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Biomedical subjects

N Pfeiffer

Publications and source records attributed to N Pfeiffer.

At least 19 recordsLinked to original sources

[Goldmann applanation tonometry and dynamic contour tonometry. Comparison of intraocular pressure measurements in the course of product certification according to EN ISO 8612:2001].

BACKGROUND: The aim of the study was to compare intraocular pressure (IOP) measurements between Goldmann applanation tonometry (GAT) and dynamic contour tonometry (DCT) during product certification according to the international requirements for ophthalmic instruments (tonometers, ISO 8612:2001). METHODS: The study included 160 eyes of 80 subjects. IOP measurements were performed four times consecutively on each instrument in randomized order. The difference of mean IOP measurements between GAT and DCT was analyzed. Furthermore, Bland and Altman analysis was performed to assess agreement between the instruments. RESULTS: The mean difference between DCT and GAT IOP measurements was 0.30+/-2.18 mmHg. At low to normal IOP values of 7-16 mmHg and higher IOP values of > or =23 mmHg, the difference between DCT IOP measurements and GAT IOP measurements increased in the opposite direction (1.44+/-1.59 mmHg and -1.47+/-2.57 mmHg). The Bland and Altman analysis revealed a fixed bias of -0.4+/-2.0 mmHg. CONCLUSIONS: The test tonometer DCT exceeds the requirements for the international standard for tonometers ISO 8612:2001. The results are valid for a central corneal thickness of 540+/-40 microm.

Calibration↗

[Blindness in Germany--today and in 2030].

Due to demographic developments in Germany, it is inevitable that the number of age-related diseases will grow. The aim of this survey is to forecast the extent of this development in ophthalmology. How many people will be blind or visually impaired in 25 years from now? According to the German Federation of Blind and Visually Impaired People, the number of blind people in Germany is about 145,000 and the number of the partially sighted people can be estimated at approximately 500,000. These figures are based on the legal definitions of blindness and visual impairment, which are stricter in Germany than in other countries. Due to the ageing population, there will be one third more blind people and about 60% more new cases of blindness in 25 years time. In particular, the incidence rate of blindness due to age-related macular degeneration will rise sharply, but the number of blind people and new cases of blindness are only the top of the "iceberg". The number of people suffering from age related eye diseases in future will be even larger. This large number of future patients already should be part of health economic considerations.

Age Distribution↗

Biaxial microincision versus coaxial small-incision clear cornea cataract surgery.

OBJECTIVE: To compare clinical outcomes of biaxial microincision (1.5 mm) and coaxial small-incision (2.75 mm) clear cornea cataract surgery. DESIGN: Randomized controlled clinical trial. PARTICIPANTS: Seventy eyes of 70 patients were examined at a German university eye hospital. INTERVENTION: The 70 patients (70 eyes) were assigned randomly (1:1) to a biaxial or conventional coaxial incision group. Both groups underwent phacoemulsification using pulsed ultrasound energy with variable duty cycles, followed by microincision intraocular lens implantation. MAIN OUTCOME MEASURES: Best-corrected visual acuity (BCVA), astigmatism, laser flare photometry value, effective phacoemulsification time (EPT), and endothelial cell count were evaluated. RESULTS: The treatment groups did not differ in baseline characteristics (median BCVA of 20/40 preoperatively in both groups, P = 0.97). On postoperative day 1, BCVA was better in the biaxial group than in the coaxial group (20/25 vs. 20/33, P = 0.018). Eight weeks after surgery, median BCVAs were 20/20 in the biaxial group and 20/25 in the coaxial group (P = 0.015). Median changes in astigmatism were -0.15 diopters (D) in the biaxial group and -0.31 D in the coaxial group. Neither clinically relevant nor statistically significant differences were found in laser flare photometry values. Effective phacoemulsification time was >3 seconds in only 34% of biaxial procedures, versus 68% of coaxial procedures (P = 0.013). At 8 weeks after surgery, endothelial cell counts were decreased similarly in the biaxial (14.5%) and coaxial (14.1%) groups (P = 0.408). CONCLUSIONS: With the biaxial microincision technique, EPT is shorter and BCVA improves more rapidly, with no difference in astigmatism, laser flare photometry results, or endothelial cell count relative to the coaxial small-incision technique for phacoemulsification.

