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The purpose of this paper is to present a case study illustrating the importance of electrophysiological investigation in the diagnosis and serial monitoring of isolated congenital nystagmus.Serial electophysiological monitoring was undertaken in the male proband over a 9-year period commencing with initial assessment at 12 weeks of age: Skin electroretinograms (sERGs) were initially absent but subsequently revealed low-amplitude responses, electronegative morphologies and notched flicker responses suggestive of incomplete congenital stationary night blindness (CSNB2), but with an absent dark-adapted rod-specific response, while flash visual evoked potentials (fVEPs) demonstrated persistent crossed asymmetry, typical of albinoid misrouting of the optic nerves. Molecular investigation confirmed a novel hemizygous frame shift mutation in the CACNA1F gene, considered to be pathogenic and causative of X-linked CSNB2; additionally, a novel heterozygous missense variation in one copy of the RIMS1 gene was identified, pathogenic mutations of which underpin late-onset autosomal dominant cone-rod dystrophy (type 7). Segregation studies confirmed maternal inheritance of both mutations in the clinically asymptomatic mother in whom depressed rod-specific responses were confirmed on sERG. The child's visual acuity has remained stable as have the sERGs which have been verified by recordings using scleral electrodes.The importance of recording ERGs as part of evaluating infants who present with nystagmus, even with a normal fundus appearance, is supported. Further, sERGs were able to distinguish an apparent variant of CSNB2 and could give consistent results over many years. FVEP results add to the evidence that albinoid misrouting of the optic nerves may occur in cases of CSNB2. ERGs and fVEPs can provide valuable information in discriminating the relative diagnostic importance of multiple genetic abnormalities.

The very common ocular clinical ocular condition in children juvenile onset myopia results from axial elongation of the eye. In humans, some studies have found an association of myopia with greater levels of nearpoint activity and with differences in accommodation and convergence function. This paper reviews a variety of laboratory and clinical studies which are consistent with the hypothesis that retinal image defocus is biochemically transformed into an axial elongation expressed through increased posterior segment growth, and thus myopia. This paper also reviews theories of emmetropization, and classifies them as correlational, feedback, and combination. Evidence is presented to suggest that a combination theory, which combines both correlation of the ocular dioptric components and some feedback mechanism for growth of the eye, is the most correct. Current laboratory research suggests that quality and/or focus (defocus) of retinal imagery is involved in this feedback mechanism and that experimentally induced myopia might be enhanced, reduced or eliminated by pharmaceutical application. Direction of defocus may affect the rate of posterior segment growth, and thus the rate of ocular axial elongation.

The first part of this paper describes the process of optical holography, and discusses the possibilities and some of the merits of the application of optical holographic techniques in the field of ophthalmology, such as: 1. Holographic observation of the eye and the light-path through the cornea and the lens, leading to the evaluation of the optical constants of the eye. 2. Holographic interferometric measurements of the configuration changes which accompany accommodation or changes in the intra-ocular pressure. 3. Three-dimensional observations of the fundus. The second part of the paper is devoted to long wave holography, which has attained special attention in electromagnetic (non-optic) and ultrasonic wave propagation. Although these two forms of wave propagation differ in their physical properties, there are many similarities in their signal processing techniques, the collection of wave fronts emerging from the object, and in the visualization of images.

In this paper we examine several key properties of the moving 'windmill' target used in evaluation of the psychophysical transient-like function. Magnitude of the transient-like function, herein defined as the difference in threshold-determining background field luminance between stationary and moving windmill conditions, was greatest for a rate of approximately 6-8 on-off transitions/second for the moving windmill. Increasing the light/dark ratio of the windmill also augmented the magnitude of the transient-like function. The one-, two- and four-section 'windmill' targets exhibited essentially similar results, indicating that the number and length of borders do not influence this response. In conjunction with previous stationary windmill results (Enoch and Johnson, 1976), these data define the relevant transient-like function properties and provide a basis for comparison with findings in the companion paper (Enoch, JohnsonFitzgerald, 1976a) which describes the application of these properties to clinical populations for diagnostic purposes.

Normal retinal correspondence is not stable. The arguments for the plasticity of correspondence in normal binocular vision have been given into previous papers (Nelson, 1975, 1977). In this paper, both laboratory research and the clinical strabismus literature are reviewed to show similarities between normal and abnormal binocular vision. In particular, it is argued that sensory fusion (Panum's areas) and anomalous retinal correspondence (AC) obey similar principles, and so a sensory fusional model of AC may be developed. Recent advances in the neurophysiology of binocular vision are reviewed, but current laboratory knowledge cannot account for many phenomena known clinically unless certain postulates are made. Two hypothesized intracortical interactions among binocular disparity detectors, termed disparity domain inhibition and spatial domain facilitation, play key roles in extending the neurophysiology of binocular vision to an account of both normally - and clinically - observed plasticities of correspondence. The fusional model of retinal correspondence developed here from postulated domain interactions contrasts with the older concept of fixed corresponding points, an approach which has failed to provide a unified foundation for the treatment of normal and abnormal binocular vision.

