Essentielle (benigne) Hypertonie und Augenhintergrund

Zusammenfassung An 130 Patienten wird der Nachweis geführt, daß die essentielle (benigne) Hypertonie kein eigenes Augenhintergrundsbild bestizt. Ganz abgesehen von der Häufigkeit eines unveränderten Augenhintergrundes, die beobachteten Retinagefäßveränderungen gehen nicht über jenes Maß hinaus, wie es älteren Personen überhaupt zusteht; sie finden in Alterkslerose eine treffende Bezeichnung. Namengebungen wie Fundus hypertonicus oder Retinitis hypertonica und dergleichen sind auf das Gebiet der malignen Hypertension bzw. malignen Nephrosklerose verwiesen.     

Relaxing incisions with compression sutures for control of astigmatism after penetrating keratoplasty

Background: Ten percent of patients with persisting postoperative astigmatism following penetrating keratoplasty (PK) require surgical re-intervention, despite an otherwise successful transplant. Relaxing incisions (RIs) in combination with compression sutures seem to be the preferable procedure. However, poor predictability and lack of long-term experience complicate the issue. Here we report the 2-year follow-up results of 25 patients with high PK astigmatism treated by means of RIs and compression sutures Methods: Commonly, free-handed RIs were placed at the graft-host interface and 10–0 nylon compression sutures were placed perpendicular to the incisions. PK sutures had been removed no less than 4 months prior to refractive surgery Results: Nineteen eyes regained a functional vision of >- 0.4. The net decrease in astigmatism was 6.1 ± 4.3 D (47 ± 21 %). The mean vector-corrected change in astigmatism was 13.1 ± 5.7 D. Cylinder axis variation was reasonably low, with a correlation of attempted versus achieved axis of r=0.85. Within the first 3 months after operation the induced astigmatism regressed by, on average, 5.5 ± 4.3 D, making intraoperative overcorrection necessary. As an inevitable side effect, refractive procedures resulted in a myopic shift (4.7 ± 6.9 D) in spherical equivalence Conclusion: RIs and compression sutures are very useful in reducing postkeratoplasty astigmatism if correction of extremely high cylinder (> 10 D) is not intended. However, predictability still remains unsatisfactory and more than one operation may be required.     

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.

     

Course of the optic nerve fibers through the lamina cibrosa in human eyes

Background: This study investigated whether regional variations in the course of the optic nerve fibers through the lamina cribrosa may be one of the reasons why the local susceptibility for glaucomatous optic nerve fiber loss differs among the various regions of the optic disc. Methods: The study included 34 human eyes enucleated because of a malignant melanoma of the peripheral choroid without involvement of the anterior chamber angle or the optic nerve. Anterior-posterior sections through the pupil and the optic disc were histomorphometrically evaluated. In the central region and the peripheral part of the optic disc, we measured the thickness of the lamina cribrosa and the length of the lamina cribrosa channels through which the nerve fibers pass. Results: In the peripheral parts of the disc, compared with its central region, the lamina cribrosa was significantly thicker (P<0.0001, Wilcoxon test), the lamina cribrosa channels with the nerve fibers passing through were significantly longer (P<0.0001), and the ratio of length of the fiber channels to the thickness of the lamina cibrosa was significantly higher (P=0.0001). Conclusion: The lamina cribrosa is thicker and the course of the optic nerve fibers through the lamina cribrosa is more curvilinear in the disc pheriphery than in the disc center. These variations in the anatomy of the lamina cribrosa may be one of several factors influencing the regional susceptibility for glaucomatous optic nerve fiber loss within the optic nerve head.     

Eye references in the Homeric Epics

After a short introduction to the Homeric Epics, the name of Homer and the time and place where the poems were written, the authors refer to the terms of the eyes and to the verses where they are found. Among these terms, the most important is the term oaó, the first term for the eye in ophthalmology, which has remained throughout the years unchanged.Finally, they refer to the injuries of the eyes, the participation of the two sons of Asclepios in the Trojan campaign and to the verses including the classical paragraph ... a doctor is more capable than the other men ...Both Epics relating to the cardinal human values: prudence, temperance, fortitude and justice, contain the lofty ideal of human excellence, called by the Greeks a.     

