This is a biography of Allvar Gullstrand (1862-1930) on the occasion of the centennial of his 1911 Nobel Prize in physiology or medicine. We reviewed pertinent literature and we did archival studies at the Uppsala University Library and the Regional State Archives at Lund as well as the Nobel Archives at the Royal Swedish Academy of Sciences in Stockholm. Allvar Gullstrand was a brilliant scientist with an exceptional personality. He gave mathematical descriptions of the dioptric system of the human eye with unprecedented accuracy, and he invented and designed ophthalmological instruments of far-reaching importance. The two most valuable ones are the slit lamp and the reflexless ophthalmoscope. Both are in everyday use by any ophthalmologist in the world. Allvar Gullstrand is so far the only ophthalmologist who has been given a Nobel Prize for work in ophthalmology, and he deserved it well.

This study documents the ophthalmological findings in a six-generation Swedish family with autosomal dominant retinitis pigmentosa with a previously unknown rhodopsin, exon 2, mutation, Arg-135-Leu (CGG to CTG). Six affected patients from the family were available for analysis and were all found to be heterozygous for the mutation, whereas eight clinically normal family members and 29 unrelated normal individuals did not have it. The disease appears to be of a type with comparatively rapid progression to blindness.

Purpose: To study early signs of neuronal and glial differentiation in the human embryonic retina. Materials and Methods: 6.5-to 8-week-old human embryos were obtained from elective abortions. The neuroretinas were kept in culture as full-thickness sheets for 7–42 days. Results: The control retinas consisted of a neuroblast cell layer and a thin marginal zone. Most explants displayed presence of retinal lamination, but also contained regions of disorganization. Vimentin labeling showed vertically arranged Müller cells in all explants. Recoverin-labeled photoreceptors appeared in explants kept 14 days and longer. By labeling with antibodies against PKC and parvalbumin, rod bipolar cells and amacrine cells could be seen in explants kept for 42 days in culture.Conclusions: We have shown that the embryonic full-thickness neuroretina can survive in a culture environment for at least 6 weeks, and can develop several types of the retina-specific neuronal and glial cells.

The Swedish Ophthalmological Society was formed on May 30th and 31st, 1908. This paper presents some of the highlights of its history selected from a centennial volume published by the Society (Ehinger et al. 2008). The first international meeting of ophthalmologists was held in Brussels in 1857. Subsequent gatherings in major European cities became regular events and were attended by, among others, Swedish physicians and surgeons, who brought important medical information back to their home country. In 1900, the time was considered ripe to inaugurate a regional gathering of Nordic ophthalmologists, the first of which took place in Stockholm (Granström 1955; Ehinger et al. 2008). As in other specialties (e.g. surgery, and ear, nose and throat medicine), it was considered appropriate to instigate national Swedish ophthalmological meetings and, after some preliminaries, 17 ophthalmologists gathered in Uppsala on May 30th and 31st, 1908 (Havelius 2008). These included the four founding fathers of what was to become the Swedish Ophthalmological Society, of whom Allvar Gullstrand is now the best known, having become a Nobel laureate in 1911. However, the other three were also well known at the time. They included Johan Widmark, professor of ophthalmology in Stockholm, Erik Nordenson, who ran a private eye hospital in Stockholm, and Ernst Forsmark, who acted as the Society’s secretary and who went on to become head of the Sabbatsberg Eye Clinic in Stockholm in 1910 (1-4). Allvar Gullstrand. Erik Nordenson. Johan Widmark. Ernst Forsmark. Allvar Gullstrand was a most remarkable man. He had shown great mathematical ability already as a teenager, and his parents had facilitated his learning by moving from Landskrona to Jönköping, where a better gymnasium teacher in mathematics was available. Gullstrand took up medical studies in Stockholm, where his ease with infinitesimal calculus quickly led him to realize that the frequent exclusion of higher-order terms from contemporary solutions to the complex equations that describe optical astigmatism resulted in incorrect and often inadequate conclusions. In his subsequent MD thesis, published in 1890, Gullstrand’s improved handling of the equations was impressive. His feat was most remarkable because he had no local tutors or predecessors. The thesis was compact and included a small number of well designed experiments that clinically validated Gullstrand’s theoretical results (Fig. 5). Two characteristic pages from Gullstrand’s doctoral thesis, published in 1890. Gullstrand’s thesis received the highest acclaim and he was immediately offered various academic positions. He went on to study physiological optics, for which he needed to obtain various measurements of the human eye. He promptly and skilfully designed appropriate equipment to meet his purpose. From a clinical point of view, his most important innovations were the slit-lamp and the great reflex-free stationary indirect ophthalmoscope, both initially presented