| Chapter 41 The History of Glaucoma PETER C. KRONFELD Table Of Contents |
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400 BC TO 1600 AD 1600 TO 1854 1854 TO THE PRESENT REFERENCES |
| The history of the diseases categorized today under the term “glaucoma” may be divided into three major periods. The first is the early period from approximately 400 BC to approximately 1600 AD; during this time, “glaucoma” was used to refer to a general group of blinding ocular diseases without the distinctions that historians now can recognize. During the middle period from the beginning of the 17th century to the middle of the 19th century the cardinal signs of glaucoma, singly and in combination, began to emerge clearly in published texts. The third period extends from the time of the introduction of the ophthalmoscope (1854) to the present. |
| 400 BC TO 1600 AD |
| As a diagnosis by physicians, glaucoma is first mentioned in Hippocrates' Aphorisms; thereafter the term appears in most early medical texts, but with only the smallest bits of information regarding the types of diseases thus diagnosed. All that can safely be deduced from the writings of the early period is that the term was applied to afflictions of the elderly in which some abnormality (probably a change in color) could be recognized in the pupillary area; attacks of severe pain due to overdistention of the ocular coats could be associated with this change. The inevitable outcome was total blindness. |
| 1600 TO 1854 |
| Glaucoma in the adult or elderly patient became more distinct with the
emergence of four characteristics: (1) the consistent failure of cataract
operations to improve vision, (2) the clinical appearance of eyes
in terminal stages of the disease, (3) a specific history indicating self-limited
forerunners of the severe disease, and (4) the elevated intraocular
pressure. The anatomic site of cataracts was not clearly established until the anatomic findings of Brisseau (1707) and the introduction of the process of lens extraction by Daviel (1752). This led to a search for the site of glaucoma in other structures of the eye and to concentration on clinical signs that could be helpful in distinguishing between cataract and glaucoma. Since a majority of the eyes in which the diagnosis of glaucoma was made in the 18th century were in an advanced stage of visual loss and iris atrophy after one or several acute attacks or after a prolonged chronic course, the clinical picture was dominated by congestion (varicosities) of the anterior ciliary veins, a dilated, poorly reacting pupil, and a varying degree of nuclear lens opacity. On examination with the light sources of that period, a greenish reflex could often be obtained; since this seemed to point to the real location of the disease, it became a prominent sign listed in the literature of the 181h and early 191h centuries. The fact that the clinical features of advanced glaucoma were occasionally preceded by attacks of blurred vision that recurred with a high degree of uniformity was first recorded in St. Yves' “Treatise of the Diseases of the Eyes” (1741) and was described in more detail by Weller (1826). Elevation of the intraocular pressure as a distinct sign of ocular disease, recognizable by undue resistance of the eyeball to indentation by the physician's finger, was first clearly mentioned in the “Breviary” of the itinerant English oculist Banister (1626). In 1738 an equally clear reference to hardness of the eye appeared in the independent writings of Johann Platner, professor of anatomy, surgery, and therapeutics at the University of Leipzig. As a distinct clinical symptom, hardness of the eyeball was apparently generally known and accepted in the 1820s, as one may judge from the almost simultaneous but independent texts by Demours of France ( 1818 ), Guthrie of England ( 1823 ), and Weller of Germany ( 1826 ). Between 1830 and 1854 William Mackenzie (1) exerted a great influence on European and American ophthalmology through his personal teaching and through his textbook. He distinguished between acute and chronic glaucoma and gave a detailed description of the course of the latter from a stage 1 characterized just by a greenish hue reflected from the pupil to a stage 6 in which the eyeball, after perforation of a corneal ulcer in absolute glaucoma, has become atrophic. Mackenzie was well aware of the abnormal hardness of the glaucomatous eye from the second stage on; also, he apparently was the first to recommend a form of posterior sclerotomy to relieve the abnormal hardness. For a more detailed review of the second period one may refer to the introduction to the section Glaucoma and Hypotony in Duke-Elder's System of Ophthalmology (2). |
| 1854 TO THE PRESENT | ||||||||||||||||||||||||||||||||||||||||||||||
| Eduard Jaeger, the son and grandson of distinguished Austrian ophthalmologists, was
the first investigator to place a description and a picture
of the ophthalmoscopic appearance of the glaucomatous disc in the literature. He
was misled by the relative depth clues provided by monocular
