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1.
Laryngorhinootologie ; 95(11): 755-761, 2016 Nov.
Article in German | MEDLINE | ID: mdl-27829259

ABSTRACT

One of the most common sensory impairments of elderly people is hearing loss. Glaucoma is one of the leading causes of blindness worldwide. Hearing and vision loss typically increase with older age. There is scientific evidence that the coincidence of hearing and vision loss is more frequent than expected by the prevalence of individual disorders. With regards to demographic changes and an aging population, in future, it is probable that the incidence of combined hearing and vision impairments will increase, representing a particular challenge not only for doctors and nurses but also a high burden for the private environment of the patients. Therefore, it is of particular importance to diagnose and to treat hearing and vision loss (dual sensory loss) as early as possible. The treatment of hearing disorders and glaucoma as well as possibly underlying systemic diseases such as circulatory disturbances is as important as responsible rehabilitation measures and the supply of hearing and low vision aids. During the last years, knowledge about the molecular biological background of hearing loss and glaucoma has continuously increased but it is currently still at the level of laboratory and animal experiments. Therefore, it remains to be seen whether and to what extent a real therapy for the underlying genetic, immunological and in particular mitochondrial disorders may be accessible in the future.


Subject(s)
Glaucoma/complications , Hearing Disorders/complications , Hearing Loss , Hearing Tests , Humans , Vision Disorders
2.
Open Ophthalmol J ; 8: 60-6, 2014.
Article in English | MEDLINE | ID: mdl-25317217

ABSTRACT

PURPOSE: To test whether latanoprost has an influence on ocular haemodynamics, considering the general reputation of prostaglandins which is frequently associated with vasoconstriction. The effect of latanoprost on the retinal blood supply of treatment-naïve glaucoma patients was tested. MATERIALS AND METHODOLOGY: 13 patients (7 male, 6 female) who had just recently been diagnosed with primary open-angle glaucoma (POAG) were treated with latanoprost (0.005%). The average age of our study group was 63.8 years (+/- 2.9 years). The drug's effect on retinal autoregulation was assessed by flicker test using the Dynamic Vessel Analyzer (DVA). Examinations took place before initializing treatment, after 4 weeks and once again after 4 to 6 months. RESULTS: In our group of POAG patients, the IOP under treatment was significantly reduced about 25%. No intraindividual differences in systemic blood pressure and heart rate were observed. In DVA measurements of glaucoma patients, the maximum flicker dilation of the arteries was significantly lower than reported for healthy volunteers. Beyond that, POAG patients did not show significant differences in vessel diameters, peak amplitudes as well as maximum dilations of retinal arteries and veins before and under treatment with latanoprost (0.005%). CONCLUSION: Latanoprost markedly lowered the IOP but it did not exert a significant effect on retinal haemodynamics. There was neither a tendency towards vasoconstriction nor towards vasodilation. Sustaining reperfusion damage after topical latanoprost therapy thus seems to be highly unlikely. Further studies must show if sole IOP lowering or a dual positive effect - IOP lowering and improvement of retinal vessel autoregulation - have a more positive impact on the long term follow-up of glaucoma patients.

3.
Klin Monbl Augenheilkd ; 231(2): 144-50, 2014 Feb.
Article in German | MEDLINE | ID: mdl-24532402

ABSTRACT

One of the most common sensory impairments of elderly people is hearing loss. Glaucoma is one of the leading causes of blindness worldwide. Hearing and vision loss typically increase with older age. There is scientific evidence that the coincidence of hearing and vision loss is more frequent than expected by the prevalence of individual disorders. With regards to demographic changes and an aging population, in future, it is probable that the incidence of combined hearing and vision impairments will increase, representing a particular challenge not only for doctors and nurses but also a high burden for the private environment of the patients. Therefore, it is of particular importance to diagnose and to treat hearing and vision loss (dual sensory loss) as early as possible. The treatment of hearing disorders and glaucoma as well as possibly underlying systemic diseases such as circulatory disturbances is as important as responsible rehabilitation measures and the supply of hearing and low vision aids. During the last years, knowledge about the molecular biological background of hearing loss and glaucoma has continuously increased but it is currently still at the level of laboratory and animal experiments. Therefore, it remains to be seen whether and to what extent a real therapy for the underlying genetic, immunological and in particular mitochondrial disorders may be accessible in the future.


