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Biomedical subjects

W Wiegand

Publications and source records attributed to W Wiegand.

At least 19 recordsLinked to original sources
PubMed2006

[Intraocular pressure and corneal thickness. A comparison between non-contact tonometry and applanation tonometry].

OBJECTIVE: Corneal thickness and deformation seem to have a considerable influence on intraocular pressure measurement. Due to differences in the corneal deformation in either non-contact tonometry or applanation tonometry, both methods should be compared in the same patient group depending on central corneal thickness. METHODS: In 106 eyes of 55 patients (18 males, 37 females, age 17-89 years, mean 63.3 years) with glaucoma and central corneal thickness between 409 and 644 microm (Orbscan II pachymetry) intraocular pressure was measured in each eye with non-contact tonometry (Reichert AT550) and 30 min later with Goldman applanation tonometry. RESULT: Non-contact tonometry as well as applanation tonometry showed a positive correlation between measured intraocular pressure and corneal thickness. The steepness of the line of regression was 0.33 mmHg per 10 microm of corneal thickness in non-contact tonometry and 0.17 mmHg per 10 microm of corneal thickness in applanation tonometry. CONCLUSION: Independently of the large differences in individual pressure measurements between non-contact tonometry and applanation tonometry, we found higher IOP values with non-contact tonometry in thicker corneas as compared with applanation tonometry. In thinner corneas there was a better correspondence between both methods. Thus, it seems very likely that corneal rigidity increases with corneal thickness.

Adolescent↗
PubMed2006

[Bilateral serous detachment of the neurosensory retina and retinal pigment epithelium with rip of the peripheral pigment epithelium].

HISTORY: A 52-year-old patient with atypical plasmocytoma presented with a bilateral serous detachment of the retina as well as a huge detachment of the pigment epithelium (PE) in the periphery. Shortly thereafter the PE ruptured. In the left eye this led to substantial central macular fibrosis. DIAGNOSIS: The clinically healthy patient showed a nephrotic syndrome; neither typical monoclonality was detectable nor was erythropoiesis or myelopoiesis reduced. THERAPY: To avoid further reduction of VA pars plana vitrectomy (ppV) with silicone oil tamponade and laser coagulation was performed. Clinical findings were reduced significantly and VA was stabilized for 2.5 years. DISCUSSION: PE detachments and serous retinal detachments in patients with nephrotic syndrome are only mentioned in a few cases. However, a peripheral rupture of the PE to this extent seems to be very rare. Early ppV with silicone oil and laser coagulation may prevent further macular fibrosis.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2005

[Anatomical and functional results after elective macular surgery].

PURPOSE: The purpose of this paper is to assess the anatomical and functional results after macular surgery in a large group of patients. METHODS: Between June 1995 and December 2001, 381 eyes underwent vitreous surgery for macular pucker (n=244) or macular holes (n=137) with a standard pars plana vitrectomy (PPV) with induction of posterior vitreous separation, membrane peeling, peeling of the internal limiting membrane (no ICG staining was used), and gas instillation (SF(6)). RESULTS: A second surgical intervention due to vision-threatening complications after PPV had to be performed in 8 of 381=2.1%. In the macular pucker group, metamorphopsias improved in 46.6% and the median of visual acuity (VA) improved from preoperative 0.3 to postoperative 0.5. Hole closure of macular holes was obtained in 92.2%; the median of VA improved in this group from preoperative 0.2 to postoperative 0.4. CONCLUSION: In our group a second vitreoretinal procedure due to vision-threatening complications had to be performed in 2.1%. Compared to the spontaneous course, PPV for macular pucker or macular hole has a very positive influence on functional parameters.

Aged↗
PubMed2005

[Analysis of optical parameters after cataract surgery and implantation of foldable lens].