Adult↗

[Systemic fibrinolytic therapy using urokinase in central retinal artery occlusion. A case study].

BACKGROUND AND OBJECTIVE: Systemic fibrinolysis has become an important therapeutical option in patients with thrombotic occlusion of coronary or pulmonary arteries. In view of the hemorrhagic risk systemic fibrinolytic therapy for retinal vessel occlusion has been discussed controversial. In the present case study results and complications of systemic fibrinolysis should be investigated in patients with central retinal artery occlusion. PATIENTS AND METHODS: From 1995 to 2002 a case series of 19 consecutive patients (8 female, 11 male, age: 63.2+/-14,3 years) with central retinal artery occlusion were treated by systemic application of urokinase using a standardized scheme. The latency from initial symptoms until the initiation of therapy and the medical history of the patients were documented. Visual acuity was determined on admission and before discharge and possible complications were documented. Additionally, screening investigations for genetic thrombophilia were performed. RESULTS: 15 patients showed an improvement of the visual acuity (79 %, 95 %-KI: 54 %-94 %). For 3 patients no improvement and for one patient a decrease of the visual acuity was determined. Hemorrhagic complications were observed in two patients (11 %, 95 %-KI: 1 %-33 %). As these minor bleedings were self-limiting the fibrinolytic therapy was discontinued only in one patient. As risk factors most commonly arterial hypertension (68 %) and smoking (26 %) were identified. In 4 patients a genetic thrombophilia was diagnosed. CONCLUSIONS: Considering the poor prognosis of central retinal artery occlusion and the disappointing results of conservative treatment, an improvement of the visual acuity in the absence of critical complications was observed with systemic fibrinolytic therapy in the presented case study. However, only controlled trials can provide proof for the effect of fibrinolysis versus spontaneous improvement.

Contraindications↗

[Results of the "Ocular hypertension treatment study"].

Ocular hypertension (OHT) is defined as intraocular pressure (IOP) elevated above normal levels which occurs without detectable damage to the papilla or visual field. It is considered to be the most important risk factor for developing primary open-angle glaucoma (POAG). The "Ocular hypertension treatment study" (OHTS) addresses the issue of whether lowering IOC before damage to the papilla or visual field occurs can hinder their development and whether OHT can be treated categorically. This randomized, prospective, nonmasked and non-placebo-controlled, multicenter study documents the protective effect of prophylactic lowering of IOC and identifies and explains the risk factors for developing POAG. These include advancing age, reduced corneal thickness, increased pattern standard deviations in white-on-white perimetry, and elevated vertical or horizontal cup to disc ratio. Due to the large individual differences in risk distribution and the very high costs of treating OHT, the question of whether OHT should be treated on principle remains open in the OHTS. This decision must be made on an individual basis after each patient's risk has been assessed.

Adult↗

[Laser in situ keratomileusis (LASIK) and scanning laser ophthalmoscopy].

