Biomedical subjects
Publications and source records attributed to R Witmer.
The problems associated with performing penetrating keratoplasty in private practice are briefly discussed: access to an eye bank, high-risk patients, immunosuppressive therapy, complications, and results. One negative aspect is the relatively high incidence (10%) of primary graft failure, but allograft reactions are less frequent (5%). The best results are obtained in keratoconus cases.
The author presents a personal review of the changing approach to the problem of the etiology of uveitis and its treatment during the past 40 years. Goldmann's ingenious idea concerning local antibody formation within the eye was the starting point of many research projects.
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We studied the serologic findings in serum and aqueous humor samples from 693 cases of uveitis. Specimens were tested for the presence of humoral antibodies against tuberculosis, toxoplasmosis, antistreptolysin-O, herpes simplex and herpes zoster viruses, mumps virus, and adenovirus. Serologic analyses rarely indicated tuberculous or streptococcal infections, but frequently showed toxoplasmosis and viral diseases.
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Specular microscopy enables the examination of the endothelium of the isolated and perfused cornea. It is of great help in evaluating donor material in an Eye Bank. The in vivo observation and microphotography of the corneal endothelium makes it possible to detect early degenerative, traumatic surgical and other pathological changes of the monolayer.
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Contacts between melanocytes and nerve terminals in human iris stroma were investigated by means of electron microscopy. Four distinct types of nerve terminal making synaptic contacts with melanocytes can be distinguished: (1) nerve terminals containing only empty synaptic vesicles (400-800 A in diameter) and with intervening basement membrane material (separation 1000 A); (2) nerve terminals with both empty vesicles and granulated vesicles (600-1100 A in diameter) also with intervening basement membrane material (separation 750 A); (3) nerve terminals containing empty vesicles and forming close contacts with melanocytes (distance about 400 A) without interposed basement membrane material, and (4) nerve terminals containg both empty and granulated vesicles (750 A in diameter) which make closer contacts with melanocytes (distance 270 A) without interposed basement membrane material. Type (1) and type (3) nerve terminals are thought to be cholinergic; type (2) and type (4) nerve terminals appear to be adrenergic. Taking into consideration these morphologic findings and previously reported data, it seems justified to postulate the presence of trophic innervation of melanocytes in the human iris.
Electron-microscopic analysis of iris biopsy material was carried out paying particular attention to vessels and infiltrating cells. Characteristic changes of vessels and cells were found in two cases. One showed abundant lymphodiapedesis, perivascular infiltration, and vessels appearing morphologically normal. The other showed diffuse infiltration of cells and numerous fenestrated newly formed vessels. In the latter, three different types of opening in the endothelium were observed: (1) separation of intercellular junctions; (2) small pores or defects in the endothelium, and (3) large holes or defects in the endothelium. Cell leakage from normal and newly formed vessels was considered. We concluded that lymphocytes may migrate through the cytoplasm within membrane-bounded vesicles in normal vessels, whereas in newly formed fenestrated vessels cells, including small lymphocytes, may pass through three different types of opening in the endothelium.
Seven human corneae were preserved 1 or 2 weeks in a continuous tissue culture medium at +37 degrees C. 200 microgram/ml gentamycin and 2.5 microgram/ml amphotericin B were added, and no infection was noted after 2 weeks. Histological and electronmicroscopical findings presented a picture of well-kept cellular and subcellular structures. Comparable electron-optical examinations taken on seven corneae kept at +4 degrees C in a modified medium 199 showed the beginning of endothelial necrobiosis.
The secondary rise of i.o. pressure in uveitis may lead to a true secondary glaucoma or to hypertensive uveitis. The etiology of the endogenous inflammation does not seem to play a role. Pathogenetically the occlusion of the pupil with the formation of iris bombé and the obliteration of the chamber angle by exudate are important factors, while the hypersecretion of aqueous humor plays a minor role. Medical treatment consists in mydriatics and steroids. Surgical treatment depends on the pathogenetic mechanism and consists either in sector iridectomy or a filtering procedure.
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Although there is parctically no contraindication for general anesthesia and the risks for the patient have become considerably less, local anesthesia is still indicated for many ophthalmic surgical interventions. Here different factors have to be considered: The physical and psychological state of the patient, the nature of the intervention (above all cataract and glaucoma operations, as well as lamellar and perforating keratoplasties), the technique of the local anesthesia, the pre-medication, the relationship surgeon-patient, economic factors and possible complications of general anesthesia.
(1) 36 patients with a certified retinal detachment and a dense senile cataract who underwent cataract surgery prior to retinal surgery, (2) 32 patients with a history of detachment of one eye and a senile cataract of the other eye, who suffered a retinal detachment after cataract surgery. Discussion of the results of retinal surgery in the first group and on the incidence of retinal detachment and results of retinal surgery in the second group.
Ultrastructural analyses of iris biopsies in 17 cases of uveitis with different etiology revealed that all cells involved in immunological reactions are present. Many plasmacells and lymphocytes, but also macrophages and mastcells are found. Destruction of cells and even necrosis as well as damage of blood vessels are run. No specific germs could be demonstrated and etiology was not further elucidated. But there remains no doubt on the immunological nature of uveitis.
The corneal endothelium of intact donor eyes was evaluated by means of a specular microscope. In a series of 278 corneas, different morphologic changes were found in the endothelium. These changes are described and systematically classified. The findings are analogous to results obtained on experimental animals and with light- and electron-microscopic studies of other authors.
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