PubMed Health⌕ Search

Biomedical subjects

A W Fryczkowski

Publications and source records attributed to A W Fryczkowski.

At least 37 records · Page 2Linked to original sources
PubMed1987

Vascular casting and scanning electron microscopy in diabetes.

Scanning electron microscopic (SEM) studies of the vascular casts of human eyes removed at autopsy from subjects with a long-standing history of Diabetes Type I were performed. Changes in the choroidal vasculature include: Venal focal dilations and narrowings, increased tortuosity, hypercellularity, increased formation of vascular loops and microaneurysms in choriocapillaries and formation of sinus-like structures between choroidal lobules. This study strongly supports earlier light microscopic and transmission electron microscopy observations on changes in the choroid. The retinal vascular changes shown by SEM are microaneurysm formation, drop-out of capillaries and neovascularization. Changes in the choroid, especially in diabetic choriocapillaries can be suspected to be a supporting factor in diabetic retinopathy by a decrease of oxygenation of the outer layers of the retina.

Capillaries↗
PubMed1986

Delivery of antifibroblast agents as adjuncts to filtration surgery--Part II: Delivery of 5-fluorouracil and bleomycin in a collagen implant: pilot study in the rabbit.

A pilot study was performed in order to determine if filtration bleb longevity could be enhanced in rabbits by delivery of 5-fluorouracil or bleomycin in a collagen sponge implant. Results showed that both agents prolonged bleb longevity and lowered intraocular pressure when compared to controls. Bleomycin treated animals had the best bleb appearance and function at the longest postoperative intervals.

Animals↗
PubMed1985

Vascular casting and scanning electron microscopy of human ocular vascular abnormalities.

Plastic casts of ocular vessels were made from postmortem specimens obtained from patients who had had hypertension and arteriosclerosis, diabetes mellitus, and retinopathy of childhood. In conjunction with scanning electron microscopy, the casts serve as models of pathologic vascular changes, including arteriovenous crossing defects, microaneurysm, localized capillary nonperfusion, and rapidly growing peripheral choroidal vessels. These preliminary findings should serve to encourage further study of ocular vascular abnormalities with the use of plastic casting techniques.

Adult↗
PubMed1985

Scanning electron microscopy of the ocular vasculature in retinopathy of prematurity.

Clinicoanatomopathologic correlations in a case of the retinopathy of prematurity are reported. A premature infant delivered at 28 weeks of gestation (weight, 900 g) was hospitalized for a number of health problems, including bronchopulmonary dysplasia and respiratory distress syndrome. Ophthalmic examination, at the age of 5 months, disclosed stage 1B retinopathy of prematurity. The patient died at the age of 161 days; both eyes were taken for scanning electron microscopy and histopathologic studies. Scanning electron microscopy findings included absence of retinal capillaries, anterior uveal neovascularization originating from the venous side, and a coincidental typical coloboma of the optic nerve and choriocapillaris. Histopathologic findings confirmed iris stromal neovascularization, showed retinal neovascularization with proliferation into the vitreous and avascular areas between the midperiphery and ora serrata.

Blood Vessels↗
PubMed1985

Intravenous digital subtraction angiography of orbital and ocular circulation. A preliminary experimental study.

In serial experiments on cats, intravenous digital subtraction angiography (DSA) was utilized to observe orbital and ocular circulation. Images of the orbital arterial system as well as normal ocular vasculature were obtained, utilizing dosage of contrast material acceptable for human study. Images obtained after intra-arterial DSA had no advantage over those obtained with intravenous DSA. After retrobulbar injection of 3 ml of saline, intravenous DSA demonstrated straightening of the external ophthalmic arteries showing the potential of this method for identifying orbital vascular pathology.

Angiography↗
PubMed1985

Pathology of corneal hydrogel alloplastic implants.

Hydrogel keratophakia is a new form of lamellar refractive surgery which, in theory, can deal with almost all forms of refractive error. We examined the histopathological effects of several types of hydrogel materials on the cornea of non-human primates. With the exception of one type of hydrogel material, which was associated with endothelial cell degeneration, only minor histopathologic changes were seen up to a maximum of one year of observation, including thinning of the epithelium and decreased population of stromal keratocytes. These changes did not correlate with any clinical abnormalities. Additional extensive preclinical testing and eventual human clinical trials will determine the safety and efficacy of this procedure.

Animals↗
PubMed1984

Scanning electron microscopy of vascular casts of the human scleral lamina cribrosa.

Vascular casts of the human lamina cribrosa region were studied in three autopsy specimens utilizing scanning electron microscopy (S.E.M.) in own modified technique. The lamina cribrosa is supplied from two major sources, the short posterior ciliary artery within the sclera and the distal optic nerve sheath pial vasculature. Recurrent choroidal arteries supplied a small number of centripetal branches to the lamina cribrosa. The central retinal artery did not give off centrifugal branches as it coursed through the lamina. The findings in these three human cases in three-dimensional visualization support other recent studies using serial histologic sectioning techniques. The photomicrographs are presented as a first successful images in S.E.M. for additional appreciation of the topographic morphology of radial arterioles.

Aged↗
PubMed1984

Effect of tissue fit on corneal shape after transplantation.

