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Biomedical subjects

M Spitznas

Publications and source records attributed to M Spitznas.

At least 91 records · Page 5Linked to original sources
PubMed1991

Combined relaxing incisions and epikeratophakia for the correction of aphakia and high postkeratoplasty degree astigmatism.

A combined surgical procedure consisting of corneal relaxing incisions and epikeratophakia was used to correct high-degree postkeratoplasty astigmatism and aphakia in two patients. Both patients achieved their final refractive result as soon as 1 month after suture removal (2 and 3 months after surgery, respectively). Keratometric readings showed a reduction of approximately 20.00 diopters in one case and 10.00 D in the other, while the spherical equivalent changed from +10.00 D to +0.50 D in one eye and from +7.50 D to +1.75 D in the other. Spectacle correction was prescribed for both patients. At the last follow-up visit, about 2 years after surgery, these values were unchanged. The main advantage of the combined technique over two separate procedures was that postoperative visual rehabilitation was faster. Equally important was the stability of the refractive result over a long period of time after surgery, as well as the absence of negative effects on the preexisting corneal graft. In spite of the technical complexity of a combined surgical procedure, this approach probably represents the best choice in rare cases such as the ones reported here.

Aphakia↗
PubMed1990

Ultrastructural pathology of anterior persistent hyperplastic primary vitreous.

Using transmission electron microscopy, the fine structure of anterior persistent hyperplastic primary vitreous (PHPV) removed from the eyes of four infants was studied. The tissue mass was composed of vessels derived from or representing the tunica vasculosa lentis posterior and the vasa hyaloidea propria. They were embedded in a loose connective-tissue matrix containing many fibroblasts and mature collagen fibrils. Toward the posterior surface, the fibroblasts became more numerous, elongated and densely packed. At the point of its entry into the posterior pole of the mass, the hyaloid artery was found to be surrounded by glial cells, probably representing an extension of the wall cells of the hyaloid canal. Venous drainage of the PHPV nodules seemed to occur via the ciliary body to which they were connected by tiny vessels bridging the distance from the PHPV lump to elongated ciliary processes. The anterior surface of the tissue lump was covered with lens fragments. These remnants showed signs of very early disturbance of lens development, with a failure to form posterior lens fibers. Based on these findings, the authors suggest that PHPV may be secondary to a primary defect in lens development.

Eye Diseases↗
PubMed1990

Complications of sulcus-supported intraocular lenses with iris sutures, implanted during penetrating keratoplasty after intracapsular cataract extraction.

In a retrospective study, the authors analyzed visual results and postoperative complications in a series of 14 consecutive patients who had undergone penetrating keratoplasty and implantation of a posterior chamber intraocular lens (PC IOL) in the absence of the posterior capsule. Seven patients suffered from aphakic bullous keratopathy and seven from pseudophakic bullous keratopathy. Postoperative follow-up was 7.6 months on the average. Best-corrected postoperative visual acuity was 20/60 or better in four cases and 20/200 or better in eight. Glaucoma was present before surgery in four eyes, which persisted in all cases and developed in four new cases. Results of gonioscopic examination showed the postoperative development of goniosynechiae in four eyes. Pseudophakodonesis of various extent was present in ten eyes. Preoperatively, cystoid macular edema was diagnosed angiographically in one case. It did not improve after surgery and was seen in three additional eyes postoperatively. Causes for postoperative visual acuity lower than 20/200 were cystoid macular edema in three cases, graft rejection in one case, central retinal scar in one case, and optic nerve atrophy in one case. A distortion of the pupil was seen in three eyes in miosis and in four additional eyes in mydriasis. Corneal thickness as well as anterior chamber depth were within normal limits. Fluorophotometric evaluation of the blood-aqueous barrier showed values comparable with those obtained after intracapsular cataract extraction and implantation of an iris-fixated IOL. Despite the relatively good visual results, the high postoperative incidence of cystoid macular edema and/or glaucoma may discourage the use of this technique.

