Biomedical subjects

Carl Erb

Publications and source records attributed to Carl Erb.

12 recordsLinked to original sources

PubMed2007

Age-related changes in central and peripheral corneal thickness: determination of normal values with the Orbscan II topography system.

PURPOSE: The thickness of corneal tissue is an important parameter in refractive surgery, Goldmann applanation tonometry, and corneal diseases. The purpose of the study was to record system-specific normal values with the Orbscan II system and to investigate the influence of sex and age on central and peripheral corneal thickness to characterize more precisely the anatomy of the cornea. METHODS: The Orbscan II topography system is a computer-assisted slit-beam scanning technology that can map the anterior section of the eye. It was used to take 2 measurements at 10-minute intervals on 777 eyes of 390 normal white subjects ranging in age between 10 and 80 years. Two hundred forty-two participants were men and 148 were women. The central corneal thickness and the nasal, superior, inferior, and temporal peripheral corneal thickness at a distance of 3 mm from the center were analyzed. No correction factor was used. Using nonparametric test methods, we carried out a statistical analysis of the parameters of sex and age. RESULTS: The mean central corneal thickness of all 777 eyes was 595 +/- 41 microm. No sex-specific central difference was identifiable (P = 0.33), there was no significant difference between the sides (P = 0.23), and no significant difference was found between the first and second measurement. The group of 10- to 39-year-olds had a mean central corneal thickness of 591 +/- 41 microm, whereas that of 40- to 80-year-olds was 600 +/- 39 microm, which was a significant difference (P = 0.03). The mean peripheral corneal thickness was 689 +/- 46 microm nasally, 688 +/- 42 microm superiorly, 667 +/- 40 microm inferiorly, and 655 +/- 42 microm temporally. Nasally and superiorly, we found a significant negative correlation with age (Spearman rank correlation, P = 0.02). CONCLUSIONS: The normal values presented here are a suitable reference basis for future studies in whites. Peripheral corneal thickness is asymmetric and seems to undergo age-related anatomic changes. This information should be considered when planning penetrating keratoplasty and refractive surgery.

Adolescent↗

PubMed2005

White-to-white corneal diameter: normal values in healthy humans obtained with the Orbscan II topography system.

PURPOSE: The corneal horizontal diameter (white-to-white) is abnormal in diseases like microcornea, relative anterior microphthalmos, and corneal dystrophies. Because normal values are described imprecisely in the literature, the purpose of this study was to reevaluate the horizontal corneal diameter as a scientific parameter. METHODS: The horizontal corneal diameter was measured with the Orbscan II system in 370 right eyes and 373 left eyes of 390 healthy white subjects aged 10-80 years. There were 148 female subjects and 242 male subjects. Each measurement was repeated twice. Differences in gender, between right and left eyes, and age-related alterations were analyzed statistically. RESULTS: The average corneal diameter was 11.71 +/- 0.42 mm. The average corneal diameter was 11.77 +/- 0.37 mm in males compared with 11.64 +/- 0.47 mm in females. The resulting normal ranges were 11.04 to 12.50 for males and 10.70 to 12.58 mm for females. Differences in gender were not significant in the t test for independent samples (P = 0.071). There were no statistically significant differences between right and left eyes in the t test for dependent samples (P = 0.16). Corneal diameters decreased slightly with age. CONCLUSIONS: With the obtained normal values, more precise determination of microcornea and macrocornea will be possible in the future. The horizontal corneal diameter was not significantly greater in males than in females. Further studies are needed to show the reasons for the age-related decrease in measurements.

Adolescent↗

PubMed2003

[Visual field in patients with arterial hypertension].

