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Biomedical subjects

M Reim

Publications and source records attributed to M Reim.

At least 73 records · Page 4Linked to original sources
PubMed1995

Remarks on the vitality of the human cornea after organ culture.

The purpose of this study was to obtain further information on the viability of organ-cultured human cornea. We thus used a specific staining method for succinate dehydrogenase (SDH), which is located in the membrane system of vital mitochondria. We examined fresh and long-term-cultured human corneas. After an initial incubation period in dextran-free culture medium, corneas were stored in a medium containing dextran. With respect to different appearances of the SDH staining, minimal essential medium without dextran seems to have a positive effect on the condition of epithelial cells. After renewal of the medium, keratocytes showed a brief improvement followed by a delayed deterioration, while the endothelial cells were severely damaged. However, best results for all three cell types were observed on the fourth day in a medium containing dextran. We therefore conclude that these corneas were best suited for transplantation.

Adolescent↗
PubMed1995

Protein C, protein S, and antithrombin III in acute ocular occlusive diseases.

Hereditary and acquired deficiencies of protein C, protein S, and antithrombin III are important risk factors of thrombosis, especially in peripheral veins. In a prospective study, concentrations of these factors were measured to determine the prevalence of deficiencies of these proteins in ocular vascular occlusive disease. A total of 167 patients with acute retinal arterial (28%) or venous occlusion (55%) or ischemic optic neuropathy (17%) were included. Exclusion criteria were anticoagulant therapy, renal insufficiency, and hepatic disease. The mean values obtained for all patients were in normal range (protein C, 102 +/- 25%; protein S, 109 +/- 22%; antithrombin III, 23.6 +/- 3.1 IU/ml). Antithrombin III was pathologically reduced in one patient with branch venous occlusion. Proteins C and S were severely altered in two patients with central venous occlusion, in one individual with ischemic optic neuropathy, and in one patient with branch arterial occlusion. Subnormal values were found in 21 patients for antithrombin III (16.1-19.9 IU/ml), in 7 patients for protein C (55-65%). Two of these five patients with pathologic findings showed severe vascular manifestations in the form of current deep-vein thrombosis and multiple retinal occlusions. Their age was 30 and 53 years, respectively, and differed considerably from the mean age of the entire group (65 +/- 12 years). This study suggests that these proteins were important factors for the development of ocular vascular occlusive diseases in single patients. Although the prevalence is low, measurement of these parameters in young patients may be useful in preventing other vascular complications.

Acute Disease↗
PubMed1994

Hemodilution therapy in central retinal vein occlusion. One-year results of a prospective randomized study.

Systemic hemorheologic abnormalities may play a part in the pathogenesis of central retinal vein occlusions. A statistically significant elevation of plasma viscosity was found in patients with acute central retinal vein occlusion compared with control patients. Local retinal blood flow parameters including arteriovenous passage time and mean arterial dye bolus velocity were significantly altered in the central retinal vein occlusion patients compared with age-matched controls at baseline examination. We performed a randomized, prospective, single-blind clinical investigation to determine the effect of hemorheological manipulation on the clinical course and retinal blood flow of eyes with central vein occlusion. Hemodilution included plasma expansion with hydroxyethyl-starch, withdrawal of whole blood if the hematocrit was above 42%, and rheologic manipulation with parenteral pentoxifylline. We found a statistically significant improvement in visual acuity at 1 year post-treatment for the treated group compared with the control group (increase of visual acuity of 1.5 lines vs decrease of 1.5 lines). The retinal blood flow parameters were markedly improved soon after the institution of therapy, and this may have contributed to the improvement in visual acuity in the treated group. There was no statistically significant difference between the two groups in the progression to ischemic central vein occlusion.

Aged↗
PubMed1994

Perifoveal microcirculation with non-insulin-dependent diabetes mellitus.

Fluorescein angiograms were performed to evaluate perifoveal capillary blood velocities (v), capillary density (perifoveal intercapillary areas: PIA) and the foveal avascular zone (FAZ) by means of the scanning laser technique (SLO-101 Rodenstock). The angiograms were digitally stored and the data quantified off-line with an image analyzing system (IBAS). In the present study 46 patients with non-insulin-dependent diabetes mellitus (NIDDM) were examined and their data compared with that of 31 healthy volunteers. The perifoveal capillary flow velocity of the NIDDM subjects (v = 2.33 +/- 0.36 mm/s) was significantly (P < 0.01) decreased as compared to healthy subjects (v = 2.86 +/- 0.41 mm/s). The perifoveal intercapillary areas in the foveal avascular zone were significantly increased in patients with NIDDM (PIA = 10029 +/- 3402 microns2; FAZ = 0.415 +/- 0.272 mm2) as compared with healthy subjects (PIA = 3965 +/- 467 microns2; FAZ = 0.221 +/- 0.071 mm2). These data suggest the possibility that a decrease in perifoveal capillary blood velocities in combination with decreased capillary density (enlarged PIA) and an enlargement of the foveal avascular zone may occur in patients with NIDDM. The determination of these parameters could help in monitoring the progress of diabetic retinopathy and diabetic maculopathy.