The purpose of this paper is to report a case of idiopathic isolated fovea plana showing asymmetry in the multifocal electroretinogram (mfERG). We carried out optical coherence tomography (OCT) imaging, macular pigment density measurement, genetic testing and electrophysiological testing with visual evoked potentials and mfERGs on a young, highly myopic female of Pakistani origin, who had good visual acuity and no nystagmus. OCT imaging revealed a complete absence of any foveal pit in either eye. Macular pigment density was normal and visual evoked potentials indicated normal chiasmal crossings, excluding albinism. Genetic testing revealed normal PAX6 coding data, excluding aniridia as a cause. mfERGs showed asymmetry consistent with off-centre fixation to the temporal side of the fovea in both eyes, but were otherwise normal. Lack of a foveal pit is a well-known finding in conditions such as oculocutaneous albinism and PAX6 gene-related aniridia. Isolated fovea plana is less common, and this case illustrates that the absence of a foveal pit does not necessarily result in a poor visual outcome. The finding of asymmetry in the mfERG in such a case is novel, and may indicate a functional adaptation to the structure of the fovea.

Steady-state evoked potentials are popular due to their easy analysis in frequency space and the availability of methods for objective response detection. However, the interpretation of steady-state responses can be challenging due to their origin as a sequence of responses to single stimuli. In the present paper, issues of signal extinction and some characteristics of higher harmonics are illustrated based on simple model data for those readers who do not regularly hobnob with frequency-space representations of data. It is important to realize that the absence of a steady-state response does not prove the lack of neural activity. For the same underlying reasons, namely constructive and destructive superposition of individual responses, comparisons of amplitudes between experimental conditions are prone to inaccuracies. Thus, before inferring physiology from steady-state responses, one should consider an alternative explanation in terms of signal composition.

The mfERG, when first introduced by Erich Sutter used long sequences with short periods (∼15 ms) between steps (flashes). Since then a number of studies have introduced slower or modified sequences to emphasise Oscillatory Potentials (OPs), Optic Nerve Head Components (ONHC) or the s-wave. With this reduction in the rate of presentation many of the investigators have reduced the length of the sequence to allow a shorter recording period. This is also desirable for patient comfort and co-operation in diagnostic investigations. When reducing the length of the sequence there is a risk that it will be too short to ensure orthogonality of the first order component and all significant higher order components, particularly when a large number of areas (hexagons) are stimulated. This paper aims to verify that a short sequence (using the sequence used by the Roland Retiscan® stimulating 19 hexagons) is capable of keeping responses of both first and higher orders separate for each stimulating area. The sequence was investigated by placing photodiodes connected to a Diagnosys Espion® and then exported to Excel® and MATLAB® for analysis. It was determined that the sequences used were m-sequences length n = 9. The photodiode only responded to flashes of light so was unable to detect a correcting 0 at the end of sequence. The sequences driving each hexagon were then determined and found to be shifted 26 steps from each other. The correlation coefficients between all sequences was found to be −1/(2 n −1). The sequences to decode the second order kernels were determined and the correlation coefficients between each of these sequences, and between these and the original sequences, were also −1/(2 n −1). This work provides a mathematical validation of the use of short sequences for slow mfERG, and describes an empirical test method.

Visual disruption in patients diagnosed with epilepsy may be attributable to either the disease itself or to the anti-epileptic drugs prescribed to control the seizures. Effects on visual function may be due to perturbations of the GABAergic neurotransmitter system, since deficits in GABAergic cortical interneurons have been hypothesized to underlie some forms of epilepsy, some anti-epileptic medications increase cortical GABA levels, and GABAergic neural circuitry plays an important role in mediating the responses of cells in the visual cortex and retina. This paper characterizes the effects of epilepsy and epilepsy medications on the visual evoked response to patterned stimuli. Steady-state visual evoked potentials (VEP) evoked by onset-offset modulation of high-contrast sine-wave stimuli were measured in 24 control and 54 epileptic patients. Comparisons of VEP spectral amplitude as a function of spatial frequency were made between controls, complex partial, and generalized epilepsy groups. The effects of the GABA-active medication valproate were compared to those of carbamezepine. The amplitude of the fundamental (F1) component of the VEP was found to be sensitive to epilepsy type. Test subjects with generalized epilepsy had F1 spatial frequency-amplitude functions with peaks shifted to lower spatial frequencies relative to controls and test subjects with complex partial epilepsy. This shift may be due to reduced intracortical inhibition in the subjects with generalized epilepsy. The second harmonic component (F2) response was sensitive to medication effects. Complex partial epilepsy patients on VPA therapies showed reduced F2 response amplitude across spatial frequencies, consistent with previous findings that showed the F2 response is sensitive to GABA-ergic effects on transient components of the VEP.

