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Biomedical subjects

P Janknecht

Publications and source records attributed to P Janknecht.

At least 19 recordsLinked to original sources
PubMed2005

Frequency of ocular hemorrhages in patients with subarachnoidal hemorrhage.

BACKGROUND: Vitreous hemorrhage (Terson's syndrome) and other intraocular hemorrhages have been reported in up to 40% of patients with subarachnoidal hemorrhage (SAH). Our objective was to determine prospectively the frequency of intraocular involvement and its relationship to the grade of SAH. METHODS: Seventy-four consecutive patients with SAH were prospectively examined. The patients were classified according to Hunt and Hess and ophthalmological examination was performed by an ophthalmologist. RESULTS: In all patients SAH was caused by a ruptured cerebral aneurysm. Intraocular hemorrhages were present in 28% of the patients, all of whom had retinal hemorrhages, which were detectable unilaterally in 45%, while 15% of these patients exhibited typical retrohyaloidal or vitreal hemorrhages. Ocular involvement was statistically more frequent in patients with a higher grade of SAH according to Hunt and Hess. CONCLUSIONS: Due to ocular involvement in more than a quarter of the patients with SAH and due to the fact that ocular involvement is related to the severity of SAH, screening of patients with SAH is recommended, especially when no reliable data about visual function are available. Early vitrectomy of vitreous hemorrhages provides a more effective rehabilitation.

Aneurysm, Ruptured↗
PubMed2005

[Phacoemulsification combined with cyclophotocoagulation].

INTRODUCTION: Cyclophotocoagulation and phacoemulsification procedures may be combined to treat patients with glaucoma and cataract. To the best of our knowledge data concerning this combination have not been published as yet. PATIENTS AND METHODS: 28 eyes (23 patients, mean age 78.1 +/- 7.6 years) were operated upon between 9.04.2002 and 29.06.2004. Patients were compared to a group with phacoemulsification alone. RESULTS: A median of 15 laser flashes (duration 2000 ms, power 1750 mW) were applied. Complications at discharge from hospital (and after 6 weeks) were: corneal oedema 18 % (4.0 %), fibrinous reaction 25 % (7.1 %), hyphaema 7.1 % (0 %), 1 decentred IOL, 7.1 % capsular tear. Visual acuity increased statistically significantly from 0.3 to 0.5. Mean intraocular pressure decreased statistically significantly from 23.7 +/- 5.6 mmHg to 16.0 +/- 3.4 mmHg after 166 days. Success rate was 76 % after 6 weeks and 85.7 % after 166 days. The mean number of antiglaucomatous drugs could be reduced from 1.6 to 1.1 after 166 days. In the control group there was a transient corneal edema in 14.3 % (7.1 % cornea guttata), other complications were not found. CONCLUSION: The combination of cyclophotocoagulation and phacoemulsification is as successful as other combinations of cataract and glaucoma surgery with a similar or lower complication rates. Cyclophotocoagulation is cost efficient, can be repeated and is adaptable to the intraocular pressure.

Aged↗
PubMed2002

Outbreak of Empedobacter brevis endophthalmitis after cataract extraction.

BACKGROUND: We present a series of patients who were operated upon on the same day by the same surgeon. All of those patients developed postoperative endophthalmitis due to Empedobacter brevis - a bacterium hitherto unknown in ophthalmologic literature. METHODS: Twelve patients were referred because of endophthalmitis after cataract extraction. The patients' files were studied and the intraoperative and postoperative outcome was analysed. RESULTS: Twelve patients (five male, seven female, mean age 75 years) presented 1-6 days after uncomplicated cataract extraction. Although some suffered from medical or ophthalmological diseases there was no association with the severity of the endophthalmitis. Eleven patients required vitrectomy, seven as primary procedure, one primary with extraction of the lens and three secondary after anterior chamber lavage and intravitreal antibiotics. In three cases vitrectomy had to be repeated together with extraction of the intraocular lens. There were two postoperative retinal detachments that required silicon oil and in one case an encircling band. Mean visual acuity rose from 0.02 to 0.47 by 9 months after operation. Empedobacter brevis was found in the anterior chamber and in the vitreous in all except one patient. CONCLUSION: In high-volume cataract surgery endemic endophthalmitis is always possible. Sources of infection may be anything from the lens to the sterilisation process, the latter being the primary suspect in our series. Prompt, adequate and (if necessary) aggressive treatment by vitreous surgery may lead to favourable results.

