[Do We Still Need Electrophysiology in Ophthalmology?] / Brauchen wir noch Elektrophysiologie in der Augenheilkunde? Indikationsstellung für elektrophysiologische Untersuchungen.

Electrophysiological methods in clinical ophthalmology include the full-field electroretinogram (ERG) for assessment of outer and middle retinal layers, pattern ERG (PERG) for assessment of ganglion cell function, the electrooculogram (EOG) for assessment of retinal pigment epithelium function, as well as visual evoked potentials (VEP) for assessment of the visual pathway, including the optic nerve and visual cortex. Multifocal recording techniques for ERG and VEP are used for tests within selected areas of the visual field. Technical progress in ocular imaging, especially optical coherence tomography (OCT) and fundus autofluorescence (FAF), allows high-resolution imaging of subtle morphological changes of the retina and posterior fundus. Typical retinal diseases may then be diagnosed at an early stage, without conventional electrophysiological investigations (e.g. x-linked retinoschisis, Stargardt disease, vitelliform macular dystrophy). OCT outclasses electrophysiological methods in the quantification of optic atrophies. With newly developed optic techniques, peripheral retinal structures (wide angle optics) and subtle structures up to the photoreceptor level (adaptive optics) can be imaged with increasing quality. However, differentiation of central retinal disorders (e.g. macular dystrophy) from generalised retinal diseases requires electrophysiological diagnostic testing. The same applies to discrimination between different functional disorders in generalised retinal diseases (e.g. enhanced S-cone syndrome, congenital stationary night blindness, achromatopsia).

[Evidence-based diagnostic approach to inherited retinal dystrophies 2009]. / Evidenzbasierte Diagnostik hereditärer Netzhautdystrophien 2009.

BACKGROUND: Hereditary retinal dystrophies comprise a heterogeneous group of inherited retinal disorders with variable clinical presentation and multiple associated genes. Clinical diagnosis and differential diagnosis are difficult. The purpose of the current paper is to provide guidelines for an effective diagnostic approach. METHODS: A literature search was carried out and our own data on clinical (n = 3200) and molecular genetic (n = 4050) diagnosis of patients with retinal dystrophies were evaluated. RESULTS: For an early diagnosis it is of importance to include inherited retinal dystrophies in the differential diagnosis of unexplained visual disturbances. The most important clinical test is the full-field electroretinogram (ERG), which allows detection or exclusion of generalised retinal dystrophies. If the full-field ERG is normal, a multifocal ERG will distinguish macular dystrophies. Fundus autofluorescence, near-infrared autofluorescence and high resolution optical coherence tomography improve the early diagnosis because morphological alterations can be detected prior to their ophthalmoscopic visibility. In addition, these non-invasive imaging techniques reveal new phenomena which are important for the differential diagnosis and follow-up of retinal dystrophies as well as for an improved understanding of their pathogenesis. Routine molecular genetic diagnosis is available for an increasing number of retinal dystrophies. A succinct clinical diagnosis is a prerequisite to allow selection of the gene(s) to be analysed. If genetic testing is indicated, a human geneticist should be involved for counselling of the patient and possibly further family members and initiation of the necessary steps for DNA testing. CONCLUSION: The combination of electrophysiological testing, retinal imaging and molecular genetic analysis allows a differentiated diagnosis of inherited retinal dystrophies and an individual counselling of patients. If inherited retinal dystrophies are suspected, a detailed examination in a retinal centre specialised on inherited retinal dystrophies is recommended.

Five-Year Trends in Multifocal Electroretinogram for Patients With Birdshot Chorioretinopathy.

PURPOSE: The aim of this study is to investigate temporal trends in multifocal ERG (mfERG) parameters and analyze their relationships with anatomic and functional markers in patients with birdshot chorioretinopathy (BSCR). DESIGN: Prospective observational case series. METHODS: Sixteen BSCR patients were include and underwent 2 standardized follow-up (FU) visits within 5 years following a baseline examination, including mfERG, visual acuity (VA), visual field (VF), Lanthony desaturated panel D-15 test for color vision, quality of life (QoL), fluorescein and indocyanine green angiography, and optical coherence tomography (OCT). RESULTS: A significant trend toward a decrease in absolute N1 amplitude values was observed over the follow-up period (P < .001) while N1 implicit time remained unchanged. In contrast, P1 amplitude decreased (P < .001) and P1 implicit time increased (P < .001) over the same period. No significant temporal change was found for VA, color vision score, foveal threshold, mean deviation of VF, and QoL. After adjusting for time to FU, increasing N1 and P1 IT were both associated with decreasing values of logMAR, foveal threshold, and QoL and with increasing color vision score and mean deviation of VF. A significant relationship was observed between decreasing P1 amplitude values and increasing mean deviation of VF. Lower absolute values of N1 amplitude were associated with venous vasculitis, whereas lower P1 amplitude values correlated with alteration of the outer retina in OCT. CONCLUSIONS: Progressive deterioration in mfERG during a 5-year period is detected in BSCR, whereas classical functional test results were unchanged. This study suggests a better sensitivity of mfERG in monitoring the retinal function of BSCR patients.

Moderate perinatal thyroid hormone insufficiency alters visual system function in adult rats.