BACKGROUND: To determine the influence of Laser in situ keratomileusis (LASIK) on the measurements of retinal thickness and optic nerve head topography using the Retinal Thickness Analyzer (RTA). METHODS: RTA measurements were performed before and after LASIK. Forty-eight eyes of 25 healthy subjects were included. Mean age was 40.0+/-10.6 years. Mean preoperative refractive error (spherical equivalent) was -3.3+/-3.6 dpt, and 0.2+/-0.9dpt postoperatively. Correlation between ablation depth and duration and change of retinal thickness postoperatively was performed. All patients received a pachymetry preoperatively. RESULTS: Postoperatively, mean retinal nerve fiber layer thickness (MRNFL) and cross sectional area (RNFL cross section area) significantly decreased after LASIK (MRNFL preop: 0.18 mm, postop: 0.11 mm, P =0.026, RNFL cross section preop: 1.17 mm(2), postop: 0.71 mm(2), P =0.015). Ablation depth revealed a significant correlation with changes in retinal thickness measurements postoperatively (Delta MRNFL: Ablation depth, P =0.001, r=-0.5). Duration of the ablation was not significantly correlated to the MRNFL measurements postoperatively (P =0.27, r=-0.08). No correlation was found between the central corneal thickness and the change in retinal thickness after LASIK (P =0.51). CONCLUSION: Due to changes in corneal architecture after LASIK, measurements using RTA reveal a decrease in MRNFL and RNFL cross section area. These changes are likely artifacts. Further studies with a longer follow-up are desirable.

Adult↗

Capsular bag shrinkage after implantation of a capsular bending or capsular tension ring.

PURPOSE: To evaluate the influence of a capsular bending ring (CBR) or tension ring (CTR) on capsular bag shrinkage. SETTING: Department of Ophthalmology, Johannes Gutenberg-University, and Department of Medical Biometry, Epidemiology and Informatics, University of Mainz, Mainz, Germany. METHODS: In 92 eyes of 92 patients, a capsular measuring ring (CMR) was implanted after phacoemulsification to measure capsular bag size in vivo. Patients were randomized into 3 groups: The first received a CMR and CBR, the second received a CMR and CTR, and the third received a CMR alone. Measurements were performed preoperatively, intraoperatively, during the first 3 postoperative days, and after 1 and 3 months. Preoperative biometric characteristics such as axial length (AL) and anterior chamber depth were determined. Primary clinical end points were capsular bag size and capsulorhexis diameter measured intraoperatively and by means of slitlamp biomicroscopy and retroillumination photography postoperatively. RESULTS: There were no clinically relevant group differences in AL, anterior chamber depth, or capsulorhexis diameter. Eyes implanted with the CBR showed shrinkage of the capsular bag from 10.6 to 10.4 mm after a median of 3 months (sign test; P = .023); eyes with a CTR showed comparable median capsular bag shrinkage from 10.5 to 10.2 mm (P<.001), whereas eyes without a CTR showed a median shrinkage from 10.5 to 10.0 mm (P<.001). Intraindividual shrinkage was of a similar, although significantly different, order among these groups (median shrinkage 0.15 versus 0.23 and 0.38 mm, respectively; all pairwise Wilcoxon test; P = .050, P = .020, P<.001, respectively). CONCLUSIONS: Capsular shrinkage can be inhibited by a CBR and, to lesser extent, a CTR; the gain in shrinkage prevention is limited when compared with a CMR, however. This conclusion can be drawn only for the specific CBR or CTR and hydrophobic acrylic intraocular lens (IOL) used in this study. Reduction of capsular bag shrinkage after CTR implantation may reduce IOL dislocation and tilt and help to maintain postoperative visual acuity.

Adult↗

Direct costs of glaucoma and severity of the disease: a multinational long term study of resource utilisation in Europe.

BACKGROUND: Resource utilisation and direct costs associated with glaucoma progression in Europe are unknown. As population progressively ages, the economic impact of the disease will increase. METHODS: From a total of 1655 consecutive cases, the records of 194 patients were selected and stratified by disease severity. Record selection was based on diagnoses of primary open angle glaucoma, glaucoma suspect, ocular hypertension, or normal tension glaucoma; 5 years minimum follow up were required. Glaucoma severity was assessed using a six stage glaucoma staging system based on static threshold visual field parameters. Resource utilisation data were abstracted from the charts and unit costs were applied to estimate direct costs to the payer. Resource utilisation and estimated direct cost of treatment, per person year, were calculated. RESULTS: A statistically significant increasing linear trend (p = 0.018) in direct cost as disease severity worsened was demonstrated. The direct cost of treatment increased by an estimated 86 for each incremental step ranging from 455 euro per person year for stage 0 to 969 euro per person year for stage 4 disease. Medication costs ranged from 42% to 56% of total direct cost for all stages of disease. CONCLUSIONS: These results demonstrate for the first time in Europe that resource utilisation and direct medical costs of glaucoma management increase with worsening disease severity. Based on these findings, managing glaucoma and effectively delaying disease progression would be expected to significantly reduce the economic burden of this disease. These data are relevant to general practitioners and healthcare administrators who have a direct influence on the distribution of resources.