in 1911. Ophthalmologists now use a slit-lamp several times daily, and the reflex-free indirect ophthalmoscope represents the basis of any fundus camera design. Allvar Gullstrand was not only a brilliant mathematician, but also a strong-willed administrator with an excellent sense of fair play. He therefore heavily influenced not only his own medical faculty, but many others in Sweden. It is revealing to learn that when, in the 1920s, the dormant faculty of medicine in Lund failed to see a need for the talents of one of its scholars, Fritz Ask, it was Gullstrand who coaxed the faculty into making Ask a professor. Gullstrand’s indisputable virtues enabled his contemporaries to disregard his less favourable traits: he had an unsurpassed level of self-esteem, which he made patently obvious, and he was highly interested in nobility and social status, specifically considering himself to rank above almost everybody else. Gullstrand and his contemporaries were keen to further their professional ophthalmological skills and services, and this aim has always been a mainstay of the Society’s activities. Over the years, these have taken several forms, but, initially, the dissemination of ophthalmological information at various local meetings was considered the predominant activity. This included the delivery of presentations on interesting single-patient observations, experiences with new treatment strategies and advances in ophthalmological instrumentation, as well as reports from international conferences. Gullstrand, for example, demonstrated his first slit-lamp as early as 1911, when the optical instrument manufacturer Carl Zeiss simultaneously introduced his design internationally. Furthermore, theoretical lectures were given by physiologists and other basic scientists, such as Hans Gertz, by Gullstrand himself on ophthalmic optics, and by Ragnar Granit on the electrophysiology of vision. Another aspect of the Society’s drive to improve ophthalmological services in Sweden was manifested in the often rather bitter conflict between ophthalmologists and dispensing opticians in the first half of the 20th century. When the Society was formed, the vocational training of opticians was purely practical, in accordance with the long-established system of apprenticeship. The opticians of the time were undoubtedly good at manufacturing spectacles, but they were not subject to examination or any other form of guarantee that they had adequate biomedical knowledge. Trained ophthalmologists were therefore horrified when, at the beginning of the 20th century, dispensing opticians began more or less openly to assert that their abilities equalled those of medical doctors in terms of their skills in handling eye diseases or vision problems. Tensions ran high, no doubt to some extent fuelled by a shortage of job opportunities for ophthalmologists in the 1920s and 1930s. Young ophthalmologists probably felt that opticians were depriving them of their living. In the 1930s, the Ophthalmological Society managed to take some particularly offending dispensing opticians to court – a most unusual step in Sweden – but lost its case! As the Swedish judicial system was clearly unwilling to accept a hard-nosed approach, the Society successfully tried a different strategy: it formed an alliance with a group of concerned and well-trained opticians, who were eager to improve the standard of services provided by Swedish opticians. This helped significantly, but memories of past offences lingered long, and the controversies did not really subside until several decades later. World War II was at least a partial cause for the delay. A system for state certification of opticians was then introduced, and their training raised to a level where it compared favourably with that of medical students and ophthalmologists in general in terms of basic biomedical sciences and selected applied ophthalmic matters. Today, ophthalmologists usually regard state-accredited opticians as respected and welcome partners in the Swedish health care system. In the first half of the 20th century, the Swedish Ophthalmological Society represented a forum for keen debates on how ophthalmological care in the country should best be organized. Some advocated centralization, as in certain neighbouring Nordic countries, whereas others argued that at least one eye clinic should be established in every county (defined in Swedish as ‘län’ or ‘landsting’ in those days), most of which had a few hundred thousand inhabitants. When it was first proposed in around 1920, this suggestion required the number of clinics to be more than doubled, which the centralists regarded as a hopelessly utopian wish, far beyond the resources of the country. When the Swedish Ophthalmological Society was formed, there were about 20 ophthalmologists in the country, most of whom were engaged in private practice (Fig. 6). This figure rose slowly, so that by the middle of the 20th century it was just barely possible to have one ophthalmologist in every county. By contrast, during the second half of the century, the number increased substantially, approximately in pace with the general increase in physicians in Sweden. In 2007 there were almost 800 active ophthalmologists in the country, which had 9.1 million inhabitants at the time. Most received their income from the government, either as employees in public or