Aged↗
PubMed2001

Steady-state electroretinograms and pattern electroretinograms in pigs.

BACKGROUND: Electroretinograms (ERG) or pattern-electroretinograms (PERG) could be valuable for the quantification of potential damage to the pig retina by experimental erbium:YAG laser treatment. We therefore performed a normative study of ERGs and PERGs in pigs. METHODS: We recorded ERGs and PERGs under general anaesthesia in two experiments. In experiment 1 we examined eight eyes from six pigs of 20-25 kg body weight; in experiment 2 we examined four eyes from four pigs of 40-45 kg body weight. We used flash and checkerboard stimuli. In experiment 1, the stimulus parameters were mean luminance 48.3 cd/m2 for checkerboard stimuli, 96.6 cd/m2 for ERG, check sizes of 4 degrees, 8 degrees, and 16 degrees, temporal frequencies were 16 Hz for ERG and 8 rev/s for PERG. Three measurements were repeated after two weeks. Stimulus parameters for experiment 2 were luminance 175 (350) cd/m2, check sizes 1.6 degrees, 3.2 degrees, 6.7 degrees, and 16 degrees, temporal frequencies 6.3 Hz for ERG and 8 rev/s for PERG. Recordings were subjected to Fourier analysis. RESULTS: In experiment 1 the mean ERG amplitude was 1.02 +/- 0.89 microV with a coefficient of variation of 42% for repeat sessions. The mean PERG amplitudes were 0.53 +/- 0.25 microV for 16 degrees checks, 0.36 +/- 0.21 microV for 8 degrees, and 0.25 +/- 0.17 microV for 4 degrees. The mean coefficient of variation between two measurements was 103% for 16 degrees checks, 24% for 8 degrees, and 116% for 4 degrees. In experiment 2 the mean ERG amplitude was 9.72 +/- 3.96 microV. The mean PERG amplitudes were 0.77 +/- 0.50 microV for 16 degrees checks, 0.09 +/- 0.16 microV for 6.7 degrees, 0.07 +/- 0.13 microV for 3.2 degrees, and 0.08 +/- 0.09 microV for 1.6 degrees. CONCLUSIONS: It was possible to record ERGs and PERGs in pigs. However, the ERG amplitudes were small; PERG amplitudes were even smaller in both groups and cannot be reliably recorded. A problem for both ERG and PERG was the high intra-individual and interindividual variability. Therefore, only very extensive damage to the retina by vitrectomy or Er:YAG laser treatment might lead to a significant change in the ERG or PERG amplitudes.

Animals↗
PubMed2001

Internal limiting membrane ablation in pig eyes with the Er:YAG laser under perfluorodecalin.

PURPOSE: The aim of our study was to evaluate the in vivo feasibility of non-contact Er:YAG laser ablation of the internal limiting membrane (ILM), which is recommended for the treatment of macular holes. METHOD: Vitrectomy was performed in 16 eyes of 15 pigs. After perfluorodecalin filling, it was attempted to remove the ILM using a free-running fiber-guided Er:YAG laser (lambda=2.94 microm, pulse length 250 micros, repetition rate 1.7 Hz, radiant exposure 0.6-2.05 J/cm2). The eyes were enucleated either immediately (11 eyes, group 1) or 2 weeks after laser therapy (5 eyes, group 2). Furthermore, in one additional pig eye the retina was carefully treated with microforceps after vitrectomy to assess the damage produced by conventional techniques of ILM peeling. All eyes were examined histologically. RESULTS: Group 1: Nine eyes could be examined (problems with fixation in two eyes). In four of nine eyes, the ILM was either removed or detached, in one eye there was a superficial retinal hemorrhage, and in four eyes the ILM was still intact. In the latter cases, there was no intraoperative whitening or bleeding and no posterior vitreous detachment was present histologically. Group 2: Four eyes (problems with fixation in one eye) could be examined. The ILM was either removed or detached in three eyes. In one eye there was a superficial retinal hemorrhage. In one eye the ILM was not removed and there had neither been intraoperative whitening or hemorrhage nor histologically visible posterior vitreous detachment. In both groups, the nerve fiber layer in treated areas was thicker than in adjacent untreated retina. In one eye the retina was gently manipulated with microforceps in an attempt to perform ILM peeling. This led to damage to all layers of the retina. CONCLUSIONS: Removal of the ILM by Er:YAG laser is possible in vivo. However, the variability of the laser effects calls for further improvement such as a reliable indicator of ablation depth. In any case, any damage to the retina was lesser than that produced by microforceps.