PURPOSE: Within the first few weeks after cataract surgery, changes of refraction can occur in patients with "clear cornea" surgery and implantation of foldable lenses. The possible reasons were analyzed. METHOD: In 71 consecutive patients we determined axial length, anterior chamber depth, corneal refraction, and corneal thickness prior to cataract surgery, on the 1st postoperative day, and at a follow-up control after obtaining stable refraction. We divided the patients into three groups: patients with no change of refraction between the 1st postoperative day and the follow-up (group A), patients with hyperopic shift of refraction (group B), and patients with myopic shift of refraction (group C). RESULTS: In all three groups we measured no significant postoperative change of the axial length. Central corneal thickness increased by approximately 37 microm on the 1st postoperative day and had normalized at the time of control. Anterior chamber depth decreased in all groups by approximately 0.44 mm between the 1st postoperative day and the follow-up. Central corneal refraction showed an decrease in groups B and C and an increase in group A. The standard deviation was very high in all groups. CONCLUSIONS: The postoperative change of refraction depends on multiple factors among which changes of the anterior chamber depths, the corneal refraction, the swelling of the cornea, and the axial length can play a role.

Cataract↗
PubMed2005

[Theoretical basis of goldmann applanation tonometry].

For more than 50 years Goldmann applanation tonometry has been the internationally accepted method for measuring intraocular pressure. In Goldmann applanation tonometry, however, some basic physical properties are oversimplified and the method has some flaws and restrictions. This paper is intended to promote the understanding of the methodological basis of Goldmann applanation tonometry and describes the most important factors influencing the measurement of intraocular pressure (e. g., corneal thickness, corneal radius, axial length and corneal morphology). Furthermore, the basic principles of other commonly used tonometer devices will be discussed. New developments are anticipated that will measure the true intraocular pressure more accurately than Goldmann applanation tonometry.

Equipment Design↗
PubMed2005

[Corneal pachymetry and intraocular pressure].

Just recently studies on glaucoma have emphasised the significance of intraocular pressure in the diagnosis of glaucoma and the importance of intraocular pressure reduction in the management of glaucoma. Central corneal thickness appears to play an important role in the exact measurement of intraocular pressure and in the diagnostic assessment of glaucoma. Numerous studies have verified that corneal thickness shows systematic differences in different forms of glaucoma. Since deviations of corneal thickness from normal can possibly result in an artificial change of Goldmann applanation values, it would be a most important source of error in the diagnosis of glaucoma to ignore central corneal thickness. Corrections of intraocular pressure measured with applanation tonometry can be achieved in various ways but there is considerable divergence in the results. The absence of a generally accepted algorithm for the correction of intraocular pressure measured with applanation tonometry should not prevent us from a wide application of pachymetry, since it delivers valuable additional information on the individual risk of glaucoma.

Cornea↗
PubMed2004

[Psychiatric-psychotherapeutic inpatient treatment for depression. Process and outcome quality based on a model project in Baden-Wurttemberg].

During 1998-2000 a quality assurance program for diagnosis and treatment of depression was conducted in 24 hospitals for psychiatry and psychotherapy in Baden-Wurttemberg (southern Germany). Process and outcome quality of 3,000 depressive patients was documented at admission and discharge. The article focuses on therapeutic measures, duration, outcome, patient satisfaction, and their interactions. The results show that the patients' satisfaction with the care received is very high and the pre-post effect sizes of inpatient treatment for depression are high.

Adjustment Disorders↗
PubMed2004

[Vitreoretinal secondary procedures following elective macular surgery].