Electroretinography, using laboratory animals, is a commonly used technique for determining the retinal toxicity of chemical agents. In this paper, guidelines for performing this test are provided. The physiologic basis for visual testing is presented with attention to inter-species differences. Technical aspects of animal recordings are reviewed, including animal preparation, stimulation, signal conditioning, recording and data analysis. Finally, suggested protocols for recording in diurnal and nocturnal species are presented.

Vigabatrin (GVG) is an effective antiepileptic drug used for treating partial seizures in adults and children. Over the last years, an increasing number of articles have been published reporting visual field defects (VFD) associated with GVG therapy in adults. To date, however, only an small number of pediatric patients have been reported. This paper is a retrospective review of clinical review to evaluate the prevalence and features of VFD in pediatric patients on GVG monotherapy.Fifteen children, on GVG therapy in the Department of Child Neurology, underwent visual field examination by static threshold automated perimetry using the Humphrey Field Analyzer Program 30-2. The age of these patients ranged from 6 to 18 years (12.4 +/- 3.6 years), 10 of them being male and five female.Three patients (20%) on GVG monotherapy showed VFD. These consisted in localised, bilateral, and relatively symmetrical, nasal field loss, with relative preservation of the temporal field within the central 30 degree area.

Trachomatous low vision can be prevented by treating or preventing infection or through surgery to treat trichiasis. Resource allocation to prevent trachomatous low vision should be directed to those interventions that are the most cost-effective. In order to assess which of many potential interventions are the more cost-effective, data on the epidemiology of the disease, the effectiveness of community- and facility-based interventions, and the cost of the interventions are required. This paper provides a stylized model of the path from risk of infection through disease to trachomatous low vision or blindness that delineates the points at which interventions may occur and for which data are required. The literature reveals a considerable amount of data regarding the epidemiology of the trachoma and its sequelae but little on the effectiveness of community-based interventions and only one study that measured costs directly. More data are needed to assist policy makers and international program partners who seek to make efficient resource allocation decisions in an effort to eliminate trachoma as a cause of incident blindness in the developing countries in which trachomatous blindness remains prevalent.

To evaluate the ability of the multifocal ERG (mfERG) to detect small defects in the stimulus array was the objective of this paper. Seven normal subjects had mfERGs recorded with a VERIS system. Stimulus arrays composed of 61, 103 or 241 hexagons were covered in part by small masks of different light transmittance properties. Only masks that covered at least one-half of a single 103 hexagon stimulus cell caused a significant reduction in signal. Different-shaped masks of about 5 degrees diameter were detectable using a 61-hexagon array only when they fully covered a stimulus cell. Detection was better, but marginal for some of the masks, with the 103 hexagon array. The 241 hexagon array showed sharp defects for all masks. Masking the stimulus screen is not equivalent to having a pathologic scotoma, but it demonstrates the greatest possible spatial sensitivity of the mfERG system. Thus, the mfERG appears to be able to detect small retinal lesions if they reduce local retinal function by at least 50% and correspond to at least half the area of one stimulus hexagon. Scotomas 5 degrees or smaller would be best detected using a fine (241 hexagon) stimulus array. With coarser stimulus arrays (e.g. 103 or 61 hexagons), the effect of a small scotoma depends on its location relative to the stimulus cells. These issues should be considered when selecting mfERG recording conditions.

This study describes the effects of stopping of the anti-epileptic drug vigabatrin on the visual field and electrophysiological changes in one third of the group of patients which is described in the paper 'Visual field and electrophysiological abnormalities due to vigabatrin' (Van der Torren and Graniewski, 2002). In 1997 several reports described the possible oculotoxic effect of vigabatrin followed by a reconsideration of this medication in epileptic patients. Vigabatrin was discontinued in one-third of the patients on chronic medication (mean duration 4.8 years). The visual field and electrophysiological examinations were repeated every 3 months if possible, otherwise at 6-month intervals. The EOG Arden index and the ERG rod b-wave showed a significant improvement when vigabatrin was discontinued. Repeated examinations of visual fields and electrophysiology shortly after discontinuation of the drug (between 1 and 3 months) and later on after 6 months and 1 year showed a recovery of the EOG Arden index and the ERG rod b-wave during this period. The visual fields did not change in either direction.the recovery effect is a strong argument for the hypothesis that the reduction in EOG and ERG b-wave is an oculotoxic effect. The electrophysiological improvement during 6 months or longer after discontinuation and the unchanged visual fields are an argument for the hypothesis that the visual field represents the irreversible intoxicating effect on the retina, whereas the electrophysiology represents a more direct effect on the retinal glial cells level.

