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M Spitznas

Publications and source records attributed to M Spitznas.

At least 109 records · Page 6Linked to original sources
PubMed1988

Ultrastructural observations on the development of the human conjunctival epithelium.

In human embryos with a gestation age of 8.6-22 weeks, the palpebral conjunctival epithelium was examined by transmission electron microscopy (TEM). During the gestation period studied, the structural integrity of the tissue is established by an increase in the quantity of tonofilaments, desmosomes, and hemidesmosomes as well as by the undulating appearance of the cell membranes, the widening of the intercellular space, and the development of cytoplasmic protrusions into it. The superficial cells display a chronological sequence in the elaboration of transport mechanisms. A precursor stage is described for hemidesmosome formation at the interface between the basal cell membrane and the conjunctival stroma.

Conjunctiva↗
PubMed1988

The fine structure of the developing human choriocapillaris during the first trimester.

In human embryos with a gestational age ranging from 6.5 to 13 weeks the development of the choriocapillaris was studied by electron microscopy. A continuous maturation process was observed over the whole period, which was most pronounced between weeks 6.5 and 9.7. During the earlier weeks, the endothelium appeared to be rather thick and contained many cytoplasmic vesicles; it was markedly flattened and less vesiculated than at week 9.7. This process was accompanied by an enlargement in the vascular lumina. Fenestrations directed towards the primitive Bruch's layer were found to be already present at week 7.2 but increased in number from week 9.7 to week 13. In the early weeks, basement membrane structures were present in small, discontinuous tufts of cloudy material adjacent to the endothelium. These structures became continuous at week 9.7 and increased in thickness towards week 13. In the earlier weeks, punctate junctions were seen. Beginning with week 9.7, adultlike tight junctions between the endothelial cells became observable. Pericytes were already present at week 6.5. It is suggested that both pericytes and endothelial cells are derived from the differentiating mesenchymal cells of the surrounding ocular stroma.

Basement Membrane↗
PubMed1988

Surface morphology of the human ciliary body during prenatal development. A scanning electron microscopic study.

The development of the ciliary body was examined by scanning electron microscopy in human embryos and fetuses with a gestation age of 9.5 to 24 weeks. During this period it was possible to follow up the main morphogenetical events, beginning with the appearance of the first radial folds up to the occurrence of ciliary processes with a rather adultlike arrangement. The ciliary processes observed during week 24 differed from those of the adult eye only by their dimensions and the lack of surface infoldings. A primitive pars plana could only be identified during week 24. The morphological basis for aqueous humor production is discussed.

Ciliary Body↗
PubMed1988

Development of the human sclera. A morphological study.

Differentiation of the sclera in human embryos and fetuses with a gestation age from 6.4 to 24.0 weeks was studied by light and electron microscopy. The developmental route was found to be anteroposterior and directed from inside outwards. Continuous cytological maturation begins anteriorly during week 7.2 with a loss of free ribosomes and polysomes and an increase in the amount of rough-surfaced endoplasmic reticulum (rER) and Golgi complex components. From the region of the future limbus, these cytodevelopmental events progress posteriorly. By week 13 there are no marked differences between anterior and posterior localization. The cytodevelopmental events directed from inside outwards were found to begin during week 7.2, with a marked increase in the addition of glycogen and lipid droplets in the choroidal half of the anterior scleral condensation and from there progressing to the outer (episcleral) half. With the beginning of week 10.9 no more differences were identified between the outer and the inner portions of the sclera. Portions of the ER denuded of ribosomes close to the plasmalemma were observed during the whole gestational period studied. The role of these structures and the involvement of the Golgi complex for the biosynthesis of collagen are discussed. In week 24, the diameter of the collagen fibrils had increased more than three times in comparison with week 6.4. Elastic microfibrils were found beginning with week 7.2, whereas the elastic deposits with central electron-translucent cores were characterized for the first time beginning with week 18.

Collagen↗
PubMed1988

Differentiation of the ciliary muscle in the human embryo and fetus.

In human embryos and fetuses with a gestation age of 10.3 to 22 weeks, differentiation of the ciliary muscle was examined both by light and transmission electron microscopy. The smooth muscle cells develop from mesenchymal elements or early fibroblasts located in the region between the anterior scleral condensation and the ciliary pigment epithelium. The first musclelike cells exhibiting myofilaments and dense bodies could be distinguished during week 12. Smooth muscle cells with an adultlike appearance become apparent during week 15/16. Up to week 22, a cellular maturation process can be observed. Fibroblasts separating the muscle cell layers from each other also derive from the same precursor cells, as do the smooth muscle cells, thereby pointing to the close relationship between the two cell types.

Ciliary Body↗
PubMed1988

Sustained gentamicin release by presoaked medicated bandage contact lenses.

Current therapeutic regimens for external ocular infections require instillation of antibiotics up to every quarter of an hour in concentrations higher than those commercially available. As an alternative to topically applied gentamicin eye drops, the possibility of sustained gentamicin release by bandage contact lenses was investigated. Ten hydrogel bandage contact lenses (61.4% HEMA and 38.6% water content) were soaked overnight in a 0.5% solution of sterile, unpreserved, commercially available gentamicin, and fitted thereafter on ten eyes of healthy adult volunteers. Gentamicin concentrations in the tear film were determined 10, 30, and 60 minutes, and 4, 8, 24, 48, 72, and 96 hours after fitting, using agar diffusion bioassay. Bactericidal concentrations (greater than 1.6 micrograms/ml) were found up to 3 days after contact lens fitting in all subjects. No toxic topical or systemic effects were seen.

