Search PubMed⌕ Search

Biomedical subjects

R Guthoff

Publications and source records attributed to R Guthoff.

At least 37 records · Page 2Linked to original sources

[Dacryocystostomy and microsurgical lacrimal sac reconstruction in dacryolithiasis].

BACKGROUND: The incidence of dacryoliths ranges between 8 and 14% of patients undergoing a dacryocystorhinostomy. Lacrimal duct stenoses with dacryoliths can be managed either by surgery or minimally invasive techniques. We present two patients who underwent removal of dacryoliths by dacryocystotomy and microsurgical reconstruction without osteotomy. PATIENTS AND METHODS: Case report 1: A 47-year-old male patient presented with chronic epiphora. The dacryocystogram revealed a filling defect in the dilated lacrimal sac. Case report 2: A 22-year-old female patient suffered from a hemorrhagic right-sided dacryocystitis. Two years previously the patient had undergone lacrimal endoscopy with silicone intubation for 3 months. Preoperative dacryocystography showed an obliteration of the superior portion of the lacrimal sac. In both patients, we performed the extraction of the dacryolith by dacryocystotomy followed by silicone tube intubation of the lacrimal system for 3 months. Both patients with a follow-up of 24 and 29 months, respectively, showed good clinical results and patent nasolacrimal pathways on digital dacryocystography. RESULTS: Methods to extract dacryoliths include minimally invasive techniques such as nonsurgical radiologic or endoscopic removal during dacryoplasty or surgical approaches such as external or endonasal dacryocystorhinostomy. CONCLUSION: Dacryocystotomy with primary microsurgical lacrimal sac reconstruction combined with silicone intubation is an alternative surgical procedure to remove dacryoliths. An osteotomy is not always required.

Adult↗

[Modified Heidelberg Retinal Tomograph HRT. Initial results of in vivo presentation of corneal structures].

BACKGROUND: At present, confocal tandem scanning microscopes with halogen or mercury lamps are used to depict all corneal structures in vivo, e.g., before and after PRK or LASIK. Insufficient imaging quality and irregular corneal illumination are the main problems for automatic quantitative evaluation of the keratocyte density when applying this instrument. A high correction is required for correcting the background irregularities of pictures. Our aim was to find out whether it is possible to change the Heidelberg retina tomograph (HRT) into a high-resolution digital laser scanning microscope for the visualization of anterior segments of the eye, coupled with a special evaluation software. MATERIAL AND METHOD: We developed a lens adapter for the HRT that focusses the laser beam onto the cornea by combining with an external, computer-controlled hydraulic z-scan sledge. By using a programmable adaptation for the external stepmotor on the z-scan sledge in combination with all internal control functions and patient data, it is possible to create a digital confocal laser scanning microscope with retention of all the original HRT functions. For evaluation of the corneal images and automatic count of keratocytes, we used special 3D and Chemotaxis software. RESULTS: First investigations show a regular illumination of all corneal structures as the epithelium, endothelium, and keratocytes. The hydraulic z-scan allowed a precise shift of the focus through the cornea to take series of images for the evaluation of the keratocyte profile and 3D reconstruction of all corneal structures.

Cell Count↗

[3 years experience with low dosage fractionated percutaneous teletherapy in subfoveal neovascularization. Clinical results].

AIM: The effect of low dose fractionated percutaneous teletherapy to visual acuity and the changes in subfoveolar neovascular membranes in age-related macular degeneration were investigated. PATIENTS AND METHOD: 126 eyes of 118 patients (age 55-89 years; mean 74 ys.) were treated. Best distal and near visual acuity was assessed prior to (= initial visual acuity [IVA]) and 3, 6, 12, 18, 24, 30 and 36 months after teletherapy. Fluorescein angiography was performed prior to and 6, 12, 24 and 36 months after radiation therapy. For analysis patients were divided into different groups by IVA and membrane size. Maximal duration of observation was 36 months. Teletherapy was done by a 9-MeV photon linear accelerator through a lateral port in half-beam technique with a single dose of 2 Gy up to a total dose of 20 Gy within 12 days. RESULTS: No severe negative side effects have been observed. Eight patients reported of epiphora and four patients complained of transient sicca syndrome. Visual acuity decreased more than one line in the group IVA 0.05-0.2. The group IVA 0.3-0.5 remained unchanged for 1 year. We found a tendency for increased visual acuity in group IVA > or = 0.6 for 18 months. After that time both groups showed decreased visual acuity, but all these patients reported of reduced metamorphopsia and increased color and contrast perception. CONCLUSIONS: There is an influence of low dose fractionated percutaneous teletherapy on visual acuity, subfoveal neovascular membranes and metamorphopsia. IVA and duration of anamnesis play an important role. There seems to be no persistent effect; possibly increased dosage will bring a benefit.