Aged↗
PubMed1990

Evaluation of functional and morphologic parameters of the cornea after epikeratophakia using prelathed, lyophilized tissue.

Up to now, the attention of ophthalmic surgeons has been focused mainly on the clinical results of epikeratophakia, demonstrating its safety, relative predictability, and capability of correcting a wide range of refractive errors. However, no prospective study has ever been undertaken to evaluate the influence of epikeratophakia on various physiologic and morphologic parameters of the cornea. The authors investigated some of these parameters prospectively in eight consecutive patients undergoing epikeratophakia with prelathed, lyophilized tissue. Fluorophotometric evaluation of the epithelial barrier function, corneal densitometry by means of Scheimpflug photography, and endothelial specular microscopy were performed preoperatively and 2, 4, 8, 12, and 24 weeks after epikeratophakia. The epithelial barrier function was shown to return to normal 4 weeks after surgery. The optical density of both the epi-lenses and the host corneas increased early after surgery, but was comparable to that of unoperated corneas 6 weeks postoperatively in all cases but one. The endothelial cell density was not altered by surgery in any patient. Despite the limited number of patients, this study indicates that most functional and morphologic parameters of the cornea are normal as early as 6 weeks after epikeratophakia in most cases.

Aphakia↗
PubMed1990

Role of the posterior capsule in the aqueous-vitreous barrier in aphakic and pseudophakic eyes.

Clinical observations have shown that an intact posterior capsule between aqueous and vitreous may function as a barrier to low and high molecular weight substances, e.g., prostaglandins or the angiogenic factor. To determine if this protective barrier breaks down after posterior capsulotomy, we examined the distribution of fluorescein in human eyes after intracapsular cataract extraction (ICCE), extracapsular cataract extraction (ECCE) and intraocular lens (IOL) implantation with capsulotomy, and ECCE and IOL implantation without capsulotomy in 12 patients each. After ICCE and after ECCE and IOL implantation with capsulotomy, diffusion of fluorescein into the vitreous showed similar values. These values were significantly higher than those obtained in patients after ECCE or ECCE and IOL implantation without capsulotomy. This leads us to believe that an intact posterior capsule prevents the diffusion of soluble substances.

Aphakia↗
PubMed1990

[Barrier function of the corneal epithelium of contact lens patients].

The corneal epithelium of contact lens wearers is permanently under stress. The aim of the present study was to examine the following questions prospectively and quantitatively: (1) whether or not wearing contact lens leads to a disturbance of corneal epithelial barrier function and (2) if there is a difference between CAB and HEMA contact lenses in this respect. For this reason, the corneal epithelial permeability to sodium fluorescein in 50 individuals was measured before and 8 weeks after fitting contact lens using an automated computerized fluorophotometer (Coherent Radiation Fluorotron Master). Twenty five of the 50 individuals were provided with CAB or HEMA (38%) contact lenses, respectively. Eight weeks after fitting the contact lens corneal epithelial permeability was found to be increased about 1.5 times (p less than 0.001). There was no significant difference between the HEMA and CAB group before and 8 weeks after wearing contact lens (p = 0.5 and p = 0.7, respectively). In conclusion, the corneal epithelium of contact lens wearers is obviously significantly more permeable to watery ionic substances, e.g., water-soluble drugs and toxic products.

Adolescent↗
PubMed1989

Influence of artificial tears on corneal epithelium in dry-eye syndrome.

The corneal epithelium of patients with dry-eye syndrome is stressed by both tear film insufficiency and the frequent use of eye drops (artificial tears). In order to quantify corneal epithelial damage, the permeability of corneal epithelium to sodium fluorescein was determined in 40 consecutive patients with dry eyes (BST less than 10 mm), who did not exhibit visible corneal lesions upon slit-lamp examination. The corneal epithelial permeability of dry-eye patients was shown to be 2.8 times greater than that of individuals without ocular disease. Corneal epithelial permeability of patients using artificial tears containing benzalkonium chloride was increased 3.1 times and that of patients using drops preserved with chlorobutanol only 1.7 times.