government-subsidized hospitals, or via the compulsory and comprehensive national social security system introduced in the middle of the 20th century, which requires the patient to pay a nominal fee for each outpatient visit, currently usually about SEK300 (∼ €30), which is used for the cost of all examinations, hospitalizations and surgery fees, the balance of which is covered by monies raised through taxation. Annual membership of the Swedish Ophthalmological Society and its predecessors. The dots show numbers which include retired members. At the beginning of the 20th century, only five public hospitals in Sweden provided an ophthalmological service and all of these were located in large cities. There was one large private hospital in Stockholm and a few smaller ones in different towns in the southern half of the country. By 1940, only insignificant remnants of the private eye hospitals remained and, instead, the number of public county hospitals with ophthalmological wards had increased. They continued to do so, numbering almost 40 around 1970, with the number of ophthalmological hospital beds then reaching slightly over 12 per 100 000 inhabitants. Subsequent developments and improvements in outpatient surgery have resulted in a decrease in the number of beds, which has dropped to slightly below two per 100 000 inhabitants (Thorburn 2008). The number of beds at a clinic is no longer an indicator of its importance, as it was until perhaps 1980–90. As part of an early effort to support the professional standards of its members, in 1923 the Swedish Ophthalmological Society, together with corresponding societies elsewhere in the Nordic countries, launched the journal Acta Ophthalmologica. The journal rapidly became widely read by Nordic ophthalmologists and, for more than half a century, often represented their main source of written ophthalmological information. Originally, Acta was a clearly Nordic journal, but in recent decades it has become increasingly international and its impact has grown. It is now the official journal of not only its founding societies, but also of the European Association for Vision and Eye Research (EVER) (Kivelä 2006). The dramatic evolution of communications and techniques for the dissemination of information in the 20th century, as well as the monumental growth in biomedical knowledge, has forced continual and ongoing change in the ways the Society works to maintain and further the professional skills and services of its members. Originally, vocational training was considered a private matter, and it was therefore the Society, a private organization, that accredited ophthalmologists in Sweden. After World War II, it was increasingly felt that academic education as well as vocational training and certification should be a national public responsibility and the task of accrediting medical specialists was therefore transferred to the Swedish National Board of Health and Welfare in 1961. In line with national legislation that came into effect in 1955, and which was subject to many later revisions, health care employers (mainly local county councils) were also made responsible for providing adequate clinical training for young physicians. The Society strongly supported this in many ways. However, local county councils were reluctant to accept this responsibility and were sluggish to acknowledge the need for continuing medical education (CME), to say the least. One of the consequences of this is that, in Sweden, the only examination currently required for accreditation as a medical specialist is the basic MD. In order to fill the resulting void, in 1989 the Society established a voluntary specialist examination, which is now passed by a steadily increasing number of ophthalmologists, as is the continental general EU specialist examination. For more than two decades, the Society has also supported proposals for a compulsory public system for scoring CME credits, as in the USA and several Western European countries, but this has still not been established. In response to needs that emerged in the last decades of the 20th century for improved training of young ophthalmologists and for CME, the Society has progressively changed the structure of its general meetings from one that was largely scientific to a format that is predominantly tutorial and, since 1997, has offered at least one full day of courses for ophthalmologists in training. Advanced scientific discussions usually work better in smaller groups, satellite meetings or international conferences, which are now much more accessible than they were only a few decades ago. Because public employers failed to provide adequate specialist training and CME in the second half of the 20th century, the medical technology and pharmaceutical industries stepped in to provide courses that were very much wanted and usually of excellent quality, but which at times had unfortunate consequences. For this reason, in 2002 responsibility for specialist training and CME was transferred to a collaborative independent organization, the IPULS (Institutet for Professionell Utveckling av Läkere i Sverige, the Institute for the development of physicians in Sweden), which handles the sometimes-conflicting interests of the various stakeholders involved. For several decades at the end of the 20th century, the Society was heavily engaged in specifying how