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Biomedical subjects

K M Zinn

Publications and source records attributed to K M Zinn.

At least 19 recordsLinked to original sources

Clinical aspects of ophthalmic argon laser.

This paper reviews the historical events leading to the development of the ophthalmic laser. The formation of the argon laser beam and its biological effects on ocular tissues are outlined, with the major emphasis on the retinal and choroidal tissues. The clinical indications, contraindications, and complications of ophthalmic argon laser photocoagulation for the anterior segment as well as the posterior segment structures of the eye are also thoroughly discussed.

Argon

Proton-beam irradiated epithelioid cell melanoma of the ciliary body.

A malignant ciliary body melanoma received proton-beam irradiation. After an apparent failure of the tumor to respond, the eye was enucleated. A predominantly epithelioid cell tumor appeared viable by light microscopy, and a low degree of mitotic activity persisted, despite therapy. The tumor cells, however, displayed degenerative changes ultrastructurally, presumably results of the radiotherapy. These consisted of numerous cytoskeletal filaments, lipid vacuoles, prominent phagolysosomes, and nuclear convolutions and fragmentations. The mitochondria were fewer in number in the present tumor than typically encountered in epithelioid cells. A rare leptomeric structure was discovered, probably an organizational modification of the cytoplasmic filaments. The tumor's capillaries showed radiation-induced changes in terms of thickened basement membranes and perivascular fibrin deposition. The foregoing features are indicative of cellular and metabolic injury from the radiotherapy, but these were evidently not sufficiently injurious to sterilize the tumor.

Adult

Iatrogenic intraocular injection of depot corticosteroid and its surgical removal using the pars plana approach.

A four-year-old girl, while undergoing a repeat excisional biopsy for a progressive orbital hemangioma, sustained an accidental intraocular injection of methylprednisolone acetate (Depo-Medrol) resulting in a mass of intravitreal and subretinal depot material as well as a retinal tear, retinal detachment, and rapid cataract formation. Pars plana lensectomy, vitrectomy, xenon arc endophotocoagulation and air fluid-gas exchange techniques were used to restore the ocular tissues for visual functions in the affected eye and to save the globe from the devastating toxic effects of the vehicles in the depot corticosteroid preparation.

Biopsy

Removal of intravitreous cysticerci from the surface of the optic nervehead. A pars plana approach.

Two larvae of Taenia solium (eg, Cysticercus cellulosae) were identified in the posterior vitreous attached to the optic nervehead of a 13-year-old Guatemalan girl. Preoperative evaluation showed the larvae to be viable. The vitreous showed a mild cellular reaction. The larvae were dissected off the optic nervehead and removed via a pars plana approach, without incident. To our knowledge, this is the first case report of cysticerci attached to the optic nervehead that were removed successfully by the pars plana approach. The patient was treated with a very short preoperative and postoperative course of corticosteroids. No inflammatory flare-ups or recurrence of the cysticercosis were found during the one-year follow-up period.

Adolescent

Removal of an intraocular foreign body from the optic nerve head.

A 29-year-old man sustained a metallic (98% iron) foreign body in the optic nerve head, which resulted in a massive vitreous hemorrhage and a secondary branch retinal artery occlusion. An initial pars plana vitrectomy was successful in removing the vitreous hemorrhage, but numerous attempts with pars plana and intravitreal electromagnets failed to dislodge the foreign body. A second operation using a microscalpel and foreign body forceps with the bimanual pars plana technique was successful in removing the steel foreign body from the optic nerve-head.

Adult

Electron microscopic observations of intravitreal Cysticercus cellulosae (Taenia solium).

Cysticercus cellulosae, the larval stage of Taenia solium, was studied by light and electron microscopy after its removal from the vitreous. The ultrastructure of the larva is highly organized and displays a superficial tegument and deeper parenchyma. The tegument contains a microvillous surface overlying a syncytial cytoplasm. A deeper muscular layer overlies the parenchyma, within which are highly specialized structures important in water balance, flame cells, and acid-neutralizing calcareous corpuscles.

Adolescent

A new endoillumination infusion cannula for pars plana vitrectomy.

A new endoillumination infusion cannula has been developed that allows for wide field illumination of the retina during pars plana vitrectomy surgery. This frees the surgeon from having to use one of the intravitreal probes for endoillumination when using the bimanual technique in pars plana vitrectomy. This innovative endoillumination source also can be used with indirect ophthalmoscopy, at surgery, avoiding the glare generated by the indirect ophthalmoscope's light beam interacting with the corneal surface and the condensing lens surfaces.

Catheterization

An improved endoillumination probe for pars plana vitrectomy.

A newly modified endoillumination probe using the Ocutome handle has been developed that has 2.5 times more total light output and over four times more light intensity than the conventional endoillumination probe. The new probe is particularly useful in situations where there is extremely dense vitreous hemorrhage and when one requires additional light for 16-mm cinematography.

Ciliary Body

Role of cardiovascular disease in the pathogenesis of rhegmatogenous retinal detachments.

In 100 patients with fresh rhegmatogenous retinal detachments complete ocular and physical examinations including electrocardiograms were carried out. The incidence of coronary artery disease and systemic hypertension in these patients with retinal detachments was much greater than that found in the general population of similar age and sex. A vascular theory is proposed to explain these findings in light of our current concepts of the pathogenesis of retinal detachments. It is also suggested that retinal detachments may be one element of a generalized vasculopathy that involves the coronary arteries, the pulmonary vasculature, and perhaps the renal circulation in patients with systemic hypertension.

Adolescent