Animals↗
PubMed2000

Erbium: YAG laser ablation of retinal tissue under perfluorodecaline: determination of laser-tissue interaction in pig eyes.

PURPOSE: To evaluate the effect of Er;YAG laser on pig retina using a perfluorodecaline/retina interphase with the goal of precisely determining the extent of retinal tissue ablation. METHODS: Free running (tau = 250 microsec) Er:YAG laser pulses were transmitted through a zirconium fluoride (ZrF4) fiber guarded by quartz rod (d = 1000 microm). Laser pulses were applied to the retinal surface of enucleated pig eyes. Eyes were mounted in a specially designed rotating sample holder. The fiber probe was elevated 1.0 +/- 0.3 mm above the retinal surface with perfluorodecaline serving as transmitting medium. The laser energy was applied in a circular pattern with a radius of 3.0 mm. Radiant exposures were set to 1, 3, 5, and 10 J/cm2. RESULTS: Tissue ablation linearly increased with radiant exposure from 3.2 +/- 3.7 microm at 1 J/cm2 up to 40.9 +/- 12.9 microm at 10 J/cm2. Thermal tissue changes extended 70 +/- 10 microm vertically into the retina and 25 +/- 5 microm horizontally. Distortion of outer photoreceptor segments was noticed when the retina was exposed to radiant exposures of 3 J/cm2 or higher. CONCLUSIONS: The Er:YAG laser in combination with perfluorodecaline produced precise ablation of the pig retina, which suggests the feasibility of this technique for safe ablation of epiretinal membranes.

Animals↗
PubMed1999

Long-lasting contamination of a vitrectomy apparatus with Serratia marcescens.

OBJECTIVE: To investigate the contamination of a vitrectomy apparatus with Serratia marcescens. DESIGN: Descriptive microbiological and molecular environmental study. SETTING: An 1,800-bed university hospital. RESULTS: S. marcescens was found inside the vitrectomy apparatus at the pressure transducer. Molecular typing by randomly amplified polymorphic DNA-automated laser fluorescence analysis and pulsed-field gel electrophoresis identified a single pattern for all strains isolated from the apparatus. Surprisingly, the contaminating strain was identical to two strains of S. marcescens isolated nearly 2 years earlier from two patients who were involved in a small outbreak of acute postoperative endophthalmitis following cataract surgery at another hospital. The emergency vitrectomies in these patients were performed at our hospital with the same apparatus that was found to be contaminated 2 years later. CONCLUSION: Performing a systematic environmental search for the assumed bacterial reservoir within the system of the vitrectomy apparatus finally made it possible to find and eliminate the nidus for the gram-negative rod. Molecular typing demonstrated that all isolates belonged to a single genotype, and revealed unexpectedly a link to two vitrectomies performed 2 years earlier. The data support the hypothesis that the source of the contamination was one of these patients, and thus contamination of the apparatus was present for almost 2 years.

DNA, Bacterial↗
PubMed1998

Bacterial contamination of the pressure receiver of a vitrectomy machine.

On a routine sterility check, the authors found bacteria in their vitrectomy machine. Serratia marcescens was detected in the pressure receiver of a roller pump vitrectomy machine. The authors improved the machine by installing a millipore filter in front of the receiver that prevents bacteria from entering it without interfering with the pressure measurements. The origin of Serratia was probably a patient with endophthalmitis who was operated on long before the routine check. Although this appears to be the first report of a bacterial contamination of a vitrectomy machine, the results of testing show that this situation is indeed possible. The authors strongly recommend routine checks of the equipment and suggest mounting an antibacterial filter.

DNA, Bacterial↗
PubMed1997

Diameter of the optic nerve in idiopathic optic neuritis and in anterior ischemic optic neuropathy.