indirect ophthalmoscopy and described (and depicted) the glaucomatous
disc as a swelling of the papillary tissues with respect to the surrounding
retina (3). Just a few months later, Albrecht von Graefe also placed himself on record as having observed a prominence of the papilla in glaucoma (4). His original description of the glaucomatous disc included a detailed account of the phenomenon of pulsation of the retinal arteries in the glaucomatous eye; this phenomenon became a reliable and, at the time, clinically useful indicator of elevated intraocular pressure. The ring-shaped zone around the “swollen” disc was officially named “halo glaucomatosus.” The matter of the apparently swollen disc was cleared up by observations in von Graefe's clinic. In a rabbit with a congenital fundus anomaly, ie, a coloboma of uvea and of optic nerve, different examiners could not agree from ophthalmoscopic examinations whether certain parts of the eyeground were elevated or depressed. The anatomic examination revealed tissue defects, ie, depressions. This prompted an analysis of the optics of monocular indirect ophthalmoscopy by Adolf Weber (5), one of von Graefe's assistants, who in his later life made significant contributions to the understanding of the mechanism of glaucoma. His analysis of monocular indirect ophthalmoscopy revealed several factors, partly optic and partly perceptual, that could cause misinterpretations of relative depth in the fundus. The corrected ophthalmoscopic observation of a depression of the disc was promptly confirmed by pathologic findings and was interpreted as the effect of elevated pressure, ie, as “pressure excavation.” This had a profound effect on von Graefe's thinking and made him examine all known symptoms of glaucoma in the light of their possible relationship to elevated pressure. This analysis led him to regard the elevation of intraocular pressure not as just a symptom but as the “essence” of glaucoma. THE GLAUCOMAS AT VON GRAEFE'S CLINIC One type of glaucoma seen at von Graefe's clinic was the acute or inflammatory glaucoma which in 70% of the cases began with self-limited prodromal attacks of misty vision with the patient seeing rainbows around candle flames. The attacks increased in length, severity, and frequency until the real disease suddenly erupted in the form of an acute attack of inflammation and severe reduction of vision. Temporary remission with some recovery of vision could occur spontaneously or in response to treatment consisting of antiphlogistics, opiates in large doses, and paracentesis. During the remissions the affected eye lent itself to more penetrating examination than was possible at the height of the attack. From close observation of all phases of the disease, von Graefe arrived at the concept that acute glaucoma was a choroiditis or an iridochoroiditis with diffuse impregnation of vitreous and aqueous with exudative material which caused the rise in pressure through an increase in volume. The second type of glaucoma seen was the chronic glaucoma in which the prodromal attacks, without any signs of congestion, swelling, or irritation, gradually lengthened and finally fused into a chronic state of dilatation of the anterior ciliary veins, shallowness of the anterior chamber, atrophy of the iris, reduction in vision, glaucomatous cupping, and arterial pulsation in the fundus. For the third type of case in which the anterior segment remained normal and only the excavation of the optic nerve paralleled the gradual deterioration of vision, von Graefe (6) coined and for several years used the term “amaurosis with excavation of the optic nerve,” placing it outside the group of glaucomatous diseases. To complete his classification of glaucomas, von Graefe used the designation “glaucomatous diseases” for disorders or diseases which secondarily lapse into glaucomatous states and which thereby may result in blindness; only in his last communication (1869) did he introduce the terms “primary glaucoma” and “secondary glaucoma.” In 1861, von Graefe (7) declared that the exclusion of the amaurosis with optic nerve excavation from the glaucomas was an error of his, the correction of which he credited to his friend Donders of Utrecht, who had found the palpable tension in many of the eyes with so-called amaurosis with optic nerve excavation to be perceptibly above normal. Donders suggested the name “glaucoma simplex,” meaning the typical glaucoma without complications. For the glaucomas with other manifestations, particularly in the anterior segment, Donders proposed the term “glaucoma with ophthalmia.” He attributed the common cause of all glaucomas, ie, the elevated pressure, to hypersecretion of intraocular fluid due to irritation of secretory nerves. Von Graefe had also recognized slight degrees of ocular hypertension in some of his cases of amaurosis with optic nerve excavation. He therefore accepted Donders' term “glaucoma simplex” for that entire group; of course, he was unable to foresee that posterity (at first Schnabel [8]) would reinstate his amaurosis with optic nerve excavation, implying that