Anomalies of refraction and of the muscles of the eye

Front matter

Chap. Copyright No.

.HI

UNITED STATES OF AMERICA.

Table Of Contents

CHAPTER VI.

How to Examine the Eye.

Test with trial lenses from trial box— Snellen's test type— Test with keratoscope— Examination by the prisoptometer — Examination by the ophthalmoscope — Direct method — Indirect method— Oblique method — Enlargement of ophthalmoscopic images and how to determine the amount — Skiascopy — Chromatic test — Scheiner's test — Optometry by the perimeter 84-131

Part I

Synopsis of data gathered from the examination of 2,040 school-children of the public schools of Kansas City, Universities of Kansas and Missouri, State Normal and other district schools (taken from a paper read before the Ninth Interna-, tional Medical Congress at Washington, D. C, 1887) 280-284

PART II. Cabinet for test types — Prism-measarmg and lens-centering

instrument — Lens-measurer 285-289

Test types 290-294 preface: to first edition.

In no branch of medicine or surgery withm the last decade has there been more attention given or more discoveries or advancements made than in the department of ophthalmology; particularly, the anomalies and affections of the ocular muscles and of refraction; and yet, these vast subjects of heterophoria and ametropia are still wrapped in a halo of uncertainties. That some anomaly of the ocular muscles, of refraction, or of both, is accountable for many of the pains, aches, and ills of the body and for many of the different forms of chorea and hysteria, is being more and more recognized by the profession in general.

In no branch of medicine have there been invented so many instruments and apparati for the disclosure of disease as for those anomalies and affections which are incident to this little organ of vision ; and in no branch of the science, it would seem, is it so necessary that a settled and definite plan be adhered to in the ferreting out of these occult affections and complications as in ophthalmology. The general practitioner is often unable to cure cases of these anomalies, and sends them to the oculist, and the oculist is frequently put to his wits end and ofttimes completely "stumped" in trying to disclose the real pathological or functional disorder or defect.

It is said that the inmates of insane asylums, homes for the feebleminded, and prisons are, with few exceptions, either ametropic or heterophoric. It would seem, then, that these anomalies may bear some intimate relation to mans moral nature. The manner and degree in which a ray of

8 PREFACE.

light is bent from its course as it passes through the different dioptric media, together with the beautiful and complete mechanism of accommodation which enables the eye to receive these impressions, whether they come from near or afar, has much to do with man's correct estimate of the material world about him.

That the faculty of vision shapes largely the destiny of man, warps or fashions his fate or his moral nature, there is little doubt.

The subject of " eye-sight 1 ' of school children is now attracting the attention not only of the medical profession, but of thinking people throughout the land, and especially of educators. Our venerated teacher, Prof. Donders, taught us that the ideal eye, the normal eye, as to its refraction, is so constructed and adjusted as to bring parallel rays of light to a focus upon its retina without any effort of accommodation; in other words, it is the emmetropic eye.

In some recent publications it has been asserted that the hyperopic eye is the normal condition, and that this normal eye is always keyed up to a certain amount of muscular tension, whether it is adjusted for near or for distant objects, and one writer says that the whole subject of refraction and accommodation, in his opinion, should be rewritten. Be this as it may, the subject under consideration is still in a mist, and I may be pardoned if I, in my humble way, contribute my mite in the endeavor to shed more light on the subject, from my personal experience and observation, both in my public clinic and private practice.

In writing this little volume, it has been my purpose to present the subject in as clear, brief, and concise a manner as possible, embracing all essentials, besides collaborating recent advancements not to be found in the existing books. I have also been stimulated to write the book from repeated requests made by my students to whom I have presented this subject didactically and clinically for the past thirteen years. To one of these students in particular am I indebted for the valuable assistance he has rendered by his knowledge of Stenography, by the making of many of the drawings, assist-

PREFACE. 9

ing in the proof-reading, etc. It is to my friend and former student, H. D. Jerowitz, M.D., I say, that I am indebted for valuable assistance.

To another, who by her keen, bright intellect and accurate, honest mind has rendered me much assistance in this as in other of my literary efforts, am I indebted, and to whom I dedicate this book — my wife, Olive E. F. Tiffany.

Flavei, B. Tiffany, A.M., M.D.

Kansas City, April, 1894.

Preface To Second Edition

■ When the first edition of this work was placed upon the market (now about a year and a half ago), it was with some anxiety upon the part of the author as to how it would be received by the profession, and what place it might take among the many kindred works already out. It is certainly gratifying to know that the book has been so pleasantly received. It is evidently filling a need, as the first edition is already exhausted. The second edition has been carefully revised, and contains some additional data and illustrations, together with some of the more recent developments.

