Cyclosporine-A in the treatment of serpiginous choroiditis

Summary Seven patients affected by bilateral inflammatory serpiginous choroiditis have been treated with Cyclosporine-A for 6-21 months. Nine outof the fourteen eyes showed a significant improvement in their visual acuity; five eyes did not change.Cyclosporine-A may, therefore, be considered effective in the treatment of this disease.Its usefulness seems to be greater when the serpiginous choroiditis is in its acute stage; chronic stages, however, also seem to improve under treatment.Its main indication is, in our opinion, the involvement of the macular region of the second eye, when the first eye is already damaged. We consider Cyclosporine-A, in these situations, to be a first choice treatment.     

Freeze-fracture replica of the primate lens fibers

Summary Using freeze-fracture techniques, we studied the fine structure of monkey lens fibers, with special reference to intercellular junctions. Gap junctions were frequently observed at the ball- and-socket interdigitations, the tongue- and-groove interdigitations, and between cortical lens fibers, while tight junctions were never apparent.     

Background light adaptation of the retinal neuronal adaptive system. II. Dynamic effects

The dynamic effects of continuous exposure to light on the neuronal adaptive system of the retina, as indicated by the oscillatory response (OPs) of the electroretinogram (ERG) were studied in the albino rat. Digitally filtered OPs and the a- and b-waves of the corneal ERG were simultaneously recorded in dark adaptation, during continuous light adaptation to four levels of background light (BGL) changing in steps of two log units from 1.43×10^–6cd/m², referred to as low and high scotopic, low and high mesopic levels. Exposed to high scotopic BGL the total oscillatory response (SOP) significantly enhanced within the first minute, whereas the amplitudes of the a- and b-waves were unaffected. In low mesopic BGL the SOP increased within the first minute, whereas the a- and b-waves significantly decreased. High mesopic BGL instantaneously and profoundly reduced both the SOP and the slow potentials. The individual OPs changed in amplitudes mainly within the first minute of BGL. In general, the earlier OPs (O1 and O2) reacted more to the two scotopic BGL levels, whereas the later OPs (O3 and O4) were more affected by the relatively brighter two mesopic conditions. In conclusion, the rapid increase of the OPs within the first minute of high scotopic and low mesopic BGL exposure may represent a rudimentary light adaptational effect in the rod-dominated rat retina. These findings also suggest that the neuronal adaptive mechanism of the retina seems to be a robust system, probably attaining preservation of visual abilities in the rat on exposure to light.     

Flow patterns of blood cells in the retinal capillaries

We present a new technique for retinal blood cell angiography which was used to investigate flow patterns of blood cells in the retinal capillary net of normal cats. Capillary paths were defined to be the path taken by the labelled blood cells from the terminal arteriole to the entry point into a collecting venule. We were able to define two types of capillary paths. The simple paths were minimally coiled and had a high blood cell flux. The complex paths were coiled, structurally complex and had a low blood cell flux in comparison to the simple paths of the same eye. A simultaneous fluorescein angiogram was performed to reveal the complete anatomy of the capillary net in which the functional paths exist. The possibility that such flow patterns exist in the human retina should be considered.     

The influence of δ9-Tetrahydrocannabinol on intraocular pressure in the anaesthetized cat

⁹-Tetrahydrocannabinol (⁹-THC) was injected both intravenously and into the brain stem via the left vertebral artery. Contrary to results obtained with clonidine, neither the fall in intraocular pressure (IOP), nor the arterial hypotension induced by ⁹-THC, were enhanced after the central administration of the drug. For clonidine, a central mechanism underlying the ocular hypotensive effect has recently been proposed. This suggestion is based upon the enhanced fall in IOP after central administration of clonidine. The pontomedullary area is considered to be the main initial target of this drug. Obviously, the IOP-lavering mechanism of ⁹-THC is different from that of clonidine.     

