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S Kwasniewska

Publications and source records attributed to S Kwasniewska.

50 records · Page 3Linked to original sources
PubMed1987

Transscleral iridotomy using a neodymium: YAG laser operated both with standard equipment and an optical fiber system--a preliminary report: Part II--Light and electron microscopic findings.

We report the morphology of transscleral iridotomies applied to human cadaver eyes using a free-running Nd:YAG laser (pulse duration: 20 ms, pulse energy: 1.5-6 J) with and without a fiber optic system. The pigment epithelium, which represents the barrier to the aqueous humor for passing through the iris, is damaged and blasted away over great areas. The mesothelial layer at the anterior surface of the iris is also broken up by the laser beam. Using low pulse energies, the iris stroma is only partially damaged. The destruction of the iris is caused by generation of heat due to absorption of radiated energy.

Fiber Optic Technology↗
PubMed1986

Advantages and limitations of the spatially adaptive program SAPRO in clinical perimetry.

The SAPRO program devised for the OCTOPUS 201 automated perimeter, consists of a number of program components. It is designed to be used on the Octopus 201 computer. In its measurement mode, it employs an algorithm which achieves high speed and efficiency. This is made possible by a threshold bracketing strategy which is simpler than the normal OCTOPUS bracketing. Moreover, three grids with test location distributions of increasing resolution are superimposed in succession on the whole or on part of the visual field to be analyzed. Out of the distribution of test locations, only those which fulfill a number of criteria are actually utilized. These criteria must be given and are adaptable to any given clinical problem. As a result, despite the high spatial resolution achieved, only a fraction of the test locations are utilized using SAPRO as compared with a program using a fixed pattern of test locations. The algorithm is thus able to imitate human intelligence, which tends to concentrate stimuli at places which appear to be relevant for the solution of a problem. The results of program SAPRO are disturbed by short- and long-term fluctuations. Their validity is limited, in a manner similar to that encountered in any other threshold determination procedure. A number of printout modes is available which are oriented towards an optimal understanding of the information contained in various examinations. These principles will be illustrated by one case of inactive disseminated chorioretinitis.

Computers↗
PubMed1986

Thermal effects on the trabecular meshwork induced by laser irradiation: clinical implications deduced from ultrastructural studies on the macaca speciosa monkey.

The pressure lowering effect brought about by irradiating the chamber angle with argon laser light according to Wise and Witter was studied by ultrastructural methods and was analysed in order to ascertain the mechanism responsible. To this end, the effects induced in 4 macaca speciosa monkeys by such irradiation were examined using scanning and transmission electron microscopy. It was noted that the phenomena observed depend critically on the precise location of the irradiation site. When the anterior trabecular meshwork is irradiated, a proliferation of monocellular, atypical corneal endothelium cells occurs which tightly surround the irradiation location. In irradiation of the posterior trabecular meshwork, however, this effect is much less prominent. In both cases, by the end of the twelfth week a progressive, lytic degeneration of the entire trabecular meshwork was observed which reached the inner wall of Schlemm's canal.

Animals↗
PubMed1986

A new contact lens for posterior vitreous photodisruption.

Effective and safe photodisruption requires that the laser pulse be brought to a fine focus. Contact lenses are generally required to compensate for the optical aberrations of the eye which degrade the laser focus. The theoretical analysis of these aberrations has led to the construction of a contact lens which minimizes aberrations in the posterior vitreous. Clinical applications confirm the increased efficacy and safety of posterior vitreous photodisruption using this contact lens.

Contact Lenses↗
PubMed1986

Aiming accuracy in ophthalmic laser microsurgery.

A number of aiming/focusing systems, oriented toward guiding the treatment beams of photodisruptive, high power Nd:YAG lasers, are analyzed and evaluated. A system, consisting of two frequency modulated, rotating laser beams, which outline the Nd:YAG laser beam shape, is shown to be the optimal solution.

Humans↗
PubMed1986

Evaluating the applications of the spatially adaptive program (SAPRO) in clinical perimetry: Part I.

