Introduction

Hermann von Helmholtz was a Germanphysiologist and physicist, and one of themost important individuals in the history ofphysics and medicine of the 19th century. Hemade important findings in muscle and nervephysiology, thermodynamics, and physiologi-cal acoustics. In addition, his contributions toophthalmology were enormous. He inventedthe ophthalmoscope in 1850, developed theophthalmometer in 1853, and his major pub-lication, ‘Handbook of physiological optics’ in1856 explained the mechanism of accommo-dation and produced the first accurate modeleye among numerous other things. The in-vention of the ophthalmoscope can be consid-ered as the single most importantadvancement in the history of ophthalmology.Prior to the ophthalmoscope, examining theposterior pole of the eye in a living humanwas not possible. The ophthalmoscope al-lowed for diseases that were previously un-known to be recognised, making its inventionone of the greatest triumphs in ophthalmol-ogy.1,2

Biography

Hermann Ludwig Ferdinand Helmholtz wasborn on August 31, 1821 in Potsdam, Ger-many. He was the first-born child of four chil-dren. His mother was a descendent ofWilliam Penn, the founder of Pennsylvania.His father was in the Prussian army andwould later become a teacher at the Gymna-sium in Potsdam where Helmholtz attended.Helmholtz was passionate about physics andwanted to become a physicist, but his fathercould not afford to send him to university.Instead in 1838, with a scholarship, he stud-ied medicine at the Royal Medical and Surgi-cal Friedrich-Wilhelm Institute in Berlin,where he was able to combine physics withhis medical degree. As a medical student, hemade his first contribution to medicine whenhe discovered that nerve fibres originated inganglia through his research on the nervoussystem of invertebrates. After graduationfrom medical school, he was assigned to eightyears of service in the military. During histime as a surgeon in the Prussian army inPotsdam, he devoted time to conducting ex-periments on heat production during musclecontraction. This resulted in the developmentof the conservation of force principle that wascrucial to underpinning the law of conserva-tion of energy, and the first law of thermody-namics.1,3-14

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Hermann von Helmholtz:

THE OPHTHALMOSCOPE AND SOME OF HIS OTHER CONTRIBUTIONS

TO OPHTHALMOLOGY

Chu Luan Nguyen & Jean-Paul Wayenborgh

Chu Luan Nguyen, B.Optom, MBBSDepartment of Ophthalmology, Royal North Shore Hospital, Sydney; Reserve Rd, St Leonards NSW 2065, Australiachuluannguyen@gmail.com

Abstract

Hermann von Helmholtz was a German, and one of the most important individuals in the history of physics and me-dicine. He made important findings in muscle and nerve physiology, physiological acoustics, and thermodynamics. Inaddition, his contributions to ophthalmology were enormous. He invented the ophthalmoscope in 1850, developedthe ophthalmometer in 1853, and his major publication, ‘Handbook of physiological optics’ in 1856 explained the me-chanism of accommodation and produced the first accurate model eye among numerous other things. The inventionof the ophthalmoscope can be considered as the single most important advancement in the history of ophthalmology.Prior to the ophthalmoscope, examining the posterior pole of the eye in a living human was not possible. The oph-thalmoscope allowed for diseases that were previously unknown to be recognised, making the invention of the oph-thalmoscope one of the greatest triumphs in ophthalmology. This report provides a brief biographical account ofHelmholtz’s life, and reviews his major contributions to ophthalmology, in particular the ophthalmoscope and it’simpact on ophthalmology.

Hist Ophthal Intern 2015,1: 165-177

In 1848, after his early release frommilitary duty, Helmholtz would dedicate hislife to research, and would not practice med-icine again. A year later he was appointedprofessor of physiology at the University ofKonigsberg in Germany. He worked there forsix years and while there he was able to meas-ure the propagation speed of nervous stimuli.

He started his research on physiolog-ical optics, and invented the ophthalmoscopein 1850. This revolutionized the practice ofophthalmology, allowing for visualization andunderstanding of diseases of the posteriorpole of the eye.2,3,5

He also explained the mechanism ofaccommodation by demonstrating thechanges in lens surface curvature during ac-commodation. Individuals had attempted todevelop methods to measure corneal curva-ture using rulers and compasses, but thesewere inaccurate. In 1853, Helmholtz createdhis ophthalmometer that doubled imageswith two glass plates. His ophthalmometerwas largely for research but its use as an im-portant clinical tool would develop lateron.15,16

In 1855, Helmholtz moved to theUniversity of Bonn, in Germany where hewas professor of anatomy and physiology.Helmholtz’s extensive work on the eye andoptics resulted in the publication of, ‘Hand-book of physiological optics’ in 1856. Thispublication described eye physiology and

anatomy, accommodation, and contained de-scriptions of his ophthalmoscope. Therewould be two more volumes published lateron, which described visual acuity, binocularvision, and perception of vision, along withnumerous other topics on optics. His workalso produced the first accurate eye model.