Benzalkonium Compounds↗
PubMed1989

Impairment of corneal epithelial barrier function in diabetics.

Corneal epithelial permeability was determined using an automatic fluorophotometer in 80 consecutive diabetic patients. The corneal epithelium, which is the most important part of the corneal diffusion barrier, showed a significant increase of permeability to watery, ionic substances (natrium fluorescein). The permeability was increased 5.4 times in comparison with nondiabetic individuals and a distinct correlation of increased permeability with the presence and duration of retinal nonperfusion areas was observed.

Aged↗
PubMed1989

Factors influencing the results of vitreous surgery in diabetic retinopathy. I. Iris rubeosis and/or active neovascularization at the fundus.

A consecutive series of 100 vitrectomies for tractional retinal detachment involving the macula in proliferative diabetic retinopathy was analyzed to determine the influence of preoperative iris rubeosis (NVI) and active neovascularization at the fundus (NVF) on surgical results. The minimum follow-up was 12 months. Preoperatively, iris rubeosis was present in 52% and active neovascularization at the fundus in 85%. Surgery was performed under Spitznas wide-angle observation, using a stereoscopic diagonal inverter, either with the panfundoscope or binocular ophthalmoscopy through the operating microscope. Most of the eyes were phakic (94%). No lensectomy was performed. Anatomical success was achieved in 81%, ambulatory vision in 77%. Anatomical success was reduced to 63% in cases with preoperative NVI and to 78% in cases with preoperative NVF. Including 5 cases of re-vitrectomy, silicone oil was used for internal tamponade in 9%, SF 6/air 50:50 in 39% and air in 26%. In 26%, no internal tamponade was applied. Postoperative complications consisted of vitreous hemorrhage (25%), increased rubeosis (22%), neovascular glaucoma (2%), and redetachment (7%). The final causes of failure in 19% of eyes were: neovascular glaucoma (1%), rubeosis/hypotony/cataract (14%), and phthisis bulbi (4%).

Adult↗
PubMed1989

Automated corneal topography: computerized analysis of photokeratoscope images.

The analysis of corneal topography has recently become popular, mainly as a consequence of the rapid development of refractive surgery techniques. To date, computer-assisted evaluation of photokeratoscope pictures has been the most popular method used to assess corneal topography. The processing system described previously by other authors requires hand-digitizing of the photokeratoscope pictures and therefore the constant presence of an operator for a considerable amount of time. We have introduced the use of a video camera to digitize the photokeratoscope images, making the processing automatic and quicker. Moreover, precision glass spheres have been used to calibrate the system in order to minimize the intrinsic errors even further. The data obtained from the computerized analysis are presented in three different ways. Besides having the numerical values in diopters, corneal maps with various shades of grey are used, together with the quantitative, three-dimensional representation of corneal astigmatism. An automated system for the analysis of corneal topography was tested for both experimental models and clinical conditions. It was easy to use and showed high precision (less than 1% error when processing photographs of precision glass spheres).

Cornea↗
PubMed1989

Retinal wound healing after surgical contusion injury.

The lesion was caused by a compression injury to the retina with a vitrectomy instrument in a rhesus monkey; the lesion was examined by electron microscopy 8 years later. The inner surface of the choroid was lined by a layer of cells with the characteristics of fibroblasts. The choriocapillaris was missing. Bruch's membrane was extremely thickened and showed numerous changes. In the center of the scar, the retinal pigment epithelium was discontinuous. The neuroretinal portion of the scar was composed of distorted and dislocated nerve cells, nerve fibers, and glial elements that were probably Müller cells. Towards the vitreous cavity, the surface of the scar contained numerous microvillous processes. A band of zonulae adherentes resembling the outer limiting membrane was seen immediately adjacent to the surface. No inner limiting membrane was seen in the entire scar area.

Animals↗
PubMed1989

[Endothelial function in contact lens-induced deep corneal opacities].