OBJECTIVE: The spectrum of reoperations after macular surgery was investigated retrospectively in a large group of patients. All secondary surgical procedures except for cataract surgery were considered. METHODS: Between July 1995 and June 2001 353 eyes underwent macular surgery (218 due to macular pucker, 135 due to macular hole) with a pars-plana vitrectomy (PPV), creation of vitreous detachment, membrane peeling and SF(6)/air-instillation. The vitrectomies were performed by 4 different surgeons. In all patients a preoperative circular peripheral cryoretinopexy was performed 3-4 weeks before macular surgery. The follow-up was 20.9 months on average. The number of revitrectomies as well as the postoperative retinal detachment rate were investigated. RESULTS: In 33 cases (9.3%) a second vitrectomy had to be performed due to an unsatisfying postoperative macular finding: 17/218 (7.8%) after macular pucker surgery with a recurrent pucker and 16/135 (11.8%) after macular hole surgery with persistent or recurrent macular hole. In 7/353 (2.0%) a postoperative rhegmatogenous retinal detachment was observed and in 2/353 (0.6%) a postoperative endophthalmitis had to be treated. CONCLUSION: In 9.3% of our patients a second PPV due to an unsatisfying macular finding became necessary. The rate of postoperative retinal detachment of 2.0% is considerably lower than in most other studies. Therefore, a possible prophylactic effect of the preoperative circular peripheral cryoretinopexy is suggested to reduce the risk of postoperative retinal detachment.

Elective Surgical Procedures↗
PubMed2004

[Intraocular pressure after cyclophotocoagulation with the diode laser].

BACKGROUND: The reduction of intraocular pressure (IOP) following a single cyclophotocoagulation (CPC) procedure with a diode laser was investigated retrospectively. METHOD: CPC was performed on 150 eyes with a diode laser using standard parameters. The decrease of IOP between the 1st and 3rd day after surgery, after 6 months and after 1 year was investigated for different types of glaucoma and complications were documented. RESULTS: Overall and also in the individual groups the mean reduction of IOP within the first 3 days postoperation was 35%. The main effect, however, occurred within the 1st day after CPC. In the long-term results for 6 months and 1 year, the mean pressure values remained relatively stable but with a high standard deviation. A postoperative inflammatory reaction in the anterior chamber was observed in 15 eyes, 1 eye showed a temporary hypotension and 2 eyes a phthisis. Success of CPC was almost identical in all treatment groups with a 38% decrease of IOP after the 1st year. Additionally IOP was stable at a low level during the 1st year after CPC. After 1 year 42% of all eyes were still successfully treated: 38% of eyes needed further CPC treatment. CONCLUSIONS: CPC is an effective procedure for surgical reduction of intraocular pressure. The initial pressure-reducing effect of CPC was not related to the type of glaucoma. The individual predictability of the effect of CPC, however, is difficult because of the high interindividual differences. The rate of complications is low.

Ciliary Body↗
PubMed2004

[Measurement of corneal thickness in glaucoma patients].

BACKGROUND: For the past 5 decades, Goldmann's applanation tonometry has been the basis for measurement of intraocular pressure. In this process, it is assumed that the corneal architecture-and particularly corneal thickness-does not have significant influence on the applanation tonometry. The aim of this study was to assess central corneal thickness in patients with primary open angle glaucoma (POWG), normal tension glaucoma (NDG), and ocular hypertension (OHT) compared to the central corneal thickness of control subjects. METHOD: In 200 consecutive glaucoma patients corneal pachymetry was performed with the Orbscan II system and a pachymetry map was obtained. Simultaneously, corneal pachymetry was also performed in 200 age- and sex-matched control subjects. To avoid diurnal variations the pachymetry measurements were performed at the same time of the day. RESULTS: The central corneal thickness (CCT) distribution turned out to be a near-Gaussian curve in patients with glaucoma and in the control subjects. The mean CCT in glaucoma patients was 561+/-49.4 micro m with a minimum of 448 micro m and a maximum of 732 micro m. In control subjects the mean CCT was 555.9+/-34.6 micro m with a minimum of 480 micro m and a maximum of 635 micro m. Further evaluation of CCT of glaucoma patients demonstrated that the CCT in patients with POWG was 559.5+/-43.5 micro m, in patients with NDG was 530.3+/-51.1 micro m and with OHT was 624.2+/-25.4 micro m. CONCLUSIONS: Central corneal thickness in patients with OHT was significantly greater, and in patients with NDG significantly lower, compared to control subjects. In defining the desired intraocular pressure in glaucoma patients, in the future CCT measurements should be considered along with intraocular pressure measurement and visual field analysis.