it was an optic nerve disease unrelated to elevated intraocular pressure. Von Graefe held on to the concept of some form of inflammation as the primary cause of the rise in pressure and to “inflammatory” as a designation for the glaucomas that showed signs of inflammation connected with the rise in pressure. The term “inflammatory” was retained by some schools of ophthalmology until the clinical discovery of the angle-closure mechanism in the 20th century; there were early dissenters who suggested alternate terms, such as “irritative” (de Wecker [9]), “congestive” (Hansen-Grut), and, much later, “uncompensated” (Elschnig). In the literature of Great Britain the preferred terms were “acute,” “subacute,” and “chronic” glaucoma. GLAUCOMATOUS OPTIC NERVE DISEASE The anatomic counterpart to the ophthalmoscopically observed depression of the disc was first described by the German anatomist Heinrich Mueller in the late 1850s (10) and was interpreted as having been produced by abnormally increased vitreous pressure acting upon the lamina and forcing it to recede. To account for the atrophy of optic nerve fibers, Mueller and his followers assumed that the receding lamina had taken the entire papilla with it, placing the nerve fibers on a steadily increasing stretch or pressing them against the sharp edge of the excavation. When subsequent pathologic studies confirmed the displacement of the lamina in some glaucomatous eyes but not in others, the assumption of preexistent physiologic differences in the laminar resistance to pressure was added to the basic pressure hypothesis. In this form the concept gained wide acceptance, but doubts about its general applicability were voiced early and gradually built up as new ophthalmoscopic and pathologic facets of glaucoma were revealed. In the 1890s an eloquent champion for an alternate theory emerged in the person of the Austrian ophthalmologist Isidor Schnabel (1842-1908) (8), who was the first to describe in detail the nerve fiber breakdown with the formation of cavities as a characteristic of the glaucomatous process in the optic nerve. In Schnabel's pathologic material this cavernous atrophy appeared to be the earliest sign; in some eyes, for a long time this was the only glaucomatous change. In later stages the atrophy affected all portions of the optic nerve up to the entrance of the central vessels. Schnabel interpreted retroplacement of the lamina as its dropping or sinking into large retrolaminar caverns. In his opinion, cavernous atrophy was the glaucomatous atrophy. From its histologic characteristics and its initial selectiveness, ie, not involving the supporting elements of the nerve, Schnabel saw the mechanism of the glaucomatous optic nerve disease in a process of imbibition of pathologic fluid from the vitreous by the nerve fibers, a process independent of the intraocular pressure. Schnabel's findings were partly confirmed and partly refuted by subsequent investigators. Differences in material and technology account for most of the divergence of opinions. One other view regarding the nature of the glaucomatous optic nerve disease was voiced early (Priestley Smith [11 ] ): The truth of the matter appears to be that the glaucomatous cup is not a purely mechanical result of exalted pressure, but is in part at least, an atrophic condition which, though primarily due to pressure, includes vascular changes and impaired nutrition in the area of the disc and around its margin which require a considerable time for their full development. The notion that the rise in pressure may cause damage to the tissues of the disc through its influence on blood circulation can be traced from Priestley Smith's original wording to the present. MECHANISM OF OCULAR HYPERTENSION The elevation of the intraocular pressure, recognized in the mid-1850s as the essence of glaucoma, was attributed to excessive formation of intraocular fluid or “hypersecretion,” the cause of which was assumed to be either a form of choroiditis (von Graefe) or a secretory neurosis (Donders). Basic science at the time did not provide a clear concept of the mechanisms involved in the buildup of pressure within the eye. The systematic experimental study of the fluid exchange of the eye began with the work of the German anatomist Schwalbe in the 1860s. Searching for lymphatics in the anterior segment of the eye, Schwalbe (12) made the observation that when certain dyes are injected into the anterior chamber in aqueous solution or suspension, they promptly appear in veins on the surface of the globe. He concluded that the anterior chamber was a lymphatic space in open communication with anterior ciliary veins. His view was contested by Theodor Leber (13 ), whose dye injections into the anterior chamber of the eye of a rabbit indicated a discriminating border structure. This stimulated a number of anatomic studies of the structures of the chamber angle in animals and in man by Schwalbe and others and further anterior chamber cannulation studies by Leber and his co-workers. Thus Leber discovered the normal outflow from the fresh enucleated