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Biomedical subjects

J Svĕrák

Publications and source records attributed to J Svĕrák.

At least 19 recordsLinked to original sources
PubMed2005

[Congenital stationary night blindness (CSNB)--a case report].

PURPOSE: To document occurrence of the congenital stationary night blindness type Schubert-Bornschein in some members of one family, to put together the family tree, and to evaluate the examination methods. Among others the electroretinogram (ERG) is substantial in the diagnosis of the disease and to distinguish different types of CSNB. In the affected family, only in men the disease is expressed, females are transmitters. This corresponds to the X-linked inheritance. Simultaneously with CSNB, in this family, high myopia occurs not only in men, but also in women. CONCLUSION: CSNB is an inherited disease, mostly with X-linked inheritance. Affected are predominantly males, females are transmitters. This disease is not possible to treat. Despite this, to determine proper diagnosis is important and use of ERG is mandatory.

Adolescent↗
PubMed2003

[Ocular subclinical changes in significant carotid stenosis].

58 patients (40 men, 18 women) affected by high-grade carotid stenosis were examined using automated perimetry and electroretinography. Patients' ages ranged from 53 to 83 years with a mean of 67 years. We examined 29 patients with unilateral and 29 patients with bilateral symptomatic stenosis of carotid arteries and cerebrovascular alterations, without ocular changes. Visual field defects were found by 41 patients (70.6%), by 51.3% patients there were mild or middle defects, by 48.7% hard defects. The results using electroretinography showed significant amplitude decrease and prolonged latencies of the oscillatory potentials on ipsilateral side in unilateral cases. Significant decrease of amplitudes OP2 in patients after the attack of amaurosis fugax has been observed too. The critical value of this amplitude was estimated to 37 muV. High-grade stenosis of carotid arteries are accompanied by visual field defects and electric retinal functions disorders at the time when objective finding on the fundus is normal. The cause of these disorders might be decreased arterial perfusion or microembolization. The perimetry and ERG findings didn't correlate, nevertheless both tests can be useful for detection of early retinal alterations and represent a help-method to determine indications for carotid endarterectomy.

Aged↗
PubMed2002

[The photopic ERG response in diabetes mellitus].

The authors made photopic ERG examinations according to the international standard in 82 diabetic patients. They recorded a significant reduction of amplitudes of the b wave in a group of 38 patients who at the time of the examination did not have yet any pathological changes on the fundus. Regressive analysis did not prove after laser photocoagulation in these patients, contrary to a control group and diabetic patients with simple diabetic retinopathy, any correlation between the patients age and the extent of the retinal response. Photopic electroretinograms must be included in the electrophysiological diagnostic arsenal in diabetes.

Adaptation, Ocular↗
PubMed2002

[Optic disc pits and maculopathy (electroretinography study)].

An ERG examination according to the international standard was made in 55 patients with pits in the optic nerve disc. 19 of them suffered from concurrent maculopathy. Electroretinography revealed in scotopic responses a significant reduction of amplitudes of oscillatory potentials and reduction of potentials of the b wave in standard (maximal) reactions. Even more markedly the cone reactions and flicker were reduced--responses to intermittent (30 Hz) photostimulation. The authors consider maculopathies with pits a separate nosological unit with possible hereditary transmission. ERG signalizes a more extensive alteration of retinal structures than affection of the centre, probably on the basis of the circulation. Maculopathies with pits are also characterized by the fact that the dramatic drop of amplitudes is associated with the patient's age or the duration of the disease.

Adolescent↗
PubMed2001

[The scotopic electroretinogram and age].

1. Electroretinographic examination according to recommendations of the International Society for Clinical Electrophysiology of Vision (ISCEV) was implemented in 115 healthy subjects of different age groups. 2. No significant difference was recorded in the results of men and women. 3. The amplitudes of all investigated retinal responses decline in a linear fashion with age and their peak latencies are prolonged. The mentioned changes are statistically significant even if changes of 0.5 to 0.8% per year are involved.

Adaptation, Ocular↗
PubMed1999

[Electrophysiology in hypovitaminosis A].

Electroretinographic examinations performed according to the international standard were used in two patients with alimentary hypovitaminosis A. In one instance a mentally caused long-term deficiency of dietary vitamin A intake was involved, in the second instance a fistula from the proximal jejunum into the transverse colon. In both instances night blindness was reported. The initial vitamin A values were 1.0 and 0.6 micromol/l resp. and after substitution therapy they rose to 2 micromol/l. While the rod and maximal ERG responses improved gradually, the oscillation potentials remained pathological as regards amplitudes and latencies. We consider them therefore a sensitive indicator of the electric sensitivity of the retina also in other cases of confirmed or suspected vitamin A deficiency. The existence and orientation of our metabolic and gerontological clinic provides adequate opportunities for these investigations.

Electroretinography↗
PubMed1999

[Hereditary occurrence of deep cavities in the optic nerve associated with Best's disease].

The authors present a pedigree where in three generations in male members deep excavations of the optic discs along with Best's disease of the centres in a variable form were recorded. The heredity is autosomal dominant. Retinal changes conditioned by defects of the pigmented epithelium reduce vision to a maximum of 6/60. The anomaly is associated with a pathological EOG record and normal ERG response. The observation is a contribution to discussions in the literature about the hereditary character of excavations of the optic nerve.

Adult↗
PubMed1998

[Oscillatory potentials in human electroretinography during adaptation to light and dark].