Vitreous Fluid Levels of β-Amyloid(1–42) and Tau in Patients with Retinal Diseases

Purpose A decrease in -amyloid_1–42 (A42) and an increase in tau in the cerebrospinal fluid are reported to be characteristic phenomena in Alzheimers disease patients. To test the idea that A42 and tau contribute to the development of retinal diseases, we measured A42 and tau concentrations in the vitreous fluid from patients with macular hole (n = 13), diabetic retinopathy (n = 15), or glaucoma concurrent with other ocular diseases (n = 8).Methods Vitreous samples were collected from patients who underwent vitrectomy, and sensitive and specific enzyme-linked immunosorbent assays were used to determine the concentrations of A42 and tau.Results By comparison with the levels in the control macular-hole patients (33.9 ± 7.1pg/ml for A42; 3.3 ± 3.2pg/ml for tau), there was a significant decrease in the A42 level and a significant increase in the tau level in patients with diabetic retinopathy (1.8 ± 1.9pg/ml for A42, P = 0.002; 153.7 ± 71.6pg/ml for tau, P = 0.041) or glaucoma concurrent with other ocular diseases (2.8 ± 1.8pg/ml for A42, P = 0.006; 113.6 ± 43.1pg/ml for tau, P = 0.023).Conclusions Our findings indicate the possibility of a role for A42 and tau in the pathogenesis of some retinal diseases. Jpn J Ophthalmol 2005;49:106–108 © Japanese Ophthalmological Society 2005     

Tierexperimentelle Untersuchungen zur Bestimmung der Dauer der „mechanisch-effektiven Periode“ des Muskelfasermembranaktionspotentials und der „elektro-mechanischen Latenzzeit“ der „fast fibres“ äußerer Augenmuskeln bei Kaninchen in vivo

Zusammenfassung Es wird über tierexperimentelle Untersuchungen zur Bestimmung der Dauer der mechanisch-effektiven Periode des Muskelfasermembranaktionspotentials und der elektro-mechanischen Latenzzeit von fast fibres äußerer Augenmuskeln bei Kaninchen in vivo berichtet.Die Untersuchungen wurden mit einer international standardisierten Glasmikroelektrodentechnik durchgeführt. Die statistische Auswertung basiert auf 250 Einzelregistrierungen in Superpositionstechnik.Den Mittelwert der mechanisch-effektiven Periode des Muskelfasermembranaktionspotentials bestimmten wir mit ¯x=0,52 ms, Standardabweichung s=0,08 ms. Die Vertrauensgrenzen lagen bei 99 % statistischer Sicherheit bei 0,43 ms und bei 0,55 ms. Nach diesen Untersuchungen beträgt die Dauer der mechanisch-effektiven Periode der fast fibres äußerer Augenmuskeln nur 1/3 der mechanisch-effektiven Periode der vergleichbaren Skelettmuskeln.Der Mittelwert der Dauer der elektro-mechanischen Latenzzeit der fast fibres wurde mit ¯x=1,97 ms berechnet, Standardabweichung s=0,30 ms. Die Vertrauensgrenzen lagen bei 99 % statistischer Sicherheit bei 1,86 ms und 2,08 ms. Die elektromechanische Latenzzeit der fast fibres äußerer Augenmuskeln ist also wesentlich geringer als die vergleichbarer Skelettmuskeln, sie liegt unter der 50 %-Grenze der elektro-mechanischen Latenzzeit der analogen Skelettmuskulatur.Durch diese Untersuchungen konnten die wichtigsten elektrophysiologischen Parameter bestimmt werden, die den Grenzwert der maximalen Geschwindigkeit einer Blickrichtungsänderung bedingen.