Adult↗
PubMed1994

Measurement of retinal hemodynamics with scanning laser ophthalmoscopy: reference values and variation.

High resolution video fluorescein angiography using scanning laser ophthalmoscopy allows the assessment of retinal macro- and microcirculation. Data on the retinal macrocirculation were obtained from 221 healthy subjects. The data were derived from estimations of the arm-retina time, the arteriovenous passage time and mean arterial dye velocity, characterizing the passage of fluorescein to the eye, the mean arterial plasma velocity, and the arteriovenous passage through the entire vascular bed of one segment. Additionally, the transit of hypofluorescent segments in the capillary macular network were measured in 90 healthy subjects. These parameters provide a wide range of information for understanding the physiology of healthy and diseased eyes. Fundamental for all interpretations is the knowledge of the physiological variations. In the present study the inter- and intraindividual variability of retinal hemodynamics in healthy volunteers were assessed. The interindividual variation was 23.8% for the arm-retina time, 20.7% for the arteriovenous passage time, 23.7% for the mean arterial dye velocity, and 14.2% for the capillary flow velocity; the coefficient for variation, characterizing the intraindividual variation, was 26.6%, 15.6%, 16.7%, and 7.9%, respectively. The knowledge of the inter- and intraindividual variation of retinal blood flow indices allows for a priori power estimations for pathophysiologic and pharmacological studies.

Adult↗
PubMed1994

[Autologous transplantation of nasal mucosa after severe chemical and thermal eye burns].

BACKGROUND: Extensive conjunctival scarring is common after severe chemical and thermal eye burns. There is often not enough healthy conjunctiva from the other eye available to correct the symblepharons, therefore other autologous tissues have to be transplanted. PATIENTS AND METHODS: From February 1992 until March 1993 13 patients were treated with free nasal mucosal grafts from the inferior turbinates for reconstruction of the fornices. The newly created deep fornices were secured by a silicone band. In 3 patients an Illig plastic shell was used additionally. The surgical treatment was supplemented with an intensive treatment with topical corticosteroids to decrease the inflammatory reaction. RESULTS: The patients were followed for an average of 7-18 months. The interval between the accident and the transplantation ranged from 2-26 months. In 10 patients a reconstruction of the fornices was achieved. In all patients, however, some slight scars could be observed. Postoperative Schirmertest was markedly improved. These results encourage us to plan a penetrating keratoplasty in 7 cases. 3 patients showed a recurrence of the symblepharon 2 months after the transplantation. CONCLUSION: The nasal mucosa graft material is best suited for repair of extensive symblepharon. The advantages of this tissue are the availability of large pieces of mucosa and the transplantation of intraepithelial goblet-cells. Long-term effects are the improvement and stabilisation of the tear film.

Adolescent↗
PubMed1994

[Examination procedure in automated determination of far and near vision].

BACKGROUND: Although the measurement of visual acuity at distance is more important in ophthalmological practice, the visual acuity at near should be tested additionally. In a recently published paper we showed that with today's computer technology visual acuity at distance can be measured in standardized procedures according to DIN 58220. We describe here an additional, integrated setup, which allows the measurement of visual acuity also at near. METHODS: For testing visual acuity at near, the whole set of optotypes is presented on a transparent overlay mask in front of a computer monitor which is used as a program-controlled light source. A certain optotype is chosen by illuminating its background. The patient's responses are read via a small console by the computer. The test procedure follows the DIN requirements. RESULTS AND CONCLUSIONS: First reliability tests showed that the test arrangement is qualified for rapid and standardized determination of visual acuity at near and at distance under nearly natural viewing conditions.

Adult↗
PubMed1994

[Intraocular complications after severe chemical burns--incidence and surgical treatment].