BACKGROUND: The aim of this study was to investigate the quantitative changes of visual field in patients with arterial hypertension using standard white-on-white perimetry. MATERIALS AND METHODS: Sixty-two patients (f : m = 33 : 29) with arterial hypertension without damage in end-organs were included and divided into three groups: Group 1: systolic/diastolic blood pressure: 120 - 139/80 - 89 mm Hg (n = 18, f : m = 14 : 4, mean age 55 +/- 13 years), group 2: systolic/diastolic blood pressure: 140 - 159/90 - 99 mm Hg (n = 24; f : m = 9 : 15, mean age 55 +/- 12 years), group 3: systolic/diastolic blood pressure: 160 - 179/100 - 109 mm Hg (n = 20; f : m = 10 : 10, mean age 55 +/- 12 years). We compared these patients with an ophthalmological and healthy control group (systolic/diastolic blood pressure < 120/80 mm Hg, n = 20, f:m = 12 : 8, mean age 55 +/- 9 years). Beside the ophthalmological examinations (visual acuity, refraction, intraocular pressure, slit lamp and fundus examination) quantitative analysis of visual field by Octopus 1-2-3 perimeter was performed. Different parameters (mean deviation (MD), mean sensitivity (MS), loss variance (LV), pattern standard deviation (PSD) and the test-duration) were statistically compared using the Mann-Whitney-U test and the Wilcoxon test. RESULTS: Hypertensive retinopathy grade I - II was found in 10 patients with arterial hypertension. Statistic analysis showed no significant difference of MD, MS, LV, PSD and test duration between the patients with arterial hypertension and the control group (Mann-Whitney-U test: p > 0.05). There was also no significant difference between the three hypertonic groups (Mann-Whitney-U test: p > 0.05). CONCLUSIONS: The examination of visual field using standard achromatic automated perimetry based on investigation of the parvocellular system. Arterial hypertension, however, does not damage this parvocellular system enough to assess disturbances in the white-on-white perimetry. Further studies are necessary to clarify the value of Frequency Doubling Perimetry, which is based on the detection of early damage of the magnocellular system.

Adult↗

PubMed2002

Plasminogen activator inhibitor-1 mRNA expression in cultured pigmented ciliary epithelial cells of the porcine eye.

BACKGROUND: Plasminogen activator inhibitor-1 (PAI-1) is a main regulator of the fibrinolytic system. PAI-1 inhibits tissue plasminogen activator and urokinase-type plasminogen activator, resulting in reduced plasminogen activity and attenuated fibrinolysis and proteolysis. The present study was performed to determine the gene expression encoding for PAI-1 in cultured pigmented ciliary epithelial cells of the porcine eye and to detect PAI-1 activity in cell culture supernatants. METHODS: Total mRNA of respective confluent primary cultures of porcine ciliary epithelial cells, porcine liver cells and porcine kidney cells was isolated. Reverse transcribed PAI-1 mRNA was measured by real-time polymerase chain reaction (TaqMan PCR) with PAI-1 primers and probes deduced from the human PAI-1 gene. PAI-1 activity in supernatants of the cell cultures was determined by a specific chromogenic test (Coatest PAI). RESULTS: PAI-1 mRNA was localized in all samples of primary cultures of porcine pigmented ciliary epithelial cells. As a negative control we analyzed total mRNA of porcine kidney cells. PAI-1 mRNA was not detectable in these cells. On the other hand, we established PAI-1 mRNA in porcine liver cells as a positive control. High levels of PAI-1 activity were found in all samples of cell culture supernatants. CONCLUSIONS: Our results indicate that PAI-1 is produced and secreted by the porcine ciliary epithelium. We suggest that PAI-1 together with components of the fibrin/fibrinolytic system may be involved in aqueous humor outflow. Overproduction of PAI-1 may induce less fibrinolysis and extracellular proteolysis in aqueous humor and trabecular meshwork, which could result in an elevated intraocular pressure by increasing the outflow obstruction. Therefore stimulation of PAI-1 production may perhaps contribute to the pathogenesis of primary open-angle glaucoma.

Animals↗

PubMed2002

Anomaloscope matches in patients with diabetes mellitus.