In developmental biology, zebrafish are widely used to study the impact of mutations. The fast pace of development allows for a definitive morphological evaluation of the phenotype usually 5 days post fertilization (dpf). At that age, a functional analysis is already feasible using electroretinographic (ERG) methods. Corneal Ganzfeld ERGs were recorded with a glass microelectrode in anaesthetized, dark-adapted larvae aged 5 dpf, using a platinum wire beneath a moist paper towel as reference. ERG protocols included flash, flicker, and ON/OFF stimuli, both under scotopic and photopic conditions. Repetitive, isoluminant stimuli were used to assess the dynamic effect of pharmacological agents on the ERG. Single flash, flicker, and ON/OFF responses had adequately matured at this point to be informative. Typical signs of the cone dominance were the small scotopic a-wave and the large OFF responses. The analysis of consecutive single traces was possible because of the lack of EKG, breathing, and blink artefacts. After application of APB, which selectively blocks the ON channel via the mGluR6 receptor, the successive loss of the b-wave could be observed, which was quite different from the deterioration of the ERG after a circulatory arrest. The above techniques allowed to reliably obtain Ganzfeld ERGs in larvae aged 5 dpf. This underlines the important role of the zebrafish as a model for the functional analysis of mutations disrupting the visual system.

This paper considers the recommendation that Oscillatory Potentials (OP) be extracted by filtering in the frequency domain. This recommendation presumes that filtering isolates OPs from other ERG waveforms. However, we show that the leading edge of the a-wave has substantial frequency overlap with the OP spectrum at high intensities and that it contaminates these wavelets in the frequency domain. We propose a method of signal conditioning that removes a-waves prior to filtering. When this is done, the OPs show a bimodal distribution in the frequency domain that is well approximated by two Gaussians having means (+/-std. dev.) of 91.0 +/- 14.6 Hz and 153.1 +/- 17.1 Hz. This implies that two functions can be used to model the OPs in the time domain. However, we show that as most of the power of the Fourier spectrum (74%) is contained in a single Gaussian, a reasonable OP model can be derived by using a single function in the time domain. We test such a model on humans (n=5) and pigmented (n=14) and albino (n=14) guinea-pigs and show that it provides excellent fits to data across a range of flash exposures. Furthermore, changes in OP amplitude and timing between strains of guinea-pigs are easily detected with this model. We show that there is no statistical justification for making the model more complex by including multiple functions. Such paramatisation of the OP envelope provides a valuable and intuitive description of the OP waveforms in the time domain. The model provides an excellent description of OPs obtained with the current paradigm, however the single gaussian model may be deficient under stimulus conditions which produce highly asymmetric OP envelopes.

The vision of 12-13-year-olds in Sweden was examined in a field study. The study was designed as being a part of a large European-Latin American study, the DESAMI project. The objective was to evaluate the prevalence of residual amblyopia and ocular disorders, aetiologies of subnormal vision and some normal visual parameters in this group of children. The children had to be born in Sweden in 1985 in order to have the opportunity to be included in the voluntary screening visual examinations. The full results of the study will be presented elsewhere. This paper presents clinical and VEP data of those children who had visual acuity of 0.8 or below in one or both eyes which could not be increased with glasses, or other visual/eye disturbances not explained as common amblyopia, i.e., subnormal visual acuity or pathological visual states of unknown cause, SVAS (subnormal visual acuity syndromes).In all, 1046 children were examined: 76 had visual disturbances of such severity that they were referred to a paediatric ophthalmologist (AS). Eighteen children could not be pathologically classified, and they were referred to another ophthalmological examination and VEP (visual evoked potential) recordings. VEP reveals an asymmetric response after monocular stimulation in albinism.Twelve children turned up for a second examination and VEP was recorded from 10 children. Nine children showed iris translucency. Seven children showed an asymmetric VEP and were classified as albinos. The albinoic VEPs could be subdivided into two types, (1) including all parts of the response and (2) partly excluding the P1/P100 potential complex. The VEP response was normal, showing symmetry and no other abnormality, in three of the children.The results indicate that albinism is common in Sweden. A prevalence value of approximately 1% is about 100 times higher than previous figures. This high prevalence may indicate another form of heredity, with genetical contribution to albinism from a varying number of albino genes and varying expression in the phenotypes, in the Scandinavian population. It is emphasised that in investigations of children with SVAS, electrophysiological examinations are important, not only to reveal albinism but also to exclude or verify neurometabolic conditions, for example.

The purpose of this paper is to compare and evaluate the multifocal ERG response from raster based CRT and Digital Projection (LCD) stimulus delivery systems. A custom built p.c. based multifocal system was used to generate a 61 hexagonal element stimulus array. The stimulus was presented on a high luminance CRT display and on a back projected screen using a Digital polysilicon projection system. A fast response photodiode was used to analyse the stimulus pulse characteristics of both systems. A number of recordings were performed to assess the effect of stimulus delivery on a standard m-sequence response, inserted full-field filler response and on separation of onset and offset components. The pulse width for a CRT system is dependant on the type of phosphor and is typically 2 msec whereas the Digital Projection system produces a 13.3 msec pulse equivalent to the frame rate for the system. Slowing down the m-sequence by a factor of eight results in a pulse width of 106 msec which should enable the recovery of true offset responses. The CRT stimulus consists of a series of eight pulses of 2 msec duration each separated by 11.3 msec. First order responses are larger from the CRT system and second order responses larger from the Digital system. In conclusion, there are fundamental differences in the two delivery systems. The CRT system may have more potential in examining non-linear aspects of the multifocal response. Although both systems may be able to record offset responses, the Digital system will generate true offset responses whereas the CRT system may not allow true separation of these components.