Deep stromal and preendothelial corneal opacities have been described to be a problem of growing importance in contact lens wearers, above all in those with a more than ten-year-old history of contact lens wearing. In the present study the corneal endothelial permeability of 21 patients with a more than ten-year-old history of contact lens (HEMA 38%) wearing has been determined and compared with that of an age-matched group of 8 healthy individuals without ocular disease. The corneal endothelial permeability has been measured by a computerized automated fluorophotometer (Coherent Radiation Fluorotron Master) after topical application of a Na-fluorescein solution according to the method described by Jones and Maurice. The corneal endothelial permeability of contact lens wearers with deep corneal opacities has been found to be significantly (p = 0.05) increased when compared with contact lens wearers without corneal opacities. Contact lens wearers without corneal opacities showed no significant increase of their endothelial permeability in comparison to the control group.

Cell Membrane Permeability↗
PubMed1989

[Light and electron microscopy studies of the development of the human ciliary body].

In human embryos and fetuses with a gestation age of 9.5 to 24 weeks, differentiation of the ciliary muscle was examined by both light and transmission electron microscopy, and the surface morphology of the ciliary body was analyzed by scanning electron microscopy. Smooth muscle cells develop from mesenchymal elements or early fibroblasts located at the anterior rim of the optic cup. Musclelike cells exhibiting dense bodies and myofilaments were first distinguished during week 12 and smooth muscle cells with an adultlike appearance become apparent during week 15/16. A cellular maturation process can be observed up to week 22. Fibroblasts separating the muscle cell layers from each other also derive from the same precursor cells, as do smooth muscle cells, thereby pointing out the close relationship between the two cell types. The first radial ciliary folds could be observed at week 10.3 by scanning electron microscopy. However, true ciliary processes have only been described at week 24. The ciliary processes observed during week 24 only differed from those of the adult eye by the dimensions and lack of surface infoldings. A primitive pars plana was first identified during week 24. The morphological basis for aqueous humor production is discussed.

Ciliary Body↗
PubMed1988

Ultrastructure of the paralimbal and juxtacaruncular human conjunctiva.

The epithelial fine structure of the juxtacaruncular and the medial paralimbal human conjunctiva was evaluated. In both locations the following types of cells could be identified: (1) basal cells containing numerous intermediary filaments (dark basal cells); (2) basal cells containing many mitochondria (light basal cells); (3) wing cells (spinocytes containing numerous filaments that were fewer and formed smaller bundles than those of the dark basal cells; (4) flattened, dark superficial cells; (5) wing-cell-like superficial cells. In addition, the juxtacaruncular conjunctiva contained the following cell types: goblet cells, light wing cells containing a multitude of polysomes, light wing cells containing dilated profiles of rough endoplasmic reticulum (rare), and light wing cells containing numerous microtubules (rare).

Adolescent↗
PubMed1988

Morphology of the developing choroidal vasculature in the human fetus.

In human fetuses with a gestation age of 12 to 22 weeks, the development of Haller's and Sattler's choroidal vascular layer was examined by both light and transmission electron microscopy. Even during week 12 arterioles could be identified. However, during this week they were only found in close association to the entrance of the optic nerve. Beginning with week 15/16, arterioles were also located outwards to the choriocapillary layer more anteriorly. When the arterioles first appeared, they exhibited the same ultrastructural features as those described in adults. Arteries first became apparent during week 22. They had not developed a complete internal elastic lamina. In contrast to those of the adult eye, smooth muscle cells of the fetal choroidal arteries exhibit glycogen granules. Haller's and Sattler's layer are both arterial and venous in nature.

Arteries↗
PubMed1988

Surface differentiation of the human corneal epithelium during prenatal development.

Using scanning and transmission electron microscopy, differentiation of the anterior surface of the corneal epithelium was studied in human embryos and fetuses with a gestation age from 6.4 to 22 weeks. Up to week 6/7 microvilli/microplicae are not often found; they arise in larger amounts beginning in week 7. During week 22, the morphological appearance of the corneal surface is almost adultlike. Antennulae microvillares and microfilaments running axially in microvilli can be found beginning with week 16/17.

Cornea↗