Characterization of Deformational Isomerization Potential and Interconversion Dynamics with Ultrafast X-ray Solution Scattering.

Dimeric complexes composed of d8 square planar metal centers and rigid bridging ligands provide model systems to understand the interplay between attractive dispersion forces and steric strain in order to assist the development of reliable methods to model metal dimer complexes more broadly. [Ir2 (dimen)4]2+ (dimen = para-diisocyanomenthane) presents a unique case study for such phenomena, as distortions of the optimal structure of a ligand with limited conformational flexibility counteract the attractive dispersive forces from the metal and ligand to yield a complex with two ground state deformational isomers. Here, we use ultrafast X-ray solution scattering (XSS) and optical transient absorption spectroscopy (OTAS) to reveal the nature of the equilibrium distribution and the exchange rate between the deformational isomers. The two ground state isomers have spectrally distinct electronic excitations that enable the selective excitation of one isomer or the other using a femtosecond duration pulse of visible light. We then track the dynamics of the nonequilibrium depletion of the electronic ground state population─often termed the ground state hole─with ultrafast XSS and OTAS, revealing a restoration of the ground state equilibrium in 2.3 ps. This combined experimental and theoretical study provides a critical test of various density functional approximations in the description of bridged d8-d8 metal complexes. The results show that density functional theory calculations can reproduce the primary experimental observations if dispersion interactions are added, and a hybrid functional, which includes exact exchange, is used.

[Dilatation and tortuosity of episcleral vessels in open-angle glaucoma (author's transl)]. / Erweiterung und Schlängelung episkleraler Gefässe und einseitiges Offenwinkel-Glaukom. I. Mitteilung. Klinisches Erscheinungsbild.

We studied two patients with unilateral open-angle glaucoma and bilateral dilatation and tortuosity of the episcleral vessels; the condition was thought to be congenital. Gonioscopy showed that all the eyes were engorged with blood. Episcleral venous pressure was not measured, but resistance to outflow, measured tonographically, showed a marked increase. The clinical significance of this type of glaucoma is pointed out.

[Dilatation and tortuosity of episcleral vessels in open-angle glaucoma. II. Electron microscopy study of the trabecular meshwork]. / Erweiterung und Schlängelung episkleraler Gefässe und einseitiges Offenwinkel-Glaukom. II. Mitteilung. Elektronenmikroskopischer Befund des Trabekelwerkes.

The trabeculectomy specimen from a case of unilateral open-angle glaucoma with dilatations and tortuosities of episcleral vessels was investigated electron-microscopically. The cribriform region and the adjacent trabecular lamellae were densified and fused by extracellular depositions and hyalinization of the trabecular lamellae. These alterations permit the conclusion that the glaucoma was caused by increased outflow resistance in the inner wall of Schlemm's canal.

[Electron microscopy studies of the trabecular meshwork in pigmentary glaucoma]. / Elektronenmikroskopische Untersuchungen des Trabekelwerkes bei Pigmentglaukom.

Trabeculectomy specimens from three patients with pigmentary glaucoma were investigated electron-microscopically. The pigment accumulations were highest in the uveal and inner corneoscleral trabecular meshwork. The outer lamellae and the cribriform region were hypochromic, while the endothelium of Schlemm's canal was unpigmented. The aqueous pathways of the inner trabecular meshwork were obstructed by hyperpigmented cells, cellular fragments and released pigment granules, those of the outer trabecular meshwork by depositions of extracellular material and collagen, by degenerative cells and by collapse of the trabecular lamellae.

The trabecular meshwork of a non-glaucomatous eye with the exfoliation syndrome. Electronmicroscopic study.

The trabecular meshwork of a non-glaucomatous eye with the exfoliation syndrome was investigated. The exfoliation material was found mainly in massive deposits in the subendothelial region of the outer and inner wall of Schlemm's canal, in the cribriform area and the uveal meshwork. The other alterations of the trabeculum corneosclerale corresponded to the age of the patient. The concept that the accumulation of exfoliation material is an important pathogenetic factor in the development of glaucoma was not confirmed by this study.

[Electronmicroscopic studies of the trabecular meshwork in corticosteroid glaucoma]. / Elektronenoptische Untersuchung des Trabekelwerkes bei einem Kortikosteroidglaukom.

The tissue specimen of a 41-year-old patient with cortisonglaucoma, obtained by trabeculectomy, was examined by electronmicroscope. There are massive depositions of band-like and linear arranged structures in the cribriform area and adjacent lamellae of the trabeculum corneosclerale. The pathways for aqueous humor of this region are almost completely obstructed by this material. That is the reason for an increased outflow resistance. The cells of this area show signs of degeneration and are reduced in their numbers. -- The cortisonglaucoma differs from all the other forms of glaucoma especially from glaucoma simplex by these characteristic deposits.