This paper investigates votive gifts that people brought to sacred places in Croatia, as a gift in connection with various eye diseases. The custom of votive giving has been present in the territory of Christian Europe from ancient times until recent days. By examining the models of eyes dating from the seventeenth to the twentieth century, we came to the conclusion that they do not show any malformation, meaning that no pathological processes of eyes were shown. With their healthy form, they show the image of a healthy eye that the one who prays wishes to have. This is the opposite from the eye votives from Greek and Roman times, which were given in the ancient Esculap shrines with the desire to be healthy, because the Greek and Roman votives do show pathological processes.

The interpretation of binary kernels derived by means of the mulifocal ERG has frequently been the source of confusion and controversy. The aim of this paper is to provide an intuitive understanding of the concept of kernels and to demonstrate with models and examples, the relationship between the kernels and individual responses. The sample data used to illustrate the various aspects of the technique were derived and analyzed by means of the multifocal VERIS instrument using bipolar Burian-Allen contact lens electrodes. From the kernel data, response waveforms are synthesized that can be readily compared with those obtained with conventional flash, double flash and multi-flash ERG techniques. From the kernels of a single multifocal record, waveforms are synthesized that describe responses at various times after a preceding focal flash. It is shown that the observed adaptive changes in the waveforms depend not only on the flash interval but also on retinal eccentricity. Features on the response waveform exhibit independent adaptive behavior suggesting that they originate from different retinal sources. On one hand, the examples presented here illustrate the rich information on retinal dynamics contained in the kernels. On the other hand, they demonstrate how the interpretation of multifocal data can be facilitated when the kernel series is transformed into representations with more direct physiological appeal.

As this year marks the 200th anniversary of the birth of Friedrich August von Ammon (1799-1861), it presents an opportunity to recall and celebrate Ammon's life and his many contributions that helped shape both ophthalmology and plastic surgery into independent specialties. Some 250 years after Georg Bartisch, Ammon reestablished Dresden as a major center of ophthalmology, through the creation of a teaching institute, the publication of influential periodicals, and his personal publication of important monographs and journal articles. Ammon's Zeitschrift für die Ophthalmologie (founded 1830) was only the third journal in history that had been entirely devoted to ophthalmology. His prize-winning treatise, De Iritide (1835), correctly categorized iritis and gave a detailed description of sympathetic ophthalmia. His beautiful color-plate atlas, Klinische Darstellungen (1838-1841), contains landmark descriptions of congenital eye anomalies and has been described by Norman as 'the best summary of the knowledge of diseases of the eye prior to the introduction of the ophthalmoscope.' Ammon made most of his literary contributions in ophthalmology but he also contributed to another emerging field, plastic surgery. His monograph, Die plastische Chirurgie (1842), critically and comprehensively surveyed the entire history and current practice of plastic surgery, one of the very first textbooks to achieve this goal. In his last monograph (1858) Ammon returned to the subject of embryology of the human eye and drew upon his 30 years of study. Before his death, two of his last papers reported ophthalmoscopic observations, demonstrating his exploration of the frontiers of ophthalmology that characterized his entire career.

The purpose of this paper was to provide evidence for the reintroduction of simultaneously performed fluorescein angiography and electroretinography in the detection of diabetic retinopathy. ERG observations were made in conjunction with fluorescein angiography of 13 patients suffering from type I diabetes mellitus for five to 13 years. Only patients without any fluorescein leakage during angiography and without any morphologic changes in the fundus were involved in the study. Gold foil electrodes were used for recording. A stroboscopic lamp provided flashing light stimulation through a monochromatic blue filter. Intravenous fluorescein administration caused an immediate reduction in the ERG response. This reduction was seen both in the control subjects and in diabetes patients. In the control group, the reduction was over in 30-45 min, while in the diabetes group a considerable amplitude elevation was seen in all recordings between 15 and 60 min post-fluorescein. In the adaptation control group, where only repeated ERG recordings were employed every 15 min, a slight decrease in the a wave and a slight elevation of the b wave were observed during the whole recording period. No complaints or side-effects were detected during the observations. As all the patients displayed a normal fluorescein angiography besides elevated b wave after fluorescein administration, and this elevation was seen exclusively in the diabetic group, our study raises the possibility that this diagnostic method can be used in the detection of diabetic retinopathy.