ophthalmologists should be trained. Because employers were often reluctant to provide adequate training, these plans have successively become more detailed. For similar reasons, the Society has developed a system for inspecting and assessing clinics that train young clinicians (‘SPUR inspections’; SPUR is an acronym for ‘Specialistutbildningsrådet’, the Swedish Specialist Education Council). Ophthalmological science has always been central to the Society. Many of its members have achieved international acclaim and have been the recipients of prestigious awards, such as the Nobel Prize (Allvar Gullstrand and Ragnar Granit), the Proctor Medal (Johan Stjernschantz), the Friedenwald Award (Ernst Bárány and Anders Bill), and the Alcon Research Institute Award (Albert Alm, Anders Bill, Berndt Ehinger, Anders Heijl, Torsten Krakau and Per Wistrand), to name but a few. The implantation of intraocular lenses (IOLs) was tried in a small number of Swedish patients by Bengt Rosengren in Gothenburg in 1953, only about a year after Harold Ridley’s full publication of his technique for this procedure (Ridley 1952). However, the results did not merit further attempts, and it was not until 1977 that IOLs were tried again in Sweden, first by Maurizio Pandolfi in Malmö, who had been encouraged by international developments in the procedure. The introduction of the successful hyaluronan preparation, Healon®, by Pharmacia (Later Pharmacia Ophthalmics, now merged with Pfizer), then a Swedish pharmaceutical company (Pape & Balazs 1980), did much to eliminate postoperative cornea problems, and the results of cataract surgery improved dramatically. The public demand for surgery increased correspondingly, well beyond the level the welfare system could handle. Swedish ophthalmologists responded by switching to outpatient cataract surgery, first introduced in Stockholm by Bo Philipson in 1985 and endorsed by the Swedish Ophthalmological Society as well as the Swedish National Board of Health and Welfare (‘Socialstyrelsen’). Many other surgeons were swift to follow suit. It is easy to regard the improvements made in cataract surgery as among the most significant advances in all of 20th century medicine. The operation is now by far the most common of all elective surgical procedures, which has prompted the development of good quality control systems. Mats Lundström, Ulf Stenevi, William Thorburn and their collaborators have performed internationally pioneering work in this respect, enabling them to establish a national centre for medical quality control systems, EyeNet Sweden. This centre supports quality registries outside ophthalmology (Fig. 7). Number of cataract procedures performed in Sweden during 1980–2007. Data from EyeNet Sweden 2008 (Lundström et al. 2008). In 1885, Frithiof Holmgren, of Uppsala, published his discovery of the electrical signals generated by the retina in response to light. More than half a century later, the development of electronic amplifiers made it possible for Ragnar Granit to take up studies in electrophysiology in Charles Sherrington’s laboratory in England and at the University of Pennsylvania in the USA. In subsequent work with the retina in Helsinki and later in Stockholm, Granit ingeniously managed to explain the electroretinogram (ERG), a feat for which he became a Nobel laureate in 1967. He was gifted with both scientific and social talents, and his many students regarded him as an erudite, eloquent and benevolent master. His work began when the development of electronic amplifiers was in its infancy, and he himself had built his first while in the UK and the USA, naming one of them ‘The Child’s Ass’ because, he said, ‘You never know what and when it [will] deliver’ (Enroth-Cugell 2001). The ERG was initially developed as a purely experimental tool with the aim of furthering understanding of the normal function of the retina. However, Gösta Karpe in Stockholm used the insights generated by Granit to develop clinical ERG. Both scientists worked at the Karolinska Institute, but they did not directly collaborate (Fig. 8). Karpe devised a method for clinically recording ERG a- and b-waves using silver–silver chloride electrodes in a corneal contact lens, and it is widely acknowledged that he, along with many of his students and colleagues, was thus responsible for introducing ERG into clinical routine work. Sven Erik Nilsson continued this research, first in Stockholm and later in Linköping. He showed the a-wave to probably originate in the photoreceptors and subsequently introduced analyses using technically demanding DC amplification systems, thereby making it feasible to study the slower elements of the ERG, predominantly the c-wave and standing potential. Nilsson and his collaborators were able to verify that these responses originate in the retinal pigment epithelium. Modern ERG recordings are widely used for studying tapetoretinal degenerations. Left to right: Gösta Karpe, Ragnar Granit, Jules Francois and Sven Erik Nilsson at the International Society for Clinical Electrophysiology of Vision (ISCEV) Symposium, Stockholm, 1984. (Photograph loaned by Sven Erik Nilsson). In 1887, Erik Nordenson, one of the four founding fathers of the Society, gave an excellent description of the microscopic anatomy of retinal detachment. He worked in Theodore Leber’s department in Göttingen (Germany) and later ran a very