Postkeratoplasty astigmatism is now a major problem preventing visual recovery. Certain postoperative topographic characteristics are felt to be dictated by the fit of the donor corneal button in its recipient bed. Deficient tissue at the wound is predicted to contribute to the location of the steep meridian and excess tissue to the location of the flat meridian. In an eight-cat sample using our Fit Assessment Method and Photogrammetric Index Method, the authors tested the relationship between button fit in recipient bed and resulting corneal curvature at approximately 42, 161, and 289 postoperative days. Corneal symmetry improved between the first and second postoperative periods. Deficient tissue led to steepened curvature and ample tissue to flattened curvature in the first measurement period. When buttons fit poorly, deficient tissue led to steepness in the first postoperative period, but led to flattened curvature 90 deg away from the deficient tissue meridian in the second and third periods. The relationship between ample tissue and flattest postoperative curvature did not depend on the magnitude of button-fed disparity in any period. Corneal elasticity appeared to influence the way tissue disparity affected postoperative topography. Our findings support Troutman's balloon mode. When there was a large amount of uncompensated tissue disparity, the tissue deficiency exerted a force that shortened the translimbal chord. This produced both steepened curvature parallel to this chord soon after surgery and flattened curvature at 90 deg to the chord in the stable postoperative cornea.

Animals↗
PubMed1984

Myopic correction using alloplastic implants in non-human primates--a preliminary report.

Hydrogel keratophakia has been studied in a non-primate model in an attempt to develop a more predictable form of myopic refractive surgery. Although the largest potential clinical use for this form of surgery is for the correction of myopia, currently available surgical techniques are not nearly as predictable as non-surgical devices such as spectacles and contact lenses. In this paper, hydrogel lenses, implanted in non-human primate corneas, were used for the first time to flatten the anterior corneal surface as would be required for the correction of myopia. Up to 9 diopters of correction was obtained. Little change in corneal astigmatism was found. The technical aspects of the surgery are quite simple, and the corneas healed rapidly and have excellent clarity. Extensive primate testing will be necessary to determine the accuracy of this procedure before clinical trials should be undertaken.

Animals↗
PubMed1984

A new photogrammetric method for quantifying corneal topography.

Attempts to describe normal corneal shape and to represent corneal topography by an array of discrete points have limited usefulness. A quantitative photogrammetric method that produces indices to describe corneal shape was developed. Four indices depict the departure of keratographic rings from circularity, and two indices express the trends and consistencies of all the rings from one keratograph. This photogrammetric index method (PIM) was evaluated against established measurement techniques. Values for the six indices were computed for groups (10 corneas each) of symmetrical, regularly astigmatic, and keratoconic corneas that had been defined by keratometry and clinical criteria. Predictions of the differences among groups were formulated for each index based on group descriptions and anticipated manual tracing and/or digitization error. Parametric and nonparametric tests of significance supported most predictions. The asymmetry of irregularly astigmatic keratoconic corneas, the variability of their orthogonal principal meridians, and an increasing symmetry toward their peripheries were documented clearly. The circularity of symmetrical group rings and the ellipticity of regularly astigmatic group rings were also evident. Preliminary norms are offered to illustrate the usefulness of the PIM in defining groups of corneas with the same histories and in classifying individual corneas.

Adult↗
PubMedDate not supplied

Witelo--Polish vision scientist of the middle ages: father of physiological optics.

Unknown to the Western hemisphere, a Polish scientist, naturalist, anatomist, physiologist, philosopher and optician, Witelo, wrote an important ten volume manuscript, Peri-Optikes, usually cited in the literature as Perspectiva. This classic textbook was first published in 1535 in Nuremberg under the title: Vitellionis mathematici doctissimi ... vulgo Perspectivam vocant libri X, which is translated to English as Perspectiva. It was a vital source of information for such scientists as Leonardo da Vinci, Keppler and others in the next few centuries. Although many of his ideas were similar to Alhazan's, who earlier had written a significant optical manuscript De aspectibus, Witelo developed his own interpretation of many optical issues. He was one of the first scientists to discover spherical aberration of concave lenses and concave mirrors. He was also first to point out "that deflection of the light ray increases with the angle in which they approach two different optical substances and each increase is smaller than the previous one." Until recently, Witelo's achievements and contributions to the understanding of optical and anatomical aspects of the eye and visual function have remained unknown in western literature. Undoubtedly, Witelo should be recognized as the father of physiological optics.

History, Medieval↗
PubMedDate not supplied

Experimental intravenous digital subtraction angiography (DSA) of orbital and choroidal circulation: preliminary study.

The development of the radiologic technique, digital subtraction angiography (DSA), has substantial importance in studying the uveal vasculature and its orbital blood supply. After rapid intravenous injection of commercially available contrast material, images of the orbital and uveal vessels of rabbits, cats, and the nonhuman primate can be observed. Advantages and limitations of this new technique for visualization of uveal and orbital vasculature were evaluated in serial experimental animal studies. Future potential clinical applications are discussed.

Angiography↗
PubMedDate not supplied

Congenital glaucoma associated with cutis marmorata telangiectatica congenita: two case reports.

Two cases of cutis marmorata telangiectatica congenita are described in association with nevus flammeus and congenital glaucoma. Approximately 65 cases have been reported and the association with nevus flammeus and congenital glaucoma has only been reported in one of those cases. Unlike the glaucoma associated with nevus flammeus of Sturge-Weber, this type of congenital glaucoma appears to be associated with an abnormal filtration angle rather than an increased episcleral venous pressure.

Child, Preschool↗