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Animal experimental investigations for determining the duration of the mechanical-effective period of muscle action potentials and of the electro-mechanical latency period of fast fibres of external ocular muscles

Summary A report is given of an animal experimental study for determination of the duration of the mechanical effective period of the muscle fiber membrane action potential and the electromechanical latency period of fast fibers of the external ocular muscles in rabbits in vivo.The studies were carried out with an internationally standardized glass micro-electrode technique. The statistical values are based on 250 tests employing the superposition technique.The mean mechanical effective period of the muscular fiber membrane action potential was determined with SE=0.52 ms, SD=0.08 ms. The confidence thresholds were 99% statistically reliable with 0.43 ms and 0.55 ms. According to these studies, the duration of the mechanical effective period of the fast fibers of the external ocular muscles was only one-third off the mechanical effective period of the skeletal muscles.The mean duration of the electromechanical fast-fiber latency period was calculated with SE=1.97 ms, SD=0.30 ms. The confidence threshold was 99% statistically reliable with 1.86 ms and 2.08 ms. The electromechanical latency period of the fast fibers of the external ocular muscles was therefore significantly less than the skeletal muscles, lying under the 50% limit of the electromechanical latency period of the analogous skeletal musculature.These studies permit determination of the most important electrophysiological parameters which define a threshold value of maximal speed in vision direction changes.

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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     

Antifibrotic and uveitogenic properties of gamma interferon in the rabbit eye

The feasibility of gamma ()-interferon injection for the treatment of ocular fibrotic conditions was studied in rabbits using recombinant rabbit -interferon and the cell-injection model of tractional detachment. A toxicity study revealed that intravitreal injection of >10⁴ units -interferon consistently produced panuveitis. For tractional detachment, 250,000 rabbit dermal fibroblasts were injected intravitreally into 20 eyes; 1 day later, 5 of these eyes received intravitreal injections of 10⁴ units -interferon, another 5 were given 10⁶ units, and the remaining 10 received balanced salt solution. Slit-lamp examination and fundus photography were performed at regular intervals for 21 days and were graded by a masked observer. The eyes were then enucleated and processed for histology. Doses of 10⁴ units -interferon significantly reduced the severity of detachments, but injections of 10⁶ units induced panuveitis.The authors have no proprietary interest in the companies mentioned or the products used in this study Offprint requests to: L.M. Hjelmeland     

Optic disc histomorphometry in normal eyes and eyes with secondary angle-closure glaucoma

Parapapillary atrophy has been reported to occur in glaucoma eyes. Seeking the microscopical equivalent, we evaluated histomorphometrically serial sections of 21 human eyes enucleated due to secondary angle-closure glaucoma and 28 nonglaucomatous eyes with malignant choroidal melanoma. In the parapapillary region two zones were differentiated: in zone B adjacent to the optic disc, Bruch's membrane was denuded of retinal pigment epithelium cells; zone A peripheral to zone B showed pigment irregularities in the retinal pigment epithelium. Both zones B and A were significantly larger and zone B occurred more frequently in glaucomatous eyes than in the control group. Additionally, the outer and inner retinal layers and the parapapillary retina as a whole were significantly thinner in the glaucoma eyes than in the control eyes. Photoreceptors were completely lost or markedly decreased in number in zone B The findings may indicate that zones B and A represent the histological correlate of the glaucomatous parapapillary chorioretinal atrophy. Offprint requests to: J. JonasSupported by Deutsche Forschungsgemeinschaft DFG Nan 55/61/Jo, and Förderverein Augenheilkunde Erlangen     

Localization of the cytoadhesin integrins in the human cornea

Cell-matrix interactions play a fundamental role in normal and pathological conditions. They can be mediated by the cytoadhesin subgroup of the integrin superfamily of adhesion molecules. Its members include the vitronectin receptor (VNR) and the platelet glycoprotein IIb/IIIa (GP IIb/IIIa). Both receptors are composed of an -chain (_v and a_IIb, respectively) coupled to a ₃-chain. Using in situ immunohistochemistry and monoclonal antibodies, the authors studied the distribution of GP IIIa (common ₃-chain), GP IIb/IIIa (_IIb-chain) and VNR (_v-chain) in normal and pathological corneal tissues. In the normal cornea, the limbal vascular endothelium was weakly _v-positive. Occasionally, faint and granular staining was seen in the epithelium. In the pathological samples, an upregulated expression of the _v chain was noticed on the corneal epithelium as well as on fibroblasts and corneal endothelium. The a_IIb and ₃-chains were consistently absent. These data suggest that expression of the VNR-_v- chain in the human cornea is modulated by soluble factors released during inflammation and wound healing. Dissociation of expression of the _v and ₃-chains suggests usage of an alternative -chain by the VNR-_v-chain. Offprint requests to: B. Lauweryns     