The global burden of trachomatous visual impairment: I. Assessing prevalence

This paper summarizes primary epidemiologic studies of trachomatous blindness to develop age-/sex-/region-specific estimates of the global prevalence of trachomatous blindness and low vision. These studies are first examined for their validity and then employed to derive a minimum prevalence of trachomatous visual impairment. This method yields a global total for 1990 of approximately 640,000 cases of trachomatous blindness, corresponding to a prevalence of 0.12/1,000 (lower and upper bounds, 0.10 to 0.14/1,000). When those with low vision due to trachoma are included, 1.5 million cases of visual impairment are estimated, corresponding to a prevalence of 0.28/1,000 (lower and upper bounds, 0.15 to 0.75/1,000). A second approach, labeled the projected prevalence of trachomatous visual impairment, selects country-wide studies to derive representative regional prevalence values. A global total of 2,899,000 blind (projected prevalence of 0.55/1,000 with lower and upper bounds, 0.37 to 0.83/1,000) is estimated for 1990. With trachomatous low vision included, greater than 6.7 million individuals in 1990 have visual impairment from trachoma (projected prevalence of 1.28/1,000 with lower and upper bounds, 0.53 to 4.29/1,000). Analysis of the distribution of the global prevalence by age, gender, visual acuity and region provide direction for trachoma research and programme priorities. Attention is drawn to the limited studies and resulting wide variation in the estimates of trachomatous visual impairment prevalence as indicated by the lower and upper bound estimates. It is recommended that this epidemiologic uncertainty be reflected in global and regional estimates of trachomatous visual impairment prevalence in order to draw attention to how little is known and emphasize the need for further surveys. A second paper incorporates these findings in an assessment of the global burden of trachomatous visual impairment.Supported by the Edna McConnell Clark Foundation.     

Visual field testing with reduced sets of test points

A computerized analysis of visual fields is described. In a second step these results are condensed into a reduced set of test points so constructed that if testing is limited to 6–8 points nearly all defective visual fields would have been spotted with at least one defective point.The reduced set is suggested as the basis in programmes for spotting glaucoma cases at an early stage.Using a reduced set involves the testing of few points several times in a session rather than spending very few trials on a great number of points. This is a new approach which merits further investigation.     

The neural crest origin of uveal melanomas

On the basis of two cases the relation between neurogenic tumours (neurinomas, neurilemmomas, Schwannomas, neurofibromas) and malignant melanomas of the uvea is discussed with emphasis on the close association of both groups of neoplasms with the ciliary nerves. The great histopathological diversity between different cases of melanoma as well as within individual cases is also pointed out. On histological and cytological criteria it may be difficult to differentiate between the neurogenic tumours and the highly differentiated, spindle cell variants of the melanomas. Since all these tumours are derived from the neural crest, they might be grouped under one common heading. It is postulated that neurogenic tumours have been overdiagnosed to the disadvantage of the highly differentiated spindle cell melanomas.     

Some aspects of cataract morphology: A SEM-study

Two lenses from patients of very advanced age with senile cataracts were processed for SEM, fractured equatorially, sputtered with Au and examined by SEM. In the cross-fracture various areas could be observed. Although the overall structure of the lens-fibres appeared to be intact, higher magnifications showed that the len-fibre material had changed into a brittle structure, with either a granular appearance or a fibrillar character. At other places clearly recrystallization of lens-fibre proteins had taken place, with the formation of finger-like substructures, sometimes organized into plate-like structures or running parallel to each other in a kind of undulating pattern.Between the various areas of chemically changed lens-fibre material certain canal-like areas were found with cellular structures, the so-called waterclefts or Wasserspalten. Structures which, together with the chemical change in the lens proteins, account for the dramatic change in light dispersion.The work was carried out at the Centre for Medical Electron Microscopy, 69/2 Oostersingel, 9713 EZ Groningen.     

Alternating hyperphoria

Alternating hyperphoria (synonyms: dissociated vertical deviation (DVD) or occlusion hyperphoria) and variants like dunilateral patching hyperphoria (periodic vertical squint) and monocular vertical nystagmus, which may arise after strabismus operations or loss of the function of one of the eyes, have dynamic properties which differ from those of the vertical vergences or fusional movements in normal binocular vision. Alternating hyperphoria is the result of an early intense disturbance of binocular vision, leading to the absence of vertical fusional vergence or the detection of disparity necessary for this. Vertical disparity vergence is essentially a stabilizing and adaptive system.     