successful private ophthalmology hospital in Stockholm from 1895 to about 1915. However, Nordenson did not develop his work on retinal detachment pathology into any effective clinical treatment strategy. Albin Dalén studied intraocular inflammations and described the epitheloid cell accumulations in sympathetic ophthalmia, now known as Dalén–Fuchs noduli (Dalén 1904). Von Hippel–Lindau syndrome was named after a Swedish general pathologist, Arvid Lindau, who convincingly showed it to be a clinical entity (Lindau 1926). Ocular pathology differs significantly from general pathology and has therefore become a discipline in its own right. In 1960, Erik Kock pioneered a Swedish ocular pathology laboratory in Stockholm, which, since 1995, has been run by Stefan Seregard. This renowned unit has largely focused on clinical ophthalmic pathology, including ocular tumours. Basic neurobiological science developed very rapidly in the second half of the 20th century and several Swedish ophthalmologists began their academic careers as neurobiologists. Sven Erik Nilsson began with electron microscopy and electrophysiology of photoreceptors, and continued with clinical electrophysiological signals related to the function of the pigment epithelium, as already described. He also studied the phagocytic activity of this tissue. Johan Sjöstrand worked in an anatomy department and studied the axonal transport of important amino acids in peripheral nerves and the optic nerve, before moving on to the study of contrast sensitivity and other psychophysical parameters of vision. Ulf Stenevi began by writing a doctoral thesis on the plasticity of brain neurons before becoming an ophthalmologist, successfully specializing in anterior eye segment surgery. In Lund, I (Berndt Ehinger) ran a basic neurobiology laboratory for more than 35 years until 2005, with the original aim of identifying the neurotransmitters of different retinal neurons and their synaptic contacts. These studies led to the discovery of a multitude of different neurotransmitters and neuromodulators in seemingly similar retinal neurons, and established that the dopaminergic interplexiform cells represent a particular type of intraretinal feedback neuron. Subsequently, this work was extended to studies on the pathobiology of degenerating retinal cells and on methods to treat degenerative retinal diseases, with some success in experimental animals. Many prominent scientists were involved, including John E. Dowling at Harvard University and Theo van Veen in Gothenburg and Lund. The work generated well over 25 doctoral dissertations and, in his history of the Medical Faculty of the University of Lund, Håkan Westling (referring to the last decades of the 20th century) noted that ‘no doubt, the ophthalmological discipline in Lund/Malmö must be regarded as the foremost in the country’ (Westling 2003). Beginning with clinical electrophysiology in 1985 and continuing with DNA-based genetic analyses, Sten Andréasson has established a nationally and internationally recognized centre in Lund for clinical studies on tapetoretinal degenerations. Diabetic retinopathy became a significant clinical problem in the middle of the 20th century when diabetes patients began to survive for decades. Nationally, photocoagulation was verified as effective in the 1970s and 1980s by Birgitta Zetterström-Karpe, Ragnar Törnquist and StaffanStenkula. More recently, Elisabet and Carl-David Agardh have shown that good clinical management can reduce diabetes complications, meeting, and in some respects even surpassing, the goals of the St Vincent Declaration of 1989. Based on studies on phagocytosis mechanisms in the retinal pigment epithelium and a small but well conducted clinical study, Sven Erik Nilsson and Christina Frennesson have argued since around 1998 that modest laser treatment of retinal drusen should be tried for preventing age-related macular degeneration. This idea is currently under investigation in large international clinical trials. More recently, international studies showed anti-VEGF treatment of the disease to be extremely successful. This strategy has now been widely introduced in Sweden, where Birgitta Bauer is one of its foremost proponents and teachers. Its development has been extremely rapid and further improvements in treatment are likely. Retinal detachment was an almost incurable blinding disease until Jules Gonin of Lausanne presented a reasonably successful treatment strategy in the 1920s. In 1932, Sven Larsson (Fig. 9) pioneered scarring of the choroid and retina with electrodiathermy in Sweden, thereby making himself the most renowned Swedish retina surgeon of the time. Slightly later, Bengt Rosengren (Fig. 10) introduced the practice of injecting air into the vitreous in order to push the retina towards the choroid, as well as scleral buckling procedures, but World War II delayed international publication and acceptance of his results (Rosengren 1966). Later, Ragnar Törnquist (Fig. 11), a brilliant surgeon and health care administrator who headed his department at Örebro during 1961–1983, turned his previously insignificant county hospital clinic into a national centre for vitreoretinal surgery. He achieved this by monitoring international developments in the field and systematically assessing and publishing his own and his collaborators’ results. This may seem simple, but