Histochemical survey of the anterior segment of the normal human foetal and adult eye

The distributions of the lysosomal enzymes [acid phosphatase (AP),N-acetyl--d-glucosaminidase (NAG), -glucuronidase (-Gluc), -galactosidase (-Gal), dipeptidylpeptidase II (DPP II)] and of the membrane-bound proteases [aminopeptidase M (APM), aminopeptidase A (APA), -glutamyltransferase (GGT), dipeptidylpeptidase IV (DPP IV)] were investigated in the normal human adult and foetal anterior segment by histochemical methods. The distribution of these hydrolases varied between ocular tissues. The most active enzymes in the adult corneal epithelium and endothelium were AP, -Gluc, NAG, -Gal and GGT; in the keratocytes, APM, APA, -Gluc and GGT predominated. The adult trabecular meshwork cells were stained by AP, -Gluc, NAG, APM, GGT, DPP II and DPP IV. The enzymes AP, -Gluc, APM and APA, however, displayed greater activity in the endothelium of Schlemm's canal. The adult ciliary epithelium stained strongly for all lysosomal hydrolases; GGT was the most active protease here. Differences in enzyme activity were noted in some tissues when foetal and adult anterior segments were compared. There appeared to be a decrease in the activity of some enzymes with age and post-mortem delay greater than 24 h. The function(s) of each enzyme and their possible roles in the respective tissues are discussed.     

The basement membrane complex of the human corneal epithelium

The present report reviews the fine structure of the basement membrane zone or complex in the normal human cornea and describes its alterations in cases of early and acute keratoconus. In normal human cornea the basement membrane zone is formed by a basal lamina (with a lamina lucida and a lamina densa), special fibrils, collagen fibrils and assemblies of filaments. These components are less evident in the central region of the cornea than in its periphery. In early stages of keratoconus the basement membrane zone is thickened and the lamina densa displays an irregular course. In acute keratoconus, the basement membrane zone is also thickened and includes a large number of special fibrils as well as bundles of microfibrils (oxytalan fibers). The conclusion that the basement membrane complex of the corneal epithelium is equivalent to the epidermal-dermal junction of the skin is discussed.This paper was presented in part at the Eighth Annual Meeting of the European Club for Ophthalmic Fine Structure in West Berlin on 28^th, 29^th March, 1980     

Phasische und tonische Funktion der Augenmuskeln

Zusammenfassung Die Augenbewegungen von 3 Patienten mit totaler Lähmung eines R. internus oder eines R. externus wurden elektronystagmographisch untersucht. Das freibewegliche Auge führte Blickzielbewegungen im horizontalen Meridian aus. Am Partnerauge (mit dem gelähmten Muskel) zeigte sich dabei folgendes: Bei Sakkaden in der Wirkungsrichtung des gesunden Muskels ruckte das Auge mit einer Amplitude, die etwa dem geforderten Blicksprung entsprach. Nach dem Ruck sank das Auge aber wieder völlig oder teilweise in die Ausgangsstellung zurück. Die verbleibende Stellungsänderung war umso größer, je weiter die Sakkade im Wirkungsfeld des gesunden Muskels ausgeführt wurde. — Aufgrund der Befunde kann geschlossen werden, daß ein normaler Augenmuskel zur Beschleunigung des Bulbus im gesamten Blickfeld gebraucht wird. Zum Halten des Bulbus wird der Muskel dagegen nur dann benötigt, wenn der Bulbus in der Blickfeldhälfte steht, die seiner Wirkungsrichtung entspricht.