BACKGROUND: The prognosis of severe eye burns is determined by the area of the injured conjunctiva and the damage of the cornea. Furthermore the extension of damage to intraocular structures influences the clinical course and the surgical management. PATIENTS: The clinical course of 66 patients with 90 severely burnt eyes in the time from January 1985 to December 1993 were examined with special regard to primary and secondary intraocular complications. RESULTS: In 62 (68.9%) eyes, the whole anterior eye segment was burnt, while in 28 (31.1%) eyes the damage was limited to the cornea and limbus. A cataract occurred in 23 (25.6%) eyes short time after the burn and an early secondary glaucoma in 14 (15.6%) eyes. In the further clinical course, 41 (45.6%) eyes developed a secondary cataract and 20 (22.2%) eyes a late secondary glaucoma. Within 3 months after the burn, 18 eyes were treated with a Tenon plasty, a penetrating keratoplasty and a cataract extraction. In 12 eyes a cataract extraction was combined with a penetrating keratoplasty more than one year after the injury. In the other cases cataract extraction and keratoplasty were performed in separate operations. In 8 eyes intraocular lenses were implanted. In 15 (16.6%) eyes secondary glaucoma had to be treated by trabeculectomy or by the implantation of a von Denffer implant. Penetrating keratoplasty was performed in 55 eyes, 35 of them were unsuccessful as a consequence of graft rejection or increasing vascularisation. One third of the patients achieved a long-term visual acuity of 0.1 and more. CONCLUSION: After severe burn a high rate of intraocular complications has to be expected. The surgical management of such eyes differs from standard procedures. Principally, all devitalized tissue of the anterior chamber like fibrinous and retrocorneal membranes should be excised in an early stage after the burn. Penetrating keratoplasties and extraction of the cataractous lens should be performed in a combined procedure. The implantation of an intraocular lens is limited to a few special cases.

Adolescent↗
PubMed1994

The microtrephine. A new diagnostic tool for obtaining corneal biopsies.

We have developed a new tool for obtaining biopsies of the cornea in a manner which is less traumatic than former biopsy techniques. The new instrument consists of a drill with an aperture of 160 microns which functions as a trephine and is powered at 30,000 rpm. The instrument contains a 120 microns mandrel to remove the samples. In order to monitor electrolyte contents in alkali burnt corneas, 32 rabbit eyes underwent an alkali burn of one cornea (1 n NaOH for 30 sec) followed by a sequence of microtrephinations at different times. A total of 81 microtrephinations were performed. Fifty samples were obtained. One corneal perforation occurred. Forty-four puncture sites were examined by means of histology. Forty-eight biopsies were examined in a scanning electron microscope and identified as punctures of corneal tissue by way of an energy dispersive X-ray analysis. Human corneas had been punctured with this device.

Animals↗
PubMed1994

Quantification of retinal capillary density and flow velocity in patients with essential hypertension.

Arterial hypertension is known to be an important risk factor for cerebral and cardiovascular disease. Previous studies in rats have demonstrated that changes in both capillary density and vessel diameter may contribute to increased vascular resistance in hypertension. In vivo studies of human subjects with essential hypertension revealed a reduction in the number of arterioles in the skin and conjunctiva; no other in vivo data are available from other tissues. By means of a new imaging technique, capillary density and capillary blood flow velocity can now be assessed in the human retina. We undertook the present investigation to determine whether patients with essential hypertension and only minor clinical retinal vascular alterations have decreased retinal capillary density and altered capillary flow velocity. Seventeen hypertensive patients with only minor retinal vascular alterations and 17 healthy volunteers matched for age were selected. All study participants underwent ophthalmologic examination and fluorescein angiographic studies by means of scanning laser ophthalmoscopy. Capillary density and capillary blood flow velocity in the perifoveal network were evaluated from the angiograms. The retinal microcirculation in the perifoveal capillary network of hypertensive patients showed significant alterations. Both the capillary density and capillary flow velocities were significantly reduced compared with the control group. For the first time alterations of capillary blood flow and capillary density in a vascular network very similar to that of the brain have been demonstrated in hypertensive patients in vivo. Further studies with this technique may help identify patients at high risk for cerebrovascular diseases.

Adult↗
PubMed1994

[Effect of hemodilution on retinal hemodynamics in retinal branch vein occlusion].

