[Oscillatory potentials in the diagnosis of glaucoma optic neuropathy].

This study proposes new, original methods for diagnosis of glaucoma optic neuropathy--oscillatory potentials (OP) in an electroretinogram (ERG) to a long-term stimulus and in the 30 Hz flicker ERG (with identification of OP at frequencies of 80 to 120 Hz). Twenty-three patients (46 years) aged 40 to 65 years with primary open-angle glaucoma were examined. OP in the 30 Hz flicker ERG (01 and 02) and that in the ERG ON-response to a long-term stimulus have a similar origin and are linked with the light ON-channels of the retinal cone system. O1, O2, and 03 in the 30 Hz flicker ERG reflect the function of neurons in the retinal cone system. The O3 oscillation displays impaired neuronal communications in the retinal ganglion cells.

[Optimization of a recording procedure of a multifocal electroretinogram].

The paper presents a procedure and conditions for recording multifocal electroretinogram (mfERG), its origin, and factors influencing small-signal ERG. The optimal conditions of ERG extraction using the existing method are appraised and indications for its use in ophthalmological care defined. The results of comparing the new types of electrodes developed in Russia for ERG recording and a DTL electrode included in the ISCEV guidelines are presented.

[Loal and multifocal electroretinography in the diagnosis of diabetic retinopathy].

The paper gives the results of electroretinography (ERG) in 38 patients (73 eyes) with type 2 diabetes mellitus at different stages of diabetic retinopathy (including in diabetic macular edema). The reductions in the macular ERG (M-ERG) amplitude parameters and in the retinal density of bioelectrical activity and the decreased amplitude and longer latency of multifocal ERG (mfERG) N1 and P1 components evidence the involvement of the retinal macular region into the pathological process and the magnitude of these changes depends on the presence of imaged macular edema. Despite the certain limitations of mfERG, assessment of the topography of retinal bioelectrical activity in the central field of vision is an important supplement to M-ERG results and may be a prognostic criterion for the development of a pathological process and its extent.

[Retinal bioelectrical activity in amblyopia].

The mechanisms of visual dysfunction in high amblyopia have not been adequately investigated. Different types of electroretinograms (ERG) as part of the ISCEV standard, as well as macular (15%) pattern and multifocal ERG were recorded in 41 children aged 5-17 years who had high amblyopia with varying gaze fixation and a visual acuity of 0.03-0.1. In high amblyopia, the mixed, macular, and flicker (30 Hz) ERGs were unchanged; however, some patients had supernormal a-wave of a mixed ERG, subnormal a-a- and b-waves of a macular ERG, and a moderately subnormal ERG pattern. Recording of a multifocal ERG showed lower retinal density values in the first and second rings. Thus, in high amblyopia, there are characteristic retinal bioelectrical activity impairments recorded under different conditions of stimulation and adaptation, which suggest that there are impaired interreceptor relations at the retinal level. These changes statistically significantly differ from those in organic retinal defects, which may be a criterion for their differential diagnosis.

[Role of active and passive modulations of ocular microcirculation in altering the morphometric parameters of the optic disk in primary glaucoma].

The authors studied the influence of active and passive modulations of ocular microcirculation on the morphometric parameters of the head of the optic nerve and their correlation in patients with primary open-angle glaucoma in the presence of elevated and normalized intraocular pressures (IOP). Ocular microcirculation was examined by the contact method on a LAKK-01 Doppler laser flowmeter. The morphometric parameters were explored by scanning laser ophthalmoscopy on a NRT device. Analysis showed a significant linear correlation of the active and passive modulations of microcirculation with the thickness of a retinal nerve fiber layer, the area and volume of the neuroretinal rim, and the volume profile of excavation in both types of microcirculatory changes. On the bases of the derived ratios, it has been concluded that in patients with the hyperemic type of microcirculation, active modulation mechanisms (enhanced neurogenic and myogenic activities of afferent microvessels) are responsive for glaucomatous optic neuropath in the presence of elevated IOP. In patients with the spastic type, decreased neurogenic and myogenic activities of afferent microvessels are an independent mechanism of tissue damage in the head of the optic nerve in normalized IOP.

[Optic neuropathy in children and adolescents with postuveal glaucoma].

Postuveal glaucoma is a severe complication of uveitis and frequently an indirect cause of severe visual acuity disturbance. Early diagnosis and determination of the efficiency of drug therapy and indications for surgical treatment require that the presence and progression of optic neuropathy should be evaluated. Examining the topography of color and contrast sensitivity and the central visual field in patients with postuveal glaucoma and peripheral uveitis has ascertained that progression of a glaucomatous process causes a reduction in the function of dark canals and green cones with the subsequent involvement of the retinal light canals in a pathological process. The decreased contrast sensitivity of the light canals and imperception of red color stimuli are observed during inflammatory processes.

[Retinal bioelectrical activity in children with congenital myopia].

