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Biomedical subjects

J Peregrin

Publications and source records attributed to J Peregrin.

At least 37 records · Page 2Linked to original sources
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

[Changes in visual functions in myopia 6 months after photorefractive keratectomy].

I. 100 myopes (-0.25-(8.75) D) divided into 3 groups (I: < -3.0 D, II: -3.0-(-5.75) D, III: -6.0-(-8.75) D) were examined before and 1, 3, 6 months after photorefractive keratectomy (PRK). As a control group 20 emmetropes were examined. Best corrected visual acuity (BCVA) was tested using logMAR charts. Contrast sensitivity (CS) was measured using a computerized system. II. Preoperative BCVA in myopes of all three groups was significantly lower (p < 0.001) compared to the control group. A significant reduction of BCVA (p < 0.05 resp. p < 0.001) in all groups at all terms after PRK was noted. III. Significantly lower values of CS (p < 0.001) were found in myopes of all groups before PRK in comparison to the control group. One and 3 months after PRK only nonsignificant changes of the mean values of contrast sensitivity (MCK) were noted. After 6 months a significant improvement of MCK (p < 0.05) in myopes of I. and II. groups was observed.

Adolescent↗
PubMed1997

Visual functions after photorefractive keratectomy.

1. 45 myopes (-3.0 to -6.0 D) were examined before and 1 and 6 months after photorefractive keratectomy (PRK). Visual acuity (VA) was tested using Snellen and logMAR charts. Contrast sensitivity (CS) was measured using a computerized system. 2. Preoperative best corrected VA (BCVA) in myopes was significantly lower in comparison with a control group using logMAR charts only. A reduction of BCVA by both methods at 1. month and its return after 6 months nearly to original values was noted. 3. Significantly lower values of CS were found in patients before PRK compared to the control group. After 1 and 6 months stayed the values on preoperative level.

Adult↗
PubMed1997

Visual functions in aphakia after secondary intraocular lens implantation.

21 aphakic eyes of 21 patients corrected by glasses (A-G) were examined 1 and 6 months before and after secondary intraocular lens implantation (SILI). Visual acuity (VA) was tested using Snellen chart and computerized method with Landolt rings (CL). Contrast sensitivity (CS) was measured using computerized Contrast sensitivity system 8010 in spatial frequencies from 0.74 to 29.55 c/deg. Preoperative best corrected VA (BCVA) in A-G eyes was significantly lower in comparison with control group of the same age only using computerized method with Landolt rings. A reduction of BCVA by both methods at 1 month and its return to original values after 6 months were noted. Significantly lower values of CS were found in A-G patients before SILI compared to the control group of the same median age in spatial frequencies from 3.69 to 29.55 c/deg. After 1 and 6 months the values stayed on the preoperative level, except the frequency 29.55 c/deg, which increased significantly (p < 0.01) 6 months after SILI.

Aged↗
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

[Cataracts and contrast].

The value of visual acuity in patients with incipient cataract, as measured using the conventional Snellen charts amounts to normal or near normal values (6/9-6/6). Nevertheless, their contrast sensitivity determined using the Ginsburg charts or optotypes with lowered contrasts is markedly depressed. The measurement of the visual acuity alone is insufficient diagnostic purposes in these patients.

Aged↗
PubMed1996

[Reproducibility of contrast sensitivity test results].

Two methods (a double staircase and an adjustment method) for repeated measuring of the contrast sensitivity in inexperienced observers (e.g. in patients undergoing the photorefractive keratectomy) were compared in 10 subjects. Using the coefficient of repeatability of Bland and Altmann it could be shown that the reproducibility is better in the method of adjustment. The coefficient of repeatability of this method amounted for 95% confidence limits to 4.78 dB, whereas in the method of double staircase it was 8.70 dB.

Adult↗
PubMed1996

[How should visual acuity be measured?].

1) The ordinary Snellen chart with letter optotypes is not suited for research purposes. Unequal legibility of letters, unequal number of optotypes on rows of the chart and unequal progression of letter sizes limit the usage of such charts for screening purposes only. 2) The results of our computerised method for determining of visual acuity correlate very well with the results gained using the standardised Landolt optotype chart (r = 0.931). Our method brings whole line acuity, threshold visual acuity with its variability and a new parameter of line slope (decrease of correct readings from 95% to 5%), expressed in standardised rows (log MAR = 0.1). The results are printed on a simple printer and stored in a database.

Adolescent↗
PubMed1996

Visual evoked potential evidence for magnocellular system deficit in dyslexia.

Some recent studies on dyslexia have suggested a selective abnormality in the magnocellular visual pathway. To verify this hypothesis, we investigated motion-onset visual evoked potentials (VEPs) (predominantly testing the magnocellular system) as well as pattern-reversal VEPs (presumably testing the parvocellular system) in 20 dyslexics and 16 controls (both groups with a mean age of 10.0 years). Although the latencies and amplitudes of the main positive peak of pattern-reversal VEPs did not differ between the dyslexic and control group, the motion specific negative peak of motion-onset VEPs was significantly delayed (p < 0.001) in dyslexics. Our results confirm a selective magnocellular pathway disorder in dyslexics and indicate that the motion-onset VEPs might serve as an objective method for early diagnosis of dyslexia.

Child↗
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

[Renal hemodynamics and albuminuria in patients with arterial hypertension].