The aim of hemodilution therapy in branch retinal vein occlusion is to lower the hematocrit (HCT) and plasma viscosity and thus to ameliorate perfusion of the affected areas. In this study we compared the influence of hemodilution therapy on the retinal hemodynamics of affected areas with unaffected areas. Thirty patients with branch vein occlusion (duration of symptoms less than 14 days) aged 40-84 years (mean 63 +/- 11 years) were examined. All patients received iso- (HCT > or = 42%) or hypervolemic (HCT < 42%) hemodilution with hydroxyethyl-starch (MW 200,000/0.5 10%, HAES-steril) for 10 days. Retinal hemodynamics were quantified by means of video fluorescein angiography assessing arteriovenous passage time (AVP) of the affected and unaffected branches. Hemodilution resulted in a significant decrease in hematocrit, plasma viscosity and erythrocyte aggregation. The arteriovenous passage time of the affected area improved significantly (before therapy 4.91 +/- 2.2 s, after therapy 3.9 +/- 1.6 s). The unaffected branch showed no significant change in the arteriovenous passage time (1.85 +/- 0.7 s before and 1.79 +/- 0.7 s after therapy). The decrease in AVP in the affected branch indicates ameliorated perfusion in the affected branch area without changing the retinal hemodynamics in unaffected areas.

Adult↗
PubMed1994

Indocyanine green video angiography in patients with age-related maculopathy-related retinal pigment epithelial detachments.

Previous studies have stressed the benefit of laser photocoagulation for patients with age-related macular degeneration (AMD) and well-defined subretinal neovascularization (SRN). However, such lesions account for only 30% of cases with exudative age-related maculopathy. Especially in patients with retinal pigment epithelial detachment (PED), SRN is usually occult. This study was performed to reveal the role of digital indocyanine green (ICG) video angiography in the diagnosis of SRN in patients with PED. A total of 34 patients with AMD-associated retinal PED participated in the current study and underwent fluorescein and ICG angiography using scanning laser ophthalmoscopy. In these patients fluorescein angiography revealed no distinct SRN, whereas in 21 eyes (62%) ICG angiography showed well-demarcated choroidal neovascularization. The present study demonstrates that SRN can be detected in more than 50% of patients with PED by means of ICG video angiography. Therefore, ICG video angiography improves the detection of SRN in patients with AMD-associated PED.

Aged↗
PubMed1994

[Anticardiolipin antibodies in vascular occlusions of the eye].

Elevated levels of anticardiolipin antibodies (ACA) have recently been found to be associated with occlusive diseases such as myocardial or cerebral infarction or venous thrombosis. In a prospective study anticardiolipin antibodies (both IgG and IgM) were measured by ELISA in 140 patients with acute vascular occlusions of the eye. Patients with clinical evidence for lupus erythematodes, HIV infection or elevated concentrations of antinuclear antibodies (IIFT with HEp-2 as antigen, LD Diagnostika, Heiden, FRG) were excluded. Elevated concentrations of IgG-ACA and IgM-ACA were found in 9% of the cases, with no correlation with the type of ocular vascular occlusion (retinal artery occlusion, retinal vein occlusion, anterior ischemic optic neuropathy). These results indicate that the anticardiolipin syndrome with elevated concentration of anticardiolipin antibodies may also have a causal role in some patients with occlusive eye diseases, whereas in most patients the concentrations were within normal ranges.

Adult↗
PubMed1994

Computational principles in Purkinje I and IV reflection pattern evaluation for the assessment of ocular alignment.

PURPOSE: To develop a standardized reasoning for the evaluation of Purkinje I and IV Reflection Pattern data in primary, secondary, and tertiary positions of gaze in the diagnosis of strabismus with a mathematical approach. To demonstrate the applicability of certain mathematical relations and the appropriate graphic representation of computed ocular alignment data. METHODS: Starting from the known Reflection Pattern Evaluation formulae, equations were derived that allowed for the computation of the relative and absolute positions of the optical and visual axes of both eyes from original data in binocular and monocular fixation. These equations were simplified for clinical use. RESULTS: The authors obtained a set of equations that could be applied to the objective, quantitative analysis of eye alignment in screening for microtropia, in concomitant and incomitant diagnoses of strabismus in primary and nonprimary positions. CONCLUSIONS: Purkinje I and IV Reflection Pattern Evaluation can be extended to the diagnosis of strabismus in nonprimary positions with sufficient clinical accuracy. The newly presented principles and equations serve as a basis for a convenient graphic representation of Purkinje I and IV Reflection Pattern data. These principles of evaluation may be applied to any data dealing with ocular alignment, independently of the method.

Afterimage↗
PubMed1994

[Objective evaluation of visual strain in computer screen and office work by recording visually evoked cortical potentials (VECP) and determining changes in contrast sensitivity and refraction].

