Hans Pau

The increasing sclerosis of the human lens with age and its relevance to accommodation and presbyopia

By means of a fine conical probe and a miniature dynamometer, the resistance to penetration of different lens layers was measured. In clear human lenses the power of resistance of the lens nucleus increases with age, mostly due to the “hardening” of the nucleus. A distinct hardening of the nucleus as opposed to the cortex has been found to occur in lenses as young as 20 years of age. This “firmness” of the lens nucleus, occurring between the ages of 20 and 60 years, coincides with the decrease in accommodation range and the onset of presbyopia.

Glutathione levels in human lens: regional distribution in different forms of cataract.

The content of glutathione is high in the anterior lens cortex (plus epithelium) and the posterior lens cortex, whereas it is substantially lower in the lens nucleus. A decrease of glutathione in the lens cortex does not occur with lenses from adults up to the highest age. The glutathione content is highest in the cortex of clear fresh lenses and shows a decrease with deep supranuclear cataract, primary nuclear cataract (cataracta brunescens nigra) and clear lenses post-mortem (approximately 20 hr). The subcapsular cataract, especially with additional secondary nuclear cataract, with cataracta matura or intumescens, shows a rapid and pronounced progressive decrease in the glutathione content.

Myofibroblast-like cells in human anterior capsular cataract

In six cases of anterior capsular cataract, cells present in the subcapsular zone were investigated. In addition to orga nelles previously described, the cells were found to contain 7 nm and 15 nm filaments, suggestive of actin and myosin. The cells varied in shape from elongated or flat to rounded. Maculae adhaerentes, gap junctions and basement membranes were present. It is concluded that these cells closely resemble myofibroblasts, by virtue of their cytology and behaviour. The significance of this observation, concerning hypotheses on the genesis of anterior capsular cataract is discussed.

Cortical and Subcapsular Cataracts: Significance of Physical Forces

Cortical cataracts usually begin with either sharp limited clear fluid clefts, resulting in opaque spokes, or clear lamellar separations, resulting in cuneiform opacities. They do not commence prior to 45 years of age. From this age on an increase in lens nuclei hardening can be detected. Therefore, during disaccommodation in older lenses, mechanical shear stresses must develop between the soft remaining cortices and the harder nuclei. These shear stresses are significant regarding the different cortical ruptures in predisposed lenses: in a privileged radial direction (according to zonular traction) of the sharp limited cortical spokes, or in parallel microridges at the commencement of lamellar separations, as observed when a rubber surface slides against a harder object. In pure cortical cataracts the ion pump (K+ > Na+) and investigated metabolic parameters remain largely intact. Therefore, it is not surprising that, in contrast to subcapsular cataracts, subcapsular opacities do not occur. Subcapsular cataracts are known to be caused by a variety of factors: aging, diabetes, corticosteroids, iridocyclitis, or X-ray, among many others. In contrast to cortical cataracts, subcapsular cataracts were found to be closely associated with ion pump damage (Na+ > K+) and a variety of metabolic activity alterations. In subcapsular cataracts passive fluids (from the vitreous and camera anterior) enter externally through the lens capsule. This initially forms numerous free clear, secondary grey, subcapsular fluid vacuoles. If the ion pump (metabolic barrier) is more severely damaged fluids may also enter the lens nucleus (secondary grey nuclear cataract), which rarely results in intumescent cataract. In cortical and subcapsular cataracts and lens perforations the main cause of grey opalescence appears to be the result of lens proteins (water-soluble crystalline) coming into direct contact with free fluids (water). In cortical cataracts this happens in the area of sharp limited mechanical cortical ruptures (fluid clefts), and in subcapsular cataracts during passive, external fluid entry, resulting in subcapsular fluid vacuoles and opacities, and also later grey-white nuclear opacities. The importance of water contact with water-soluble lens crystallines in behalf of light scattering and turbidness also has been investigated experimentally.

Ultrastructural investigations on anterior capsular cataract. Cellular elements and their relationship to basement membrane and collagen synthesis

A reinvestigation of the cellular elements in anterior capsular cataract of six lenses was performed at the light and ultrastructural levels. In addition to the fibroblastic characteristics described by previous authors, the cells were found to contain sublemmal filaments classifiable as myofilaments, as typically present in myofibroblasts. Cell shape varies in a manner consistent with contractility. Apparently contracted cells predominate within capsular folds. The number of cells was found to decrease with increasing maturity of the cataract. In old cataracts, only degenerating cells are to be found. The significance of these observations is discussed, and it is concluded that the anterior capsular cataract is a process bearing considerable similarity to wound healing.