it is, in reality, tough work, requiring an open and bold outlook, keen judgement and huge organizational talent. Contemporary university departments failed in these respects and lagged behind. Sven Larsson. Bengt Rosengren. Ragnar Törnquist. Around 1929, Henrik Sjögren, of Stockholm, began to investigate patients with dry and irritated eyes, collecting a total of 19 cases for his 1933 thesis on keratoconjunctivitis sicca (Fig. 12). However, at the time his work was regarded only marginally acceptable as a thesis and, a few years later, Sjögren left Stockholm for clinical work in the county public hospital of Jönköping, where he continued to publish observations on the disease. Today, over 75 years later, his accomplishments are regarded as pioneering and it is in retrospect hard to understand why his thesis was not well received. It contains good descriptions of the clinical course of the disease, of the histopathology of the exocrine glands involved, and of its relation to rheumatoid inflammatory disease. Sjögren worked at Sabbatsberg Eye Clinic, a comparatively small clinic in Stockholm, and academic arrogance and competition from ophthalmologists at the dominating Serafimerlasarettet facility may have influenced the contemporary evaluation of his thesis. Sjögren’s demonstration of the relationship between the main clinical components of the syndrome had previously, but much less convincingly, been noted by Henri Gougerot in 1926, which may also have been a detracting factor. Sjögren himself appears never to have commented on the inadequate assessment of his thesis. He is the only Swedish ophthalmologist whose name is used as an internationally accepted eponym (Sjögren syndrome). Henrik Sjögren. (Photograph by Per Weimersson, 1958). From around 1949 to 1977, Ernst Bárány (Fig. 13), professor of pharmacology in Uppsala, carried out brilliant and internationally acclaimed studies on intraocular pressure (IOP) and the production of aqueous humour in the ciliary processes and its circulation in the anterior parts of the eye. His administrative, general scientific and social talents were equally outstanding, and he worked with many internationally known scientists and students. One of them was Per Wistrand (Fig. 14), who demonstrated the enzyme carbanhydrase in the ciliary epithelium and showed that it can be inhibited with, for example, acetazolamide. This knowledge is now widely used in the treatment of glaucoma. Another was Anders Bill (Fig. 15), who, with unprecedented precision, measured regional blood flow in ocular tissues and examined its regulation. He also analysed the circulation of aqueous humour in the eye, discovering the uveoscleral flow (Bill 1985). Two of Anders Bill’s students and collaborators, Albert Alm (Fig. 16) and Johan Stjernschantz (Fig. 17), developed prostanoids as IOP reducers, based on Laszlo Bito’s original observations in the 1970s and 1980s, and collaborated with a pharmaceutical company in Uppsala (Pharmacia). Albert Alm performed seminal clinical work and Johan Stjernschantz developed latanoprost together with chemist Bahram Resul (Bito 2001; Stjernschantz 2001). The result was a drug with an entirely new mode of action and enormous clinical success (Xalatan®, introduced in 1996; Pharmacia Ophthalamics, now Pfizer, then in Uppsala, Sweden). Ernst Bárány. Per Wistrand. Anders Bill. Albert Alm. Johan Stjernschantz. In Lund, C. E. Torsten Krakau (Fig. 18) began clinical glaucoma studies at the end of the 1960s. Together with a number of students, he verified the claim of Erik Linnér (another of Ernst Bárány’s internationally acclaimed students) that increased IOP is not necessarily a cause for the clinical disease (Lundberg et al. 1987). At the time, it was still not possible to exclude the possibility that increased IOP in glaucoma was merely an epiphenomenon caused by some unknown common factor. As an accomplished designer of scientific equipment, Torsten Krakau and his student, Anders Heijl (Fig. 19), devised a pioneering computerized static perimeter in the 1970s. It offered much improved standards for glaucoma diagnosis and is now regarded as an ophthalmological classic (Ritch & Caronia 2000). Along with students and collaborators at Malmö University Hospital, Heijl went on to study the pathophysiology of glaucoma and, using advanced vision psychophysics, developed significantly improved clinical interpretation tools and data-gathering systems for the disease, particularly computerized perimetry. This enabled him to carry out much-needed longterm clinical glaucoma studies in large cohorts. Thanks to these and other international studies, it is now firmly established that increased IOP is indeed one of the factors that cause glaucoma to progress. The basic pathobiology of the disease is still not well understood, but this work has taken us a long way in the right direction. Torsten Krakau. Anders Heijl. My co-editors of the centennial volume of the Swedish Ophthalmological Society (Klas Göran Brege, Ulf Havelius, Peder Jahnberg, Mats Lundström, William Thorburn and Olof Wennhall) were a marvellous group and it was delight to produce a book using the facts and text they procured. They have kindly commented and improved on this presentation, as have a large number of gracious colleagues and friends, of whom there are too many to list here, although all are fondly remembered.

