundus, indocyanine green videoangiography showed angioid streaks in the form of hyperfluorescent lines with numerous associated hyperfluorescent foci. The angioid streaks were more clearly visualized and were seen to be more numerous and larger by indocyanine green videoangiography than with red-free images or fluorescein angiography. Choroidal neovascularization was suspected in six eyes but could be precisely localized by fluorescein angiography in only three eyes. Indocyanine green angiography allowed precise localization of choroidal neovascularization in all six of these eyes. CONCLUSIONS: These findings indicate that indocyanine green videoangiography provides different information than fluorescein angiography in the evaluation of angioid streaks and can more precisely localize their neovascular complications.

Adolescent↗