Subject(s)
Glaucoma/epidemiology , Glaucoma/physiopathology , Hearing Disorders/epidemiology , Hearing Disorders/physiopathology , Comorbidity , Evidence-Based Medicine , Glaucoma/diagnosis , Hearing Disorders/diagnosis , Humans , Prevalence , Risk Factors
4.
Klin Monbl Augenheilkd ; 229(2): 126-34, 2012 Feb.
Article in German | MEDLINE | ID: mdl-22334410

ABSTRACT

The term glaucoma is used as a melting pot of many different diseases which have in common that the retinal ganglion cells and their axons are damaged. Untreated, apoptosis can be induced causing ganglion cell death which subsequently leads to typical glaucomatous damage at the optic nerve head, scotomas of the visual fields, and in the worst case scenario to blindness. It is well known that patients with glaucoma can suffer a 20 to 50 % loss of retinal ganglion cells before a defect becomes evident in standard white on white perimetry. To prevent glaucomatous damage, it is important to detect changes of the retinal ganglion cells and their nerve fibre layer as early as possible and to monitor their follow-up as closely as possible in order to find an adequate treatment of glaucoma, and to control its efficiency. In the past few years, scanning laser polarimetry by means of GDx technology (Carl Zeiss Meditec, Dublin, USA) could be established as a new method to measure the retinal nerve fibre layer not only qualitatively but even quantitatively. Presently, the GDx plays an important role in actual glaucoma diagnostics on account of its high resolution, the comfort for both patient and user, and its highly reproducible measurements. Especially in difficult evaluable optic nerve heads (e. g., micro- and macrodiscs), tilted discs, and optic disc anomalies (e. g., optic nerve drusen) modern nerve fibre diagnostics by means of GDx technology is a helpful enrichment in clinical routine.


Subject(s)
Glaucoma/diagnosis , Scanning Laser Polarimetry , Apoptosis/physiology , Disease Progression , Glaucoma/pathology , Humans , Nerve Fibers/pathology , Optic Disk/pathology , Retinal Ganglion Cells/pathology , Sensitivity and Specificity , Visual Field Tests
5.
Br J Ophthalmol ; 88(10): 1259-62, 2004 Oct.
Article in English | MEDLINE | ID: mdl-15377546

ABSTRACT

BACKGROUND: Recently, in patients with normal tension glaucoma (NTG) elevated levels of antiphosphatidylserine antibodies (APSA), a subgroup of antiphospholipid antibodies (APLA) were found. Progressive sensorineural hearing loss (PSHL) is associated with autoimmune diseases and also the presence of APLA. METHODS: To investigate a possible association between NTG and PSHL, 34 patients (age range 31-81 years) with NTG were evaluated for evidence of audiovestibular disorders. Besides ophthalmological standard examinations (slit lamp, IOP, funduscopy, perimetry) scanning laser tomography and polarimetry were performed. From all patients' audiograms, stapedial thresholds and otoacoustic emissions were obtained. The serological testing of patients and controls (40 healthy blood donors older than 50 years) concerned IgG and IgM levels of antibodies against phosphatidylserine (APSA) and beta2 glycoprotein. RESULTS: 23 of 34 NTG patients had hearing loss (PSHL n = 11; presbyacusis n = 12). The NTG patients had significantly higher APSA levels than controls. Elevated APSA concentrations were significantly more frequent in patients with NTG and hearing loss compared with NTG patients with normacusis. CONCLUSIONS: These findings show that NTG and hearing loss have a high coincidence. The elevated APSA levels may indicate an association with similar systemic autoimmune processes.


Subject(s)
Antibodies, Antiphospholipid/blood , Glaucoma/complications , Hearing Loss, Sensorineural/complications , Phosphatidylserines/immunology , Adult , Aged , Aged, 80 and over , Disease Progression , Female , Glaucoma/immunology , Hearing Loss, Sensorineural/immunology , Humans , Immunoglobulin G/blood , Immunoglobulin M/blood , Male , Middle Aged
6.
Br J Ophthalmol ; 88(9): 1142-5, 2004 Sep.
Article in English | MEDLINE | ID: mdl-15317704