The present study examined the emergence of structural remodeling in explanted neonatal rat retina. Immunohistochemical analysis demonstrated signs of glial and neuronal remodeling after 11 days in vitro and included the activation of Müller cells, the formation of ectopic neuropil areas and sprouting of photoreceptor terminals. We also observed that cholinergic and GABA-ergic amacrine cells displayed signs of disorganized laminations. These results demonstrate that retinal culturing initiates structural changes that show morphological similarities to glial and neuronal remodeling identified in retinitis pigmentosa retinas and experimentally detached retinas.

Retinas from rabbit, goldfish and guinea-pig were exposed to (3H) GABA, (3H)-muscimol, (3H)-nipecotic acid and (3H)-isoguvacine either by intravitreal injectionin vivo or by incubations in a balanced salt solution and the distribution of radioactivity was then studied with autoradiography. All substances labelled a similar set of presumed amacrine cells. Incubating at 0 °C, in 10−5 M ouabain, or in 10−3 M GABA inhibited the labelling by (3H)-muscimol whereas bicuculline (10−4 M), and glycine (10−3 M) were less efficient blockers. The result is interpreted as a neuronal uptake of (3H)-muscimol rather than as a GABA receptor binding. All the substances except (3H)-isoguvacine also labelled glia to such a degree that neuronal labelling was often disguised in rabbits and goldfish. Glial labelling by muscimol was less pronounced in guinea-pig. (3H)-isoguvacine (tested only in rabbits) gave a strong labelling of cells with the distribution of GABA neurons and only little glial labelling.

Although many effects of gamma-aminobutyric acid (GABA) on retinal function have been attributed to GABA(A) and GABA(C) receptors, specific retinal functions have also been shown to be mediated by GABA(B) receptors, including facilitation of light-evoked acetylcholine release from the rabbit retina (Neal and Cunningham [1995] J. Physiol. 482:363-372). To explain the results of a rich set of experiments, Neal and Cunningham proposed a model for this facilitation. In this model, GABA(B) receptor-mediated inhibition of glycinergic cells would reduce their own inhibition of cholinergic cells. In turn, muscarinic input from the latter to the glycinergic cells would complete a negative-feedback circuitry. In this study, we have used immunohistochemical techniques to test elements of this model. We report that glycinergic amacrine cells are GABA(B) receptor negative. In contrast, our data reveal the localization of GABA(B) receptors on cholinergic/GABAergic starburst amacrine cells. High-resolution localization of GABA(B) receptors on starburst amacrine cells shows that they are discretely localized to a limited population of its varicosities, the majority of likely synaptic-release sites being devoid of detectable levels of GABA(B) receptors. Finally, we identify a glycinergic cell that is a potential muscarinic receptor-bearing target of GABA(B)-modulated acetylcholine release. This target is the DAPI-3 cell. We propose, based on these data, a modification of the Neal and Cunningham model in which GABA(B) receptors are on starburst, not glycinergic amacrine cells.

BACKGROUND:Optic nerve transection results in degeneration of axotomized retinal ganglion cells followed by the activation of resident microglial cells.METHODS:An organotypic culture of neonatal rat retina was used to examine the temporal aspect of retinal ganglion cell death and microglial cell recruitment. Retinas were fixed at various times after explantation and prepared for immunohistochemistry and lectin staining.RESULTS:Terminal deoxytransferase dUTP nick-end labeling (TUNEL) and immunohistochemistry for cleaved caspase-3 demonstrated a massive cascade of cell death in the ganglion cell layer (GCL) within hours after explantation. The rate of cell death in this layer was high and continued over a period of 48 h. In contrast, the rate of cell death was low in the outer nuclear layer (ONL) and apoptotic cells were evident after 6 days in vitro. Increases in the density of microglial cells in the GCL appeared to be recruited by proliferation within hours after explantation. In parallel, resident microglial cells also acquired an activated morphology as revealed by isolectin B(4) staining. Microglial cell activation in the GCL also included an upregulated expression for the lysosomal protein ED-1 and the cysteine protease inhibitor cystatin C. After 1 week of culture, immunolabeling for ED-1 demonstrated the presence of activated microglial cells also in the ONL.CONCLUSION:These data show rapid microglial cell recruitment and activation following the axotomy-induced cell death of differentiated ganglion cells. The processes of microglial cell activation and cell death are slower in the outer retina.