Swedish ophthalmologist, Alvar Gullstrand,would later modify Helmholtz’s eye modelwhich is used today.

His Handbuch der physiologischen Optik(Handbook of physiological optics) is consid-ered to be the foundation of the specialty ofophthalmology that was becoming moreprominent at that time (see p.168).1,4,17 Afterthree years at Bonn, Helmholtz moved to theUniversity of Heidelberg, in Germany wherehe was professor of physiology. Here he pub-lished his major piece on physiologicalacoustics, ‘On the sensations of tone as aphysiological basis for the theory of music’.This work is the foundation of what currentunderstanding of hearing and acoustics arebased on.1,18,19 In 1871, Helmholtz was ap-pointed professor of physics at the Universityof Berlin, in Germany where he would focus

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von Helmholtz aged 27Daguerrotype from the legacy of the

French physiologist Emile Dubois-Raymond

First edition of Helmholtz´s epoch making invention ofthe ophthalmoscope

Wayenborgh Collection

his research on physics. After several years ofresearch he would end up chairing adminis-trative positions at the university.1

Helmholtz suffered from migrainesas an adult. Nevertheless, he was an avidmountaineer and traveller, often making

trips to the Alps and traveling throughoutEurope for recreation and respite. Helmholtzwas married twice, first in 1849 and then in1861, and had four children.1-5,11,13 In 1893,Helmholtz visited Chicago in the UnitedStates to represent Germany at the ScienceWorld Fair. Unfortunately on the journeyback home, he fell down a flight of stairs andsustained a cerebral hemorrhage. He passedaway from complications several monthslater on September 8, 1894 at 73 years ofage.2,3,7-13

The ophthalmoscope

Prior to 1850 when Helmholtz in-vented the ophthalmoscope, there was docu-mentation from several individuals whoattempted to view the fundus but were un-able to adequately observe it. In 1704, Frenchsurgeon and anatomist, Jean Méry noticedthat a cat’s pupil would be observed to illu-minate when the cat was placed under water.Méry showed that it was an optical phenom-enon but was unable to explain it at thattime.

In 1823, Czech physiologist, JanEvangelista Purkinje, tried to examine thefundus of humans by placing a candle behindthe patient’s back and using a concave spec-tacle lens.

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Engraving from Helmholtz´s Augenspiegel (see oppo-site page)

Helmholtz´s touching dedication on the cover of Augen-Spiegel (1851) to

his first wife Olga, saying: “To his Olga to remember that her eye it was ofwhich retina was unveiled to the investigating eye„.

Formerly from the Haskell E. Norman Library (Christies cat.8922)

Extract from the record of the Proceedings of the RoyalAcademy of Sciences for the year 1704, volume 23, page277 verso (Session of Wednesday I2th November 1704).Minute of Jean Méry's lecture : " Mr. Méry a lu l'Écritsuivant: " Des Mouvemens de l´iris & par Occasion dela Partie Principale de l'Organe de la Vue' " (transl: Mr. Méry read the following paper: "On the Mo-vements of the Iris and on Occasion of the PrincipalPart of the Organ of Sight ")

( Archives o f the Academy of Sciences, Paris)

In the 1840s, English ophthalmolo-gist, William Cumming (1812-1886) in 1846,and German physiologist, Ernst Wilhelm Rit-ter von Brücke (1819-1892) in 1845, ex-plained that the axis of illumination andobservation had to coincide to be able to viewthe fundus. However, although all these indi-viduals recognised the red reflex, they werenot able to view the fundus successfully.1,20,21

Interestingly, three years prior toHelmholtz’s invention, English mathemati-cian Charles Babbage (1791-1871) nearly in-vented the ophthalmoscope. Babbage isrenowned for pioneering the calculating en-gine, which is the precursor of the moderncomputer. His ophthalmoscope consisted of atube and a plain mirror with the silveringscraped off at three small spots in the centre.Light rays falling through an opening in thetube would reflect into the patient’s eye. In1847, Babbage showed prominent Englishophthalmologist, Thomas Wharton Jones, hisophthalmoscope. However, Jones was unableto view the fundus with the instrument, pos-sibly due to being a myope. Babbage acceptedJones’ judgment and stopped developing his

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Original edition of the Physiologischen Optik. The foundation of modern physiological optics containing also Helm-holtz revival of Young´s theory of color vision

Wayenborgh Collection

In this paper, published in Graefe´s Archiv Vol.1 pp.1-74,Helmholtz explains the mechanism of accommodation withthe help of the ophthalmometer invented by himself threeyears before, in 1852. Wayenborgh Collection