Pterygium excision with or without postoperative irradiation,a double-blind study

A double-blind study (covering 40 months) of 40 eyes with a pterygium which had not previously been operated on, was carried out to study the effect of postoperative irradiation. Nineteen eyes were treated by the bare sclera operation technique only and in 13 cases (68%) a recurrence occurred within 4 months. In 18 eyes from the group of patients treated with Sr 90 irradiation on the 1st, 7th and 14th postoperative day (maximum 3×1000 rad) no recurrences were seen.Patients with a recurrent pterygium and diplopia, symblepharon, visual disturbances (growth over the pupil or severe astigmatism) or many previous operations, were treated by lamellar keratoplasty (Dake, 1980). The recurrences without these complications were treated with success by the bare sclera technique and postoperative irradiation.Complications did not occur in any of the series.     

Elektrophysiologischer Nachweis von 3 differenten Muskelfasertypen der „slow fibers“ äußerer Augenmuskeln

Zusammenfassung Der Autor berichtet über elektrophysiologische Untersuchungen äußerer Augenmuskeln bei Kaninchen in vivo mit einer standardisierten Glasmikroelektrodentechnik.Nach Erläuterung der Problematik und Aufgabenstellung sowie der Methodik und Versuchsanordnung werden die Untersuchungsergebnisse über die Muskelfasermembranruhepotentiale der slow fibers sowie über die postsynaptischen Potentiale der slow Fibers analysiert. Anhand von Abbildungen und tabellarischen Übersichten erläutert der Autor die elektrophysiologischen Parameter von 3 verschiedenen, elektrophysiologisch sicher zu differenzierenden Muskelfasertypen der slow fibers äußerer Augenmuskeln.In der Diskussion wird auf die Bedeutung der vorgelegten Untersuchungsergebnisse für die Grundlagenforschung sowie für die klinische Ophthalmo-Elektromyographie hingewiesen.Abschließend werden die erkennbaren Forschungsrichtungen der elektrophysiologischen Analyse äußerer Augenmuskeln erörtert.

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Electrophysiologic evidence of three different types of the slow fibers of extraocular muscles

Summary The author reports on electrophysiologic investigations of extraocular muscles in rabbits in vivo by means of standardized glass microelectrodes.The results of investigation on muscle-fiber membrane resting potentials of slow fibers as well as on postsynaptical potentials of slow fibers are analyzed after having elucidated the problems as well as the methods employed and the experimental setup.By figures and synopses in tabular form the author illustrates the electrophysiologic parameters of three different types of muscle fibers of slow fibers of extraocular muscles that can with certainty be differentiated electrophysiologically.In the discussion references are made to the importance of the submitted results of investigation for basic research and for clinical ophthalmo-electromyography.Finally, the trends of investigation of the electrophysiologic analysis of extraocular muscles are discussed.

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Die experimentellen Untersuchungen wurden im Physiologischen Institut der Martin-Luther-Universität Halle — Wittenberg (Direktor: Prof. dr.sc.med. L. Zett) mit Unterstützung durch Herrn Dr.rer.nat. H. Opitz durchgeführt, damaliger Direktor: Prof.Dr.med.habil. B. Lueken     

Electrophysiological evidence that early glaucoma affects foveal vision

The pattern electroretinogram (PERG) and visual evoked potential (PVEP) were recorded simultaneously using a 1.1 cpd pattern which was counterphase modulated at 1 Hz. The responses of ocular hypertensive (OHT) eyes (with normal visual fields) and eyes with early glaucoma (with early visual field defects and/or early cupping of the optic nervehead) were compared to age-matched normal observers. All patients (26 eyes) and normal observers (14 eyes) had normal transient flash electroretinograms. Delays were seen in mean PERG latency in both OHT and early glaucoma eyes, while mean PERG amplitude was significantly reduced only in the early glaucoma eyes. The PVEP responses were unmeasurable in 11/26 patient eyes because the waveforms were grossly abnormal in shape, making it impossible to identify the N- and P-components. The data were categorized in this manner: a patient response was considered abnormal if latency or amplitude exceeded normal limits (PERG or PVEP) or if the waveform was unmeasurable due to its shape (PVEP only). Of the 26 patient eyes, we found that 8 eyes had normal PERG and PVEP, 11 eyes had abnormal PERG and PVEP, one eye had an abnormal PERG and a normal PVEP, and 6 eyes (3 patients) had a normal PERG and an abnormal PVEP. These data support the proposition that foveal vision (as assessed by the PVEP) may be affected by early glaucomatous damage. The relationship between the PERG and PVEP also was evaluated using a new measurement which we call the latency window. Using this measurement, 15/26 patient eyes were abnormal - 9 of these had unmeasurable PVEPs. This measurement could be useful in classifying W-shaped PVEPs as normal or abnormal.This study was supported in part by Grants EY01708 and EY01867 from the National Eye Institute, Bethesda, MD, by Fight For Sight Grant-in-Aid G-274, and by an unrestricted grant from Research to Prevent Blindness, Inc., New York, NY.     