Adult↗
PubMed1988

[Effect of rubeosis iridis and active neovascularization of the fundus on vitreous surgery in diabetic retinopathy].

To determine the influence of preoperative rubeosis iridis and active neovascularization at the fundus on surgical results, the authors analyzed a consecutive series of 85 eyes that underwent vitrectomy for diabetic tractional detachment of the macula. Minimum follow-up was 12 months. Rubeosis was present in 51%, active neovascularization at the fundus in 82%. Surgery was performed under Spitznas wide-angle observation using a stereoscopic diagonal inverter either with the panfundoscope or binocular ophthalmoscopy through the operating microscope. In the 93% of the eyes that were phakic no lensectomy was performed. Anatomical success was achieved in 79%, ambulatory vision in 74%. Anatomical success was reduced to 58% in cases with preoperative rubeosis and to 70% in cases with active neovascularization at the fundus. Including four cases of re-vitrectomy, silicone oil was used for internal tamponade in 9%, SF 6/air 50:50 in 38% and air in 28%. In 25% no internal tamponade was applied. Postoperative complications included vitreous bleeding (21%), increased rubeosis (20%), neovascular glaucoma (2%), redetachment (6%), rubeosis/hypotony/cataract (13%) and phthisis (3.5%). In 21% of the eyes the final result of surgery was failure, due to redetachment (3.5%), neovascular glaucoma (1%), rubeosis/hypotony/cataract (13%) and phthisis (3.5%).

Adult↗
PubMed1987

Ultrastructure of the human posterior tunica vasculosa lentis during early gestation.

In human embryos with a gestational age of from 7.6 to 14.0/15.0 weeks, the posterior tunica vasculosa lentis (TVL) was examined by both scanning and transmission electron microscopy. Even at the very early age of 7.6 weeks the tunica was found to be fully developed. It consisted of a radiating network of tortuous capillaries. Their walls were composed of a continuous layer of endothelial cells, surrounded by a basement membrane and a discontinuous sheath of pericytes. The thickness of the basement membrane increased with increasing gestational age. As opposed to previous studies, the endothelial cells exhibited transitory fenestrations. In the neighborhood of the posterior TVL macrophages were found.

Blood Vessels↗
PubMed1987

A stereoscopic diagonal inverter (SDI) for wide-angle vitreous surgery.

All known methods of wide-angle observation of the fundus deliver an inverted image. To overcome these difficulties a stereoscopic diagonal inverter (SDI) was developed, which serves as an accessory to the operating microscope. This device permits the microscopic image to be vertically inverted and laterally reversed, while retaining full stereopsis, and thus makes wide-angle observation devices such as the Rodenstock Panfundoscope contact lens (150 degrees) and a modified version of the binocular indirect ophthalmoscope (70 degrees-90 degrees) usable in vitreous microsurgery.

Humans↗
PubMed1987

The effect of long-term irradiation with fluorescent light on the rat fundus.

In the rat, continuous exposure to so-called "cold light" of 800 lux leads to a nearly complete loss of retinal photoreceptors, which occurs within 4 weeks. This process is followed by vascularization of the retinal pigment epithelium (RPE). The origin, extent, and expansion of such proliferations within 6 months after the onset of irradiation were evaluated by means of light microscopy, transmission electron microscopy, scanning electron microscopy, corrosion cast preparation, india ink injection, and trypsin digest preparation. The vessels within the RPE were found to be fenestrated and to form a network with the vessels of the neurosensory retina. Invasion of Bruch's membrane and formation of chorioretinal anastomoses were not observed. The occurrence of vessels within the RPE coincided with a massive regression of capillaries in the neurosensory retina.

Animals↗
PubMed1987

Number, shape, and topography of leakage points in acute type I central serous retinopathy.

The evaluation of 430 consecutive eyes (87.5% from male, 12.5% from female patients) showed a leakage point with uniform dye spread in 93%. In 7%, a smoke-stack phenomenon was observed. The number of leakage points reached from 1 (71.6%) to 7 (0.2%). Most leakage points were found in a 1-mm-wide ring-shaped zone starting 0.5 mm from the center of the fovea. Beyond this zone the incidence dropped rapidly with the exception of the upper nasal quadrant. Of the leakage points, 33.2% were located in the upper nasal, 21.2% in the lower nasal, 19.0% in the upper temporal, and 14.8% in the lower temporal quadrant. Leakage points occurred more than 3 mm away from the center of the fovea in 11.8%. The papillomacular bundle contained 25.4% of the leakage points. Leakage points in recurrences were located within 1 mm of the primary leakage point in 80% of the cases.

Chorioretinitis↗
PubMed1987

Evaluation of endothelial cell function with anterior segment fluorophotometry in pseudophakic patients.

Determining fluorescein permeability of the endothelial cell layer provides information on the endothelial cell barrier. Following topical application of fluorescein, the time dependent change of its concentration in the corneal stroma and in the aqueous humor yields the transfer coefficient (Kc) of the corneal endothelium. Measurements with a fluorophotometer resulted in a Kc of 0.002 minute to 0.005 minute for normal eyes. Patients with corneal barrier dysfunction (cornea guttata, Fuch's dystrophy) showed an increased Kc of 0.006 minute to 0.013 minute. Up to five years postoperatively, none of the patients investigated after phacoemulsification and posterior chamber lens implantation showed a disturbance in the endothelial cell barrier function.

Aged↗