mammalian eye, which he interpreted as filtration through the trabecular meshwork and as flow from there into anterior ciliary veins as well as vortex veins. The rate of outflow was, in principle, proportional to the perfusion pressure, except during an initial period, when the perfusion fluid took up the space occupied in the living eye by blood. Leber actually determined filtration coefficients, the forerunners of today's coefficients of aqueous outflow. Since this outflow was from fresh enucleated eyes at the pressures prevailing in the living eye, Leber reasoned that the same process of outflow must also take place in the normal living eye. To maintain a stable in vivo pressure, the steady loss of fluid must be compensated for by steady formation of an equal amount of fluid, which Leber believed could also take place through a process of filtration. Thus, the filtration theory of aqueous formation and elimination was born. In a few human eyes enucleated in far-advanced stages of glaucoma, Leber found very low filtration coefficients which indicated abnormal resistance to aqueous outflow (14). This finding fitted in well with the first detailed pathologic report on the condition of the chamber angle in far-advanced glaucoma (15): “The most important finding in genuine glaucoma is the circular adhesion of the iris periphery to the periphery of the cornea or the obliteration of the space of Fontana.”* *Although Kieser of Göttingen had clearly shown in 1804 that the spaces described by Fontana in the eyes of herbivores did not exist in man, the term “Fontana's space” was still used in the 1870s and 1880s for the intertrabecular spaces of the human corneoscleral meshwork. Only the detailed studies of the region begun by Schwalbe in 1870 and continued by others made the term “Fontana's space” clearly inapplicable to the human eye. It was realized almost immediately that the peripheral anterior synechiae could be either the cause or the effect of glaucoma. In either case glaucoma could result from an inflammatory or an obstructive process within the angle or from pressure from behind. Pathologic specimens which supported these mechanisms were identified and reported. The theory that glaucoma was principally a disorder of aqueous outflow (referred to generally as the Leber-Knies theory) rapidly gained ground. The gist of Leber's filtration theory, ie, that there is a steady bulk flow of fluid through the anterior segment and out of the eye,† has stood the test of time. In the 1920s Erich Seidel, Leber's most prominent pupil, made the necessary additions of including the effects of the colloidosmotic pressure of the plasma proteins and of active transfer processes in the formation of aqueous (16). † The idea, without experimental proof, of a steady directional circulation of fluid through the chambers of the eye had been expressed by earlier observers, specifically William Porterfield, more than 100 years before Leber. EMERGENCE OF TWO MECHANISMS OF GLAUCOMA In the clinical material of the period the acute and the chronic inflammatory glaucomas composed approximately two thirds of the total; thus, the characteristics of today's angle-closure glaucoma were dominant in the observations and in the thinking of the 1880s and 1890s. A striking example were Priestley Smith's measurements of the horizontal corneal diameter, which yielded an average of 11.6 mm for normal eyes and 11.2 mm for eyes affected with primary glaucoma (17). This clearly expresses the predominance of the angle-closure glaucomas in the glaucoma populations of the period. (It stands to reason that the open-angle glaucomas, because of their mainly “silent,” insidious course, were not properly represented in the clinical populations of the period. ) In 1888 Priestley Smith introduced the concept of a predisposition to glaucoma, which consists in progressive narrowing of the circumlental space with age, due to the steady growth of the lens in eyes with small corneas. In the presence of these anatomic conditions, the ciliary processes in states of hyperemia are crowded forward, pressing the iris against the anterior angle wall. This concept was, to some extent, based on Smith's findings in the experimental animal that a small excess of pressure in the vitreous chamber (as little as 4 mm Hg) makes the lens and the suspensory ligament advance in such a manner as to close the angle of the anterior chamber. Further light was shed on the mechanism of the acute glaucomas by the discovery of the shallowness of the anterior chamber in the mates of eyes with acute inflammatory glaucoma (18). If the pupil dilates in an eye with shallow anterior chamber, the iris, particularly with its thicker portion, can occlude the filtration angle and, thereby, raise the intraocular pressure …. If contraction of the sphincter frees the filtration space, the event remains a prodromal attack. At a certain level of intraocular pressure the ocular veins are compressed at their place of entry into the sclera; venous stasis develops with increased transudation; that, and not inflammation, is the true