[Fluorescein angiographic studies of the effect of Harms' and Dannheim's trabeculotomia ab externo]. / Fluoreszenzangiographische Untersuchungen zur Wirkungsweise der Trabeculotomia ab externo nach Harms und Dannheim.

The mechanism of the outflow of the aqueous humor was investigated on 9 eyes with open angle glaucoma operated by traveculotomia ab externo. The anterior chamber was filled with 0,2% Fluorescein-Ringer-solution, before and after the operation. Comparing the fluorescein angiographic pictures it can be concluded that the effect of the operation it caused by an improvement of the outflow of the aequous humor through the system of Schlemm's canal as well as through the formation of a fistula.

[The glaucoma in heterochromic cyclitis Fuchs. Gonioscopic studies and electron microscopic investigations of the trabecular meshwork (author's transl)]. / Das Glaukom bei der Heterochromiezyklitis Fuchs. Gonioskopische Befunde und ultrastrukturelle Untersuchungen des Trabekelwerkes.

Seven patients suffering from heterochromic cyclitis Fuchs had been investigated by gonioscopy after paracentesis of the anterior chamber. Independent to previous intraocular pressure and tonographical results parts or all of the canal of Schlemm were filled with blood, followed by haemorrhage into the trabecular meshwork on several sites and bleeding into the anterior chamber. Three of the patients were operated on because of a chronic secundary glaucoma and the dissected trabecular meshwork was investigated by electron microscopy. Atrophy of the inner--and outer wall of the canal of Schlemm as well as missing of the endothelium of the trabecular meshwork was to be observed. Discussing the gonioscopical observations and electron-microscopical results the glaucoma in heterochromic cyclitis Fuchs seems to be caused by a collapse of the canal of Schlemm and not by increasing resistance in trabecular meshwork by sclerosis or hyaline membranes.

[Pathomechanism and therapy of angle-closure glaucoma (author's transl)]. / Pathomechanismus und Therapie des primären Winkelblockglaukoms.

Pathogenetically three types of primary angleclosure glaucoma can be differentiated. 1. Iridolenticular block; 2. Irido-trabecular block, 3. Cilioirido-lenticular block. The different types of angle-closure glaucoma are characterized by particular morphologic and functional criteria. Their therapy varies and should be oriented toward this classifikation.

[Electrophysiological and fluorescence-angiographical examinations in a case of fundus albipunctatus cum hemeralopia congenita (author's transl)]. / Elektrophysiologische und fluoreszenzangiographische Untersuchungen bei einem Fall von Fundus albipunctatus cum hemeralopia congenita.

Electrophysiological and fluorescenceangiographical examinations were carried out in a case of fundus albipunctatus cum hemeralopia congenita. In the ERG a diminished scotopic b-wave was conspicuous, which reached the normal size after longer dark adaptation. It was possible to distinguish between albipunctatus-dots and druses by fluorescenceangiography. While the latter became clearly visible in the phase of choroidic-fluorescence the ophthalmoscopically perceptible albipunctatus-dots lost their visibility.

[A new operative method for the treatment of malignant glaucoma (author's transl)]. / Ein neues operatives Verfahren zur Behandlung des malignen Glaukoms.

Since 1971 the University Eye Clinic Graz has used the cryocoagulation of the ciliary body as a method of therapy in cases of malignant glaucoma. In all 7 eyes treated once by coagulation the malignant course was interrupted and the tension permanently regulated. It is believed that the cyclotherapy directly interferes with the pathomechanism of the malignant glaucoma.

[The effect of filtering operations (author's transl)]. / Zur Wirkungsweise fistelbildender Operationen

The effect of filtering operations on 133 eyes was investigated by fluorescence photography after intracameral injection of fluorescein. The following drainage mechanisms could be found: 1. the transconjunctival route, 2. the diffuse resorption through degenerated veins, 3. bulkflow through lymphatic vessels, 4. bulkflow through atypic aqueous veins, 5. outflow through normal aqueous veins. A filtering bleb develops, if the transconjunctival route and the diffuse resorption is predominent. Newly incorporated veins and lymphatic vessels enable the drainage of the aqueous humour without a visible bleb. Most important for the formation of these vessels is the surgical technique. Therefore it is not only necessary to cover the fistula with a scleral flap but also to gain a physiological intraocular pressure immediately after the operation. If the tension is too low in most cases a filtering bleb will form. If it is at a physiological level (i.c. above the episcleral vein pressure) new vessels can develop and drain the aqueous humour by bulkflow from the scleral fistula and that means a good pressure regulating effect without a filtering bleb.