Adult↗
PubMed2004

[Individual postoperative refraction after cataract surgery -- a comparison of optical and acoustical biometry].

BACKGROUND: Optical biometry with the IOL-Master is an innovative technique that claims to improve the refractive results of cataract surgery compared to acoustical biometry. METHODS: In 140 consecutive non-selected eyes prior to cataract surgery firstly an optical biometry (IOL-Master, Zeiss, V.2.02) and secondly an ultrasound biometry (Sonomed) were carried out. Cataract surgery was performed using either a PMMA-IOL (n = 56) or an acrylic IOL (n = 84). The PMMA-IOL's were implanted in the capsular bag via a scleral tunnel. The acrylic-IOL's were implanted via a clear cornea incision in the capsular bag. The length of the globe was analysed and the deviations between the postoperative refraction after 3 month and the preoperative planned refraction were compared. RESULTS: The mean axial length difference between optical biometry and acoustical biometry was 0.19 mm in the PMMA-lens group and 0.16 mm in the acrylic-lens group. The deviation of postoperative refraction (spherical mean) from the planned refraction was 0.46 +/- 0.88 D in the PMMA-IOL group and 0.25 +/- 0.77 D in the acrylic IOL group when biometry was performed by ultrasonography. When optical biometry was performed the respective values were 1.15 +/- 0.83 D in the PMMA-IOL group and 0.84 +/- 0.75 D in the acrylic IOL group. The differences in mean postoperative refraction of optical and acoustical biometry can be compensated by adaptation of the A constants. The standard deviation of the difference between the postoperative refraction and the preoperatively planned refraction - that means the individual deviations between postoperative refraction and preoperatively planned refraction - were almost identical in optical and acoustical biometry. CONCLUSION: Optical biometry represents a significant simplification in the course of investigation prior to cataract surgery. The claim of optical biometry, however, to gain a higher precision and thus a significantly better prediction of individual postoperative refraction after cataract surgery is not yet fulfilled.

Acrylates↗
PubMed2003

["Refractive" cataract surgery. PMMA IOLs versus foldable IOLs].

OBJECTIVE: Modern cataract surgery claims to achieve the desired refractive result immediately after surgery. METHODS: In 104 consecutive patients who were operated on with phacoemulsification and scleral incision and received a 6 mm PMMA IOL and in 70 consecutive patients operated on with temporal clear cornea incision and implantation of a foldable 6 mm IOL (Acrysof) visual acuity, refraction and astigmatism were determined preoperatively, between days 1 and 3 postoperatively and controlled again at least 5 months after surgery. The results were compared with the desired preoperative refraction. RESULTS: At days 1-3 postoperatively,a deviation of not more than +/-1.0 D (spherical equivalent) from the desired refraction occurred in 73.1% of the PMMA IOL patients and in 77.2% of the foldable IOL patients. At control 76.0% of the PMMA and 85.7% of the foldable lens patients showed a deviation of not more than +/-1.5 D,88.5% of the PMMA and 98.6% of the foldable lens patients showed a deviation of not more than +/-1.5 D and 96.2% of the PMMA and 100% of the foldable lens patients showed a deviation of not more than +/-2.0 D from the desired refraction. The individual changes of the refraction (spherical equivalent) between the first and the third postoperative day and the time of control, however,were considerable and reached more than +/-1.0 D in 20.0% of the foldable lens patients and 16.3% in the PMMA lens patients. Only 6.7% of the patients in the PMMA lens group and not more than 12.8% patients of the foldable lens group showed no change of refraction (spherical equivalent). CONCLUSION: The goal of modern cataract surgery, which is to achieve a stable refraction corresponding to the desired preoperative refraction immediately after surgery, has not yet been achieved. At present the refractive changes in scleral incision techniques as well as in clear cornea techniques make an immediate postoperative prescription of glasses impossible.

