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Biomedical subjects

A M Shamshinova

Publications and source records attributed to A M Shamshinova.

At least 19 recordsLinked to original sources
PubMed2003

[Psychophysical and electrophysiological tests in diagnosis of the early sign of glaucomatous optic neuropathy].

Visual field losses and changes of the optic nerve disk are signs of optic neuropathy in glaucoma; psychophysical and electrophysiological tests can contribute to an early detection of glaucomatous optic neuropathy. Electrophysiological methods, like pattern electroretinogram (PERG) and visual induced cortical potentials can be useful in the diagnosis of glaucoma since they are compatible with the functions of retinal ganglion cells. A combination of psychophysical and electrophysiological examination methods contribute to an early diagnosis of glaucoma because they make it possible to study different aspects of visual functions. The results of psychophysical tests correlate to a greater extent than electrophysiological tests with defects in visual fields. Temporal, temporal-and-spatial contrast sensitivity and visual induced cortical potentials, whose changes are detected in the "preperimetric" stage of glaucoma, are the most sensitive parameters, while PERG changes later. Both the color contrast and light PERGs reduce in glaucoma. However, a significant correlation was detected only between the reduction of the color contrast PERG and visual field defects. A reduced sensitivity of dark and color channels of the retinal cone systems was also registered. Defects of color sensitivity are more pronounced and they precede the onset of light sensitivity changes. Defects of color and contrast sensitivity are an early sign of the progressing of optic neuropathy in glaucoma.

Contrast Sensitivity↗
PubMed1996

[Methods of diagnosis of thallium intoxication and its antidote therapy].

Absence of early signs specific for thallium intoxication requires objective diagnostic methods. The studies covered 4 techniques: electroretinography (ERG), assessment of urine levels of thallium and delta-aminolevulinic acid, capillaroscopy. The authors supported their previous foundation concerning diagnostic value of ERG for early diagnosis of thallium effects (higher amplitude of b-wave in one and that of a-wave in 8 out of 10 examinees). Further experimental and clinical basis for grading the intoxication through amounts of urinary thallium were found promising. Capillaroscopy method appeared informative: 8 out of 12 examinees demonstrated spastic and atonic state of hand capillaries--that provided objective verification of vascular disorders in workers exposed to thallium and its derivatives.

Aminolevulinic Acid↗
PubMed1990

Local ERG for clinical examination of eye diseases.

We used a suction electrode with a frosted front window to record a full-field (general) ERG, and a suction electrode with a short-focus lens and a red-green light diode to record a local ERG. As the suction electrode moved with the eye, the stimulus struck the macula in all positions of gaze. Our data showed that only mildly intense stimuli with an angular size of 10 to 15 degrees induced a retinal response, with a macular contribution of 70%. Patients with various dystrophic changes of the retina, such as Stargardt's dystrophy, vitelliform dystrophy of the Best type, X-linked juvenile retinoschisis, and age-related macular dystrophy of different stages, were examined. In patients with retinitis pigmentosa, the cones were involved in the pathologic process to varying degrees; the behavior of the local ERGs helped determine the final visual acuity. We also observed a reduction in the local ERG in patients with Stargardt's dystrophy that disappeared as the disease progressed. In age-related macular dystrophy, a disturbance of the electrogenesis mainly occurred in the central retina in advanced stages of the disease.

Adolescent↗
PubMed1990

Electroretinography in the diagnosis of thallium intoxication.

Appearance of dystrophic alterations in the retina was carried out by administering 0.2 ml 12 mM of tallium chloride solution into the vitreous humour of 9 rabbits. Electroretinographic examination revealed a decline in the b wave either decreasing 2-3 times or entirely disappearing as early as on day 2 after the administration of tallium chloride. Electron microscopic investigation suggested that photoreceptors of the retina were initial by involved in the pathological process. Namely, the external segments of the photoreceptors were found to be reduced, indicating impairment of the formation of photoreceptor disks, which is known to proceed continuously under normal conditions. In the absence of an electroretinogram (ERG), the photoreceptor layers were shown to have disappeared completely. An examination of 28 subjects who were exposed to tallium and its compound at work revealed impaired retinal electrogenesis, as evident from subnormal ERG responses. This was of a functional nature and became more pronounced as occupational exposure time increased. The fact that the internal retinal layers and the 3-rd neurone remained intact, as suggested by the electrical sensitivity of the eye and lability of the optic nerve as well as by static perimetry, correlated with the EM findings obtained in experiments. Ophthalmobiomicroscopic examination of 12 eyes yielded data on characteristic changes in the lens when visual functions remained intact. These findings suggest that changes in the ERG may be indicative of initial preclinical symptoms of tallium intoxication and as such can be used when persons exposed to it in industry receive check-ups.