ABSTRACT

BACKGROUND/AIMS: To determine the sensitivity and the specificity of the GDx in the detection of (1) advanced glaucoma, (2) early glaucoma, and (3) nerve fibre bundle defects (NFBD). METHODS: Group A comprised 20 eyes with reproducible glaucomatous visual field defects confirmed by octopus perimetry, group B consisted of 10 eyes with normal visual fields but either glaucomatous NFBD or deterioration of the disc over time clearly visible upon flicker comparison, and group C included 16 eyes with glaucomatous or non-glaucomatous NFBD clearly visible on red free photographs. Forty four eyes of 22 healthy volunteers served as controls. The GDx printouts of all subjects were evaluated by three independent observers in a masked fashion and without the clinical picture of the optic disc. Two of the three observers (SK, UH) were GDx experts, one (KUL) was an untrained GDx user. RESULTS: Among the GDx experts, sensitivity/specificity was 100%/100% (SK) and 90%/100% (UH) in detecting advanced glaucoma, and 100%/100% (SK) and 90%/100% (UH) in detecting early glaucoma. The sensitivity in detecting NFBD was only 37.5% (SK and UH). For the untrained GDx user the corresponding values were 50%/100% (group A), 20%/100% (group B), and 12.5%/91% (group C). CONCLUSION: Detection of (early) glaucoma damage by the GDx, evaluated by trained experts, can be extremely high. To optimise its benefit in clinical routine training in interpreting GDx printouts is highly recommended. Detection of localised NFBD is crucial, even for experts.


Subject(s)
Diagnostic Techniques, Ophthalmological , Glaucoma/diagnosis , Retinal Ganglion Cells , Glaucoma/pathology , Humans , Lasers , Middle Aged , Nerve Fibers/pathology , Reproducibility of Results , Retinal Ganglion Cells/pathology , Sensitivity and Specificity
7.
Clin Exp Immunol ; 125(2): 211-5, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11529911

ABSTRACT

The two main entities of open-angle glaucoma are primary open-angle glaucoma (POAG) and normal tension glaucoma (NTG). Both diseases may be associated with autoimmune processes. Therefore, IgG and IgM antibodies to phospholipids (APL) and their subspecies cardiolipin (ACL), phosphatidylserine (APS) and beta2-glycoprotein (beta2GP) were determined in 43 NTG patients, 40 POAG patients and 40 healthy controls in a prospective study. The most prominent observation was the increase in APS concentrations in NTG patients (IgG 20.6 +/- 2.7 U/ml, IgM 24.4 +/- 3.4 U/ml) compared with POAG patients (IgG 8.8 +/- 1.2 U/ml, IgM 11.0 +/- 1.7), and controls (IgG 7.7 +/- 1.3 U/ml, IgM 12.8 +/- 1.5 U/ml). APS may be important due to their binding specificity to phosphatidylserine molecules which become accessible during apoptosis; this in turn may lead to local thrombosis.


Subject(s)
Antibodies, Antiphospholipid/biosynthesis , Glaucoma, Open-Angle/immunology , Phosphatidylserines/immunology , Aged , Antibodies, Anticardiolipin/biosynthesis , Female , Glycoproteins/immunology , Humans , Immunoglobulin G/biosynthesis , Immunoglobulin M/biosynthesis , Male , Middle Aged , beta 2-Glycoprotein I
8.
Klin Monbl Augenheilkd ; 218(4): 263-8, 2001 Apr.
Article in German | MEDLINE | ID: mdl-11392272

ABSTRACT

BACKGROUND: In the pathogenesis of glaucoma, besides an elevated intraocular pressure (IOP), cardiovascular risk factors, such as arterial hypotension and hypertension, vasospasms, autoregulatory defects, atherosclerosis, and diabetes mellitus are of increasing importance, especially in normal tension glaucoma. Recently, there have been several reports of an additional risk factor: obstructive sleep apnea syndrome. METHODS: Literature review (Medline) and case report. RESULTS: The authors report on a 8 1/2 years follow-up of a 60-year-old patient with normal tension glaucoma. Despite successful pharmacological and surgical lowering of intraocular pressure a progressive glaucomatous damage with optic nerve atrophy and increasing visual field defects occurred. As a result of intensive investigations of possible cardiovascular risk factors, an obstructive sleep apnea syndrome was diagnosed. Since the beginning of therapy with nCPAP (nasal continuous positive airway pressure) more than 3 1/2 years ago, no further progression of glaucomatous optic nerve damage or visual field defects have been observed. CONCLUSIONS: In clinical practice, obstructive sleep apnea syndrome often is underdiagnosed. In patients suffering from glaucoma and obstructive sleep apnea syndrome, intraocular pressure lowering therapy may not be enough, whereas an additional nCPAP-therapy potentially could prevent the beginning/progression of glaucomatous optic nerve damage.