Some clinical application possibilities of a spatially adaptive program (SAPRO) are presented and analyzed. Due to the ability of the program to adapt operationally to the visual field situation that is encountered, useful clinical findings can be obtained, even in patients with complicated visual field disturbances. The spatially adaptive detection mechanism, as well as a simplified bracketing strategy, make it possible to keep the cost/benefit ratio down. Short- and long-term fluctuations, especially when these are large, may compromise the validity of the examination results or place them in doubt. Their effects can be diminished using data reduction methods (averaging). In cases where averaging cannot be applied, one can nevertheless achieve useful results by the appropriate selection of the perimetric visual fields (or portions thereof) that are measured.

Adult↗
PubMed1986

Transscleral cyclophotocoagulation using a neodymium YAG laser.

The effects of a neodymium: YAG laser, working in the free-running mode (1 and 20 millisecond pulses), upon the ciliary body via the transscleral route have been studied using 16 autopsy eyes. The experiments described were designed to find an efficient strategy of transscleral cyclodestruction of the ciliary body. It was found that pulse energies of between 6 and 7 Joules, an exposure duration of 20 milliseconds, and maximal defocusing are optimal. A beam, tangentially oriented and positioned 1/2 to 1 mm posterior to the limbus has a high probability of hitting the ciliary body and damaging the ciliary processes. In these experiments a first generation of contact lenses could not be demonstrated to have an advantageous effect.

Ciliary Body↗
PubMed1985

Vitreolysis with the Q-switched laser.

We present an overview concerning the current status of photodisruptive methods used in the treatment of pathologic changes in the vitreous space. In one series of 320 cases studied, 65% of the planned dissections of pathologic structures were successful. In a second series of 34 more complicated cases, the success rate was even lower. Complications included 15 retinochoroidal hemorrhages and one damaged posterior lens capsule. When one compares optical-surgical methods with conventional methods, it is obvious that the former aim at achieving goals that are less ambitious than those of classic vitrectomy and, in many cases, serve only to prepare for - and facilitate - a classic vitrectomy. By definition, laser vitreolysis dissects, but cannot remove, the fragments of disrupted structures from the eyeball. However, despite the obvious risks, photodisruptive laser surgery is considered less dangerous than is classic vitrectomy because photodisruption is a "noninvasive" procedure. Since laser vitreolysis is able to solve a number of clinical problems, obviating the need for vitrectomy, the former procedure should receive increasing attention for the treatment of pathologic problems in the vitreous cavity.

Adult↗
PubMed1985

Irradiation of the posterior ocular segment with the neodymium-YAG laser in its free-running mode.

A neodymium-YAG laser, operating in its free-running mode with pulse durations of 10 to 20 ms, was used to treat 63 cases of choroidal and retinal diseases. These cases included diabetic background retinopathies, thrombosis of the central retinal vein or branch retinal vein, neovascular membranes under the pigment epithelium, and retinal breaks or degenerations of the peripheral retina. Because the number of diabetic retinopathies (24) and their average follow-up time (25.5 months) are insufficient for the evaluation of irradiation effects, no definite statement as to the merits of this energy modality in such cases can be made. The irradiation of infarcted retina was followed by extensive atrophy of the involved area. No secondary glaucoma was observed during a follow-up period of 16.4 months. The irradiation in four cases of neovascular subretinal membranes was followed by disappearance of the membranes. However, relapse later occurred in all four cases. The irradiation of eight retinal breaks resulted in solid scar tissue. Two choroidal melanomas were destroyed and did not recur during a follow-up period of 22 months.

Choroid↗
PubMed1985

Neodymium Q-switched YAG laser lysis of iris lens synechiae.

The feasibility of Q-switched Nd: YAG synechiolysis in phakic patients without visible damage to the lens has been demonstrated. The value of this procedure in the management of glaucoma and its advantages over argon laser photomydriasis is discussed.

Aged↗
PubMedDate not supplied

Oculoplastic surgery with a contact Nd:YAG laser silica scalpel. A case report.

Baso-cellular carcinomas involving the medial canthal regions of both eyes were resected using a 10 W cw-Nd: YAG laser scalpel. The wound bed was repaired one side by a free, split-thickness graft and on the other by a frontal pedicle flap. Surgery was, for the most part, virtually bloodless. Since laser radiation immediately seals both capillaries and lymphatics, the incidence of postoperative hemorrhage and edema was significantly less than after cold scalpel surgery. Healing was uneventful. The advantages of laser-assisted surgery are worthy of consideration: not only is the operation time markedly curtailed, but the wound healing response is excellent, with only a minimal inflammatory reaction.

Aged↗