F. b. T.

2457 Troost Avenue, Kansas City, Mo., 1896.

Preface To Fourth Edition

Six years have elapsed since the first edition of this work was placed on the market. This edition was exhausted in a little more than a year; then a second, and subsequently a third, were issued. Both of which being now used up, and still the demand continuing, we are impelled to issue a fourth edition, having gone thoroughly over the subject, eliminating some seemingly superfluous matter and adding other data thus bringing the book carefully up to date.

F. B. T.

October, 1900.

Plate I.

j& ». jpz&j'jg

PROFESSOR VON HELMHOLTZ.

Hermann Louis Ferdinand von Helniholtz, of Berlin, was born in Potsdam, August 31, 1821; studied in the University of Berlin in 1838, as pupil in medicine and surgery; was graduated from the Frederick Wilhelms Institute in 1842, with the inaugural thesis, entitled "De Fabrica Systematis Nervosi Evertebratorum"; under-surgeon in the Charite; 1843, army physician in Potsdam; returned in 1848 as teacher of anatomy at the Academy of Arts and assistant at the Anatomical Museum at Berlin. Was called in 1849 to the professorship of physiology and universal pathology at Konigsberg, and in 1855 was transferred as professor of anatomy and physiology at Bonn; from thence he went as professor of physiology to Heidelberg in 1858; in 1871 at Berlin he accepted, together with the direction of the Physical Institute, a professorship of physics, with the character of Privy Government-Counsellor, and in 1883 was ennobled, which title he now bears.

He belongs to the class of the Johannes Miiller's school. He became famous as a physiologist and established his calling with the work "Ueber die Erhaltung der Kraft" (Berlin, 1847), in which he for the first time seeks to show that all the transactions of nature obey the fundamental laws of mechanics. In the following year Helmholtz's activ. ity was turned to the physiology of the mind. But the invaluable service he gave to human pathology and therapeutics through the invention of the ophthalmoscope, which entirely revolutionized ophthalmology, he made known in another work, "Beschreibung eines Augen-Spiegels zur Untersuchung der Netzhaut im lebenden Auge" (Berlin, 1851).

Among other worKS claiming our highest admiration, and in their special spheres pointing out new phases of science, are: "Handbuch der physiologischen Optik" (Eeip-

li

±& PROFESSOR VON HELMHOI/TZ.

zig, 1856-66), in which his whole investigations upon the eyesight are laid down, and his book (now being revised by Dr. Arthur Konig, of Berlin), "Die Lehre von den Tonempfindungen" (Braunschweig, 1862; 2d edition, 1865), which contains his acoustic investigations, displayed in collation. Besides, he has a large class of other works; for instance, Measurements of the Rapidity of Transmission of Nerve Irritation; investigations upon articles on optics, acoustics, electricity teachings; manifold articles in journals; others in Muller's Archiv. (1845-48-50-52, etc.), Poggendorff's Annalen (of 1852 et seq.), and Crelle's Journal of Mathematics; from Graefe's Archiv. (1855); also, such small works as "Ueber die Wechselwirkung der Naturkrafte," etc. (Konigsberg, 1854), "Ueber das Sehen des Menschen" (Leipzig, 1855), "Populare Vortrage" (2d part, Braunschweig, 1865-7) are published. His scientific treatises are together in two volumes (Leipzig, 1881-83); his reports and discourses are also in two volumes (Braunschweig, 1884).

The subject of this sketch, on the 8th of Sept., 1894, died at his home (Charlottenberg, near Berlin), in his 73d year. Dr. Knapp, who was a personal friend of Prof. Helmholtz, says in his obituary {Archives of Ophthalmology, October, 1894): "The allotment of his time for waking and sleeping, work and recreation, home-life and travel, was such as to make his labor in the highest degree efficient, and his life not only the most useful, but also most enjoyable and healthy. He hated to be annoyed by idlers and scientific pretenders. In the lecture-room he was always precise and unswervingly adherent to the subject, never being 'out of order,' despising jokes and stories to amuse his audience. He kept the attention of his listeners by the wealth of interesting facts and the clearness, precision, and elegance of his delivery. He was constantly in contact with his pupils, aiding and assisting them. . Taking him all in all, he was as near a perfect man as Nature has ever produced, the gift of the highest intellect combined with nobilitv of character and purity of life."

Plate II.

BIOGRAPHICAL SKETCH OF PROF. DONDERS.