Aged↗

[Measuring corneal volume. A possible quality parameter in cataract surgery?].

BACKGROUND: Phacoemulsification of the lens induces changes in the inner corneal architecture. This study quantified the corneal pre- and postoperative volumes. METHODS: Corneal volume was measured by noninvasive corneal topography using Orbscan. Following phacoemulsification with lens implantation, 56 eyes of 55 persons were examined by three Orbscan tests: preoperatively and 6 h and 24 h after cataract surgery. Healon was used as viscoelastic medium. RESULTS: The mean corneal volume in the 3-mm central corneal diameter was 4.64 mm3 preoperatively, 5.36 mm3 6 h postoperatively, and 5.05 mm3 24 h postoperatively. Corneal volume thus increased by 0.72 mm3 within 6 h after phacoemulsification and decreased by 0.31 mm3 over the following 18 h. CONCLUSION: Orbscan offers a noninvasive method for obtaining useful and accurate information in defining the corneal volume. This method may represent a new parameter for describing the function of corneal endothelial cells in cataract surgery.

Adult↗

Inhibition of lens epithelial cell adhesion by the calcium antagonist Mibefradil correlates with impaired integrin distribution and organization of the cytoskeleton.

BACKGROUND: Posterior capsule opacification is the most common complication of primary cataract surgery and is caused by migration and proliferation of residual lens epithelial cells onto the posterior capsule. Interfering with the mechanisms involved in cell adhesion is a suitable approach to prevent posterior capsule opacification. METHODS: Mibefradil, a T-type calcium-channel blocker, was used to examine the influence on adhesion-mediating mechanisms in human lens epithelial cells derived from cataract surgery. Adhesion was evaluated by light microscopy on the anterior capsules. Expression of integrin receptors was studied by flow cytometry. The influence on the distribution of integrin receptors on the cell surface and the organization of the cytoskeleton was examined by immunofluorescence using a confocal microscope. RESULTS: The calcium-channel blocker Mibefradil inhibited cell adhesion on the anterior capsule wall at concentrations between 10 and 100 pNM. The cells expressed the integrin subunits beta1 and alpha3. Mibefradil distinctly impaired the distribution of these integrins on the cell surface in culture. The cells express the cytoskeletal components actin, vimentin and, very weakly, cytokeratin. The structural organization of the actin filaments and vimentin was strongly disrupted with pronounced fragmentation of the actin filaments in the presence of the calcium-channel blocker. CONCLUSION: The results suggest that the inhibition of cell adhesion by the calcium-channel blocker Mibefradil involves the impairment of integrin-mediated mechanisms. The use of this calcium antagonist appears to be a suitable therapeutic approach to prevent posterior capsule opacification.

Calcium Channel Blockers↗

Analysis of aqueous humour proteins of eyes with and without pseudoexfoliation syndrome.

UNLABELLED: Pseudoexfoliation syndrome (PEX) has been suggested to represent a blood-aqueous barrier impairment leading to a higher protein content in aqueous humour of eyes with PEX. However, the nature of a prospective PEX protein has not yet been described. We set out to reevaluate protein content and examine protein composition for prospective PEX protein candidates in aqueous humour of eyes with PEX syndrome. Aqueous humour of 52 patients with PEX and 38 without PEX signs was sampled during cataract or glaucoma surgery. Total aqueous protein concentration in the samples was analysed in 43 PEX specimens and 32 non-PEX specimens according to Bradford. Aqueous protein composition of all samples was determined by sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS PAGE) and silver staining. Screening for amyloids was performed in nine PEX samples and six non-PEX samples by Congo Red staining and polarised light microscopy. Aqueous protein concentration was not significantly increased in PEX eyes in comparison with non-PEX eyes. Furthermore, we could not detect any characteristic difference in protein band sizes of the two groups after SDS PAGE. However, we were able to show the presence of amyloid exclusively in aqueous humour of PEX patients. CONCLUSION: our results do not confirm a generally higher protein concentration in pseudoexfoliation syndrome eyes. This does not necessarily contradict a blood-aqueous barrier impairment but illustrates the variance in protein concentration between and within the two groups. No characteristic protein band allocatable to pseudoexfoliation syndrome proteins could be detected in any of the samples. However, our findings support the theory that the pseudoexfoliation syndrome is associated with an amyloid of a serum protein.