PURPOSE: There is considerable overlap in the clinical profile of patients with idiopathic optic neuritis (ON) and anterior ischemic optic neuropathy (AION). We tested the hypothesis that the retrobulbar diameter of the optic nerve may be a criterion for the differential diagnosis between ON and AION. METHODS: The diameter of the optic nerve was measured by B-scan ultrasonography with the eye in an abducted position. Only patients with a unilateral optic neuropathy were included, 16 ON patients (mean age 24 years, 5 with and 11 without disc swelling) and 9 patients with AION (mean age 72 years). As controls for the ON patients 10 young normal subjects (mean age 25 years) and as controls for the AION patients 10 elderly subjects with eye problems not related to the optic nerve (mean age 76 years) were examined. RESULTS: In the ON patients with disc swelling the diameter of the optic nerve was 5.4 +/- 0.5 mm in the affected and 3.0 +/- 0.3 mm in the unaffected side. This difference was significant (Wilcoxon-test, p = 0.043). In the ON patients without disc swelling the diameter of the optic nerve was 4.4 +/- 0.4 mm in the affected and 3.0 +/- 0.3 mm in the unaffected side. This difference was significant (Wilcoxon-test, p = 0.003). In the AION patients the diameter of the optic nerve was 3.0 +/- 0.3 mm on the affected and 2.8 +/- 0.4 mm on the unaffected side. This difference was not significant (Wilcoxon-test, p = 0.093). Comparing the optic nerves with ON and AION to those of the controls, the diameter was significantly enlarged in the nerves with ON and normal in the nerves with AION (one factor repeated ANOVA). CONCLUSION: The diameter of the optic nerve is increased in ON without disc swelling and even more so in ON with disc swelling. The enlargement is probably due to edema of the nerve itself, not the surrounding subarachnoidal space. In AION, the diameter of the optic nerve is normal. Measuring the diameter of the optic nerve by B-scan ultrasonography is particularly useful in the differential diagnosis between ON with disc swelling and AION.

Adolescent↗
PubMed1997

[Post-traumatic endophthalmitis with multiple water pathogens].

HISTORY AND SIGNS: A 37-y-old worker for a recycling company suffered from a corneal perforation by a wire which had been in contact with dirt and moisture. THERAPY AND OUTCOME: Initially, the typical signs of an endophthalmitis were missing so that we only irrigated and instilled antibiotics into the anterior chamber. However, later on two pars-plana vitrectomies became necessary. At each operation a bacteriological examination was performed and we found four different species-Pseudomonas aeruginosa. Klebsiella oxytoca, Aeromonas caviae, Flavobacterium odoratum. CONCLUSION: The latter two species are very rare in ophthalmology. This fact and some peculiarities in the clinical course of the patient's disease make him an unusual case. After unsuccessful irrigation of the anterior chamber vitrectomy ought to be performed immediately.

Bacteria↗
PubMed1997

[Spontaneous resolution of a macular pucker].

AIM: Presentation of the spontaneous avulsion of an epiretinal membrane. CASE REPORT: A 21-y-old patient with a visual acuity of 6/6 suffered from a macular pucker. Over the course of five years, this epiretinal membrane dissolved from the retinal surface. This process was documented photographically and with the Heidelberg Retina Tomograph.

Adult↗
PubMed1995

Optic nerve head analyzer and Heidelberg retina tomograph: relative error and reproducibility of topographic measurements in a model eye with simulated cataract.