Subject(s)
Glaucoma/etiology , Intermittent Positive-Pressure Breathing , Laryngeal Masks , Sleep Apnea, Obstructive/complications , Sleep Apnea, Obstructive/therapy , Glaucoma/therapy , Humans , Intraocular Pressure , Male , Middle Aged , Polysomnography , Risk Factors , Treatment Outcome
9.
Graefes Arch Clin Exp Ophthalmol ; 238(11): 922-6, 2000 Nov.
Article in English | MEDLINE | ID: mdl-11148817

ABSTRACT

BACKGROUND: Retinal nerve fiber layer defects are part of early glaucomatous damage. In the present study, we compared the ability of retinal nerve fiber layer photography (NFP) and scanning laser polarimetry (SLP) to detect nerve fiber layer defects in glaucoma patients. METHODS: Besides ophthalmological standard examinations, we performed NFP (Zeiss Ikon fundus camera 30 degrees, green filter), SLP (GDx, 1.0.14 and 2.0.09, LDT) and automated perimetry (Oculus, Twinfield, 30 degrees) in 150 glaucoma patients [74 with primary open-angle glaucoma (POAG) and 76 with normal-tension glaucoma (NTG)]. The perimetric results were evaluated according to a modified Aulhorn classification. NFP and SLP were graded according to Quigley. RESULTS: In POAG, 42% of NFP and 5% of SLP were not evaluable. In NTG, 24% of NFP and 4% of SLP were not evaluable. In POAG, NFP and SLP revealed a direct agreement in 54.5%, and in NTG, 55%; there was a small difference of one stage in 39.5% (POAG) and 41% (NTG). In POAG, NFP/SLP showed agreement with perimetric results in 35%/30% of cases and differences of one stage in 56%/58%. In NTG, NFP/SLP agreed with perimetry in 52%/48% of cases and differed by only one stage in 32%/39%. Larger deviations were found in less than 13% of the cases. CONCLUSIONS: NFP and SLP mostly showed good agreement or little deviation as to grading of nerve fiber layer damage. In clinical use, SLP has advantages over NFP because a higher rate of good-quality images can be obtained and pupils do not have to be dilated. Additionally, SLP measurements provide quantitative data and a large normative data base exists.


Subject(s)
Axons/pathology , Glaucoma, Open-Angle/diagnosis , Nerve Fibers/pathology , Optic Nerve/pathology , Photography/methods , Retinal Ganglion Cells/pathology , Visual Field Tests/methods , Adult , Aged , Aged, 80 and over , Female , Humans , Intraocular Pressure , Lasers , Male , Middle Aged , Vision Disorders/diagnosis , Visual Fields
10.
Klin Monbl Augenheilkd ; 214(6): 378-85, 1999 Jun.
Article in German | MEDLINE | ID: mdl-10427540

ABSTRACT

BACKGROUND: In the last years, scanning laser measurements were established in glaucoma diagnostics. Techniques of special interest are scanning laser topometry (SLT) for exact measurements of the optic disc and its cup and scanning laser polarimetry (SLP) for precise assessment of the retinal nerve fiber layer thickness. As glaucoma patients often suffer from a cataract, too, and a trabeculectomy additionally favors the advance of lens opacities, in the follow up of glaucoma patients cataract surgery is often necessary. PATIENTS AND METHODS: The influence of cataract surgery in phacotechnique with intraocular lens implantation (31 PMMA-IOLs, Pharmacia/Upjohn, model 811 B, and 25 HEMA/MMA-IOLs, Technomed, Memory Lens) on SLT and SLP was evaluated before and 3 to 4 weeks after cataract surgery in 56 eyes of otherwise healthy patients. Lens opacities were classified according to LOCS III. For SLT, we applied a TopSS, and for SLP a Nerve Fiber Analyzer II and a GDx (LDT, USA). RESULTS: Our results show that SLT and SLP are mostly performable at lens opacities with visual acuity reductions down to 0.16. In SLT, we usually found no big differences in the assessed parameters before and after cataract surgeries with IOL implantation. Standard deviations between three single measurements were mostly smaller postop. In SLP, nerve fiber layer patterns were very similar before and after cataract surgeries with IOL implantation whereas total nerve fiber layer thickness values postoperatively were slightly higher. CONCLUSIONS: Our results indicate that cataract surgeries with IOL-implantation have only mild influence on SLT and SLP. These findings seem to be of clinical interest especially in the follow up of glaucoma patients.