Aged↗

Three-dimensional ultrasound findings of the posterior iris region.

PURPOSE: The aim of this study was to assess the benefit of the three-dimensional ultrasound biomicroscopy in examination of the posterior iris and ciliary body. METHODS: Three-dimensional visualisation of the anterior eye section was achieved through extension of the existing ultrasound biomicroscope system (Humphrey Instruments). Visualisation of posterior iris and ciliary body pathologies in three patients was performed with a three-dimensional reconstruction technique of B-scans. RESULTS: The extended ultrasound system provided three-dimensional visualisation of alterations of the posterior iris region, i.e. iris cysts, ciliary body cysts and solid tumours of the ciliary body and iris. CONCLUSIONS: The three-dimensional ultrasound biomicroscopy yields extended diagnostic findings regarding iris and ciliary body pathology. This method offers an improved assessment of the posterior surface of the iris and the volume of the ciliary body. Furthermore, these data can be useful for procedures in computer simulation and calculation for a better understanding of the function of the ciliary body in the accommodation process.

Adult↗

[Effect of intraocular lens design on posterior capsule opacification: an in-vitro model].

BACKGROUND: The development of posterior capsule opacification (PCO) is one of the commonest complications of modern cataract surgery. The various designs of intraocular lenses (IOL) seem to exert a barrier effect on the proliferation and migration of lens epithelial cells and the following development of PCO. METHODS: We set up a cell culture model (advanced 3D capsular bag model) and investigated six differently designed IOL made of different materials as to their effect on cell proliferation. Proliferation and migration of the cells were analysed and documented over a period of 28 days. A cell viability test using the LIVE/DEAD kit (Molecular Probes) was carried out at the end of the investigation. RESULTS: In all tests, lens epithelial cells adhered to and migrated onto the capsular bag. During the culture period, lens epithelial cells migrated only to the optical rim of two of the implanted IOL. On the other four, lens epithelial cells migrated further and covered the whole optical area of the IOL. CONCLUSIONS: Certain lens designs seem to have a reducing effect on the development of PCO. Our advanced in vitro capsular bag model is a suitable cell culture model for the investigation of the reducing effect of various IOL on the development of PCO.

Cataract↗

[Imaging of orbital metastasis of small-intestine carcinoid by octreotide scintigraphy. A critical evaluation of the methodology].

BACKGROUND: An orbital carcinoid metastasis can be specifically imaged by octreotide scintigraphy. Orbital metastases of carcinoid tumors are rare. In the current literature only 27 cases have been published. CASE REPORT: We report on a 59 year-old woman who presented with diplopia 6 years after resection of a carcinoid tumor of the ileum. She also complained about flush and diarrhea. The diplopia was caused by limited extensibility of the right inferior muscle. Computed tomography with contrast revealed an enhancing tumor in the area of the right inferior rectus muscle, which appeared in the MRT as an isointense structure in the T1-weighted image. On staging, we found a contrast-enhancing nodular hepatic lesion. In octreotide scintigraphy, enhancement of the liver, thoracic and abdominal para-aortic lymph nodes and of the right inferior orbit was found. CONCLUSION: The survival times of patients with orbital metastasis of carcinoid tumors range between 7 months and 11 years. No specific treatment is available. Surgical excision is indicated for a symptomatic solitary metastasis. Octreotide is helpful in two ways: (1) as a radiolabeled tracer to detect extra-abdominal and extrahepatic secondary tumors; (2) as a treatment modality for flush and diarrhea, which is successful in over 60% of patients (life expectancy uninfluenced). Our patient is presently being treated with 200 micrograms of octreotide three times a day subcutaneously. Flush episodes and diarrhea have been reduced, but her ophthalmologic symptoms remain unchanged, and she has recently developed cardiac insufficiency.