nature of glaucoma [18]. The next major step came in 1920 when Curran (19) of Kansas City and Seidel (16) of Heidelberg, on the basis of astute clinical observations, independently announced the concept of the relative pupillary block. Here is Curran's wording (19): Normally the aqueous passes through the pupil from the posterior to the anterior chamber, but it is here [in Curran's paper] contended that in glaucoma this passage is impeded on account of the iris hugging the lens over too great a surface extent. Some of the aqueous gets through while some passes back, forcing the lens and the iris still more forward. Although gonioscopy as a clinical method of examination was first explored by Trantas in 1907 and was elaborated by Salzmann (1915-1916), Koeppe (1919-1920), and Troncoso (1925-1930), it was not until the late 1930s that the recognition of all phases of the angle-closure mechanism in the living eye became a clinical reality. Credit for this momentous step goes to Otto Barkan (1887-1958), who made gonioscopy a routine diagnostic method in the ophthalmologist's office, thereby bringing about the separation of the glaucomas due to the angle-closure mechanism from the open-angle glaucomas (20). The recognition of a type or types of glaucoma without obstruction of the angle by the iris came slowly; since these eyes characteristically remained free of congestion, inflammation, or pain, anatomic specimens were scarce. Not until the 1890s did open-angle glaucoma become well proved and accepted. Theories regarding its mechanism emerged slowly; they attributed the elevation of the intraocular pressure to abnormal resistance to aqueous outflow caused by anatomic or functional changes within the outflow channels. SECONDARY GLAUCOMAS As the glaucomas without perceptible antecedents became more sharply defined in the 1860s and 1870s, types of secondary glaucoma were identified rapidly. In the first edition of the Graefe-Saemisch Handbook of Ophthalmology (1877), Saemisch lists the following ocular diseases as frequently giving rise to secondary glaucoma: cicatricial ectasias of the cornea, circular or total adhesions of the iris to the lens, iritis serosa, traumatic cataract, dislocations of the lens, intraocular tumors, hemorrhagic retinal processes (referring mainly, if not exclusively, to occlusions of the central retinal vein), and sclerectasia posterias (which probably referred to glaucoma in eyes with malignant myopia). Congenital hydrophthalmos was at the time also classified with the secondary glaucomas. TONOMETRY Digital estimation of the ocular tension was formally introduced by William Bowman in an address delivered at the annual meeting of the British Medical Association in 1862. This pronouncement of the place of digital tonometry in the diagnosis of ocular disease was highly effective: estimation of the ocular tension by palpation became one of the ophthalmologist's special skills, and some ophthalmologists developed so much confidence in it that they viewed instrumental tonometry with suspicion. The first efforts toward instrumental tonometry were apparently made by von Graefe, who mentions preliminary trials of mechanical tonometers in a letter to Donders dated December 24, 1862. None of these instruments, however, reached the drawing board stage. The first impression tonometers actually produced and tested on human eyes were developed in Donders' clinic in Utrecht between 1863 and 1868. They were instruments for use on the sclera. The scleral curvature at the site of tonometer application was determined first; it then served as a reference plane for the measurement of the depth of the indentation. The principal flaw of impression tonometry is that the indentation, by displacing a significant amount of intraocular fluid, changes the pressure it is intended to measure; this was clearly expressed for the first time by AdoIf Weber in 1867. He also invented the first applanation tonometer, which was intended to give a tension reading with only minimal fluid displacement. Despite its theoretic superiority, this instrument did not gain wide acceptance, because recognition of the point of perfect applanation without indentation proved to be difficult. The principle of applanation tonometry was explored again in 1885 by Maklakoff and a few years later by Imbert and Fick (father and son), none of whom had knowledge of Weber's work. It was again recognized as a sounder basis for tonometry, and several new applanation tonometers resulted. Only one of them, Maklakoff's model of 1892, has stood the test of time and has remained in use, mainly by groups in the USSR. At the beginning of the 20th century, digital tonometry was still considered the surest method of orienting oneself concerning abnormalities of the intraocular pressure (21). Not a single impression tonometer had found its way into the practice of ophthalmology. Schi øtz first reported on his impression tonometer in 1905; it did not take long for the instrument to acquire the epithet “the first clinically useful tonometer.” Comprehensive major reports on the clinical