Congenital myopia is a particular form of short sight that forms in the intrauterine development of a fetus and that is generally characterized by high myopia, a longer anteroposterior axis (APA) of the eye, and its fundal changes. The authors have studied the functional state of the central and peripheral retinal segments in children with congenital myopia by electric retinography (ERG). They examined 23 patients (46 eyes) aged 6 to 16 years, who had moderate and high congenital myopia, the diagnosis in whom had been established in their early life, with various ophthalmoscopic manifestations: without macular changes, with the hyperpigmented macula, an undifferentiated macular region, and acquired chorioretinal dystrophy. Visometry, refractometry, ophthalmoscopy, ultrasound biometry (APA measurement), and mixed, local, and multifocal ERG were performed. Four patients were diagnosed as having congenital persistent nocturnal blindness of the Schubert-Bornstein type. Varying bioelectrical activity changes in the retinal macular region were revealed in congenital myopia both in the absence of ophthalmoscopic changes and with the changes in the fundus of the eye as macular hyperpigmentation, undifferentiated macular region, and central chorioretinal dystrophy. There was a moderate and high inverse correlation between the parameters of bioelectrical activity (the amplitude of b wave of the maximum ERG, that of b wave of local ERG and the retinal density of a P1 component in all rings) on the one hand, and the spherical equivalent of refraction and the length of ADA, on the other.

[Retinal neuronal relationships in health and in optic neuropathy of glaucomatous genesis].

A new procedure is proposed to study oscillatory potentials (OP), by using long-term flash ERG. OPs for on- and off-ERG were isolated, by employing mathematical filters (80-200 Hz). This procedure was used to examine 25 healthy subjects and 40 patients with different stages of glaucoma. The procedure could ascertain the site of a pathological process in the on- or off-cone cell system, each showing a different sensitivity. The use of this study opens up new avenues for the study of both pathological processes in the on- and off-cone cell systems from distal to proximal portions and pathogenetic mechanisms responsible for development of retinal and optic nerve diseases.

[Ocular and orbital vascular blood flow in patients with endocrine ophthalmopathy].

Twenty patients with endocrine ophthalmopathy (EOP) (40 eyes) were examined, of them 11, 14, and 15 eyes were in a state of compensation, subcompensation, and decompensation, respectively. Color Doppler imaging was made in all the patients in order to study blood flow in the ophthalmic artery, retinal central artery, retinal central vein, posterior short ciliary arteries, posterior long ciliary arteries, and superior ophthalmic vein. There was a significant reduction in end diastolic blood flow velocity and a pronounced increase in the orbital arteries, which is typical of the ocular ischemic syndrome. The patients in a stage of EOP decompensation were found to have lowest values of the maximum systolic blood flow velocity in the retinal central vein and superior ophthalmic vein. The higher values of the maximum blood flow velocity in the orbital arteries in patients with decompensated EOP resulted from orbital pathological processes that may be largely determined by congestive processes rather than orbital inflammation.

[Classification of the forms of hypertensive retinopathy on the basis of estimation of the bioelectrical retinal potential and contrast sensitivity].

The paper gives the results of electroretinographic and psychophysical studies in hypertensive patients with first-, second-, and third-degree blood pressure (BP) elevation. The most characteristic functional symptoms of hypertensive retinopathy were defined at different stages of its development. There may be impaired retinal bioelectrical activity and diminished contrast and color sensitivity both in the presence and absence of ophthalmoscopically visible changes. Based on the findings, the authors have developed a functional classification of hypertensive retinopathy in relation to the degree of BP elevation.

[Modern electroretinography].

The paper describes the current types of electroretinography, the origin of electric retinal activity and its role in the diagnosis, differential diagnosis, and monitoring of retinal diseases of various origin. It presents the electroretinographic symptoms typical of pathology of the retinal cone and rod system in some hereditary diseases whose genes have been mapped and cloned to date and whose pathogenesis specified. The current concepts of retinal remodeling in its dystrophic changes are produced and emphasis is laid on the necessity of using the progress of vision biology and physiology in ophthalmological practice.

[Oscillatory potentials and ischemic processes in glaucoma].

The paper presents the results of studies made in patients with different stages of primary open-angle glaucoma, by using oscillatory potentials (OP). A significant inverse relationship was established between the OP index and the intraocular pressure; the OPI index was decreased in progressive glaucoma. The findings suggest that neuronal relationships are impaired in the proximal retina in glaucoma due to its ischemic processes.

[Morphofunctional characteristics of the retina and optic nerve in endocrine ophthalmopathy].