Antidiarrheals↗

[Analysis of the dynamics of the ciliary muscle during accommodation].

BACKGROUND: The magnitude of anterioaxial shift of the human ciliary muscle during accommodation and its ceasing of ciliary function with advanced age are still unknown. PATIENTS AND METHODS: A total 105 patients (aged 10-91 years) were examined by high-resolution ultrasound biomicroscopy during disaccommodation and voluntary accommodation. Accommodative changes in the total area of the ciliary muscle and in the outer contour were quantified with a specially developed software program for automatic contour determination. RESULTS: A significant anterior shift independent of age was observed in the total area of the ciliary muscle and defined points on the outer contour of the muscle in the range of 56-121 microns, while the inward displacement was less obvious. A decrease in the magnitude of configurational changes during accommodation was observed with age. CONCLUSION: The new software program could be useful in further investigations of the accommodative process and evaluation of the potential causes of presbyopia.

Accommodation, Ocular↗

[Imaging of the microarchitecture and dynamics of the break-up phenomena of the preocular tear film with the aid of laser scanning microscopy].

BACKGROUND: Sufficient and regular wetting of the cornea with a normal preocular tear film is an essential requirement for the accurate visual functioning of the eye. Multiple factors may cause tear film instability. Measuring the break-up time of the preocular tear film is a necessary, clinically reliable means for evaluating tear film stability. We designed a new instrument to observe the preocular tear film at high magnification which can contribute to the in vivo imaging of the physiological and pathophysiological dynamics of the tear film and its break-up phenomena. MATERIALS AND METHODS: To image the tear film phenomena at sufficient magnification (x200) we used a confocal laser scanning microscope. Modification of an additional adaptor allows the tear film to be imaged at high magnification. This study evaluated the dynamics and microarchitecture of the break-up phenomena in the preocular tear film of normal patients and patients with "dry eye". RESULTS: Laser scanning microscopy allows high magnification imaging of the preocular tear film and evaluation of a number of break-up mechanisms. The dynamics and structure of the tear film was analyzed and documented. Based on our observations we formulate a new hypothesis on the break-up mechanism of the preocular tear film caused by alterations in the epithelial surface, for example, an elevation or tear film microparticle. By evaluating video sequences in the fluorescence and reflection modus of the laser scanning ophthalmoscope we also found early thinning of the aqueous layer simultaneously with an intact lipid layer covering the aqueous layer. CONCLUSION: Additional criteria result from using high-magnification microscopy, for example, laser scanning microscopy. This method reveals more microstructures of the corneal surface and the preocular tear film. The morphological representation of break-up phenomena leads to a better understanding of the underlying mechanisms and can be used for further investigations. Confocal laser scanning microscopy supplements the examination facilities and can be used in addition to slit lamp microscopy and to diagnose "dry eye".

Cornea↗

[A 3-D capsular bag model for describing biomechanical properties of neu intraocular lenses].

BACKGROUND: This study quantified the geometric deformation of the capsular bag following implantation of various intraocular lenses (IOL) using a three-dimensional capsular bag model made of silicone caoutchouc. METHODS: After implantation of 13 different IOLs (polymethylmethacrylate, silicone acrygel) into the artificial bag, the induced capsular bag deformation was measured and analyzed. The posterior space between IOL and capsule was examined by ultrasonographic biomicroscopy. RESULTS: Polymethylmethacrylate IOLs with C-haptic design induced a greater deformation of the capsular bag than silicone lenses; however, both types showed a larger gap posterior to the IOL than acrygel lenses. Acrygel IOLs with different haptic design revealed only minimal deformation with close contact posteriorly. CONCLUSIONS: The presented three-dimensional model simulates the biomechanical and geometrical parameters of the vital capsular bag. Further investigations may determine a correlation of close posterior IOL contact and lens epithelial cell progression.

Biomechanical Phenomena↗

New osmotically active hydrogel expander for enlargement of the contracted anophthalmic socket.