GABA immunoreactivity was studied and compared with GAD immunoreactivity in the retinae of baboon, cynomolgus monkey and man. The central and peripheral parts of the retinae were investigated separately in cynomolgus monkey and in man. The same kinds of structures were stained with both antisera. Cells with a position corresponding to amacrine cells were stained, as well as processes in the inner plexiform layer and some cells in the ganglion cell layer. The outer plexiform layer and some cells with the position and configuration of horizontal cells also appeared immunoreactive. Staining was also observed in bipolar-like cells, in man most clearly when using the GABA antiserum in sections from the central parts of the retina. It is possible that horizontal cells, as well as bipolar-like cells, may play a previously unsuspected role in GABAergic transmission in the primate retina.

PURPOSE:Cystatin C is a mammalian cysteine protease inhibitor. This study describes the localization of cystatin C in the anterior segment of normal rat and mouse eyes. Cysteine proteases play an important role in protein degradation (e.g. of photoreceptor outer segments in the retinal pigment epithelium) and the balance between these proteases and their specific inhibitors is therefore of great interest.METHODS:Cells containing cystatin C were identified by immunohistochemistry and quantified by ELISA. Messenger RNA levels were analysed by quantitative real-time polymerase chain reaction.RESULTS:Cystatin C is present at biologically significant levels in the corneal epithelium, endothelium and stromal keratinocytes, lens epithelium, epithelial cells in the ciliary processes, aqueous humour and iris stromal cells. In the rat anterior segment, the highest cystatin C concentrations were found in the ciliary epithelium.CONCLUSIONS:Cystatin C is present in several cell types and is probably locally produced. The inhibitor is likely to be an important regulator of cysteine proteases in the retinal pigment epithelium, ciliary epithelium, aqueous humour, lens epithelium and in the corneal endothelium and epithelium.

BACKGROUND:As a secreted protein, cystatin C is assumed to play its role in the extracellular compartment, where it can inhibit virtually all cysteine proteases of families C1 (cathepsin B, L, S) and C13 (mammalian legumain-related proteases). Since many of its potential target enzymes in the eye reside in intracellular compartments, we sought evidence for a cellular uptake of the inhibitor in ocular tissues.METHODS:Fluorescence-labeled human cystatin C was injected intravitreally into normal rat eyes. Ocular tissues were subsequently examined using ELISA, fluorescence microscopy, and immunohistochemistry. Cystatin C uptake was additionally studied in an in vitro retina model.RESULTS:Cystatin C administered intravitreally in vivo is taken up into cells of the corneal endothelium and epithelium, the epithelial cells lining the ciliary processes, and into cells in the neuroretina (mostly ganglion cells) and the retinal pigment epithelium. The uptake is demonstrable also in vitro and was, in the neuroretina, found to be a high-affinity system, inhibited by cooling the specimens or by adding the microfilament polymerization inhibitor, cytochalasin D, to the medium.CONCLUSIONS:There is an active, temperature-dependent uptake system for cystatin C into several cell types in the cornea, ciliary body, and retina. The cell types that take up cystatin C are generally the same that contain endogenous cystatin C, suggesting that much or all cystatin C seen intracellularly in the normal eye may have been taken up from the surrounding extracellular space. The uptake indicates that the inhibitor may exert biological functions in intracellular compartments. It is also possible that this uptake system may regulate the extracellular levels of cystatin C in the eye.

Neurons displaying somatostatin or vasoactive intestinal polypeptide (VIP) immunoreactivity were detected among the amacrine cells in the retina of baboon, cynomolgus monkey, squirrel monkey, cow, pig, cat, rabbit, guinea-pig, rat, mouse, frog and goldfish. Generally, immunoreactive cell bodies were located in the inner nuclear layer with processes ramifying in three more or less well-defined sublayers in the inner plexiform layer. The density of the sublayers and their location varied with the peptide and species investigated. In most cases there was a sublayer in the outermost part (Ramon y Cajal's sublamina 1) of the inner plexiform layer and this sublayer was usually the best developed. In some species a few somatostatin fibres were also detected in the outer plexiform layer, suggesting that some interplexiform cells contain somatostatin. In the baboon VIP was found exclusively in interstitial amacrine cells which have their cell bodies and processes entirely within the inner plexiform layer.