Optic neuropathy is a serious complication of endocrine ophthalmopathy (EOP). The morphological characteristics of the optic nerve (provided by a Heidelberg, HRT II retinotomograph) were compared with the functional impairments of various canals of light, color, and contrast sensitivities (detected by an Offon programme complex, MBN, Moscow). There were decreases in contrast and color sensitivities just at the early stages of the disease and deteriorated functions of contract and color sensitivity canals as optic neuropathy progressed. The HRT II retinotomograph has shown a significant change in the thickness of optic nerve fibers, the area of the optic disk (OD), and the volume of the neuroretinal ring, which corresponds to the magnitude of clinical manifestations and the severity of OD lesion. The first retinal changes appear long before optic nerve compression at the orbital apex (orbital apex syndrome), which are caused by ischemic and hypoxic processes due to orbital soft tissue edema. The most sensitive test in detecting the latent stage of optic neuropathy in EOP is a color and contrast sensitivity topography test. In EOP, the morphological optic nerve changes correlate with functional impairments in different canals of the visual system, reflecting the stage of the disease.

[Principles of background stimulation in the treatment of amblyopia]. / Printsipy fonovoi stimuliatsii v lechenii ambliopii.

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.

[Psychophysical and electrophysiological tests in diagnosis of the early sign of glaucomatous optic neuropathy]. / Psikhofizicheskie i élektrofiziologicheskie metody issledovaniia v diagnostike rannikh priznakov glaukomatoznoi opticheskoi neiropatii.

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.

[Assessment of retinal function in cataract by electroretinography]. / Otsenka funktsii setchatki pri katarakte s pomoshch'iu élektroretinografii.

Electroretinography (ERG) was used to assess the functions of the retinal central and peripheral sections in patients with cataracts of various origins and different degrees of opacities; the method is based on the use of 18-20 degrees red saturating stimulus fit in sucker electrode for macular ERG and Hanz-Feld white stimulus for total ERG. Macular biopotential recorded in the patients with mature cataracts without pathologic changes in the macular region coincided with the mean values of local macular ERG recorded in transparent ocular media with medium-intensity stimuli. Macular biopotentials in cataracts significantly differed from the normal values in dystrophic changes of the macular area. Total ERG values in transparent ocular media and in mature cataract patients coincided only in with saturating white stimulus in cases when no retinal abnormalities were present. ERG with weak and medium-intensity stimulating light has shown has shown a significant difference of ERG parameters in these patient populations. Analysis of ERG findings in 375 patients with cataracts of various origins and with various opacity degrees has shown the possibility of extrapolating the data on ERG symptoms of retinal abnormalities known in transparent ocular media to the diagnosis of the pathologic processes in the retina when the fundus of the eye cannot be seen; this method will be useful in predicting visual functions in the postoperative period.

[Methods of recording local ERG]. / K metodike registratsii lokal'noi ERG.

Two methods for recording the retinal local biopotential with the gaze fixation control and without this control are described, to be used for the assessment of the status of any retinal or macular site, among other things. A ring-shaped sucker electrode is employed in both methods; this electrode is supplied with a transparent anterior window and infrared-illuminated mirror in one method and in the other the electrode incorporates a light-emitting diode and an optic system that helps create a 6-20 degrees stimulus. Theoretical analysis and experimental findings evidence that the minimal area on the retina from which a local response may be obtained, fit for clinical purposes, conforms to 10-15 degrees with a stimulus 5 times brighter than semisaturating brightness. The local response share in this case is 70% and the number of possible blendings 50. The results explaining the choice of the conditions for the retinal local biopotential recording are presented. The suggested methods help assess the function of the macular area, distinguish between the functions of the cone and rod systems, record the total and Hanz-Feld electroretinograms without electrode substitution, record the macular biopotential in babies and in patients with nystagmus or with cataracts of various origins.

[Possibilities of computer-assisted processing of the results of an examination of the visual system]. / Vozmozhnosti komp'iuternoi obrabotki rezul'tatov issledovaniia zritel'noi sistemy.

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.

[Clinico-physiological characteristics of albinism]. / Kliniko-fiziologicheskaia kharakteristika al'binizma.

Visual functions in albinism were examined by psychophysiological and electrophysiological methods. Impaired functioning of light, brightness, and contrast channels of the visual system was revealed, as well as specific electrophysiological parameters typical of this condition: increased wave a and shortened latent periods of waves a and b on the total ERG, reduced amplitude and a shorter latent period of P-100 peak of visual evoked potential, prolonged latent periods of waves a and b of local ERG, and increased amplitude of waves a and b of L-ERG.

[Role of biopotentials of the retina in the study of mechanisms of the development of nystagmus]. / Rol' biopotentsialov setchatki v izuchenii mekhanizmov vozniknoveniia nistagma.

Total and local electroretinograms were studied simultaneously with registration of visual evoked potentials in 174 patients with nystagmus without pathologic shifts in the anterior section of the eyeball. Clinical and electrophysiologic findings permitting dividing the patients with nystagmus into two groups with different prognosis of the disease course: that without apparent changes in the fundus oculi with normal and subnormal parameters of the total and local ERG and that with pathologic changes in the retina and optic nerve and the corresponding electrophysiologic symptoms. Central mechanisms of nystagmus origin may be supposed in Group 1; visual function improved after pleoptic treatment. In Group 2 sensory mechanisms of nystagmus development are possible; visual functions did not improve after therapy. The mechanisms of vision deterioration in nystagmus are to be studied.