Adult↗

[Deep sclerectomy using a hyaluronate implant versus trabeculectomy. A comparison of two glaucoma operations using mitomycin C].

BACKGROUND: It was investigated whether a very low target pressure could be achieved by modification of deep sclerectomy without losing the advantages of non penetrating surgery in comparison to conventional filtration surgery. PATIENTS AND METHODS: A total of 22 eyes from 22 patients with advanced open angle glaucoma were randomly assigned to receive a deep sclerectomy or a trabeculectomy. Both groups received 0.02% mitomycin C under the conjunctiva prior to preparation of the scleral flap. In the deep sclerectomy group at least parts of the outer trabecular meshwork were removed until an apparent filtration was achieved. A dry cross-linked hyaluronate served as an implant. In the other group a classical trabeculectomy was performed. RESULTS: The median intraocular pressure 12 months post-operation was 11.5 mm Hg in the deep sclerectomy group compared to 11 mm Hg in the trabeculectomy group; the median of the relative IOP reduction was -47% in the deep sclerectomy group, and -57% in the trabeculectomy group. The best corrected visual acuity was unchanged 12 months postoperatively in both groups. DISCUSSION: As a more aggressive IOP-lowering procedure (intended filtration, use of antimetabolites) deep sclerectomy proved to be as effective as trabeculectomy. Nevertheless, the advantages of the more difficult surgical procedure concerning visual acuity, complications and surgical interventions were lost postoperatively.

Adult↗

[Agreement between clinical evaluation, Heidelberg-Retina-Tomograph (HRT) and Nerve Fiber Analyzer (GDx) in glaucoma diagnosis].

BACKGROUND: We have made a comparison of clinical evaluation, Heidelberg-Retina-Tomograph (HRT) and Nerve Fiber Analyzer (GDx) in diagnosing glaucoma. MATERIALS AND METHODS: One eye of 38 glaucoma patients and 26 non-glaucoma patients was examined with HRT and GDx. Assignment of the patients into the two groups by clinical evaluation was performed on the basis of visual field and optic disc results. As classification criterion for glaucoma/non-glaucoma by means of the instruments we employed the statistical classification of the HRT and "the number" of the GDx. Statistical analysis was performed with Cohen's kappa and McNemar tests. Additionally, ROC curves for evaluation of the sensitivity and specificity of the glaucoma classification are demonstrated for HRT and GDx. RESULTS: Agreement between clinical evaluation and HRT was moderate (Cohen's kappa = 0.43), there was no significant over- or underdiagnosis by HRT (p = 0.48). Agreement between clinical evaluation and GDx (diagnosis of glaucoma when "the number" > 50) was bad (Cohen's kappa = 0.27) with a significant overdiagnosis by GDx compared to clinical evaluation (p < 0.05). Agreement between clinical evaluation and GDx (diagnosis of glaucoma when "the number" > 40) was better (Cohen's kappa = 0.54), there was no significant over- or underdiagnosis by GDx (p = 0.79). ROC curves for glaucoma classification showed no difference between HRT and GDx (area under the curve: HRT = 0.8, GDx = 0.78). CONCLUSIONS: Because of the only moderate agreement between clinical evaluation on the one hand and HRT and GDx classification on the other hand for the discrimination between glaucoma and non-glaucoma, the clinician should not completely rely on the instrument-derived glaucoma classification.