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Phasic and tonic function of eye musclesSaccades in patients with oculomotor or abducens paralysis

Summary Bye movements in 3 patients with a complete paralysis of one of the horizontal eye muscles were studied. In these cases, all horizontal movements of the affected eye were due to the opposing, well functioning muscle. No reciprocal innervation changes had to be taken into account in the paralysed muscle. The eye with the paralysed muscle, i. e. the bad eye, was occluded, and the good eye had to perform horizontal saccades which were initiated from various positions in the horizontal plane and were aimed towards the working direction of the well functioning muscle of the bad eye. The response of the bad eye always began with a phasic jerk. After this jerk the eye receded to a new position with an exponential time course. The difference between the previous and the new steady position was regarded as the tonic response. The jerks of the bad eye were only a little short of the saccades of the good eye, regardless of the position of the eyes at saccade onset. The amount of change in the tonic position largely depended on the sector of the field of gaze in which the saccade of the good eye was performed. In the off-field of the bad eye's working muscle, the tonic response was negligible, in the on-field the tonic responce reached nearly normal amplitude. These results fit nicely to Collin's measurements of in situ tendon forces in freely moving eyes and allow some inferences to be drawn as to the division of labour in the agonist and antagonist. The main task of the agonist in its off-field is to accelerate the globe during saccades. The ensuing new position is held predominantly by relaxation of the antagonist. In its on-field, the agonist is important for both, holding eccentric eye position as well as acceleration during saccades.

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Mit Unterstützung der Deutsehen Forschungsgemeinschaft SFB 70, B4.     

Die Stereo-Ultrastruktur der Cornealoberfläche bei der Ratte

Zusammenfassung Die dreidimensionale Beschaffenheit der Cornealoberfläche der Ratte wurde mittels des Scanning Electron Microscope und anhand konventioneller elektronenmikroskopischer Schnittpräparate untersucht. Dabei konnte das Vorhandensein von Mikrovilli (0,15 breit, bis 1,0 hoch) und von Mikroplicae (0,1–0,2 breit, 0,3–0,4 hoch, 1–3 lang) nachgewiesen werden. Bei diesen Strukturen dürfte es sich um während der Desquamation entstandene Ausstülpungen der Epithelzellmembran im Bereiche der Desmosomen handeln.

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The stereo ultrastructure of the corneal surface in rat

Summary Combined morphological examination of the corneal surface of rat both with the scanning and the transmission electron microscope reveals two kinds of protrusions covering the polygonal, regularly arranged epithelial cells: Mikrovilli and Mikroplicae; the former being approximatively 0.15 large and up to 1.0 high, the latter being 0.1–0.2 large, 0.3–0.4 high and 1–3 long. These formations are with high probability the remnants of desmosomes having been formed during desquamation.

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Diese Untersuchungen wurden mit Unterstützung des Fonds National suisse de la recherche scientifique (Nr. 5322.3) durchgeführt.     

Zum Kammerwasserabfluß des Primatenauges — ein Modell

Zusammenfassung An Hand eines Abflußmodells eines Primatenauges wird das Zeitverhalten des Druckes im Schlemmschen Kanal bei intraocularer Druck- und episkleraler Venendruckänderung untersucht. Die elastische Membran des Trabekelsystems folgt jeder intraocularen Druckschwankung und könnte damit als Pumpmechanismus wirken. Der entstandene Druckanstieg im Schlemmschen Kanal gleicht sich durch verstärkten Abstrom aus.

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Summary In an outflow model of primate eye the relation-time of pressure in Schlemm's channel is investigated by changes of intraocular pressure and episcleral venous pressure. The elastic membran of the trabecal system follows every oscillation of the i.o. pressure and so it effects like a mechanism of pump. The increased pressure in the Schlemm's channel is compensated by increase of the outflow.

