**12. Gonioscopy**

Another important part of ophthalmic exam. First explored in by Trantas (1907.); then ex‐ plored by Salzmann (1915-16.); Koeppe (1919-20.); and Troncoso (1925-30). Finally Otto Bar‐ kan (1887.-1958.) 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[40]that the elevation of the intraocular pressure depends of abnormal resistance to aqueous outflow caused by anatomic or functional changes within the outflow channels.

resulted a several new applanationtonometers, but 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.

The History of Detecting Glaucomatous Changes in the Optic Disc

http://dx.doi.org/10.5772/52470

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The beginning of the 20th century, digital tonometry was still a method of subjective assess‐ ment of the ocular pressure [41]. At that time neither applanation tonometer did not find widespread use in practice.Finally, in 1905.Schiøtz presented his impression tonometer and it did not take long for the instrument to acquire the epithet "the first clinically useful ton‐ ometer." First major comprehensive reports of the clinical value of Schiotz tonometer began to appear in 1910. The essence of today's knowledge of the intraocular pressure in the nor‐ mal and in the diseased human eye was acquired between 1910. and 1920. through the use

Disadvantages of digital and instrumental tonometry, realized by the pioneers of these methods, addressed to the properties of the eyeball wall, especially elasticity, affected esti‐ mation of the intraocular pressure. Early experimental attempts in that time, to measure these properties and to eliminate them revealed new variables. Schiøtz wrote in 1920: "I can not imagine any method available for living eyes by which errors due to variations of the envelope could be eliminated." [42]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 vol‐

Correcting readings taken with the Schiøtz tonometer for deviation of the particular eye from average ocular rigidity, the coefficient of ocular rigidity lost some of its clinical impor‐ tance through the tremendous progress in applanation tonometry that occurred in the early

The technology to estimate intraocular pressure (IOP) has evolved tremendously since Sir William Bowman emphasized the importance of ocular tension measurements in 1826. In an address delivered at the annual meeting of the British Medical Association, Sir William un‐ derscored the critical role that digital estimation of ocular tension played in his practice. In his address, Sir William stated that "it is now my constant practice, where defective vision is complained of, to ascertain almost at the first instant the state of tension in the eye...It is easy enough to estimate the tension of the eye, though there is a right and a wrong way of doing even so simple a thing... With medical men, the touch is already an educated sense, and a

Soon afterwards, digital tonometry became an essential clinical skill necessary to master by all ophthalmologists. When mechanical tonometry was first introduced in the late 1800s, many ophthalmologists felt so confident with their ability to estimate IOP by palpation that they viewed the new technology as inferior. Isador Schnabel, in an address to the Vienna Ophthalmological Society in 1908, was noted to state that although he did not object in prin‐

1950s through the work of Goldmann, Perkins, and Maurice.

very little practice should suffice to apply it successfully to the eye."[44]

**15. Goldman applanation tonometry**

of Schiøtztonometers.

ume [43].

Not until the 1890s did open-angle glaucoma become well proved and accepted in theories.

Thanks to gonioscopy, started recognition of a type or types of glaucoma without obstruc‐ tion of the angle by the iris.

### **13. Secondary glaucomas**

In the first edition of the Graefe-SaemischHandbook of Ophthalmology (1877), Saemisch lists the following ocular diseases as frequently giving rise to secondary glaucoma: cicatri‐ cial ecstasies of the cornea, circular or total adhesions of the iris to the lens, iritis serosa, trau‐ matic cataract, dislocations of the lens, intraocular tumours, hemorrhagic retinal processes (referring mainly, if not exclusively, to occlusions of the central retinal vein), and sclerectasia pastries (which probably referred to glaucoma in eyes with malignant myopia). Congenital hydrophthalmos was at the time also classified with the secondary glaucomas.

### **14. Tonometry**

William Bowman introduced digital estimation of the ocular tension at the annual meeting of the British Medical Association in 1862. Estimation of the ocular tension by palpation be‐ came one of the ophthalmologist's special skills, and some ophthalmologists developed so much confidence in it that they viewed instrumental tonometry with suspicion.

The early beginning of instrumental tonometry, apparently made by von Graefe, who men‐ tions preliminary trials of mechanical tonometers in a letter to Donders dated December 24, 1862. Unfortunately, none of these instruments, however, reached the drawing board stage.

The real beginning and the first 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 deter‐ mined first; it then served as a reference plane for the measurement of the depth of the in‐ dentation.

Impression tonometry had its drawbacks. The principal flaw was that the indentation, by displacing a significant amount of intraocular fluid, changes the pressure which is intended to measure; this was clearly expressed for the first time by AdoIf Weber in 1867. Weber was official inventor of the first applanation tonometer, which was intended to give a tension reading with only minimal fluid displacement. Despite its theoretic superiority, this instru‐ ment did not gain wide acceptance, because recognition of the point of perfect applanation without indentation proved to be difficult. Lately, the principles of applanation tonometry were explored by Maklakoff in 1885. andImbert and Fick, father and son, a few years later. It resulted a several new applanationtonometers, but 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.

The beginning of the 20th century, digital tonometry was still a method of subjective assess‐ ment of the ocular pressure [41]. At that time neither applanation tonometer did not find widespread use in practice.Finally, in 1905.Schiøtz presented his impression tonometer and it did not take long for the instrument to acquire the epithet "the first clinically useful ton‐ ometer." First major comprehensive reports of the clinical value of Schiotz tonometer began to appear in 1910. The essence of today's knowledge of the intraocular pressure in the nor‐ mal and in the diseased human eye was acquired between 1910. and 1920. through the use of Schiøtztonometers.

Disadvantages of digital and instrumental tonometry, realized by the pioneers of these methods, addressed to the properties of the eyeball wall, especially elasticity, affected esti‐ mation of the intraocular pressure. Early experimental attempts in that time, to measure these properties and to eliminate them revealed new variables. Schiøtz wrote in 1920: "I can not imagine any method available for living eyes by which errors due to variations of the envelope could be eliminated." [42]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 vol‐ ume [43].

Correcting readings taken with the Schiøtz tonometer for deviation of the particular eye from average ocular rigidity, the coefficient of ocular rigidity lost some of its clinical impor‐ tance through the tremendous progress in applanation tonometry that occurred in the early 1950s through the work of Goldmann, Perkins, and Maurice.