The occurrence of macular edema, or of intraretinal fluid in general, was largely unknown prior to the invention of the ophthalmoscope. One of the first reports on 'Retinitis in Glycosuria', a disease complex, which today would partly be described as diabetic maculopathy, was published in 1856 by Jaeger. His observations were confirmed less than twenty years later by Nettleship in London, and in 1875 Appolinaire Bouchardat from Paris described fluid and lipid accumulation in the macula which led--in his words--to a glucose induced amblyopia. The first pathophysiological hypotheses of fluid accumulation in the posterior pole were then put forward in 1882 by Tartuferi, who thought the edema represented swelling of photoreceptor sheaths. In 1896, the Frenchman Nuel coined the term 'oedème maculaire' which he had observed in a retinitis pigmentosa patient. However, it was not until the end of the first World War, that the Swiss ophthalmologist Alfred Vogt observed macular edema in a variety of other ocular conditions such as iridocyclitiOFF macular edema to a macular hole. A quarter of a century later Bangerter coined the German term 'Zystoides Makulaödem', and in 1950, Hruby was the first to draw attention to the development of macular edema after cataract extraction. Three years later this was followed by Irvine's classical paper on cystoid macular edema after intra- and extracapsular cataract extraction which had been complicated by incarceration of the vitreous in the anterior segment with consecutive tugging on the macula. A decade later, the phenomenon of cystic fluid accumulation in the macula after cataract extraction was further characterised by Gass and Norton using fluorescein angiography. The ensuing years saw the emergence of new concepts regarding the blood-retinal barrier and the paramount role of its dysfunction in the development of macular edema.

This paper reviews the anatomic and physiologic conditions which predispose to fluid accumulation within the retina. Retinal edema has its inception in disease that causes a breakdown of the blood-retinal barrier in retinal capillaries and/or the retinal pigment epithelium (RPE). Edema develops not only because protein and fluid enter the extracellular space, but because the external limiting membrane and the convoluted extracellular pathway within the retina limit the clearance of albumin and other large osmotically-active molecules. These molecules bind water to cause edema. Recognition of edema clinically is complicated by the facts that angiographic markers (fluorescein and ICG) do not match albumin in size, and that clinical leakage does not always correlate closely with tissue swelling or functional loss. Active water transport across the RPE is efficient at removing subretinal water, but the flow resistance of the retina limits RPE access to the water of retinal edema. Consideration of the pathophysiology of retinal edema may aid in the development of better strategies for managing retinal edema.

The electro-oculogram (EOG) can be recorded by use of skin electrodes positioned near the eye in the horizontal or vertical plane and is dependent on the position of the eye relative to the electrodes and the size of the corneo-retinal potential (CRP). By use of the functional relation between the recorded potential and the eye position - CRP is considered to be constant - the EOG is the eye movement recording method most often used. Changes in CRP dependent on luminance or metabolic influences can be measured, on the other hand, by means of the EOG when eye movements of constant amplitudes are performed. The EOG in this paper is used in the latter sense. The widely used clinical test of rentinal function based on the electro-oculogram firstly described by Arden (Arden index) has been modified to achieve more precise and reliable results by including a gradual dark adaptation procedure and a special data analysis to detect fixation periods. Using modern techniques, the complete procedure has been automated. The efficiency of the procedure and the device is demonstrated in various ways.

Old World monkeys, apes and humans all enjoy trichromatic colour vision, and the absorption spectra of the photopigments are very similar in all species and all individuals. Colour vision in New World monkeys however, is very heterogeneous. In many species, the majority of individuals is dichromatic. Recently, anatomical and electrophysiological studies revealed that the retinal organisation in Old World monkeys and New World monkeys is very similar, although the cells belonging to the parvocellular pathway do not show any colour opponency and their spectral sensitivity is similar to that of the magnocellular cells. Apparently, the magnocellular and parvocellular pathways in the retina and the LGN have not developed as an adaptation to luminance and chromatic processing. It is more likely that the two pathways originally evolved to cover different ranges in the spatio-temporal domain. In the present paper, several spatial and temporal properties of parvo- and magnocellular cells (which are identical for dichromatic and trichromatic animals) are compared.

Following Dave’s death in September of 1993, I reread many of his publications. One of the most fascinating papers Dave wrote was his unique obituary of Frederick Verhoeff, delivered as the Third Frederick H. Verhoeff Lecture to the American Ophthalmological Society in 1969. On rereading this remarkable obituary, written in the form of a letter to Dr. Verhoeff, I realized that Dave tells us as much, perhaps more, about himself than about Verhoeff. Verhoeff served as a model for him in life. In his lecture he paid tribute to Verhoeff’s intellectual honesty, his courage, his originality, his scientific spirit, his loyalty, and his wit. These are the traits that made Dave Cogan himself such a great man.

Pope John XXI was an ophthalmologist before becoming Pope. He was born in Lisbon and trained at University of Paris and was part of the early medical school faculty in Siena. He became physician for Pope Gregory X and shifted to church duties. He rose quickly in the ranks of the Catholic church and was elected Pope in 1276 AD. His term was short. He died when construction in the Papal Palace at Viterbo, collapsed on him. His text book is in two parts with introductions to the eye followed by descriptions of diseases with their mostly medical treatments. He concludes with a section about his own wonderful waters. The work survived and a copy was even found amongst Michelangelo’s papers. Unfortunately the book turns out to be a plagiarism of two earlier text books. His most notable achievement supposedly was discovering that glaucoma was a disease with a hard eye. It turns out that this section is referring only to a suppurative external disease with indurated lids called sclerophthalmia.