Elektrophoretische Trennung der Eiweifraktionen im menschlichen Kammerwasser

Es wird über das nach Einengung mittels der Ultrafiltration mit Überdruck am Sammelpunktat normaler Probanden und an der Leiche ermittelte Elektrophoresediagramm des menschlichen Kammerwassers berichtet und das Normalbild den Bildern des Liquor cerebrospinalis und des menschlichen Serums gegenübergestellt und dabei gezeigt, daß die Fraktionswerte des Kammerwassers denen des Liquors mit hohen Albumin- und niedrigen β-Globulinwerten entsprechen. Die Veränderungen der elektrophoretisch ermittelten Fraktionen bei einigen entzündlichen Erkrankungen des Auges werden besprochen, wobei auf differentialdiagnostische Möglichkeiten hingewiesen wird.

Betrachtungen zur Physiologie und Pathologie des Glaskörpers

Es wird kurz auf die in derLeber-Goninschen Glaskörperzerrungslehre und derVogtschen Degenerationslehre aufgezeigten Ursachen der cystoiden Veränderungen bzw. des Einrisses der Netzhaut eingegangen. Beide Theorien können nur einen Teil der Netzhautablösungen erklären, da für die cystoiden Areale meist weder eine Entzündung (Verwachsungen von Glaskörper-Netzhaut) verantwortlich sein dürfte, noch diese Areale bevorzugt an besonders schlecht mit Blut versorgten Fundusstellen liegen. Auch der häufig strichförmige Verlauf der cystoiden Veränderungen kann mit diesen Theorien nur schlecht erklärt werden. Als eine der häufigsten Ursachen der cystoiden netzhautdegenerationen wird der dauernde, wenn auch geringe Zug der gefältelten Membranen des Glaskörpers an ihrem Netzhautansatz angesehen. Entwicklungsgeschichtlich dürften diese Ansätze den Anastomosen von Glaskörper-mit Netzhautgefäßen entsprechen. Es erklärt sich so auch die Häufigkeit der degenerativen Netzhautveränderungen gerade im Endverzweigungsgebiet der Netzhautgefäße bzw. dem Gebiet der Obliquusansätze (Gefäßzustrom). Hingewiesen wird auf die Bedeutung des akkommodativen Ciliarmuskelzuges an den gefältelten Glaskörpermembranen sowie der Ader- Netzhaut für das Auftreten von cystoiden Degenerationen. Der mechanische Zug der gefältelten Membranen nimmt bei der Verflüssigung des Glaskörpers (Alter, Myopie) infolge der Membranzusammenziehung und der dann stärkeren Schleuderbarkeit des Gerüstes entscheidend zu. Die Form der Netzhauteinrisse und der Deckel läßt sich durch unsere Annahme gut erklären. Multiple Netzhautlöcher werden aufgefaßt als Einrisse an schon degenerierten Netzhautstellen, verursacht durch die retroretinale Flüssigkeit bei eintretender Netzhautablösung. Besonders deutlich wird die Bedeutung des Zuges der gefältelten Membranen bei Orarissen.

Zur Histologie der „cystoiden Degenerationen” in der Netzhautperipherie

An Hand von mikroskopischen Bildern wird gezeigt, daß es sich bei einem großen Teil der sog. “cystoiden Areale (Blessig-Iwanoffschen Ödeme)” um durch den histologischen Verarbeitungsprozeß verursachte und nicht um intra vitam entstandene Netzhautzerreißungen handeln dürfte. Die Unterschiede zu den zum Netzhauteinriß disponierenden “sklerotischen Arealen” und zu den eventuell bei der Amotio retinae in der abgelösten Netzhaut, bei Cyclitis usw. in Erscheinung tretenden “vacuolären Arealen” werden aufgezeigt.

The lenticular capsule and cellular migration in anterior capsular cataract

A light and electron-microscopical study was performed on six lenses harboring anterior capsular cataract. The cataracts are typically divided by numerous sheets of basement membranes that merge with the lenticular capsule at the edge of the cataract. Basally, the cataract may or may not be bounded by a basement membrane. Myofibroblastlike cells may be observed, apparently traversing the basal border of the capsular cataract. Within the substance of the lens, isolated aggregations of collagenous material are present. Degenerating cells or collagenous aggregations are situated within the lenticular capsule. It is suggested that this configuration arises through the merging of basement membrane systems, surrounding the cells within the cataract, with the lenticular capsule.

Die Neubildung des Glaskörpers und seiner Fibrillen

Auch in schwer erkrankten Augen mit verflüssigtem Glaskörper können proliferierende bzw. proliferierte Glaskörperrindenzellen an zum Teil atypischen Stellen regelrecht aussehenden, fibrillenreichen Glaskörper erzeugen. Steht dieser neugebildete Glaskörper unter Zug, dann entspricht das Bild dem der Zonula Zinnii; besteht keine Zugwirkung, dann entsteht ein Bild entsprechend der normalen Glaskörperstruktur (wie zerknautschtes Cellophanpapier). Also in severely diseased eyes with a liquefied vitreosus body, proliferating or proliferated cortical cells of the vitreous body may form normal-looking vitreous bodies rich in fibrils, in partly atypical places. If this newly formed vitreous body is under tension, the aspect is that of the zonule of Zinn; if there is no tension, the aspect corresponds to that of the normal structure of vitreous bodies (like crumpled cellophane).