BACKGROUND: Clinical anophthalmia is characterized by the absence of an eyeball within the orbit and can result in overall growth retardation of the facial skeleton. The goal of treatment consists of fitting a serial prosthesis following rapid expansion of the contracted socket as soon as possible to achieve cosmetically acceptable eyelid and orbital symmetry. METHODS: Four children, aged 3-11 months, were treated by implantation of an anhydrous, highly hydrophilic tissue expander into the rudimentary conjunctival sac. With hydration of up to 98% in 72 h, the copolymer of methylmethacrylate and vinylpyrrolidone acts like an osmotically self-inducing socket expander. RESULTS: In the course of 2 months the previous contracted socket was enlarged, the horizontal lid length increased and the hydrated expander could be exchanged for a custom-made glass prosthesis. CONCLUSION: Preliminary results suggest that this new device can be used to avoid early plastic surgery of the eyelid. In addition, it also may enlarge the volume of the bony orbit.

Anophthalmos↗

Improved penetration of aminoglycosides and fluorozuinolones into the aqueous humour of patients by means of Acuvue contact lenses.

OBJECTIVES: In order to improve the penetration of topically applied drugs in ophthalmology, the suitability of hydrophilic contact lenses (Acuvue, Vistacon, power -1.0 D) as a drug delivery system for antibiotics was tested. A prospective study was undertaken to determine the transcorneal penetration of five topically applied aminoglycosides and fluoroquinolones into the aqueous humour of patients. METHODS: Two hundred and sixty-five patients undergoing cataract extraction received 0.3% gentamicin, kanamycin, tobramycin, ciprofloxacin or ofloxacin solution by two different modes of administration: either as eye drops (nine drops every 15 min, starting 2 h prior to surgery) or by means of a drug delivery system (Acuvue contact lenses soaked for 1 h in eye drop solution without preservatives, 15 h prior to surgery). At the beginning of cataract extraction, 50-100 microl aqueous fluid was aspirated from the anterior chamber and immediately stored at -80 degrees C. Antibiotic concentrations were measured using fluorescence polarisation immunoassays (aminoglycosides) or high-performance liquid chromatography (fluoroquinolones). RESULTS: After soaking for 1h in 0.3% eye drop solutions, Acuvue contact lenses released about 190-250 microg aminoglycoside and ofloxacin and 1000 microg ciprofloxacin. These amounts are considerably lower or in the same order of magnitude than obtained with application of eye drops (1350 microg). From the aminoglycosides tested, only gentamicin and tobramycin, but not kanamycin, were able to penetrate into the aqueous humour of patients. After the wearing of antibiotic-soaked lenses, mean aqueous humour concentrations were higher than after the use of eye drops. This difference reached significance in tobramycin (1.09 (1.30) microg x ml(-1) vs 0.49 (0.79) microg x ml(-1)), ciprofloxacin (1.23 (0.60) microg x ml(-1) vs 0.38 (0.33) microg x ml(-1)) and ofloxacin (5.55 (2.53) microg x ml(-1) vs 0.56 (0.37) microg x ml(-1)). The percentage of patients with aqueous humour concentration above the MIC90 of Staphylococcus epidermidis, the most common cause of postoperative endophthalmitis, was 92% and 100% after wearing ciprofloxacin- or ofloxacin-soaked lenses, respectively. CONCLUSION: Gentamicin and tobramycin penetrated into the aqueous humour of patients, whereas kanamycin was not able to overcome the corneal barrier. Acuvue contact lenses soaked in 0.3% eye drop solutions can release sufficient amounts of gentamicin, ciprofloxacin and ofloxacin to produce bacteriostatic concentrations in the humor aquosus. Acuvue contact lenses can be recommended as a drug delivery system for fluoroquinolones.

Administration, Topical↗

Penetration of ciprofloxacin, norfloxacin and ofloxacin into the aqueous humor using different topical application modes.

