Bubble formation as primary interaction mechanism in retinal laser exposure with 200-ns laser pulses.

Background And Objective: Retinal laser photocoagulation is generally performed by laser pulses of a few hundred milliseconds. The tissue interaction mechanism is a pure thermal interaction mechanism. As pulse duration gets shorter, different, non-thermal interaction mechanisms start to appear.

The vascular component of proliferative vitreoretinopathy membranes: an immunohistochemical and ultrastructural study.

Background: The basic cellular components of proliferative vitreoretinopathy (PVR) membranes are well studied. Endothelial cells have also been documented. The importance of the vascular element in PVR has received little attention, as vascular components are clinically inapparent.

[Scanning electron microscopy studies of the human lens capsule after capsulorhexis].

Background: In order to better understand the mechanism of tearing of the human lens capsule during circular capsulorhexis, scanning electron microscopic (SEM) examinations were made particularly of the rhexis edge.

Materials And Methods: Anterior segments from cornea donor eyes, as well as capsular pieces extracted during cataract surgery, were studied after fixation in glutaraldehyde, critical point drying, and sputtering with gold.

Results: The edges of the capsulorhexis were found to be very regular even in the area of zonular attachment.

[Cyclophotocoagulation with the diode laser in contact procedure with a new focussing tip].

Unlabelled: During contact cyclophotocoagulation (CPC) energy is transmitted through the conjunctiva and the sclera by direct contact of a plain fibre tip. Alteration and scarring of the conjunctiva and the outer parts of the sclera cannot always be avoided. We used a new fibre tip which defocuses the laser light on the conjunctiva and sclera and focuses the laser light on the ciliar body.

[Case study of a solitary vitreous body cyst].

Vitreous cysts are rare and their origin unclear. We present a case of a 47-year-old woman who, after undergoing retinal detachment surgery on several occasions, developed disturbing vitreous opacities with which she presented for possible vitrectomy. Besides the typical postoperative vitreous condensations and opacifications, a solitary spherical cystic structure was present in the anterior vitreous cavity.

Alterations of Müller (glial) cells in dystrophic retinae of RCS rats.

We have carried out a light microscopical study of Müller cells in the retinae of rats with inherited retinal dystrophy (Royal College of Surgeons rats). Isolated retinae of both control and Royal College of Surgeons rats were exposed to a Procion Yellow solution which is taken up selectively into Müller cells. The shape of the cells was then studied by confocal microscopy.

Evidence of a direct role for growth hormone (GH) in mammary gland proliferation and lactation.

A panel of monoclonal antibodies to the growth hormone (GH) receptor/binding protein was used to demonstrate the existence and detail the expression of GH receptors in ductal and alveolar epithelial cells from rat and rabbit mammary glands by immunohistochemistry. Intense immunoreactivity was present in membrane, cytoplasm and some nuclei of epithelial cells during proliferation and lactation. Receptor expression decreased during weaning and was absent or weak in regressive mammary glands.

Effects of enhanced extracellular ammonia concentration on cultured mammalian retinal glial (Müller) cells.

Müller (glial) cells of the neonatal rabbit retina were cultured as confluent monolayers and exposed to enhanced concentrations of ammonia (0.25, 0.5, 1, 3, 7, and 10 mM) in medium for various periods (30 min to 10 d).

Hepatic retinopathy: morphological features of retinal glial (Müller) cells accompanying hepatic failure.

More than 80 years ago, Alzheimer described changes in the brains of patients who had suffered hepatic failure. Astrocytes are primarily affected; their nuclei become swollen, their intermediate filament protein composition is altered and their cytoplasm becomes vacuolated. Cells with these features are called Alzheimer type II astrocytes and these changes have been attributed to the toxic effects of elevated ammonia levels.

Localization of cathepsin D in rat ocular tissues. An immunohistochemical study.

Numerous studies have demonstrated that cathepsin D as a major lysosomal acid protease plays an important role in the degradation of protein in several tissues. An important function of the retinal pigment epithelium is to interact with the photoreceptor cells in the renewal process. During the renewal process, the RPE cell phagocytosis discarded photoreceptor discs which are then degraded in the RPE phagolysosomes.

[Retinal photocoagulation with a pulsed, frequency-doubled Nd:YAG laser (532 nm)].

The small difference in wavelength between an argon laser (514 nm) and a frequency-doubled Nd:YAG laser (532 nm), together with the advantage of the solid-state technology, makes the Nd:YAG laser likely to play a major role in retinal photocoagulation in the near future. For technical reasons all frequency-doubled Nd:YAG lasers work in a quasi-continuous mode, emitting a burst of highly repetitive short laser pulses during the exposure time desired. We investigated the side effects due to high peak irradiances of those short laser pulse trains (Crystal Focus Nd:YAG laser, Emerald; pulse duration 1-10 microseconds, repetition rate 13 KHz) in rabbits in comparison with a standard argon laser system (Zeiss, Visulas, Argon II).

Localization of lysosomal enzymes in the retina and retinal pigment epithelium of RCS rats.

Using ultrahistochemical and immunohistochemical techniques, localization of acid phosphatase and cathepsin D was demonstrated in the retina and pigment epithelium of 1 to 42 day old RCS rats and its nonaffected congenic rat strain. Both enzymes are present in the pigment epithelium of the normal and dystrophic rat eye. As early as the age of 1 week, it was found that the lysosomes in the dystrophic rat retina are less stable in releasing acid phosphatase than those of control animals.