[Exposure of the ciliary body. A new operative method for treatment of irreversible angle closure glaucoma and aphakiaglaucoma (author's transl)]. / Die Ziliarkörperfreilegung. Eine neue Operationsmethode zur Behandlung des irreversiblen Winkelblockglaukoms und des Aphakieglaukoms

In various forms of glaucoma with an unfavorable prognosis an operation developed by us in the Eye Clinic of the University of Graz since 1972, ciliary body exposure, has been performed. Up till now 68 such operations have been performed. In 63.2% of cases we had a good result. Technique, indications, post-operative care an complications are discussed.

[Demonstration of aqueous outflow patterns of normal and glaucomatous human eyes through the injection of fluorescein solution in the anterior chamber (author's transl)]. / Die Darstellung des Kammerwasserabflusses normaler und glaukomkranker menschlicher Augen durch Füllung der Vorderkammer mit Fluorescein

After partially injecting the anterior chamber with a 0.2% fluorescein-Ringer solution we examined using a blue filter slitlamp normal eyes, eyes with open-angle glaucoma, and eyes following iridectomy, iridencleisis, Elliot's trephination, and trabeculectomy. In normal eyes at physiological intraocular pressure, 1--9 aqueous veins were found with a mean of 4.6. The distribution of these veins was usually irregular, being more numerous and of largest caliber in the lower nasal quadrant. With only a few exceptions the aqueous veins originated 1--2 1/2 mm peripheral from the limbus and joined the episcleral veins after a short course. The venae recipientes were characterized by a straight and deep course. In eyes with an open-angle glaucoma the average number of aqueous veins was found to be increased compared to the number found in healthy eyes. However, the caliber of these veins was smaller and distribution mor uniform. Eyes having undergone iridectomy do not differ from normal eyes in the mechanism of aqueous humor outflow. After iridencleisis and after trephination the transport of aqueous humor from the anterior chamber is achieved through a filtration bleb: (1) transconjunctival, (2) by bulk-flow through lymphatic vessels, (3) diffusely through lymphatic vessels or veins. In most cases the different transport mechanisms were combined and pure types were seldom found. There was a very definite relationship found between the size of the filtration bleb and the development of draining lymphatic vessels. After trabeculectomy the following drainage mechanisms of the aqueous humor were observed: 1. Subconjunctival outflow of aqueous humor. The further drainage in this case was achieved as in the old types of fistula building operations i.e., primarily through the lymphatic vessels. 2. Direct transport of aqueous humor into the surgical area through newly incorporated veins and lymphatic vessels. 3. Drainage of aqueous humor through still functioning aqueous veins.

[The alteration of visual evoked potentials in light- and dark-adapted states as a measure for the visual field sensibility at elevated intraocular pressure (author's transl)]. / Die Anderung des visuell evozierten Potentials bei Hell- und Dunkeladaptation als Mass für die druckbedingte Abnahme der Gesichtsfeld empfindung

On 12 voluntary subjects with normal visual function the intraocular pressure was increased dependent on the ophthalmic blood pressure Pm = (Ps + Pd)/2. The visual field was tested under this pressure load by means of a subjective method and the visual evoked potential was derived under light and dark adaptation. Comparison of subjective and objective investigations demonstrated that the different visual evoked potentials which are dependent on the state of adaptation are a measure for the pressure sensibility of prelaminar optic nerve fibers.

[The mode of action and technique of trabeculectomy. II. Technique of trabeculectomy (author's transl)]. / Zur Technik der Trabekulektomie

The technique of trabeculectomy is presented as it has been done in 370 eyes at the University Eye Clinic in Graz. Possible mistake are pointed out. The knowledge of the mechanism of this operation enables us to prevent a hypotony and to create the best conditions for the incorporation of veins and lymphatic vessels in the surgic area.

[The mode of action of trabeculectomy (author's transl)]. / Zur Wirkungsweise der Trabekulektomie

We could ascertain the mode of action of trabeculectomy by clinical research in more than 370 eyes after the operation and especially by the injection of fluorescein into the anterior chamber in 90 of these eyes. The following drainage mechanisms of the aqueous humor were observed: 1. Outflow through new developed aqueous veins (trabeculectomy-veins), 2. Bulkflow through lymphatic vessels, 3. Diffuse resorption into the subconjunctival tissue, 4. Outflow through normal aqueous veins. The latter mechanism is seldom of great importance. In only three cases passed all of the visible aqueous outflow through normal aqueous veins. In these cases an opening of Schlemm's canal could be assumed. In all of the other eyes we could not find any evidence for an outflow through Schlemm's canal whether there was a filtering bleb or not. This means that from the presence or absence of a visible bleb no conclusion can be drawn as to the mode of action.