BACKGROUND: A prospective study was undertaken to determine the transcorneal penetration of three topically applied fluoroquinolones into aqueous humor. METHODS: Cataract patients (n = 224) preoperatively received topically applied gyrase inhibitors (0.3% ciprofloxacin, 0.3% norfloxacin, 0.3% ofloxacin) in two different application modes. In application mode I, patients received on the day before operation 3 x 1 eye drop at 2-h intervals, and on the day of operation 3 drops at 1-h intervals. In application mode II, patients received 9 drops at 15-min intervals on the day of operation only. Just before cataract surgery 50-100 ml aqueous humor was aspirated and stored at -80 degrees C. The HPLC method was used for measuring the concentration. RESULTS: The highest concentrations of all tested antibiotics were measured after the mode of application in which one drop was given every 15 min between 06:00 and 08:00 hours before operation. In this mode, ciprofloxacin achieved a mean aqueous level of 379.8 +/- 327.8 mg/l (range 33-1388 mg/l), norfloxacin 182.1 +/- 118.1 mg/l (range 38-480 mg/l) and ofloxacin 563.9 +/- 372.1 mg/l (range 64-1455 mg/l). These mean concentration are all above the MIC90 of gram-negative bacteria like Proteus mirabilis and Escherichia coli. In some cases the concentrations of ciprofloxacin and ofloxacin, but never norfloxacin, reached therapeutic values above the MIC90 of Staphylococcus aureus and Staphylococcus epidermidis. CONCLUSIONS: The mean concentration value of 0.3% ciprofloxacin and of 0.3% ofloxacin in the aqueous humor reached the MIC90 values of the frequently occurring gram-positive and gram-negative bacteria. Of the currently available topical fluoroquinolones, ofloxacin achieved the highest aqueous humor concentration. Considering the higher antimicrobial activity of ciprofloxacin, both ciprofloxacin and ofloxacin may be useful ophthalmic agents in antibacterial management, but they are not efficient against Streptococcus pneumoniae and Pseudomonas aeruginosa.

Administration, Topical↗

Cyclophotocoagulation: experimental investigations of dosage problems.

BACKGROUND: During cyclophotocoagulation, transsclerally applied laser light reduces the aqueous-producing structures of the eye. One problem using this therapy is patient-specific dosage of the applied laser energy. The aim of our investigations was to obtain information about intensity and distribution of tissue destruction in the coagulation area. This may provide a basis for further on-line control of cyclophotocoagulation by ultrasound-controlled engineering of the diode laser. METHODS: To visualize the process of cyclophotocoagulation, a multifunctional measurement set-up was developed. It allowed the visualization of structural changes in the coagulation area using a common light microscope and comparison in the first set-up to the results detected by high-resolution ultrasound, applied in different working modes (B-mode, M-mode and RF signal analyses). In a second set-up an infrared thermography system showing temperature distribution on the scleral surface at the contact point of the laser probe was used. RESULTS: High resolution working in B- and M-mode was unsuitable to visualize structural changes within the therapeutic width. By analyzing RF ultrasound date, structural changes within the therapeutic width could be detected. Surface temperatures measured by infrared thermography correlated with visible structural changes when long exposure times and low laser power were applied. CONCLUSIONS: In certain cases the visualization of coagulation effects was possible with the help of either high-resolution ultrasound or infrared thermography. Spectrum analysis of RF ultrasound signals seems to be a potential method for successful control of cyclophotocoagulation.

Animals↗

Treatment of congenital anophthalmos with self-inflating polymer expanders: a new method.

Congenital anophthalmos is a rare malformation in which the optic vesicle fails to develop. This leads to a small bony orbit, a constricted mucosal socket, short eyelids, reduced palpebral fissure and malar hypoplasia. The treatment includes both aesthetic and functional aspects. Therefore, a two-step procedure is described using a new self-inflating hydrogel expander. A lens-shaped expander with a diameter of 8 mm expands the lids and the mucosal socket to allow insertion of an eye prosthesis. As a second step, orbital expansion is performed with a spherical device. The expanders absorb lacrimal fluid from the mucosal socket or tissue fluid and start swelling when implanted in the orbital tissue. The insertion of an expander into the orbit as well as into the conjunctival pocket including its fixation by a single suture took only a few minutes and was an easy procedure. The expansion of the small conjunctival sockets was successfully completed in all cases within a period of 2-4 weeks. The weight (= volume in ml) of devices increased from 0.15-1.5 g (lens-shaped expander; weight in grams = volume in ml) respectively, 0.3-3.5 g (spherical device). The expanders inserted in orbital tissue increased from 0.4-4.4 g. This is equivalent to a 10 to 11 fold increase in their water-free volumes. Orbital expansion with spherical devices in combination with the inserted eye prosthesis enlarges the lid and palpebral fissures also. In contrast to conventional silicon balloon expanders, the procedure using self-inflating hydrogel expanders is simple and highly efficient.

Absorption↗