BACKGROUND: Functional visual deficits can occur in patients with diabetes mellitus who show no visible morphological alterations in the retina. In this study we examined the colour vision of diabetic patients using metameric matches. Patients with and without retinopathy, as well as those who had been treated with laser photocoagulation, were examined to ascertain how the functional alterations in the diabetic eye alter with disease status. METHODS: Rayleigh (red-green) and Moreland (blue-green) metameric matches were determined in a total of 51 diabetic patients (24 patients with no retinopathy, 12 patients with background retinopathy and 15 patients who had undergone laser therapy). Their results are compared to those of a control group of 25 subjects with normal colour vision. RESULTS: A deficit in blue-green colour discrimination found in patients without retinopathy becomes worse with the appearance of vascular alterations in the retina. There is also a significant shift towards green in the Rayleigh match midpoint and towards blue in the Moreland match midpoint, which is at least in part explicable by alterations in lens opacity. Patients who have undergone laser therapy show, on average, better colour discrimination than those with retinopathy, but there is a large variation in their results. CONCLUSION: The alterations in the colour vision of diabetics indicate that at least the early functional changes are occurring at an inner retinal location. Lens opacity changes also play a large role as the age of the patients increases.

Adolescent↗

PubMed2002

Short wavelength automated perimetry, frequency doubling technology perimetry, and pattern electroretinography for prediction of progressive glaucomatous standard visual field defects.

PURPOSE: To evaluate the clinical use of a test battery of short wavelength automated perimetry (SWAP), frequency doubling technology perimetry (FDT), and pattern electroretinography (PERG) in predicting progressive glaucomatous visual field defects on standard automated perimetry (SAP). STUDY DESIGN: A prospective, longitudinal, observational case series. PARTICIPANTS: One hundred and fifty-two patients with primary open-angle glaucoma (POAG) with bilateral glaucomatous visual field defects on SAP were followed at 6-month intervals over a period of 30 months. MAIN OUTCOME MEASURES: Short wavelength automated perimetry, FDT, and PERG results were compared between POAG eyes with and without progressive field loss on SAP. These two groups were used to evaluate whether PERG, SWAP, and/or FDT is predictive of future progression of field loss on SAP. RESULTS: Using the criteria of progressive field loss on SAP defined by the Collaborative Normal Tension Glaucoma Study, 54 eyes (study group) of 54 POAG patients showed progressive defects, whereas 84 eyes (control group) of 84 POAG patients showed no progression. Only 11.1% (6 of 54) of the eyes with a progression of field loss on SAP showed no increase of deficits on the three functional tests before progression. Short wavelength automated perimetry detected early progressive defects on SAP in 43 of the 54 eyes (79.6%). Of these 54 POAG eyes, FDT showed progressive deficits in 40 eyes (74.1%), whereas PERG amplitude P1N2 showed progressive deficits in 35 eyes (64.8%) before progression of field loss on SAP. A test battery consisting of SWAP and PERG P1N2-amplitude was able to detect 88.9% of eyes before a prediction of field loss on SAP. When comparing the results of the two functional tests, SWAP and FDT in the 84 eyes without progression of field loss on SAP between baseline and at 30 months, SWAP and FDT showed progressive deficits in 34.5% and 35.7%, respectively. CONCLUSIONS: All three tests (SWAP, FDT, and PERG) have been successful in detecting glaucoma eyes with a future progression of standard visual field defects. A test battery of SWAP and PERG P1N2-amplitude improved the power to predict these progressive defects on SAP. It remains to be seen whether the long-term follow-up in POAG eyes will improve the false-positive rate of SWAP and FDT.

Disease Progression↗

PubMed2002

Detection of optic neuropathy in glaucomatous eyes with normal standard visual fields using a test battery of short-wavelength automated perimetry and pattern electroretinography.