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While a student at the London Hospital, Cumming, by shading the eye of a fellow studentfrom the light was able to look directly into it and obtain both the retinal reflex and the whitelight from the entrance of the optic nerve. He made the first suggestion for the construction ofa device for examining the fundus. Garrison & Morton´Medical Biography 5861

Wayenborgh Collection

instrument. Helmholtz noted that if Bab-bage had added a concave lens to correct theconvergent light rays, his instrument wouldhave provided a view of the fundus.22,23

Helmholtz understood that the emit-ted light rays from the eye formed optical im-ages that if visualised, would allow the

fundus to be seen. He presented his workingophthalmoscope to the Berlin Physical Soci-ety on December 6, 1850. He demonstratedthat there were three essential componentsto the ophthalmoscope, including a correctinglens, an illumination source, and a method ofreflecting the light into the eye. His ophthal-moscope consisted of superimposed plainglass plates, one on top of the other. Thesewere at an angle of incidence that producedthe maximum illumination to achieve lightreflection into the eye. He found that byusing three or more plates, he could achievepartial polarisation of the bright, distractingcorneal reflex. His early ophthalmoscopeused a naked candle as an illuminationsource. Instrument-maker, Egbert Rekoss,from the university of Konigsberg con-structed Helmholtz’s early ophthalmoscopes.Helmholtz’s early model used only concavelenses, which had to be changed dependingon the refractive errors of the patient and ex-aminer. In 1852, Rekoss added a revolvingdisc that conveniently carried a series of cor-recting concave and convex lenses.Helmholtz’s ophthalmoscope produced anupright image, with magnification of 15times, and a small field of view. Since his in-vention, there have been numerous ophthal-moscopes developed with modifications made.The reflecting surface progressed from super-imposed plain glass plates, to mirrors, andthen to solid glass prism. Of all the changesto the ophthalmoscope, the most significantchanges have been made to the illuminationsource, which progressed from a naked can-dle, to oil lamps, gas lamps, and electricity.

In 1879, American inventor, ThomasEdison began developing his incandescentlight bulb and this would significantly im-prove the reliability of the illuminationsource.1,24-26

Helmholtz reported his invention inhis paper, ‘Beschreibung eines augen-spiegels:zur Untersuchung der Netzhaut im lebendenAuge’, which means, ‘Description of an eye-mirror: to examine the retina in the livingeye’.27 Soon after Helmholtz’s invention ofthe ophthalmoscope, he sent copies of theinstrument to prominent ophthalmologists ofthe 19th century for their judgment. SeveralGerman ophthalmologists of that time helpedwith the introduction of the ophthalmoscopeto ophthalmology. As a result of the ophthal-moscope, there was an explosion in documen-

170

Reconstruction of Babage´s instrument which can beconsidered as a precursor of Helmholtz´ ophthalmoscope.

Wayenborgh Collection

Charles Babbage. by William H.F.Talbot

tation of fundus diseases by ophthalmolo-gists. In 1853, Earnest Adolph Coccius de-scribed retinal detachment and retinitispigmentosa. In 1855, Richard Liebreich de-scribed central retinal vein occlusion andwould go on to publish the first atlas ofophthalmoscopy. Albrecht von Graefe woulddescribe retinal artery occlusion and glau-coma.1,24-26 The immediate impact of the oph-thalmoscope is seen in the dramatic increasein the volume of literature. Historical re-search, using ‘n-gram frequency’, which isthe annual frequency of phrases based onanalysis of millions of documents, has shownthat the impact of the ophthalmoscope ex-

ceeded that of the invention of the otoscope,and stethoscope.28 Since the revolutionarybirth of Helmholtz’s ophthalmoscope, thespecialty of ophthalmology progressed assymptoms previously unexplained could becorrelated with the fundus findings, openingup a new field of ophthalmology.

Conclusion

Helmholtz’s work was significant as well asdiverse with contributions to both physicsand medicine. His invention of the ophthal-moscope is possibly the most important singleadvance in the history of ophthalmology. Be-fore its invention, diseases of the posterior

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Early model of Helmholtz´s ophthalmoscope, Royal College of Ophthalmologists Collection, London

pole of the eye were largely unknown. His,‘Handbook of physiological optics’ was thefoundation for much of ophthalmology.Helmholtz’s contributions are important torecognise and have helped add to the successof ophthalmology.

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von Helmholtz on an English copperplate, dated1867

Above and left: Hermann von Helmholtz painted 1884 by the Germanartist Franz von Lenbach (1836-1904)

SOME PORTRAITS OF HELMHOLTZ

MADE BETWEEN 1867 AND 189429

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Hermann von Helmholtz 1894 (Pastel drawing by F. von Lenbach, dedicated to Helmholtz by the artist 29 April 1894)

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Hermann von Helmholtz 1894 by Franz von Lenbach (Pastel drawing)

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Hermann von Helmholtz 1891, marble bust by Adolf Hildebrand 1847-1921

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