Subject(s)
Cataract Extraction/methods , Cataract Extraction/trends , Lasers , Lens Implantation, Intraocular/methods , Tomography/methods , Aged , Aged, 80 and over , Cataract/classification , Cataract/complications , Cataract/diagnosis , Female , Follow-Up Studies , Glaucoma/classification , Glaucoma/complications , Glaucoma/diagnosis , Humans , Male , Middle Aged , Optic Nerve/anatomy & histology , Postoperative Care , Preoperative Care
11.
Graefes Arch Clin Exp Ophthalmol ; 235(9): 575-83, 1997 Sep.
Article in English | MEDLINE | ID: mdl-9342608

ABSTRACT

This report describes ocular findings obtained in four patients from three families with autosomal dominant retinitis pigmentosa (adRP) due to missense mutations in the rhodopsin gene. Phenotypes were characterized by standard ophthalmologic examinations, visual fields, electroretinography (ERG), dark adaptation, and two-color dark-adapted threshold perimetry. Two patients aged 38 and 45 years, respectively, from a family with the Cys110Phe mutation showed mild fundus changes without bone spicules as well as small arcuate scotomas in the inferior quadrants of their visual fields but displayed severe functional loss of rods and cones in the ERG. Two-color dark-adapted threshold perimetry revealed a regional type of degeneration. A 48-year-old patient with an Arg135Gly mutation had typical RP with concentrically narrowed visual fields and nondetectable ERG responses. Central visual functions were well preserved for a long time. Two-color dark-adapted threshold perimetry indicated a diffuse type of retinal degeneration. An 18-year-old patient with a Gln344stop mutation has been followed for 13 years. His ERG was clearly reduced at the age of 5 years; since that time, disease progression has been very slow. Currently, there are relatively mild alterations in visual acuity, rod sensitivity, and visual fields. Our findings confirm that there is a large phenotypic variety among patients with adRP and different rhodopsin mutations.


Subject(s)
Point Mutation/genetics , Retinitis Pigmentosa/genetics , Rhodopsin/genetics , Adolescent , Adult , Child , Child, Preschool , Dark Adaptation , Disease Progression , Electroretinography , Female , Humans , Male , Middle Aged , Pedigree , Phenotype , Photoreceptor Cells/physiopathology , Polymerase Chain Reaction , Polymorphism, Single-Stranded Conformational , Retinitis Pigmentosa/physiopathology , Visual Field Tests , Visual Fields
12.
Klin Monbl Augenheilkd ; 208(3): 201-2, 1996 Mar.
Article in German | MEDLINE | ID: mdl-8699779

ABSTRACT

A 49-year-old patient suffered from a binocular perforating trauma with metal foreign bodies in 1974. During an MRI examination in 1992 for a lumbar spine herniation a metal foreign body was mobilised from the deeper vitreal and retinal area, now causing optical disturbances freely floating in the anterior vitreous. Refusing an operation, the patient, an electrical engineer, tried himself to remove the foreign body out of the optical axis by exposing his head to the electro-magnetic field of an induction coil (pulsed magnetic induction B at t0 of 0.26 Tesla). The foreign body was split into multiple small parts no longer disturbing the patient. To early detect a siderosis regular ophthalmological controls including ERG are necessary. This example stresses that even small intraocular metal foreign bodies are a contraindication for the usually applied field strength of MRI examinations.


