PubMed · 10850915
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R J Mackool. 2000. Capsule stabilization for phacoemulsification.. https://doi.org/10.1016/s0886-3350(00)00454-5
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Secondary chronic open-angle glaucoma associated with pseudoexfoliation (PEX) syndrome accounts for approximately 25% of all glaucomas and represents the most common identifiable cause of glaucoma overall. The underlying disorder, PEX syndrome, is a generalized process of the extracellular matrix characterized by production and progressive accumulation of an abnormal extracellular material in many intra- and extraocular tissues. Recent data support the pathogenetic concept of PEX syndrome as a type of elastosis affecting particularly elastic microfibrils. Active involvement of the trabecular meshwork in this characteristic matrix process may lead to glaucoma development in 40-60% of the patients. In addition, PEX syndrome also represents an important risk factor for a broad spectrum of spontaneous or intra- and postoperative ocular complications as well as for systemic cardiovascular diseases. PEX-associated open-angle glaucoma represents a relatively severe and progressive type of glaucoma with a generally poor prognosis due to high intraocular pressure levels and fluctuations in the diurnal pressure curve. The primary cause of chronic pressure elevation appears to be local production of PEX material by trabecular meshwork cells and Schlemm's canal cells with subsequent degenerative changes of Schlemm's canal and juxtacanalicular tissues. Additional pathogenetic factors contributing to pressure increase include pronounced melanin dispersion, increased protein concentrations of the aqueous humor, vascular factors, and connective tissue alterations of the lamina cribrosa. Other types of glaucoma, such as acute open-angle glaucoma, provoked by melanin showers during diagnostic mydriasis, or secondary angle closure glaucoma due to pupillary or ciliary block, are also common in PEX patients. The pathogenetic factors TGF-beta1 and TIMP-1/2 appear to be causally involved in this fibrotic process and thus may represent potential targets for specific, rational therapeutic approaches.
John G. Lindberg, a young Finnish ophthalmology resident, started a research project in 1914 aiming at an academic dissertation. His plan was to elucidate Axenfeld's observations on iris changes in senile eyes. Axenfeld had described two types of degeneration of the iris: a hyaline degeneration of the iris pupillary zone causing poor pupillary dilatation with mydriatics and an atrophy of the iris pigment epithelium at the pupillary border. For his research Lindberg had to construct a slit-lamp biomicroscope by studying Gullstrand's monograph on the matter; slit-lamp biomicroscopes were not commercially available at that time. A Sach's lamp was used for transillumination of the iris. While conducting his research Lindberg paid attention to greyish flakes and fringes at the pupillary border. He also noted how this strange material formed a membrane on the anterior lens surface. Documentation was made by skillful hand drawings. The new phenomenon was found to be as common in cataract patients as in non-cataractous controls older than 55 years. The phenomenon was observed in 50% of glaucoma patients. Age was the decisive factor; the phenomenon was more prevalent with advancing age. Lindberg published his results as a thesis at the University of Helsinki in 1917. When attending a Nordic Congress of Ophthalmology in 1921, Lindberg met Norwegian ophthalmologist, Birger Malling, and gave him his thesis and explained the new findings. In 1920-21 Lindberg worked at Axenfeld's clinic in Freiburg, Germany. During this period he met in Basel, Switzerland, a Swiss ophthalmologist, Alfred Vogt. He told Vogt about his research and provided him with copies of his thesis. Both Malling and Vogt published papers on exfoliation in 1923 without referring to Lindberg's work. Lindberg did not, however, interfere with these papers. Thus Lindberg was forgotten by his contemporaries as a scientist. However, his main conclusions on exfoliation are still valid today. The life of this remarkable ophthalmologist is described in the present paper.
Exfoliation (pseudoexfoliation; PEX) syndrome is the single most common identifiable cause of open-angle glaucoma, however, very few investigators are engaged in basic research on this disease. To stimulate the field, the First International Think Tank on Exfoliation Syndrome was held in New York in July 1999, comprising clinicians and scientists. This report is a summary of the proceedings of this meeting.