Aged↗
PubMed2000

[Haze and regression after photoreactive keratectomy (PRK)].

UNLABELLED: According to the recommendations of the German Ophthalmological Society (DOG), PRK in myopic patients between -1.0 dpt and -6.0 dpt is a scientific acknowledge treatment. The risks of the treatment, however, increase in myopia above -6.0 dpt. MATERIAL AND METHODS: Between june 1994 and october 1997 we performed PRK on 338 eyes from 212 myopic patients in the ALZ Eye Clinic Hamburg. Myopia ranged between -1.25 and -11.25 diopters. All treatments were performed with the Keracor 116 (Fa. Chiron Technolas). The procedure was the same in all cases: mechanical abrasion, excimer laser treatment, antibiotic and nonsteroidal antiphlogistic drops for three days followed by a corticosteroid therapy for 5 months. RESULTS: Out of these 338 eyes, 17 eyes after 12 months had a persistent haze grade 1-2 or more according to Stein, Cheskes and Stein. These 17 eyes had also an average regression of -1.67 diopters (SD 1.8) and lost at least in minimum two lines of the best corrected visual acuity 12 months postoperatively. The refraction of the 17 eyes was more than -6 dpt preoperatively. CONCLUSION: Haze after PRK is in most cases only transient. Haze of grade 1-2 or more after 12 months postoperatively is correlated with regression and a loss of best corrected visual acuity. PRK below -6 dpt in our hands never showed haze grade 1-2 or more 12 months postoperatively. Therefore patients with a refraction of more than -6 dpt before PRK should be informed about this potential risks. In these cases LASIK should be taken into consideration.

Adult↗
PubMed1999

Vitreopapillary traction in proliferative diabetic vitreoretinopathy [ssee comments].

AIM: To present the clinical profile of a new entity in advanced proliferative diabetic vitreoretinopathy (PDVR). Mechanisms of vision loss due to vitreopapillary traction on the nasal optic disc are described, followed by an introduction of methods for prevention and treatment in such cases. METHODS: 17 patients with PDVR and traction on the nasal side of the optic disc, pallor of the optic nerve head, and reduced visual acuity were included in the study. Six patients were observed retrospectively and 11 patients prospectively before and after pars plana vitrectomy. Pre- and postoperative examinations included visual acuity, Goldmann's visual field, fluorescein angiography, and measurements of visual evoked potentials (VEP). RESULTS: During a postoperative follow up period of 3 to 24.5 months (mean 14.5 months) an improvement in optic disc appearance combined with an increased visual acuity (mean increase in VA = 0.171) was observed in 15/17 (88.3%) patients. In addition, 8/17 (47%) of these patients showed higher VEP amplitudes (mean 3.83 microV), and eight (6/8 of the same patients as VEP amplitudes) patients showed a reduction of latency (mean reduction 22.25 ms) during VEP assessment. CONCLUSION: These results suggest that vitreopapillary traction may damage the anterior optic nerve, via decreased axoplasmatic flow in the optic nerve fibres and/or mechanical reduction of perfusion in the posterior ciliary arteries. The effects of each mechanism appear to be reversible, but in the long term might lead to irreversible optic nerve atrophy. Therefore, in patients with vitreopapillary traction, early vitrectomy should be considered as a method to prevent optic neuropathy.

Adult↗
PubMed1998

[Change in twilight vision and glare sensitivity after PRK].