Aged↗

Endotoxins in ophthalmic viscosurgical devices.

PURPOSE: To measure the endotoxin concentration (EC) of 25 commercially available, hyaluronic acid- and hydroxypropylmethylcellulose-based (HPMC) ophthalmic viscosurgical devices (OVDs). METHODS: The in vitro Limulus amebocyte lysate (LAL) assay, which indicates the presence of endotoxins originating from gram-negative bacteria, was used to determine the EC. The procedure was performed according to the European Pharmacopoeia/USP. EC including duplicate determinations, negative controls, dilution series with control standard endotoxin, dilution series with sample extract and positive sample control. RESULTS: 16 OVDs (Amvisc, Amvisc Plus, Biolon, Coatel, Healon, Healon GV, Healon, HPMC Ophtal L, Microvisc, Microvisc Plus, Ocucoat, Provisc, Rayvisc, Viscoat, Visco Shield 2%, Visko 1.4%) had an EC under 1.2 endotoxin units/mL, five (Adatocel, HPMC Ophtal H, LA Gel, Viscorneal, Viscorneal Plus) had an EC > or = 1.2 and < or = 24 EU/ml, and four (Biocorneal, Dispasan also named Ophthalin, Dispasan Plus, Visko 1%) had an EC of > 24 EU/ml. DISCUSSION: To avoid viscoelastic-related inflammatory or immunological reactions, the use of pure OVDs is recommended, especially for surgical procedures with an inherent possibility of leaving viscoelastic remnants in the eye (e.g., cataract surgery, visco-canalostomy or penetrating keratoplasty).

Endophthalmitis↗

Immunological effects of allopurinol in the treatment of experimental autoimmune uveitis (EAU) after onset of the disease.

PURPOSE: Allopurinol reduces oxidative tissue damage and exerts immunomodulating effects in the treatment of experimental autoimmune uveitis (EAU). However, the mechanism of the immunologic pathway remains unclear. In previous studies, treatment was started at the time of immunization. Therefore, whether allopurinol prevents the onset of the disease (i.e., acts in a protective manner) is not known. METHODS: Sixteen male Lewis rats were used: 6 EAU without therapy [control]; 4 EAU with allopurinol treatment starting 7 days after immunization [AL7]; and 6 EAU with allopurinol treatment starting 11 days after immunization [AL11]. Their sera were tested against Western blots of sodium dodecyl sulfate-polyacrylamide gel electrophoresis of retinal proteins. Based on digital image analysis, analysis of discriminance was done. RESULTS: There were significant immunomodulating effects in both therapy groups (Wilks' lambda 0.001, P < 0.008) compared to controls. However, the effects were more pronounced in the AL7 group, where peak intensities and the number of peaks were markedly more reduced. CONCLUSIONS: Immunomodulating effects of allopurinol can be detected even if the therapy starts after the onset of the disease. Thus allopurinol strongly influences the immunologic mechanism in this model of autoimmune disease. In view of its minimal side effects, the drug could be a promising alternative for the therapy and prophylaxis of uveitis and other autoimmune diseases.

Adjuvants, Immunologic↗

Changes in the tear proteins of diabetic patients.