value of tonometric results began to appear in 1910. The core of today's knowledge of the intraocular pressure in the normal and in the diseased human eye was acquired between 1910 and 1920 through the use of Schi øtz tonometers. Most of the pioneers in digital or instrumental tonometry realized that properties of the eyeball wall, viz, distensibility and elasticity, affected their estimates of the intraocular pressure. Early experimental attempts to measure these properties revealed multiple variables which defied all efforts to eliminate them. Schi øtz wrote in 1920 (22): “I can not imagine any method available for living eyes by which errors due to variations of the envelope could be eliminated.” Thirty years later, the electronic form of his instrument came closest to yielding reasonable estimates of “ocular rigidity,” the term introduced by Friedenwald for the resistance that the in vivo eyeball offers to a change in intraocular volume (23). As a means of correcting readings taken with the Schi øtz tonometer for deviation of the particular eye from average ocular rigidity, the coefficient of ocular rigidity lost some of its clinical importance through the tremendous progress in applanation tonometry that occurred in the early 1950s through the work of Goldmann, Perkins, and Maurice. PERIMETRY As in so many other fields, von Graefe became a leader in the use of measurements of peripheral vision for the diagnosis and follow-up of ocular disease. With a primitive campimeter—a sheet of paper with radial rows of dots which served as stimuli—he was probably the first (1856) to plot paracentral field defects in chronic glaucoma and to use them in the evaluation of surgical results. With a similar approach, Haffmanns of Donders' clinic discovered the greater frequency in glaucoma simplex of serious involvement of the upper half of the field, which gave rise to an easily detectable nasal step (24). The introduction of the first perimeter by Förster in 1857 placed the accent on large targets, such as the 10/330, which permitted only very gross measurements. The observations of this era did suggest partial reversibility of field defects if the pressure was lowered substantially by an iridectomy or sclerotomy. A momentous step in the development of techniques most appropriate for glaucoma was the introduction by Bjerrum in 1889 of the 2-meter screen, the 2-meter test distance, and the 2- to 5-ram white test objects. With his method Bjerrum discovered the relative or absolute scotomas, circling the point of fixation and including the blind spot, which became the hallmark of chronic glaucoma. Conceptually, it means the beginning of the nerve fiber bundle theory of the glaucomatous optic nerve disease. The next major event occurred when Peter (25) brought to light the occurrence in early glaucoma of small scotomas in the zone from 12° to 20° from the point of fixation; in the beginning these scotomas are not connected with the blind spot, but they reach it later via expansion. In the 1920s, the constriction of the smaller isopters, another characteristic of early glaucoma, was clearly established with Bjerrum's technique. The 1920s brought confirmation with Bjerrum's technique of the regression of early glaucomatous defects following normalization of pressure documented by instrumental tonometry. The close relationship between pressure and field of vision was demonstrated further by Samojloff's observations (26) of temporary enlargement of the blind spot concurrent with osmotically induced pressure elevations. By stereocampimetry with minute targets, Evans was able to detect a gross form of parallelism between diurnal pressure fluctuations and the size of paracentral scotomas (27). The attention of the ophthalmologists of the 1920s was drawn to unfavorable effects of pressure-lowering operations on the visual field in the late stages of glaucoma. In patients with glaucomatous defects close to the point of fixation, a surgical procedure, particularly iridectomy, could have an unfavorable effect and lead to further rapid shrinkage of the visual field. The specific incrimination of the iridectomy referred originally to the period when the alternative, the sclerotomy, had proved relatively free of unfavorable effects on the visual field. Subsequent experience with filtering operations temporarily led to the distinction between two classes of glaucoma operations, viz, the less risky cyclodialysis and sclerotomy and the riskier iridectomy, sclerectomy, and trephination. The history of the treatment of glaucoma is dominated by the discovery of the curative action of the iridectomy in certain glaucomas (7), the development of the filtering operations (29), and the discovery of the first three ocular hypotensive drugs, viz, eserine, pilocarpine, and epinephrine (30). A summary of the early phases of the treatment of glaucoma is presented in the following lists:
The world literature on glaucoma before 1973 has been classified and indexed by Leydhecker and is available to the interested reader (43). | ||||||||||||||||||||||||||||||||||||||||||||||