PURPOSE: To evaluate the clinical use of a test battery of short-wavelength automated perimetry (SWAP), frequency-doubling technology (FDT) perimetry, and pattern-electroretinography (PERG) in patients with definite primary open-angle glaucoma (POAG) but normal results on standard automated perimetry (SAP). STUDY DESIGN: Prospective, comparative, observational case series. PARTICIPANTS: Thirty-six patients with POAG with standard visual field defects in one eye and normal standard visual fields in the contralateral eye and 36 normal controls were enrolled. MAIN OUTCOME MEASURES: SWAP, PERG, FDT, and SAP were performed in all eyes, and global indices and amplitudes were used for statistical analysis. RESULTS: When contralateral POAG eyes with asymmetric glaucomatous damage was compared, a paired t test showed significant differences in SAP mean deviation (MD) (P < 0.0001), SWAP-MD (P = 0.0003), FDT-MD (P = 0.0008), and PERG amplitudes (P < 0.0001). When comparing between POAG eyes with normal results on SAP and normal controls, Student's t test showed significant differences for SWAP-MD (P < 0.0001), FDT-MD (P = 0.0006), PERG N1P1-amplitude (P = 0.0486) and P1N2-amplitude (P < 0.0001); receiver operating characteristic analysis revealed promising accuracy for SWAP-MD of 73.6% (P < 0.0001). SWAP-MD (P < 0.0001) and FDT-MD (P < 0.0001) correlated significantly with SAP-MD and with each other (range, P < 0.0001 to P = 0.0020). Regression analysis revealed that PERG P1N2-amplitude could improve the power of SWAP-MD from 73.6% to detect early POAG in eyes with normal results on SAP to an accuracy of 81.9%. CONCLUSIONS: A test battery of SWAP-MD and PERG P1N2-amplitude could detect glaucomatous optic neuropathy in POAG eyes with normal standard visual fields, whereas FDT-MD and SWAP-MD significantly correlated with each other and with SAP-MD. All tests were able to detect the eye with the more severe glaucomatous optic neuropathy in patients with asymmetric POAG.

Electroretinography↗

PubMed2002

[Use of memantine in progressive glaucoma. Case report].

BACKGROUND: Several animal models demonstrated that NMDA-receptor antagonists like memantine inhibit the excitotoxic action of glutamate in glaucoma. Furthermore, this also enables to slow down the degeneration of retinal ganglion cells. In the following case report we investigated the use and tolerability of memantine in a glaucoma patient. PATIENT AND METHODS: We report on a 73-year old male with progressive glaucoma damage. Treatment with memantine à 20 mg/d lasted for 6 months and was preceded by one week à 10 mg/d. Follow-ups with perimetry and VEP were performed at beginning and 2, 4, 6 and 12 months after. RESULTS: The first control showed an improvement of perimetry. The following examinations demonstrated a stabilization of perimetry and VEP. Because of side-effects there was no tolerability of a higher dose of memantine à 30 mg/d or continuation of the therapy after 6 months. CONCLUSION: Memantine seems to be neuroprotective in glaucoma patients. At present a multicentric study is under way. More results may be expected shortly.

Aged↗

PubMedDate not supplied

[Positive influence of color experience on result of color-arrangement-test Roth 28-hue (E) desaturated - a clinical study on 44 patients].

BACKGROUND: The color arrangement test can be applied for early diagnosis of diabetic retinopathy, even small confusion of colors influence clinical diagnosis. It is therefore necessary to be aware of influential factors. METHODS: Forty-four patients with color-experience (VW-Werk Wolfsburg) were included and devided in two groups: group 1: non-smokers without ophthalmological and systemic diseases (n = 27, 42+/-9 years), group 2: smokers without ophthalmological and systemic diseases (n = 17; 43+/-8 years). The control group 3 (n = 30; 42+/-4 years) included non-smokers and the control group 4 (n = 10; 42+/-8 years) smokers, both groups without color-experience, ophthalmological and systemic diseases. Besides the ophthalmological examinations (visual acuity, refraction, intraocular pressure, slit lamp and fundus examination) the color-vision was tested by the color-arrangement-test Roth 28-hue (E) desaturated monocularly under standard conditions: The background used was black cardboard, illuminated by two Osram fluorescent lamps (L36W/12LDL Daylight) providing 2000 lux at the test table. RESULTS: Ophthalmological examination in all subjects was without pathological findings. The mean error score in the non-smokers with color-experience (median+/-mean absolute deviation: 48+/-47) was lower than in the non-smokers without color experience (72+/-45; Mann-Withney-U-Test: p = 0.02). The mean error score in the smokers with color-experience (60+/-60) was lower than in the smokers without color-experience (156+/-65; p = 0.0014). No statistically significant difference was found between the measurements of the right and left eye (Wilcoxon-Test: group 1: p = 0.89; group 2: p = 0.9; group 3: p = 0.77; group 4: p = 0.87). CONCLUSION: Color experience improves the results in color-arrangement-tests like the Roth 28-hue (E) desaturated and should be considered in quantitative evaluation.