Subject(s)
Eye Foreign Bodies/therapy , Eye Injuries, Penetrating/therapy , Magnetic Resonance Imaging/instrumentation , Electromagnetic Fields , Eye/pathology , Eye Foreign Bodies/diagnosis , Eye Injuries, Penetrating/diagnosis , Humans , Male , Middle Aged
13.
Ophthalmologe ; 92(5): 704-7, 1995 Oct.
Article in German | MEDLINE | ID: mdl-8751001

ABSTRACT

Inherited retinal degenerations cause severe visual handicaps or blindness later in life. In typical rod cone dystrophy (retinitis pigmentosa) there is relevant visual loss in the third decade with implications for the patients' professional life, their mobility and their private life. For this reason, the disease is relevant for the individual patient as well as for society in general. We investigated social issues in 233 retinitis pigmentosa patients: 9.9% are not able to read any more; 40.9% have never had a driver's license and 27.8% quit driving because of a visual handicap. The mean reduction in the capacity for work is 86%; 12.7% are unable to work and therefore receive public financial support; 22.6% are unable to work in their profession; 20.9% are receiving public support because of legal blindness. Against this background it seems to be important that ophthalmologists inform their patients thoroughly about the implications of the disease for their professional and private lives. Doing this, he/she should ask for support from social service professionals.


Subject(s)
Blindness/rehabilitation , Disability Evaluation , Rehabilitation, Vocational , Retinitis Pigmentosa/rehabilitation , Social Security , Activities of Daily Living/classification , Adolescent , Adult , Female , Follow-Up Studies , Germany , Humans , Male , Middle Aged
14.
Klin Monbl Augenheilkd ; 206(4): 277-8, 1995 Apr.
Article in German | MEDLINE | ID: mdl-7791291

ABSTRACT

A 22 year-old-man and owner of several tarantulas visited his ophthalmologist because of red itchy eyes. Additionally to kerato-conjunctivitis epidemica, uncommon hairs were found especially in his left cornea. Corrected visual acuity was 0.8. According to literature these spider hairs can induce granulomas in the meaning of ophthalmia nodosa, and even migrate inside the eye. Therefore we removed as many hairs as possible, but we left two, not to cause iatrogen perforation. The penetration depth was measured by laser tomography. Local steroids successfully prevented further granuloma formation. Regular ophthalmological controls are important to early detect possible changes, and if necessary to remove these hairs even from deeper corneal layers, in case by keratectomy.


Subject(s)
Cornea , Eye Foreign Bodies/diagnosis , Hair , Keratoconjunctivitis/etiology , Spiders , Adult , Animals , Eye Foreign Bodies/complications , Eye Foreign Bodies/therapy , Granuloma, Foreign-Body/complications , Granuloma, Foreign-Body/diagnosis , Granuloma, Foreign-Body/therapy , Humans , Keratoconjunctivitis/therapy , Male
15.
Ophthalmologica ; 209(2): 70-8, 1995.
Article in German | MEDLINE | ID: mdl-7746649

ABSTRACT

Previously, it has been shown that in healthy persons the function of the eye assessed by visual evoked cortical potential (VECP) amplitudes changes in a characteristic way during stepwise artificial elevation of intraocular pressure (IOP). It has been demonstrated that a stepwise increase in IOP leads to a decrease in the amplitude followed by an increase or a stabilization of the function during a further rise of IOP. At pressure values of 62 mmHg, the amplitude falls to the noise level. In order to examine whether this behaviour can also be observed if the procedure is reversed, we initially increased the IOP to values, at which the VECP amplitudes could not be distinguished from noise (standstill pressure). During a subsequent stepwise decrease in the artificially increased IOP, we investigated 5 persons. The function did not recover before the IOP had reached values below 46 mmHg. Thus, at the same IOP value, the VECP can assume different amplitude values depending on wether the pressure rises or falls. In 24 further persons, the artificial IOP increase was decreased directly to the starting values. The function recovered immediately. Factors influencing the eye shape (e.g. astigmatism), as ascribed at artificially increased IOP, cannot explain the different behaviour of VECP amplitudes in the experiments done here, because mechanical changes are the same in IOP increase and its reverse. But the behaviour observed here is not contradictory and can be explained by the known characteristics of microcirculation.(ABSTRACT TRUNCATED AT 250 WORDS)


Subject(s)
Evoked Potentials, Visual/physiology , Intraocular Pressure/physiology , Ocular Hypertension/physiopathology , Visual Cortex/physiology , Adult , Eye/blood supply , Humans , Regional Blood Flow , Rheology
16.
Ophthalmologica ; 209(5): 233-41, 1995.
Article in German | MEDLINE | ID: mdl-8570144