In this paper an assessment is made of the evidence that exposure to solar ultraviolet radiation is causally associated with cataract. The evidence is reviewed separately for cortical, nuclear and posterior subcapsular cataract. The assessment examines the consistency and magnitude of an association, the dose-response relationship, supporting ecological data, and data from animal studies. Based on the assessment, it is concluded that there is sufficient experimental evidence that exposure to artificial sources of UV-B can cause cortical opacities in laboratory animals. However, there is only limited evidence that exposure to solar UV-B causes cortical opacities in humans. Similarly, there is only limited evidence that exposure to solar UV-B causes posterior subcapsular cataract in humans. The epidemiological evidence is consistent in suggesting that nuclear cataracts are not causally associated with exposure to solar UV-B.

Several therapeutic concepts are in favour of the treatment of intermittent exotropia. The presented paper will try to answer the question, whether this leads to different results, by the review of the 1989 and 1990 cases of two centres. In the Munich Right Isar Eye Hospital (Centre II) during this period 72 patients (already published data) were treated by recession and resection eye muscle surgery against intermittent exotropia or decompensating exophoria. The 111 compared patients of the Department of Orthoptics and Pleoptics at the University Eye Hospital Kiel (Centre I), were mostly treated with bimedial resection procedures. Another difference: diagnostic occlusion and prism correction were done in the Munich patients. There is major evidence that there are two widely different clinical pictures incorporated in the diagnostic frame of the so-called ‘Intermittent Exotropia’. In a third prospective group of patients (10/91 – 3/92), therefore, the prism-acceptance was evaluated.

On referral by ophthalmologists, the Visual Advice Centre provides the partially sighted with advice and prescriptions for illumination and visual aids. In this paper the multidisciplinary structure of the centre is presented and the results obtained in the first 18 months of its existence are discussed. Two hundred and ninety-eight patients were referred to the centre in this period. The majority of these patients (79.2%) were older than 60 years. The main cause of visual impairment was macular disease (45.3% of the patients). An interesting finding is that, although reading is an important need, reading problems only constituted 35.9% of the total number of demands for help. From an inquiry into the situation of 125 patients 6 months after prescription, it appears that more than 90% of the aids prescribed are used regularly. The conclusion is drawn that patients referred to the Visual Advice Centre benefit from the multi-disciplinary approach to their problems.

We examined the depth of ablation of the recipient bed with different counts of oscillations of excimer laser beam, to determine the correlation between planned and real depth. The ablation rate per oscillation was tested preoperatively by blackened photographic paper of defined thickness and thus was calculated to be 5 microns. Forty pig eyes were used for the first study. Each eight eyes were ablated in the planned depth 100 microns, 200 microns, 300 microns, 400 microns and 500 microns. The corneal thickness was measured with an ultrasonic pachymeter before and after the procedure. The depth measured after the photoablation was 99.4 +/- 36.4 microns for 100 microns planned depth, 186.7 +/- 55.3 microns for 200 microns, 298.4 +/- 68.5 microns for 300 microns, 373.9 +/- 65.7 microns for 400 microns and 480.1 +/- 59.3 microns for 500 microns. Comparing the depth measured after the photoablation to planned depth, there was a significant correlation (correlation coefficient: R = 0.93; p0.0001). Five other corneas trephinated from pig cadaver eyes were ablated from the endothelial side to the desired thickness (100 to 500 microns) of lamellar graft. In a second step a donor mask was placed onto the cornea and a laser light spot was led until perforating on all sides. The lamellar keratoplasty was completed by suturing the corneal graft into the bed. Macroscopic and microscopic examination of sutured eyes after fixation showed a good fit of wound margins and stromal interface. These results indicate that excimer laser is useful for reproducible corneal photoablation in lamellar keratoplasty.

In the last century German medical sciences made up the chief inspiration to the medical profession in Europe. The influence of German ophthalmology spread to Denmark, and accordingly the first Danish professor, Edmund Hansen Grut was trained in the Graefe clinic. His successor, Jannik Bjerrum grew up in southern Jutland, a district later on lost to the German Empire. The hitherto prevailing Danish sympathies with the neighbour in the south vanished after this. Bjerrum thus wrote all his papers in Danish and made no efforts to achieve an international reputation. In contrast, Marius Tscherning, received widespread recognition as a scientist. He spent many years in France. His scientific insights at last brought him to the Danish chair of ophthalmology. The history of the first three professors of ophthalmology, so different in their attitudes, has narrative value, but exemplifies as well the rapid development of the profession in the years 1886–1925.

The authors, before starting the discussion about ultrasound findings in infants with ROP, present a review of the history of ultrasound in this disease. Early A-scan reports are mentioned while the B-scan literature from 1984 to 1988, consisting of seven papers, is reviewed extensively. The most important echo patterns in the various stages of the disease are described along with the most intriguing ones. There is disagreement as to whether it is always possible to show by echography if the retina is in place or not. This is due to the fact that the acoustic properties of the retina seem sometimes to change as time goes by and is quite independent of any technical difficulties which are still very great and the know-how of the examiner.