Adult↗

PubMedDate not supplied

Age-corrected normal values for perimetry.

PURPOSE: Age-corrected values are indispensable in assessing discrete changes in light difference sensitivity (LDS) when evaluating perimetric results. In order to detect incipient visual field defects, the present study aimed particularly to determine function of normal values depending on age and eccentricity. METHODS: A test group (n = 83) of ophthalmologically and clinically unremarkable subjects 18-74 years of age was examined with the 'Centerfield' perimeter. A brief introductory program was first used to familiarize each test person with the situation. Then values in the central visual field (30 degrees) were determined with a threshold-splitting program. In addition, the peripheral visual field was examined after a short break. RESULTS: Age-related normal values were calculated both as group averages and as lines of regression by statistical analysis of the resulting data. In contrast to other perimetric studies, decreases in LDS at different test points for persons aged 20 years to persons over 60 were not linear. CONCLUSIONS: Age-related normal values should be reviewed for other perimeters.

Adolescent↗

PubMedDate not supplied

Ascorbic acid as a free radical scavenger in porcine and bovine aqueous humour.

AIM: To study the antioxidant activity, UV absorption, concentration and stability of ascorbic acid (AA) in porcine and bovine aqueous humour (AH). METHODS: Porcine and bovine AH was taken within 5 min after death and frozen at -70 degrees C. The characteristic UV absorption band of AA and the concentration of AA in AH was determined by UV spectrophotometry. The antioxidant activity of AA to serve as a free radical scavenger in AH has been determined by using a novel fluorescent probe for antioxidants, the azoalkane 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO). The fluorescence lifetime and intensity of this probe reflect the concentration of dissolved antioxidants. The time-resolved fluorescence of DBO (laser excitation at 351 nm) in AH and in a neutral phosphate-buffered saline (PBS) solution containing only the natural amount of AA as an additive were measured. RESULTS: The characteristic UV absorption band of AA has its maximum at 266 nm in AH. The concentration of AA in porcine and bovine AH was found to be 0.547 +/- 0.044 and 1.09 +/- 0.16 mM, respectively, by spectrophotometry. The fluorescence lifetime of the probe DBO was reduced from 320 +/- 5 ns in pure aerated PBS to 205 +/- 5 ns in porcine AH and 165 +/- 3 ns in bovine AH. A detailed kinetic analysis of the lifetime shortening suggests that AA contributes approximately 75 and 85% to the antioxidant activity of porcine and bovine AH, respectively. CONCLUSIONS: Our experiments suggest that AA is the major contributor to the antioxidant activity of porcine and bovine AH. The role of AA to serve as an antioxidant in AH is discussed. In addition, UV spectrophotometry is established as an alternative method to determine the concentration of AA in AH.

Animals↗

PubMedDate not supplied

Comparison of intraocular pressure measurements with the digital tonometer TGDc-01 'PRA' and the Goldmann applanation tonometer.

BACKGROUND: To compare intraocular pressure (IOP) measurements obtained with the digital tonometer TGDc-01 'PRA' with those from a Goldmann applanation tonometer (GAT). METHODS: The IOP in 176 eyes of 88 healthy volunteers was measured prospectively in a sitting position. One single measurement, generated by the TGDc-01 PRA, was compared with a single reading from the GAT. RESULTS: Mean IOP values were 13.0 +/- 3.7 mm Hg for the TGDc-01 PRA (range, 4-22 mm Hg) and 14.9 +/- 3.2 mm Hg for the GAT (range, 8-27 mm Hg). The mean difference was 1.9 mm Hg with a standard deviation of 2.77 mm Hg, and this was statistically significant (p < 0.001, paired t test). CONCLUSIONS: In comparison to the GAT, the TGDc-01 PRA underestimated IOP on an average of 1.9 mm Hg. Only 50.6% of all measurements were within the +/-2 mm Hg difference range. Thus, the TGDc-01 PRA has no high coincidence degree with the GAT. Both methods were not equivalent.

Adolescent↗