BACKGROUND: Morphological changes in the corneal surface after PRK may result not only in refraction fluctuations and reduction in visual acuity, but also in changes of contrast sensitivity. The aim of this study was to investigate whether PRK has an influence on contrast sensitivity with and without glare with a subsequent effect on the ability to drive cars. PATIENTS AND METHODS: Anonymous inquiries were made by means of a questionnaire sent to 114 patients after bilateral PRK in which the patients were asked to assess subjectly their driving ability. Additionally, in 66 eyes of 66 patients with a mean myopia of -5.3 D, an investigation on contrast sensitivity was performed according to the recommendations of the DOG (German Ophthalmological Society) using a Rodenstock nyctometer. RESULTS: Postoperatively, 55% of the patients felt more comfortable driving a car than preoperatively, 31% did not recognize any change, and 14% felt more uncomfortable driving car. Contrast sensitivity with or without glare 2 weeks postoperatively was so much reduced in 77% or 53%, respectively, of the patients that the criteria for driving a car in Germany were not fulfilled. Within the first 12 months after PRK the number of impaired patients diminished but even 1 year after PRK the number of patients with reduced contrast sensitivity with and without glare was higher than before PRK. Surprisingly, however, the criteria for driving a car with respect to contrast sensitivity with and without glare were not fulfilled even before PRK by as much as 44% and 24% of the patients, respectively. CONCLUSIONS: All patients must be in formed about the possible impairment for driving a car before PRK is performed.

Adult↗
PubMed1997

[Measuring device for determining monochromatic aberration of the human eye].

BACKGROUND: After refractive or cataract surgery, ocular optical errors can occur that are not correctable with spherical or astigmatic lenses and are probably responsible for the fact that in many cases the best possible (retinal) acuity is not achieved in spite of an optimum refraction. Assessment of these aberrations in the clinical routine is an important first step towards documentation and correction of these errors with modern photorefractive methods. PRINCIPLE OF MEASURING: Ocular optical errors are assessed from the viewpoint of the wave property of light as an aberration of the real wavefront of a central retinal image point from the ideal spherical from (wavefront aberration). The measurement is based on the principle of the Tscherning aberroscope. RESULTS: A test setup is presented consisting of a laser system, a CCD fundus camera and a PC. A bundle of parallel equidistant rays is refracted by means of a lens in front of the eye producing an equivalent pattern of light spots on the retina. This pattern is more or less distorted according to the ocular aberrations. The deviations of all spots from their ideal (equidistant) positions are measured by means of the PC and from these values the wavefront aberration is computed in the form of Zernike and Taylor polynomials. The first results of emmetropic eyes are presented. CONCLUSIONS: The method allows sufficiently accurate assessment of the ocular wavefront aberration and might be on principle suitable for clinical use, provided that some technical improvements are installed.

Adult↗
PubMed1996

Prognostic value of magnetic resonance imaging in monosymptomatic optic neuritis.

PURPOSE: Magnetic resonance imaging is able to depict lesions in the optic nerve in the acute stage of monosymptomatic optic neuritis. Most patients have lesions located intraorbitally, intracanalicularly, and/or intracranially. The goal of this study is to determine whether these lesions resolve after visual recovery, change in length or localization, or could be correlated to the visual function. METHODS: Between 1987 and 1992, the authors examined 22 patients with acute optic neuritis using magnetic resonance imaging short-time inversion recovery sequences. Additionally, the authors determined visual acuity, visual field, color vision, contrast sensitivity, and visual-evoked responses. All patients were re-examined between 1993 and 1994 in the same manner. Visual recovery in the re-examination was divided into three groups: group 1 with complete visual recovery (visual acuity better than 20/25); group 2 with incomplete recovery (visual acuity better than 20/25 but defect in at least one of the other tests: visual field, color vision, and contrast sensitivity); and group 3 with partial recovery (visual acuity remained less than 20/25, defect in all the other tests). RESULTS: All group 1 patients initially had lesions less than 17.5 mm, group 2 patients had lesions greater than 17.5 mm (44%) and/or lesions located intracanalicularly (66%), and most of group 3 patients initially had lesions greater than 17.5 mm (79%). CONCLUSION: Eyes with lesions less than 17.5 mm in the optic nerve in acute optic neuritis have a good prognosis for visual recovery. Lesions greater than 17.5 mm or lesions involving the intracanalicular portion of the optic nerve lead to incomplete or partial visual recovery.

Acute Disease↗