Thyroid hormone (TH) is critical for many aspects of neurodevelopment and can be disrupted by a variety of environmental contaminants. Sensory systems, including audition and vision are vulnerable to TH insufficiencies, but little data are available on visual system development at less than severe levels of TH deprivation. The goal of the current experiments was to explore dose-response relations between graded levels of TH insufficiency during development and the visual function of adult offspring. Pregnant Long Evans rats received 0 or 3 ppm (Experiment 1), or 0, 1, 2, or 3 ppm (Experiment 2) of propylthiouracil (PTU), an inhibitor of thyroid hormone synthesis, in drinking water from gestation day (GD) 6 to postnatal day (PN) 21. Treatment with PTU caused dose-related reductions of serum T4, with recovery on termination of exposure, and euthyroidism by the time of visual function testing. Tests of retinal (electroretinograms; ERGs) and visual cortex (visual evoked potentials; VEPs) function were assessed in adult offspring. Dark-adapted ERG a-waves, reflecting rod photoreceptors, were increased in amplitude by PTU. Light-adapted green flicker ERGs, reflecting M-cone photoreceptors, were reduced by PTU exposure. UV-flicker ERGs, reflecting S-cones, were not altered. Pattern-elicited VEPs were significantly reduced by 2 and 3 ppm PTU across a range of stimulus contrast values. The slope of VEP amplitude-log contrast functions was reduced by PTU, suggesting impaired visual contrast gain. Visual contrast gain primarily reflects function of visual cortex, and is responsible for adjusting sensitivity of perceptual mechanisms in response to changing visual scenes. The results indicate that moderate levels of pre-and post-natal TH insufficiency led to alterations in visual function of adult rats, including both retinal and visual cortex sites of dysfunction.

[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.

Comparison of full-field electroretinogram in diabetic and non diabetic dogs with cataracts / Estudo comparativo do eletrorretinograma de campo total em cães diabéticos e não diabéticos com catarata

Being the commonest ocular disorder, dense cataracts disable fundoscopic examination and the diagnosis of retinal disorders, which dogs may be predisposed. The aim of this study was to compare the electroretinographic responses recorded according to the International Society for Clinical Electrophysiology of Vision human protocol to evaluate retinal function of diabetic and non diabetic dogs, both presenting mature or hypermature cataracts. Full-field electroretinogram was recorded from 66 dogs, with ages varying from 6 to 15 years old allocated into two groups: (1) CG, non diabetic cataractous dogs, and (2) DG, diabetic cataractous dogs. Mean peak-to-peak amplitude (microvolts) and b-wave implicit time (milliseconds) were determined for each of the five standard full-field ERG responses (rod response, maximal response, oscillatory potentials, single-flash cone response and 30 Hz flicker). Comparing CG to DG, ERGs recorded from diabetic dogs presented lower amplitude and prolonged b-wave implicit time in all ERG responses. Prolonged b-wave implicit time was statistically significant (p< 0.05) at 30 Hz flicker (24.0 ms versus 22.4 ms). These data suggests full-field ERG is capable to record sensible alterations, such as flicker's implicit time, being useful to investigate retinal dysfunction in diabetic dogs.

Catarata madura e hipermadura, alteração frequentemente observada em cães, impossibilita a visibilização do fundo do olho e provável diagnóstico de degenerações retinianas. Objetivou-se comparar as respostas retiniana de cães diabéticos e não diabéticos, ambos portadores de catarata madura ou hipermadura, com auxílio do eletrorretinograma de campo total, utilizando o protocolo da International Society for Clinical Electrophysiology of Vision. Sessenta e seis cães, com idades variando entre 6 a 15 anos de idade foram divididos em dois grupos: (1) CG, cães não diabéticos com catarata madura ou hipermadura e (2) DG, cães diabéticos com catarata madura ou hipermadura. Mensurou-se amplitude pico a pico (microvolts) e tempo de culminação da onda-b (milisegundos) para as cinco respostas do ERG (resposta de bastonetes, máxima resposta, potencial oscilatório, resposta de cones e flicker a 30Hz). Avaliando-se as respostas obtidas com o exame, o grupo de cães diabéticos apresentou menor amplitude e maior tempo de culminação da onda-b em todas as respostas. O aumento do tempo de culminação da onda-b em DG foi estatisticamente significante (p<0.05) no flicker a 30 Hz (24.0ms versus 22.4ms). ERG de campo total é capaz de registrar alterações em respostas sensíveis como o tempo de culminação da onda-b do flicker, podendo ser útil para investigar retinopatias em cães diabéticos.

[Developments in ophthalmologic electrophysiology]. / Entwicklungen in der ophthalmologischen Elektrophysiologie.

During the last years electrophysiology in ophthalmology has been facilitated to a big extent by computerized methods. Thus it has become a suitable method for an increasing number of relevant diagnostic problems. To make comparisons between test results of different diagnostic places easier an international standard concerning the methodology of the electroretinogram (ERG) has been elaborated by the "International Society of Clinical Electrophysiology in Vision" (ISCEV). Aim of the present article is to give a short description of the ERG-standard and to review recent developments in clinical electrophysiology in ophthalmology (ca. since 1989).

Recent advances in the electrophysiology of visual disorders.

There have been a number of technical developments in the field of visual electrodiagnosis in recent years, some of which are beginning to "bear fruit" in terms of improving accuracy of diagnosis. In addition there is more information available from electrophysiology and neurochemistry of retinal function that will lead to a clearer understanding of the physiological basis of clinical tests.