Monitoring demyelination in multiple sclerosis with multi-flash campimetry

Multi-flash campimetry is a computer-implemented psychophysical technique that allows a rapid and extensive assessment of visual flicker sensitivity. Multi-flash field maps generated from the data typically reveal the presence of islands of degraded temporal resolution in multiple sclerosis (MS) patients, but not in normal control observers. These distinct islands presumably reflect the influence of demyelination as well as a variety of other possible transient factors, such as edema and inflammation of the optic nerve. The question addressed in the present study concerned a means of distinguishing among such influences.The strategy employed was to test MS patients more than once over a period of several months. Under the assumption that there is little or no significant remyelination in the central nervous system, it was argued that islands that remain present over time should be those that principally reflect demyelination. Transient changes that appear in the fields of MS patients probably reflect the influence of other mediating factors. Examples of multi-flash field maps are presented to illustrate this point and to serve as an initial assessment of the reliability of the technique. It is concluded that multi-flash campimetry may prove to be an effective aid in documenting the degree of progressive visual involvement in MS, and provide a means of monitoring the clinical course of demyelination in the visual system.     

Xenon arch photocoagulator used for transpupillary hyperthermia

The technique of near-infrared irradiation to obtain tumour necrosis in experimental pigmented melanomas is described. The xenon arch photocoagulator was modified and adapted for hyperthermia treatment. The adaptations included: filtering the light and changing the electronics, the aiming beam and the diameter of the beam.This study was supported by a grant from the Haags Oogheelkundig Fonds, The Hague, The Netherlands.     

Tierexperimentelle Untersuchungen der elektrophysiologischen Parameter der „fast fibers“ äußerer Augenmuskeln mit Glasmikroelektroden

Zusammenfassung Der Autor berichtet über tierexperimentelle Untersuchungen der elektrophysiologischen Parameter der fast fibers äußerer Augenmuskeln von Kaninchen in vivo mit einer standardisierten Glasmikroelektrodentechnik.Die vorgelegten Untersuchungsergebnisse erweitern unsere Kenntnisse der elektrophysiologischen Parameter der fast fibers. Anhand der Abbildungen werden die statistisch analysierten Ergebnisse über die Muskelfasermembranruhepotentiale, die Parameter der Muskelfaseraktionspotentiale, die Reizzeitspannungskurve und Angaben über die elektromechanische Latenzzeit der fast fibers erläutert.Die wichtigsten Schlußfolgerungen für die Grundlagenforschung über die fast fibers, für die klinische Ophthalmo-Elektromyographie und die Dualitätstheorie der Okulomotorik werden dargelegt.

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Animal experimental investigations of the electrophysiologic parameters of fast fibers of extraocular muscles by means of glass microelectrodes

Summary The author reports on animal experimental investigations of the electrophysiologic parameters of fast fibers of extraocular muscles in rabbits in vivo by means of standardized glass microelectrode.The submitted results of investigation enlarge our knowledge of the electrophysiologic parameters of fast fibers.The statistically analyzed results on musclefiber action potential parameters, on musclefiber membrane resting potentials, strengthduration curves and the data on the electro-mechanical latency period of fast fibers are illustrated by figures.The most important conclusions for basic research on fast fibers, for clinical ophthalmo-electromyography and for the duality concept of eyemovement control are given.