In 20 healthy subjects no changes of the peak-latencies of the four wavelets of electroretinographic oscillatory potentials (OP) was found in the course of dark- and light-adaptation. On the other hand, their peak-to-peak amplitudes and dominant frequencies diminish significantly with rising levels of light adaptation. No single OP wavelet was affected by these changes selectively. The OP peak latencies are well suited for clinical diagnostic testing owing to their stability and low variability. On the other hand, because of the great interindividual variability of the peak-to-peak amplitude values of the OP a better clinical tool appears to be a sum of their amplitudes.

Adaptation, Ocular↗
PubMed1998

[Contrast sensitivity in glaucoma and ocular hypertension].

It is known that contrast sensitivity declines with advancinG age and during different ophthalmological diseases. The authors examined 263 eyes of 141 patients with different types of glaucoma and 213 eyes of 107 patients with ocular hypertension. The patients were divided into two groups by age: A = under 60 years (mean 53.2 in glaucoma, 51.1 in OH) and B = 60 years and above (mean 67.5 in glaucoma and 65.6 in OH). For examination of contrast sensitivity the authors used a VCTS 6500 board from a 3 m distance, the visual field was examined by means of Goldman's kinetic perimeter or a static Optifield II perimeter and the discs of the optic nerve were examined biomicroscopically or a photograph of the disc was taken. Impaired contrast sensitivity was found in group A in 71.7% of glaucoma patients and in 61.6% in ocular hypertension. In group B in 81.7% glaucoma patients and in 75.1% of patients with ocular hypertension. The authors also proved an association between the decline of contrast sensitivity and impairment of the perimeter and enlargement of the glaucoma excavation of the optic disc. The authors recommend examination of the contrast sensitivity as a supplementary method for screening and observation of ocular hypertension and glaucoma.

Aged↗
PubMed1997

[Replacement of the Herschel revolving double prism and the Maddox double wing with a prismatic glass for testing of heterophoria].

After the short summary of investigation methods of latent Squint the authors report about the method using the standard Trial Frame Okula and prism with a power of 16 pdpt, with Maddox lens from common trial case Okula. This method is used for an indication of magnitude of latent Squint for a short and a long distance. After the meaning of the authors is exoforia for a short distance one of the most frequent causes of muscular asthenopic disorders.

Humans↗
PubMed1996

[Congenital stationary night blindness].

The clinical and electrophysiological data in 48 cases of congenital stationary night blindness (CSNB) are analysed. The existence of the complete (with only the cone part of the dark adaptation curve) and incomplete (some rod activity also present) form of this anomaly has been confirmed. The Schubert-Bornschein's type of ERG responses corresponds to the complete CSNB. After 12 years of observation period in some patients the diminution of both the a and b potential of the ERG curves but not the extinction of the ERG potentials has been found. PERG curves and PVEP responses in CSNB are normal. Two pedigrees of CSNB are presented. The first reflects the autosomal dominant mode of heredity in 4 generations, in the second pedigree (5 generations) it is not possible to estimate the mode of heredity.

Adolescent↗
PubMed1996

[ERG findings in structured conditions (PERG) in the diagnosis of glaucoma].

In 34 patients admitted to the clinical examination on the basis of the finding of the higher intraocular pressure stated in the private praxis the PERG examination has been performed. After the clinical examination (intraocular pressure, Humphrey perimeter, gonioskopy, C/D ratio) two groups of patients have been classified: 1. Glaucoma patients (21 persons) 2. Patients without glaucoma (13 persons). In the first group a significant lowering of the b65 amplitude of the PERG has been found. Thus the diagnostic value of the PERG in early glaucoma has been confirmed.

Adolescent↗
PubMed1996

[Dystrophic changes in the macular pigment epithelium as a sequela of exudative diabetic maculopathy].

This work is concerned with the treatment of diabetic exsudative maculopathy using hypolipemic and laser therapy. It shows correlation between the decrease of lipemia and the reduction of the area of hard exsudates in the central region of retina after the hypolipemic therapy. But the corresponding improvement of the vision could not be reached because in 31.2% of cases there were permanent changes of the pigment epithelium of central retina in the original locations of the hard exsudates.

Adult↗
PubMed1996

[Visual function in hypophyseal tumors].

Visual acuity measured using the Snellen method in 29 patients with hypophyseal tumors amounts to normal or nearly normal values (6/9-6/6), with mean value of 0.75. Measuring of visual acuity with the more accurate "log MAR" optotype tables yields acuity values which decline with the severity of the disease from 1.04 to 0.87 with a mean value of 0.97. Not withstanding, in all of these patients markedly lowered contrast sensitivity values were found in all of the frequencies tested (1.15-29.25 c/deg). The use of the visual acuity determinations only is insufficient for early detection of functional visual disturbances in compressions of the visual pathway.

Adenoma↗
PubMed1995

[Transparency of intraocular lenses and contrast sensitivity].

A loss of contrast sensitivity was noted in patients with inciplent cataracts and also in artephakias. As all these patients displayed normal visual acuity (6/6-6/9), our data suggest that the use of high-contrast optotypes is insufficient. Low-contrast optotypes are recommended for testing visual acuity in the above mentioned groups of patients.

Aged↗
PubMed1994

[Variability of vision].

The variability of the visual acuity in repeating testing using the whole-line method corresponds to three standardized optotype lines. A significant change of the visual acuity represents at least a doubling of the minimal angle of resolution. From the practical point of view the use of the interpolation method of Ferris is recommended. The mean variability of this method amounts only to 1.3 optotype lines and its realization is based on simple mathematical operations.

Adult↗