     

Cytotoxic effects of antiproliferative agents on human retinal glial cells in vitro

Purpose: Proliferative vitreoretinopathy (PVR) is characterizedby the formation of cellular membranes on the detached retina and also in the vitreous. Glial cellscan be found in epiretinal and subretinal membranes from eyes with PVR, proliferative diabeticretinopathy (PDR), idiopathic macular pucker, uveitis and other diseases affecting theretina. Proliferation and contraction of glial cells appears to play a role in the pathogenesisof PVR. This study is designed to inspect the effectiveness of harringtonine, as well as colchicine,daunomycin and fluorouracil, against cellular proliferation of cultured human retinal glial cellsthat might be involved in the retinal and/or vitreous proliferation. Methods: Cultures of human retinal glial cells were preparedusing the enzyme digesting method. Cells that had been in culture for 2–5 passages were usedin this study. Harringtonine (0.063 g/ml 2.0 g/ml), colchicines(0.5 g/ml 16.0 g/ml), daunomycin (0.1 g/ml 3.2 g/ml) and 5-fluorouracil(0.5 g/ml 16.0 g/ml) were added to cultures of human retinal glial cellsand the proliferation rates of the cells were measured by the MTT method. Results: Harringtonine at the dosage of 0.063 g/mlinduced suppression of cellular growth, but the changes were not statistically significant (p > 0.05).At a dosage ranging from 0.125 g/ml to 2.0 g/ml, harringtonine significantly suppressedcellular growth according to the test (p < 0.01). Likewise, other antiproliferativeagents inhibited cellular growth significantly at a dosage from 1.0 g/ml to 16.0 g/ml(colchicine), 0.2 g/ml to 3.2 g/ml (daunomycin) and 1.0 g/ml to 16.0 g/ml(5-fluorouracil), but not at 0.5 g/ml (colchicine), 0.1 g/ml (daunomycin) and0.5 g/ml (5-fluorouracil). The ID₅₀ were 0.33 g/ml (harringtonine), 3.11 g/ml (colchicine), 0.79 g/ml (daunomycin) and 5.23 g/ml (5-fluorouracil), respectively.Conclusions: Harringtonine was extremely effective ininhibiting human retinal glial cell proliferation, like other antiproliferative drugs such as colchicine,daunomycin and 5-fluorouracil. Harringtonine, therefore, may be a candidate for further studies regardingthe treatment of experimental PVR.     

Immunologische Bestimmung von Lipoproteinen im Kammerwasser

Zusammenfassung Im menschlichen Kammerwasser konnte mit immunchemischen Methoden nur das -Lipoprotein nachgewiesen werden. Das -Lipoprotein mit einem Molekulargewicht von 3 200 000 war in keinem untersuchten Kammerwasser zu identifizieren, da die Blut-Kammerwasser-Schranke für dieses Riesenmolekül nicht zu durchdringen ist.

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Immunological determination of aqueous humor lipoproteins

Summary The solely present protein of lipid metabolism in human aqueous humor is -lipoprotein. -Lipoprotein (molecular weight 3 200 000) cannot pass the blood-aqueous-barrier and was therefore undiscoverable in the normal aqueous humors we analysed.

     

Akute arterielle Hypotonie durch Natrium-Nitroprussid und intraoculare Tension

Zusammenfassung An 19 Katzen wurde der Zusammenhang zwischen akuter arterieller Hypotonie und intraocularer Tension in Intubationsnarkose untersucht. Dabei ging eine kontrollierte arterielle Blutdrucksenkung durch intravenös gegebenes Natrium-Nitroprussid von im Mittel 168 mm Hg auf 89 mm Hg (d.h. 47%) mit einer Erniedrigung des intraocularen Druckes von im Mittel 22 mmHg applanatorisch auf 10 mmHg (d.h. 55%) einher. Diese Befunde am geschlossenen Auge sind wichtig für ein Verständnis der Effekte von Natrium-Nitroprussid am offenen Auge.

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Acute arterial hypotension by Sodium-Nitroprusside and intraocular tension

The relationship between intraocular pressure by short-term intravenous Sodium-Nitroprusside induced arterial hypotension in intubationanaesthesia was studied in 19 cats. A reduction of the blood pressure from an average of 168 mm Hg to 89 mm Hg (that is 47%) was followed by a clearly reproducible reduction of intraocular pressure from an average of 22 mm Hg to 10 mm Hg (that is 55%). These findings for the closed eye are a prerequisite for the understanding of the effects of sodium-nitroprusside in the open eye.