Visual evoked cortical potentials (VECP) elicited with checkerboard pattern reversal stimuli of high spatial frequency and low contrast were recorded. The changes in the VECP depending on the duration of task-oriented activity at video display units (VDU) and in the office were determined. The testing procedure can be used to decide on adequate recovery periods (breaks) for any visual workload and requires only a short time. We investigated 30 probands: 10 subjects tested before and after 4 h of VDU work under controlled standard conditions had statistically significant increases of latency (P < 0.001) and decreases of amplitude in VECP recordings (P < 0.05). Another 10 subjects tested at the same intervals but exposed to standard office working conditions also showed statistically significant increases of latency (P < 0.0001) and decrease of amplitude in VECP recordings (P < 0.01). The 10 control subjects tested at the same intervals spent the time between recording sessions on leisure activity (walking) and showed no significant VECP changes. Statistical evaluation was performed with Student's t-test for paired samples. Contrast sensitivity (Ginsburg test) decreased in both VDU and office groups after completion of their workload, but remained within normal limits. The maximal changes in refraction amounted to +/- 0.25 D after 4 h and +/- 0.5 D after 6 h and showed no bias. Extended periods of working at VDUs and conventional office work increase the latency and decrease the amplitude of the pattern-evoked VECP. This method can be used to determine optimal scheduling of breaks in for people working at VDUs and doing conventional office work.

Adult↗
PubMed1994

The influence of the cause of death and age on human corneal metabolism.

PURPOSE: Little is known about the metabolic status of human corneas before transplantation. The authors attempted to determine the influence of both cause of death and age on the corneal metabolism. METHODS: Adenosine-triphosphate (ATP), adenosine-diphosphate (ADP), glucose, and lactate were measured in the stroma and endothelium of 30 human corneas. The corneas were divided into four groups according to cause of death and four groups according to age. Corneas from donors with diabetes were excluded. RESULTS: Corneas from patients who died suddenly--because of cardiac infarction, for example--have good metabolic status even 24 hours after death. In corneas of patients with cancer or sepsis, the metabolism has run down. In comparison, corneas from patients with cancer are in better metabolic condition than those from donors with sepsis because they have adapted to catabolism. Corneas donated from patients with renal insufficiency show results somewhere in between. Statistical evaluation revealed significant differences in ATP concentrations for corneas from donors who died suddenly and from patients with renal insufficiency compared to corneas from patients with sepsis. It could be shown that glucose concentrations as a resource for metabolism increase with age. The best ATP-ADP ratios were found in the group of 40- to 59-year-old donors. Nevertheless, differences between the age groups were not statistically significant. CONCLUSION: From our results it can be concluded that the cause of death and systemic metabolism have an influence on corneal metabolism. Results concerning donor age reflect the well-known fact that donor age has no influence on the quality of keratoplasty material.

Adenosine Diphosphate↗
PubMed1994

[Computer-assisted measurement of ocular misalignment in infants and young children using the digital Purkinje reflection pattern procedure].

A digital image recording and processing system is presented that allows a quick diagnosis of microstrabismus in non-cooperative children. It is thus particularly suited for screening purposes. METHOD: The Purkinje Reflection Pattern Evaluation (RPE) method is used: three small flashes are used to produce the desired Purkinje images. Two horizontal rows of the three 1st Purkinje images (anterior corneal reflections) and of the three 4th Purkinje images (posterior crystalline lens reflections) stemming from the three light sources form the characteristic Purkinje image reflection pattern. Each eye's position is calculated from the shift between the upper and lower rows of reflections by means of two simple formulae. From the angles obtained in binocular fixation and monocular fixation the manifest angle of strabismus corresponding to the angle measured in the simultaneous prism-and-cover test is computed. The measurement is performed at a fixation distance of 50 cm under natural viewing conditions. To obtain a picture one only has to get the child's attention for a short moment. The primary position is triggered with the fixation light, which is operated by a switch. APPARATUS: The digital image recording is done with a hand-held device comprising two miniaturized video cameras, three photo flashes and a fixation light that is operated manually. An IBM-compatible PC equipped with a hard disk and two frame grabbers was adapted for the storage and processing of the pictures. The pictures are evaluated interactively in a few minutes on the workstation's monitor immediately after the measurement. To this end specially designed menu-driven software was implemented. RESULTS: Examples of the measuring procedure and clinical results in infants with microtropic highlight the potential of the system as a screening apparatus and for the exact measurement of small and large squint angles. Usually even 1-year-old children can cooperate well enough to get good-quality pictures in binocular fixation. The new digital system allows easy and rapid application of the Purkinje Reflection Pattern Evaluation method since the time-consuming photographic film processing and evaluation are no longer necessary. For the first time small angles of strabismus under 5 degrees (10 PD) can be measured with a precision of less than 1 degree (2 PD) under clinical conditions in non-cooperative children.

Adult↗