ABSTRACT

The visual evoked cortical potentials (VECP) are changed by the artificial increase in intraocular pressure (IOP). The exact location of the damage is still unclear. One possibility is that the increased ocular pressure reduces the blood flow in the optic nerve head. The function of the optic nerve fiber function would be decreased by this effect. Another possibility is that the generation of the signals in the retinal ganglion cells could be influenced by the artificial pressure enhancement. We developed a method of simultaneous recording pattern reversal electroretinograms (PERG) and VECP during artificially raised IOP. The PERG was recorded by cutaneous electrodes (Grass, USA; diameter 5 mm), which were positioned close to the lid margins. The pattern reversal rate was 7.9 reversals/s. In a pilot study, we examined 10 healthy volunteers with artificially increased ocular pressure. In 9 cases, amplitudes showed a more stable behavior in the VECP than in the PERG: the mathematical behavior of the amplitude/pressure curves was more stable in the VECP of 6 volunteers and once in the PERG. Signs of very sufficient autoregulation could be found in the VECP of 7 volunteers and once in the PERG. The critical pressure, at which a further increase in IOP causes a continuous amplitude decrease to the noise level, was 9 times more stable in VECP (median 53 mmHg) than in PERG (median 48 mmHg). The results lead to the conclusion that in healthy persons the artificial pressure rise influences the ganglion cells at an earlier timepoint than the signal transmission in the axons.


Subject(s)
Evoked Potentials, Visual/physiology , Intraocular Pressure , Ocular Hypertension/physiopathology , Adult , Blood Flow Velocity , Electrodes , Electroretinography , Female , Fourier Analysis , Humans , Male , Optic Nerve/physiology , Pattern Recognition, Visual , Retinal Ganglion Cells/physiology , Visual Cortex/physiology
17.
Ophthalmologe ; 91(2): 181-4, 1994 Apr.
Article in German | MEDLINE | ID: mdl-8012133

ABSTRACT

Usually, amplitudes and latencies are measured to analyze visual evoked cortical potentials (VECP). From the physical point of view this means an analysis in the time domain. Generally it is possible to get important information on oscillations by testing to see which frequency the power is transmitted at (frequency domain). We made such experiments on visual evoked cortical potentials with Fourier analysis during an artificial stepwise rise in the intraocular pressure. We recorded the VECP of 60 healthy young persons at a stimulus rate of 1.9 checkerboard reversals/second and analyzed the curves by Fourier transformations. We proceeded in the same way with 30 volunteers using a stimulus rate of 3.1 checkerboard reversals/second. In comparison to the VECP curves without Fourier analysis, no systemic changes in the amplitude spectra appeared during the rise in intraocular pressure. Because of this we feel that Fourier analysis mostly renders no further information and is probably dispensable for experienced clinicians when testing pressure tolerance of the optic nerve head. On the other hand, the analysis clearly showed the appearance of distortion frequencies. This may be of clinical interest in cases of severe distortion and in patients with almost extinguished VECPs. It might also be helpful to clinicians who are less experienced in electrophysiology.


Subject(s)
Electroencephalography/instrumentation , Evoked Potentials, Visual/physiology , Intraocular Pressure/physiology , Signal Processing, Computer-Assisted/instrumentation , Adult , Female , Fourier Analysis , Humans , Male , Microcomputers , Pattern Recognition, Visual/physiology , Reference Values , Visual Cortex/physiology
18.
Doc Ophthalmol ; 81(2): 189-96, 1992.
Article in English | MEDLINE | ID: mdl-1468349

ABSTRACT

By recording steady-state visual evoked cortical potentials while intraocular pressure is artificially increased, information can be obtained on the pressure tolerance of the optic nerve head. Such experiments have previously been performed by a vector voltmeter technique. We studied the visual evoked cortical potentials in 30 healthy volunteers with artificially increased intraocular pressure, but we used an averager instead of a vector voltmeter. The results were similar except that the noise level in averaging was higher than with the vector voltmeter technique. This observation confirms that the signal-to-noise ratio is much better with the vector voltmeter technique than with the averaging technique. Our results show that averaging can be used in pressure tolerance testing, but the amplitude cannot be observed as far down as in the vector voltmeter technique. This limits the clinical value of averagers in this application.


Subject(s)
Evoked Potentials, Visual/physiology , Intraocular Pressure/physiology , Optic Disk/physiopathology , Adult , Female , Humans , Male , Ocular Hypertension/physiopathology , Visual Cortex/physiology
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