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.
In this paper we present strong evidence that the aberrations in keratoconus corneas are not directly related to alterations in collagen composition and distribution. This conclusion is based on comparative studies of collagen types I, III, IV, V and the recently described collagen types VI and VII in keratoconus and normal corneas. The data are derived from biochemical analysis of collagen fractions sequentially extracted with pepsin and sodium-dodecylsulphate, from amino acid analysis of hydrolysates of entire corneal tissues as well as from immunoblotting of the extracted collagens with specific antibodies. These antibodies were also used to examine the distribution of the collagens in immunofluorescence experiments on corneal sections. The yields of the collagen extractions were demonstrated to be age dependent but were not altered in keratoconus samples. Apart from one case associated with osteogenesis imperfecta type I, comparative studies of keratoconus and normal corneas showed no differences in collagen composition of the extracts. This was confirmed by amino acid analysis of tissue-hydrolysates. The distributions of collagen types I, III, IV, V, VI and VII in corneal sections were in general unchanged in keratoconus corneas, the only differences being in scar tissues observed in the Bowman layer of some keratoconus samples.
The organisation of the academic career is incomplete in many ways. Too much emphasis is put on scientific research. Very little instruction is given in teaching and none at all in administration and managing a whole group of people. Therefore, a young physician appointed head of a department is confronted with many duties which he may not be able to cope with. It is suggested that candidates for an academic career should attend special management schools, as do bankers, for example.
Chronic anterior uveitis in children suffering from juvenile rheumatoid arthritis may develop very early, when the patient is as young as two or three years old; it affects twice as many girls as boys. The arthritis is often localized in one joint (pauciarticular or oligoarticular form); Still's syndrome is very rare. Local treatment with cycloplegics and steroids has to be combined with systemic immunosuppressive medication with cyclophosphamide. Chronic intermediate uveitis (pars planitis) usually affects teenagers in good health. Peripheral fundus changes can be detected most easily by biomicroscopy with the three-mirror contact lens. Cystoid macular edema is frequent and, together with vitreous opacities, is responsible for a deterioration in central vision. In most cases local treatment with subconjunctival injection of depot steroids is sufficient. Immunosuppressive treatment or surgical intervention is only indicated in severe cases where there is a risk of complete loss of vision.
Report on the clarity of 45 corneal regrafts with a minimum follow-up time of 1 year. The results of regrafts in keratoconus are good. In herpetic disease with corneal vascularization and frequent secondary glaucoma the results are poor. In patients with failed grafts for corneal dystrophies or degenerations the regrafts can be beneficial.
Collagen type VI is shown to be present in the human cornea. This finding is based on comparative peptide mapping relative to type VI collagen isolated from placenta and on immunoblotting using antibodies specific for human type VI collagen. Scanning of polyacrylamide gels indicates that type VI collagen comprises as much as one quarter of the dry weight of the cornea. Indirect immunofluorescence shows this collagen to be distributed throughout the corneal stroma. Thus, type VI collagen must be considered a major component of the extracellular matrix of the human cornea.
The three classical angiomatoses of the retina are described on the basis of the clinical picture. If early diagnosis is possible, the otherwise inevitable progression to exudative retinal detachment and secondary glaucoma may be avoided through extensive coagulation by laser, xenon or cryopexy. - The prognosis is best in Leber's retinitis; it in much poorer in cases of von Hippel-Lindau angiomatosis and primary Coats' disease.
The various forms of secondary glaucoma are discussed on the basis of their different pathogenesis. Elevation of IOP is most frequently associated with inflammation of the uveal tract. Vascular changes in the uvea, in particular rubeosis iridis but also angiomatoses of the retina, can cause secondary glaucoma. Tumors of the uvea and retina often lead to increased intraocular pressure; and lastly, blunt and perforating injuries are frequently followed by glaucoma. Treatment of all these different forms of secondary glaucoma is discussed.
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In many cases antibiotic treatment is indicated; steroids are not always needed. In special cases of uveitis (Behcet's syndrome, sympathetic ophthalmia, anterior uveitis in children with JRA) cytostatic treatment seems justified. Inflammations of the optic disk and nerve require very extensive diagnostic evaluation. Medical treatment is usually limited to steroids, administered systemically and locally; however, its efficacy is still a matter of debate.
The three classic angiomatoses of the retina are described according to the clinical picture. If early diagnosis is possible, then the inevitable progression to exudative retinal detachment and secondary glaucoma may be avoided by extensive coagulation with laser, xenon or cryopexy. Prognosis is best with Leber's retinitis, much less so in cases of von Hippel-Lindau angiomatosis and primary Coats' disease.
Between 1971 and 1982 33 corneae were excised for therapeutic keratoplasty because of ulcerative herpetic keratitis. The histologic findings and the clinical course enabled distinction of a nonreactive form with a rather good prognosis for keratoplasty (62% clear grafts) and an inflammatory form with bad prognosis (20% clear grafts) because of many herpetic recurrences. Perforating keratoplasty and first interventions in particular did better than lamellar keratoplasty or retransplantation. Existence of preoperative corneal vascularization compromised the prognosis of the graft. Preoperative perforation of the ulcer occurred rather often in nonvascularized corneae without compromising the prognosis of the graft.