Immunohistochemical localization of growth hormone receptor binding protein in the mammalian cerebellum.

A panel of monoclonal antibodies to the growth hormone (GH) receptor/binding protein was used to demonstrate the existence and detail the expression of GH receptors in the cerebellum of 2, 10, 28 days old postnatal and adult rats and 10, 20 days old and adult rabbits by immunohistochemistry to define potential targets for endogenous GH action in the cerebellum. Receptors were localized in membrane and cytoplasmic components of neurons and glial cells and expression decreased with age. Intense immunoreactivity was observed in the cytoplasm and dendrites of Purkinje cells and in cells of the cerebellar nuclei.

[Experimental studies on the effect of the Er:glass and Cr:Tm:Ho:YAG laser in thermokeratoplasty].

So far the dose-effect ratio of the Holmium laser (wavelength 2.12 microns) and the erbium laser (1.54 microns) for laser thermokeratoplasty (LTK) are not defined in detail.

Ultrastructure and regression of the tunica vasculosa lentis in newborn Wistar rats.

In this study, regression of the hyaloid vessels has been followed in the tunica vasculosa lentis (TVL) of the Wistar rat using light, transmission and scanning electron microscopy. The investigation extended from the 1st to the 32nd postnatal day. On day one, the posterior tunica vasculosa lentis is made up of radiating capillaries connected by side-arm branches, the vascular walls of which possess a continuous endothelium, a basement membrane and an incomplete pericyte covering.

Retinal lesions experimentally produced by intravitreal ultrasound.

Currently, vitreous surgical techniques combined with phakoemulsification are an established procedure for the removal of luxated natural lenses or dislocated lenticular material. This has proven to be a safe procedure, but occasionally retinal lesions have been inadvertently created. We describe the ophthalmoscopic and morphologic features of ultrasonically induced retinal lesions in rabbit eyes using a similar technique.

Lectin binding pattern in human retinal pigment epithelium.

A comparative lectin histochemical study of human retinal pigment epithelium (RPE) was performed to investigate the lectin binding pattern of normal, reactive and proliferating RPE. Normal RPE with attached sensory retina was found to bind the lectins Con A, WGA, PNA and RCA I. Reactive and proliferating RPE in retinal detachment and in photocoagulation scars revealed the same lectin binding pattern although its cellular topography changed.

[The effect of cyclooxygenase inhibitors on the course of hereditary retinal dystrophy in RCS rats].

Daily administration of acetyl salicylic acid (ASA) and ibuprofen leads to an appreciable retardation in the process of retinal degeneration in the RCS rat which is dependent on the dosage given. The photoreceptor cell nuclei and inner segments are relatively well preserved in all regions of the retina. While the outer nuclear layer of 32 day old RCS rats is usually composed of only 3-4 rows, we found 8-9 nuclear rows exhibiting minimal pyknotic change in animals which had been treated with higher doses of ASA.

[Retinal lesions after transvitreal use of ultrasound].

Removal of a dislocated natural lens into the vitreous cavity is now performed using vitreous surgery techniques combined with intravitreal phacoemulsification via the pars plana. In contrast to the earlier external surgical approach to luxated lenses, postoperative complications, particularly retinal detachment, are rare. However, retinal damage may occur when ultrasound is used at therapeutic intensities.

[Lectin histochemical studies of retinal pigment epithelium in retinal detachment].

The retinal pigment epithelium (RPE) exhibits a broad spectrum of morphological changes under pathological conditions. Since RPE cells cannot be immunocytochemically characterized with certainty, lectin histochemical investigations were performed to study the lectin binding pattern of different morphological RPE variants in human globes. Normal RPE with attached retinas was compared to reactive changes in RPE following retinal detachment.

[Lectin histochemical studies of retinal pigment epithelium following photocoagulation].

Lectins are histochemical probes for specific carbohydrate residues found in cell membranes and the cytoplasm. Lectin binding sites were determined in normal and morphologically altered retinal pigment epithelium (RPE) in photocoagulation scars using a modified PAP method. Tissue sections of human bulbi obtained during enucleation for various reasons were incubated with eight lectins of different sugar affinity: ConA, WGA, PNA, RCA I, SBA, UEA I, DBA, LPA.

[Cellular lectin binding sites in the human retinal pigment epithelium and photoreceptors--method of lectin histochemistry and results with peroxidase marked lectins in paraffin sections].

Lectins are sugar-binding proteins or glycoproteins which bind to specifically complementary sugar residues found in cell membranes and the cytoplasm. Lectin-binding sites are determined by histochemical methods. Cellular lectin-binding sites change with morphological and functional alterations of the cell, and the determination of lectin receptors can be used to identify specific cell types in histological sections.

[Canthaxanthin retinopathy and macular pucker].

Canthaxanthine retinopathy is a crystalline retinopathy following oral ingestion of canthaxanthine-containing drugs. We describe the clinical course of a patient with canthaxanthine retinopathy and a preexisting idiopathic macular pucker. The ultrastructural findings of the macular pucker removed by vitreoretinal surgery are demonstrated.

[Canthaxanthin retinopathy and macular pucker--clinical picture and ultrastructural findings of macular pucker].

Canthaxanthine retinopathy is a crystalline retinopathy that follow oral ingestion of canthaxanthine-containing drugs. We describe the clinical course of a patient with canthaxanthine retinopathy and preexisting idiopathic macular pucker over a period of 2.5 years.