This paper presents the results of a 20 year survey of ROP among less than or equal to 2000 g BW infants cared for at Pennsylvania Hospital. It relates changes in perinatal care and nutrition, survival rates, and serial serum E levels with incidence and severity of ROP. It includes our protocol for monitoring E nutrition so as to optimize its effectiveness at physiologic serum levels for prophylaxis for ROP. Also presented are the promising results of our experience with vitamin E at pharmacologic serum levels as a treatment for severe ROP (defined as in the Cryo ROP Trial). These indicate the need for a multicenter trial to assess the effect of pharmacologic Vitamin E therapy as an alternative or supplement to therapy of severe ROP with laser or cryo surgery.

The authors study and analyze the ophthalmological knowledge of the monk Meletius of the Monastery of St. Trinity in Tiveriopoli, as they appear in his paper 'De Natura Hominis'. The ophthalmological knowledge of Meletius mainly concerns the anatomy and physiology of the eye. The authors reach the conclusion that Meletius' ophthalmological knowledge for the greater part is compiled from that of the ancient authors; but they define a great number of pioneering medical ideas of Meletius, of which further research could discover the origin.

This paper describes the application of several key parameters of a windmill-shaped target (used in determinations of the psychophysical transient-like function) to clinical populations as a diagnostic tool for static perimetry. A technique for independently analyzing sustained- (Westheimer function) and transient-like retinally-based psychophysical responses is outlined, and stimulus characteristics, reliability and diagnostic potential of the tests are examined. Several particularly interesting clinical cases (one closure of a branch retinal arteriole) and two senile macular degeneration patients) are presented for illustrative purposes. In addition, a tentative 'working hypothesis' is presented as a basis for extensive future analysis of various clinical populations.

In this paper we examine the ophthalmological knowledge of the Hippocratic School as described in the Corpus Hippocraticum. An analysis is made of knowledge existing at the time concerning the anatomy of the eye and the physiology of vision, as well a diseases of the eye and ophthalmic surgical operations as depicted in the Corpus. In particular, the book "About Vision" from the Corpus Hippocraticum is discussed in detail. From our study of the extant texts it becomes apparent that not only was knowledge of ophthalmology considerably developed in the time of Hippocrates but it constituted a source of inspiration for ophthalmic treatments carried out by later physicians and in particular by those of the 19th century.

This paper describes the fundus changes in 2 patients with subacute sclerosing panencephalitis (SSPE). In both cases the ocular involvement preceded the neurological symptoms by several months. In one patient a localized serous detachment in the macular region was associated with retinal infiltrates and in the second patient an atypical unilateral macular chorioretinitis was first diagnosed. The diagnosis of SSPE was suspected when neurological signs appeared and it was confirmed by the typical EEG changes and especially by the high titers of measles antibodies in serum and CSF. The affected left eye of the second patient could be studied histopathologically and presented mainly pigment epithelial changes at the level of the scar, edema of the external plexiform layer, retinal folds and a detachment and rupture of the internal limiting membrane.

This paper explores the many aspects of the nature and measurement of the corneal surface. Its structure and the factors that influence it are described. The traditional techniques of keratometry are summarized and there is an emphasis on new experimental methods of determining corneal topography including moiré, holographic interferometric and profile techniques. The advantages and disadvantages of these procedures are considered.

Computer-aided teaching is of a growing importance in ophthalmology. The following problems are particularly reviewed: sequential, ramified and tutorial teaching, exercises in simulation and the checking of knowledge. Most of the technical obstacles have now been resolved. The aim of this paper is to overcome some psychological obstacles due to partial ignorance of the subject by most lecturers in our field.

We evaluated the perimetric concept and the technical construction of the Competer. The test procedures of the Competer are well conceived. The screening-strategy may fail in cases of central islands or large central defects. The interpretation of the visual field results is not easy, due to the use of a numerical print-out which, in addition, is different for screening and threshold examinations. The mechanical and electrical construction of the instrument could be improved. In the accompanying paper (Graniewski et al., 1982) results are presented of a comparative clinical evaluation.

This paper presents the case study of six patients suffering from acute bilateral optic neuritis simultaneously manifested in both eyes. The clinical picture and the full laboratory investigation failed to establish a real cause of the disease. Finally the lack of general neurological symptoms and the good prognosis of the disease after a two year follow-up is stressed.

There has been much recent conjecture over the apparent source location of the visually evoked potential, particularly in considering the lateralization found in halffield pattern reversal stimulation. This paper presents an alternative by directly identifying the sinks or sources present in the scalp current flow as these correspond to the maximal current flow into or out of the cortex (Nunez, 1981). Hjorth (1975) introduced a practical procedure for source derivation which has proved useful in the interpretation of the electroencephalogram (Wallin and Stalberg, 1980). We have applied source derivaton to cortical evoked potentials and present results obtained from right and left half-field stimulation, (Clement, Flanagan and Harding, 1985) and upper and lower field stimulation in normal subjects and patients with visual deficits.