BACKGROUND: The cause of hyperalbuminuria in hypertonic patients can be functional or irreversible structural changes. The objective of the present investigation was an attempt to differentiate these two possibilities by comparing data of hypertonic patients with normal albuminuria (albumin excretion < 20 micrograms/min) and those with microalbuminuria in patients with renovascular hypertension by comparing findings after successful percutaneous transluminal angioplasty of the renal arteries (n = 8). METHODS AND RESULTS: The authors examined 20 patients with normal albuminuria (12 men and 8 women, mean age 46 years) and 20 patients with microalbuminuria (12 men and 8 women, mean age 49 years). Of these patients 8 were examined repeatedly after angioplasty. The examination was made in the morning, renal haemodynamics were assessed by the infusion technique (clearance of polyfructosan and paraaminohippuric acid), in blood and urine the albumin and IgG concentration (bromcresol purpur-Lachema Brno and immunoturbidometrically-Tina-quant Boheringer Mannheim). In hypertonic patients with microalbuminuria a significantly higher (p < 0.001) IgG excretion was found (14.1 as compared with 5.12 micrograms/min.) and a reduced ratio of IgG clearance to albumin clearance (p < 0.001), 0.73 as compared with 1.60. After successful angioplasty of the renal arteries there was a significant drop of the blood pressure (p < 0.05) and of the renal vascular resistance as well as a significant decrease of albuminuria (p < 0.05) on average from 137 to 48 micrograms/min. The quantitative improvement of albuminuria, however, did not go beyond the discrimination value for microalbuminuria. CONCLUSIONS: The results suggest that microalbuminuria in hypertensive patients is as a rule a manifestation of structural renal changes, while also functional and reversible changes participate. The asset of treatment of hypertension by angioplasty of the renal arteries was manifested not only in the renal haemodynamics but also by reduced albuminuria.

Albuminuria↗
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↗
PubMed1993

[Eye manifestations of hypovitaminosis A].

Two cases of a heavy hypovitaminosis A (tumor of the pancreas and an insufficient resorption accompanying the syndrome of a short intestine) are presented. The eye symptomatology consisted of lowered dark-adaption curve, absent electrical reactivity and lowered contrast sensitivity. After restoring the normal vitamin A level in the blood the eye symptoms vanished.

Adult↗
PubMed1992

Contrast sensitivity in clinical practice.

We collected and evaluated the results of contrast sensitivity (CS) examination by means of Vistech chart with an arranged testing distance 208 and 420 cm covering spatial frequencies 1.15-27.25 cycles/degree (c/deg). Our test was comprised of normal population and patients with chronic renal insufficiency including the group of waiting patients, dialysed patients and dialysed patients after neuroretinopathy and also patients after kidney transplantation and those with Alport's syndrome. We gave our attention to the results of visual acuity (VA) and contrast sensitivity (CS) examination in patients after surgery for detached retina, aphakic patients and patients with artephakia. We examined and evaluated CS in patients with intraocular hypertension. All patients reached the VA values 6/9-6/6. 1. The results of examination of 100 healthy persons of different age displayed significant differences in age groups covering all spatial frequencies between the groups 21-50, 51-60 and 61-80 years whereas in sets of higher age we registered differences in the region of medial spatial frequencies only. These data served us to create control groups in the individual partial groups. 2. Patients with chronic renal insufficiency have CS significantly lowered. These examinations suggest that there is a certain relation between renal and retinal functions and that the dialyzation treatment is not able as yet to compensate fully all changes evoked by renal insufficiency. A clear tendency to normalize CS after renal transplantation is suggestive of a certain reversibility of these changes. This is valid for transplant patients with a clear lens. If opacity of the posterior cortex of the lens occurs after a long-time cortisone treatment, a substantial fall in the CS curve is registered in all spatial frequencies in spite of the VA being 6/9-6/6. Patients with neuroretinopathy have CS always significantly disturbed. These changes are reversible although this reversibility is not complete. The new way of dialyzation treatment secures a relatively rapid normalisation of pathological changes in the fundus and repair of subjective functions. At the same time we came to the conclusion that the prognostic outlooks of these patients have become distinctly better as far as their subjective visual functions are concerned. 3. Patients after surgery for detached retina displayed in all cases in the operated eye highly reduced CS in median and low spatial frequencies simultaneously with a statistically significantly lower threshold visual acuity and reduced slope of the acuity function in the diseased eye.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1992

Urinary albumin excretion in patients with renovascular hypertension.

Twenty-four hour urinary excretion of albumin (UEalb), IgG and beta-2 microglobulin was investigated at a 3 hour-interval in a control group (C) of healthy subjects, in 30 patients with renovascular hypertension (RVH), and in 16 patients with essential hypertension (EH). Mean UEalb in RVH was significantly higher than in C. A significant direct correlation was demonstrated between diastolic blood pressure and UEalb (p < 0.01). Microalbuminuria (MA) > or = 30 micrograms.min-1 was found in about 18% of RVH patients; it was higher than 16.7 micrograms.min-1 in approx. 31%. These results did not substantially differ from those obtained in patients with EH. The cause for increased UEalb in hypertensive patients may be functional, haemodynamic changes, or structural ones. In either case, MA indicates renal injury, and these patients should be given increased attention when monitoring their blood pressure and when selecting antihypertensive drugs.

Adult↗