BACKGROUND: We measured the relative error and reproducibility of the optic nerve head analyzer (ONHA) and the Heidelberg retina tomograph (HRT) in a model eye with a cataract that was simulated by Bangerter foils. METHODS: There were two artificial discs and one retinal elevation (the latter could not be analyzed by the ONHA) that could be inserted into the model eye. The relative error of the parameter 'cup area' ('cup volume') of the ONHA for the measurement of artificial disc no. 1 changed from 1.1% (5.4%) without Bangerter foil to 7.9% (7.6%) with Bangerter foil 0.6. The standard deviation of the ONHA increased from 0.059 mm2 (0.1 mm3) without Bangerter foil to 0.142 mm2 (0.121 mm3) with Bangerter foil 0.6. With the smaller artificial disc no. 2, no measurements with Bangerter foils were obtained. RESULTS: Relative error and reproducibility of the parameter 'volume below (above) surface' of the HRT did not show any consistent change with increasing intensity of the simulated cataract. With artificial disc no. 1, the relative error without Bangerter foil was 14.6%, while the worst relative error with one of the Bangerter foils 0.8 to 0.4 was 16.4%. The corresponding values for the standard deviation were 0.019 mm3 and 0.033 mm3. With the smaller artificial disc no. 2, the relative error without Bangerter foil was 6.3%, while the worst relative error with one of the Bangerter foils 0.8 to 0.2 was 18.3%. The corresponding values for the standard deviation were 0.016 mm3 and 0.017 mm3. The relative error in measuring a retinal elevation without a Bangerter foil was 2.3%, with a Bangerter foil 11.2-18.0%. The standard deviation was 0.068 mm3 without Bangerter foil and 0.013-0.023 mm3 with Bangerter foils. CONCLUSION: Our data support the assumption that the HRT is able to measure fundus structures even in the case of opaque optical media. The HRT is superior to the ONHA in this regard.

Adult↗
PubMed1995

Sclerochoroidal granuloma in Wegener's granulomatosis simulating a uveal melanoma.

BACKGROUND: It is known that Wegener's granulomatosis may affect the eye, but macroscopically visible granulomas in patients with this condition have not yet been described. METHODS: Results of clinical, ultrasound, and histologic examination of a patient with Wegener's granulomatosis are presented. RESULTS: A sclerochoroidal granuloma in this patient simulated an uveal melanoma. It was not possible to unequivocally differentiate the lesion from a uveal melanoma on sonographic examination, but histologic examination confirmed the diagnosis of sclerochoroidal granuloma. CONCLUSION: Macroscopically visible sclerochoroidal granuloma is another facet of Wegener's granulomatosis, and in some cases may be mistaken for uveal melanoma.

Choroid↗
PubMed1995

[Reproducibility of measurements with the Heidelberg retina tomograph in fundus elevations].

PURPOSE: The Heidelberg Retina Tomograph (HRT) was intended to evaluate the optic nerve head. It is, however, also possible to measure retinal elevations. There are no systemic data on the reproducibility of HRT measurements of retinal elevations. We now provide such data. METHODS: 117 measurements in patients with diseases which are characterized by retinal elevations were analyzed with the HRT. We measured the "volume above surface" of the retinal elevations. Each patient was analyzed three times, and the coefficient of variation was calculated. RESULTS: The coefficient of variation was between 0.55% and 40.5%. Some 42% of the coefficients of variation were between 0% and 10%, 31% between 5% and 10%, 21% between 10% and 20%, and 6% larger than 20%. CONCLUSION: The reproducibility of the HRT measurements in retinal elevations is clinically sufficient. The relation between sufficient reproducibility and accuracy is discussed.

Diabetic Retinopathy↗
PubMed1994

[Results of cyclocryocoagulation].

BACKGROUND: The success of a cyclocryocogulation is not only defined by the reduction of the intraocular pressure but also by the simplification of the therapy necessary for the regulation of the glaucoma. PATIENTS: We examined retrospectively the charts of 27 patients with glaucoma chronicum simplex (GCS) and 63 patients with various types of non-simplex glaucomas (NGCS). All underwent a cyclocryocoagulation made 51 seconds at -70 to -80 degrees C, 4 mm behind the limbus at 6 points. RESULTS: IOP was controlled (i.e. < 25 mm Hg and decreased > 20% of the preoperative value) in 69% of the cases (GCS 70%, NGCS 68%) 3-5 days after the operation. IOP decreased from 31 to 19 mm Hg on average. The effect decreased with time, more than 12 months after the operation only 36% of the eyes were still regulated. 4 eyes with persisting pain had to be enucleated. The cyclocryocoagulation never caused blindness or phthisis bulbi. Therapy with eye drops was necessary in 70% of the patients preoperatively, and in 37% postoperatively. Oral carboanhydrase inhibitors had to be used in 57% of the patients before and in 20% of the cases after the operation. CONCLUSION: Cyclocryocoagulation is considered an effective method to lower IOP and simplify drug therapy without having serious complications.

Adult↗