BACKGROUND: Previous studies have shown a significant increase in tear protein peaks in the tears of diabetic patients suffering from dry eye. The aim of this study was to analyze the tear protein patterns from patients with diabetes mellitus who do not suffer from ocular surface diseases (DIA). METHODS: A total of 515 patients were examined in this study (255 healthy subjects (controls) and 260 patients suffering from diabetes mellitus). Tear proteins were separated by sodium-dodecyl-sulfate polyacrylamide gel electrophoresis. After digital image analysis densitometric data files were created and subsequently used for multivariate statistical procedures. RESULTS: A significant increase in the number of peaks was detected in diabetic patients compared to controls (P < 0.0003). The analysis of discriminance revealed a highly significant discrimination between diabetic patients and controls (Wilks lambda: 0.27; P < 0.000001). Furthermore, a significant difference in the protein pattern of diabetic patients could be detected between those suffering from dry eye or not (P < 0.002). The changes in protein patterns of diabetic patients increased with the duration of the diabetic disease. In diabetic patients with a disease duration longer than 10 years the changes were significantly more expressed than in patients with a shorter diabetic history (P < 0.003) and in healthy subjects (P < 0.0001). CONCLUSIONS: The tear protein patterns of diabetic patients are very different in the number and intensity of spots from those of healthy subjects. Furthermore, it could be demonstrated that the differences found in the tear patterns of diabetic patients are not equal to those found in previous studies in patients suffering from dry-eye disease. The alterations in the diabetic tears were correlated with the duration of the diabetic disease. With longer disease, history changes in the tear protein patterns increased. With the course of the disease some protein peaks appeared that are not present in healthy persons. Our study shows that the analysis of electrophoretic tear protein patterns is a new non-invasive approach in the early diagnosis and analysis of the pathogenesis of diabetes induced ocular surface disease.

Diabetes Mellitus↗

[The relationship between retrobulbar blood flow velocity and glaucoma damage. An intraindividual comparison].

BACKGROUND: Glaucomatous optic nerve damage is thought to be influenced by ocular perfusion. The aim was to investigate if a difference in visual field and Heidelberg retinal tomography (HRT) between two eyes of an individual glaucoma patient is reflected in different blood flow velocities in retrobulbar vessels. METHODS: Data from 53 patients including 26 normal tension glaucoma patients (NTG) and 27 high tension glaucoma patients (HTG) were evaluated retrospectively. In 38 patients asymmetric glaucomatous damage (AGD) could be demonstrated by both structural (HRT) and functional measures (static or Goldmann perimetry). In 15 patients there was symmetric glaucomatous damage (SGD). To discriminate between AGD and SGD we used a score for HRT and visual field. Color Doppler imaging (CDI) was performed with a Siemens Quantum 2000. RESULTS: No significant differences were found when comparing group means of intraindividual deviation of CDI in patients with AGD vs. SGD. Overall analysis of CDI values in NTG vs. HTG eyes also showed no significant differences. Nevertheless we measured decreased blood flow velocities for NTG compared to HTG eyes especially in short posterior ciliary arteries, peak systolic and end diastolic velocities. CONCLUSIONS: A simple correlation between retrobulbar blood flow velocities and glaucomatous damage could not be found. However, color Doppler images can give important additional information in the diagnosis of glaucoma, especially normal tension glaucoma.

Adult↗

The efficacy and safety of unfixed and fixed combinations of latanoprost and other antiglaucoma medications.

Adjunctive therapy for the management of glaucoma is commonly used. Unfixed combinations of the prostaglandin analog latanoprost and other glaucoma medications have been demonstrated to effectively lower intraocular pressure (IOP). The range of reported additional reductions in IOP compared to a monotherapy baseline are as follows: latanoprost-timolol (13-37%), latanoprost-pilocarpine 2% (7-14%), latanoprost and carbonic anhydrase inhibitors (15-24.1%), and latanoprost and dipivefrin (15-28%). There is a fixed combination of latanoprost (0.005%) and timolol (0.5%) that has been investigated in Phase III trials in Europe and the United States. In these trials, it was noted that the efficacy of the fixed combination was superior to either of the monotherapy components. After 12 months of follow-up of patients on fixed combination, there was no evidence of long-term drift. The new formulation appears to be safe and does not demonstrate any more side effects than either of the components. The convenience of a fixed combination may enhance patient compliance. Unfixed combination therapy with latanoprost and other antiglaucoma medications and the fixed combination formulation of latanoprost and timolol provide an effective and safe option for lowering IOP in glaucoma patients.

Adrenergic beta-Antagonists↗