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Die experimentellen Untersuchungen wurden im Physiologischen Institut der Martin-Luther-Universität Halle mit Unterstützung durch Herrn Dr.rer.nat. H. Opitz durchgeführt; damaliger Direktor: Prof. Dr.med.habil. B. Lueken     

Diabetic choroidal and iris vasculature scanning electron microscopy findings

Scanning Electron Microscopy (SEM) was used to study vascular casts of twenty-four autopsy eyes taken from patients with long-standing insulin-dependent Diabetes Mellitus. These casts were compared to casts of ten normal autopsy eyes from patients without a history of diabetes or other vascular disease. The SEM findings in the choroidal vessels of the diabetic eyes included: increased tortuosity, focal vascular dilations and narrowings, hypercellularity, vascular loops and microaneurysm formation, drop-out of choriocapillaries, and sinus-like structure formation between choroidal lobules in the equatorial area. In the iris, neovascularization was evident in the vascular casts in cases with clinically recognized rubeosis iridis. These findings indicate that there is significant involvement of the uveal tract in diabetic eyes. The present study strongly supports the Hidayat and Fine light microscopic observation that the diabetic choroid demonstrates significant vascular changes (e.g. narrowed vessels with possible drop-out of capillaries and neovascularization). Changes in the diabetic choroid, especially in the choriocapillaris, may be a contributing factor in diabetic retinopathy, resulting in decreased oxygenation of the outer layer of the retina. Short reviews and updated information of diabetic eye disease provide some additional insights into the vascular problems in the eye.     

Information coding in the visual system: A new hypothesis

Experiments on subjective color sensations using a special signal generator and a standard TV monitor (black and white) led to a new hypothesis on information coding in the visual system. According to this hypothesis a trigger signal is required which restores the phase correlation of the pulse-coded spiking of the neurons transmitting visual information from the eye to the brain. The shift effect ( periphery effect), either artificially induced or initiated by microsaccades, might act as the postulated trigger.

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Zusammenfassung Experimente über subjektive Farbwahrnehmungen auf einem handelsüblichen Fernsehschirm (schwarz-weiß) führten zu einer neuen Hypothese über die Verschlüsselung visueller Information. Danach ist ein Trigger-Signal erforderlich zur Wiederherstellung der Phasen-Beziehung der Puls-kodierten Aktionspotentiale der Neurone, die die visuelle Nachricht vom Auge zum Gehirn übertragen. Der shift-effect (Peripherie-Effekt) — entweder künstlich oder durch Mikro-Sakkaden ausgelöst — könnte als der notwendige Trigger dienen.

     

Slit lamp ophthalmodynamometry

A short clinical trial of the Dynoptor Slit Lamp Ophthalmodynamometer has shown it to be a practical instrument. A mean O.A.P. of 52.3 mm/hg has been recorded.     

Electroretinogram responses and refractive errors in patients with a history of retinopathy of prematurity

Ametropias, particularly myopia, and mild retinal dysfunction are found in eyes with a history of retinopathy of prematurity. The retina is an important controller of refractive development. The aims of this study were to find out whether altered measures of retinal function and ametropias are associated and to consider mechanisms by which the retina might control refractive development. Nine infants and children with a history of stage 1, 2 or 3 retinopathy of prematurity and known courses of refractive development were studied. Spherical equivalents at the time of the electroretinogram ranged from +5.50 to –9.00 diopters. Rod photoresponse characteristics were derived from the a-wave, and postreceptoral components were also analyzed with calculation of the sensitivity and saturated amplitude of the b-wave, the sensitivity of oscillatory wavelet OP₂, and average amplitudes of OP₃ and OP₄. In hyperopic and myopic patients alike, the saturated amplitude and gain of the rod cell response were attenuated. In all patients, b-wave sensitivity was low, but in most there was little effect on saturated b-wave amplitude. In patients with courses toward myopia, the amplitude of OP₄, an OFF signal, is relatively more attenuated than that of OP₃, an ON signal. OP₄ is relatively larger in patients with courses toward hyperopia. The OP results suggest that an imbalance of ON and OFF activity in the retina is associated with development of ametropias in retinopathy of prematurity.Abbreviation ROP retinopathy of prematurity