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Herrn Grammel, unserem Tierpfleger, danken wir für die Unterstützung bei den Vorbereitungen zu den Versuchen, Herrn Dr. Schenzle vom Institut für medizinische Biometrie der Universität Tübingen für die Durchführung der Varianzanalyse.     

Ultrasound biomicroscopy of the rat eye: effects of cholinergic and anticholinergic agents

Background Over the past few years the rat has gained prominence as an animal model for the study of glaucoma. However, no systematic study of the angle structures and the effects of medications on angle anatomy in the rat has been reported to date. We investigated the normal rat anterior segment anatomy in vivo using ultrasound biomicroscopy (UBM) and determined the effect of both cholinergic and anticholinergic medications on angle structures.Methods Fourteen eyes of seven 2-month-old female Wistar rats were imaged using an ultrasound biomicroscope and a modified eyecup. Baseline measurements of the anterior chamber depth (ACD), trabecular-iris angle (TIA), iris thickness at the thickest point near the pupillary margin (IT), angle-opening distance (AOD) (distance between the posterior corneal surface and anterior iris surface measured at 200 m from the scleral spur), corneal thickness (CT) and irido-zonular distance (IZD) were obtained. Imaging was repeated 30 min after instillation of one drop of cyclopentolate 1% and 48 h later 30 min after pilocarpine 1% instillation. The same measurements were obtained and compared to baseline values.Results Baseline values for all parameters recorded were not significantly different among contralateral eyes. After instillation of either pilocarpine or cyclopentolate, ACD was the only parameter that did not change significantly from baseline. In contrast, TIA, AOD, IZD, and IT were significantly different among the three groups. Post-hoc analysis (Bonferroni test) revealed differences among all three groups of eyes for TIA and AOD. A difference was also found between the pilocarpine-treated group and the other two groups for IZD and IT. A very small difference detected between the pilocarpine-treated group and the baseline measurements for CT was caused by the zero variance of measurements in the former group. Although both pilocarpine and cyclopentolate induced angle narrowing, inspection of the ultrasonic images revealed a differential effect. Pilocarpine caused a pupillary block-like picture, while cyclopentolate caused crowding of the iris base in the angle.Conclusions Baseline characteristics of the normal rat anterior chamber anatomy were established. Both cyclopentolate and pilocarpine cause angle narrowing in the rat eye, by different mechanisms.Nicholas Nissirios and Jerome Ramos-Esteban contributed equally and should both be considered first authors.     

Comparison of Snellen acuity and objective assessment using the spatial frequency sweep PVER

Background: We compared the vision objectively assessed by spatial frequency sweep pattern-reversal visual-evoked response (SPVER) with the Snellen acuity in patients. Methods: SPVER acuity and Snellen acuity were measured in 100 patients with various ocular pathologies, including macular diseases, diffuse retinal degeneration, optic nerve diseases, glaucoma, and high myopia. For SPVER, 10 sinusoidally modulated vertical gratings were presented as stimuli. The responses were averaged and displayed through the discrete Fourier transform on the monitor display. The PVER acuity was determined by extrapolating the SPVER amplitude-spatial frequency function to baseline. Results: Vision ranged from 20/15 to 20/400 with Snellen acuity, and from 20/25 to 20/190 with SPVER. The overall correlation between the two acuities wasr=0.666. The correlation varied fromr=0.895 in eyes with glaucoma tor=0.436 in eyes with optic nerve disease. Seventy-seven eyes (77%) had a visual acuity agreement of within 1.0 octave between the two measurements. Conclusion: The SPVER acuity and the Snellen acuity correlated to a certain degree. Discrepancies were found in certain diseases, with the highest disparity in patients with optic nerve disease. We conclude that the SPVER is effective in estimating vision objectively, particularly in patients in whom the standard Snellen test is impossible to perform or yields unreliable results.This study was presented in part at the American Academy of Ophthalmology Annual Meeting, San Francisco, November 1994