Adolescent↗
PubMedDate not supplied

[Computer method for evaluating disorders in sense of color].

A new method for evaluating disorders in the sense of color has been developed and offered for practice. A total of 340 patients with diseases of the retina and optic nerve and 80 normal subjects were examined. The results indicate that different conditions of examination, selection of combination by the color, brightness, and deepness of the stimulus and background allow detection of decreased sensitivity of one, two, or three color perceptors (disorders in sense of color--color blindness) and permit a quantitative evaluation of functional disorders in the color channels of visual system. The new method can be used in the diagnosis of the initial pathological processes of different origin, involving the cone system at any level of visual route and associated with acquired disorders in color vision.

Color Perception↗
PubMedDate not supplied

[Topographic mapping of retinal function with a scanning laser ophthalmoscope and multifocal electroretinography using short M-sequences].

A new method of multifocal electroretinography making use of scanning laser ophthalmoscope with a wavelength of 630 nm (SLO-m-ERG), evoking short spatial visual stimuli on the retina, is proposed. Algorithm of presenting the visual stimuli and analysis of distribution of local electroretinograms on the surface of the retina is based on short m-sequences. Mathematical cross correlation analysis shows a three-dimensional distribution of bioelectrical activity of the retina in the central visual field. In normal subjects the cone bioelectrical activity is the maximum in the macular area (corresponding to the density of cone distribution) and absent in the blind spot. The method detects the slightest pathological changes in the retina under control of the site of stimulation and ophthalmoscopic picture of the fundus oculi. The site of the pathological process correlates with the topography of changes in bioelectrical activity of the examined retinal area in diseases of the macular area and pigmented retinitis detectable by ophthalmoscopy.

Adult↗
PubMedDate not supplied

[Psychophysical symptoms of demyelinating diseases of the optic nerve in multiple sclerosis].

Visual system channels were examined in 25 patients with multiple sclerosis. A new complex of symptoms was detected, reflecting the acute stage and the chronic demyelinizing process, which includes disorders of contrast, color, and spatial contrast sensitivity and stereoscopic vision. This can be useful in differential diagnosis of optic nerve diseases and evaluation of the visual system function in multiple sclerosis and prediction of the disease course.

Adult↗
PubMedDate not supplied

[Functional methods of research in diagnosing glaucoma].

New data on the function of the retinal cone system in glaucoma are presented, which extend the symptom complex of optic neuropathy of glaucoma origin and the potentialities of initial diagnosis of glaucoma. A new symptom is detected: disordered topography of color (red and green) sensitivity, which can serve as the early symptom of glaucomatous optic neuropathy and indicate the degree of its progress. The location of the process, detected in examination of color sensitivity topography, is more extensive than it is detected by static perimetry. Primary location of functional disorders is detected in the parafoveal area and the disorders are the more severe the further from the center during the initial stage of glaucoma. As the process progresses, the central zones are involved in it.

Aged↗
PubMedDate not supplied

[Principles of background stimulation in the treatment of amblyopia].

Described in the paper are the results of a comparative evaluation of treatment of amblyopia by computer techniques based on the modern understanding of the mechanisms of impaired visual functions, as observed in amblyopia, comprising stimulation of different canals of the visual system, which were affected or not. Better clinical-and-functional results were fixed in patients with high amblyopia by using the "Ambcar" soft stimulating the magnocellular system by sinusoidal grates with the eyes being fixed on moving objects as well as in patients with moderate amblyopia by using the "eYe" and "Krestiki" soft tools affecting different canals of the visual system and different levels of the parvocellular system. Amblyopia should be treated with respect to individual differences between affected functions of the visual system in each patient, and a therapy method should be chosen in proportion to a disease severity.

Acoustic Stimulation↗
PubMedDate not supplied

[Possibilities of computer-assisted processing of the results of an examination of the visual system].

The authors present the first results of examining the vision system with the use of an automated programmed complex realized in the 'C' program language in the IBM and Dos operation system, that helped present in a chart the distribution of the ocular light sensitivity and time of the sensomotor reaction in every site of the visual field of 40-50 degrees. The results evidence that computer-aided methods may be effectively used to assess the light sensitivity of the eye, contrast sensitivity, space summation, rod and cone interactions, the topography of color photoreceptors, and the function of the posterior section of the eye in abnormalities of the retina and the optic nerve, as well as to monitor visual function rehabilitation after treatment.

Adaptation, Ocular↗