The following brief oiographical sketch of Prof. F. C. Donders is a translation in part (by Olive E. F. T.) of a very beautiful tribute furnished by one of his disciples, our friend Le Docteur E. Landolt:

"Since the death of Von Graefe ophthalmology has not met with a loss comparable to that which it has just experienced in the person of Donders. It might be said that we do not lose the master, since his works remain and will always remain, forming the life, the soul of ophthalmology.

"When, last year, his country, his pupils, his compatriots, his admirers from far and from near, united by one common sentiment of gratitude, changed into an apotheosis the retreat from the professorship which the limitation of age imposed upon him, Donders towered above the crowd who were deifying him, by his noble presence, the loftiness of his brow, the nobility and brilliancy of his look.

"On this day, glorious among all days for him, in which every one rendered homage to his merits, he responded modestly: 'Talk not to me of my merits, but congratulate me on my lucky star.'

"Donders was born May 27th, 1818, in Tilbury, Holland, of poor parents, the ninth child, the first son. It is said that the joy of having at last an heir killed his father. Of what supreme joy did fate deprive the father by taking him off at the cradle of his only son ! The mother watched over that cradle with a double solicitude, but although the heart of this great man always kept the impress of the cares of this tender mother, it is neither the society of his town nor the school of Duizel, where he learned La an and earned his living as sub-master until he was thirteen years of age, which can claim the honor of having dc-posited in him the germs of his future greatness. lie continued his studies of Latin in the school of Boxmeer until he was seventeen years of age. He became, consequently, very strong in this use-

14 PROFESSOR DONDERS.

ful language. He threw himself with great ardor into the medical sciences in the military school of Utrecht. In 1840, at twenty-two years of age, he occupied the chair of military surgeon at La Haye. The year 1842 saw him already the distinguished professor of anatomy and physiology in the same school of Utrecht which he had but just left as pupil.

"Who would have said then that he would live sixtyseven years in this little city of Utrecht; that he would grow up in it and shine in it to such a degree as to make of this fireside of his activity a scientific center, beneficently radiating its light over the whole world, even after his death? What a brilliant epoch, moreover, was that in which Donders began to cultivate the fertile field of the sciences of man!

"Schwann had just demonstrated the cell origin of all organisms; Von Baer had just discovered the egg of mammalians; Bischoff, the segmentation of the ovule; Henle had endowed science with his marvelous book of anatomy, notably of microscopic anatomy; and the immortal Jean Miiller had opened new horizons to physiology by introducing into it the exact sciences. So emulation was not wanting in the new school, or rather in the school newly developing, which was illustrious with the names of Helmholtz, Briiche, Claude Bernard, and Ludwig. Donders was the worthy representative of Holland in this noble phalanx.

"There is not a domain in this vast science in which Donders has not left priceless traces of his labors. The life of tissues, circulation of the blood, digestion, secretions, movements, organs of senses, language, secrets of the nervous system, were, turn by turn, explored by this indefatigable seeker. He explained the formation of vowels, measured the rapidity of our thoughts, demonstrated the laws of evolution, of animal life, and the indestructibility of force.

"If there is a crowd of facts, of laws, of theories,, which make illustrious his name, there are perhaps as many which we consider as belonging to science from all eternity, without knowing that we owe them to Donders. If the acquisition of knowledge has more charm than the possession,. Donders found a joy still greater in its communication to

PROFESSOR DONDERS. 15

others. His first researches were published in the Nederlandsch Lancet, which he founded with Jansen and Ellermann; also in the Hollandische Beitrdge, which he published in German with Van Dee and Moleschott, 1846.

"What Donders preferred most of all was teaching viva voce, and what did he teach? Let us ask rather, what did he not teach? He possessed all the qualities which make the perfect professor : an erudition as profound as extensive; an excellent memory; an intelligence capable of adapting itself to his audience; a wit which colors abstract matters; a rich flow of language; a voice sonorous and flexible; gesture noble and significant; something sublime emanated from the man ; physically grand and beautiful, something at once imposing, captivating, and sympathetic; great knowledge, and great desire to impart it."

As an instance of his great modesty we cite the reply made to one who attributed to him the discovery of astigmatism: "Pardon me, my friend, astigmatism was known a long time before my day; I only discovered astigmatic people." When a hospital and laboratory were needed in Utrecht, the name of Donders was already so well known, this prophet was so esteemed in his intelligent country, that he had only to lift his voice, to see gifts flowing in from all quarters sufficient for the creation of the two institutions in which Holland has eternally honored herself.

The following is the first account rendered by himself: "I have seen the unfortunate who had believed his existence terminated by blindness thank God on seeing open before him a new period of happiness. I have seen the honest workman, once humiliated in eating the bread of charity, capable of earning again for himself and for his the savory bread of labor. I have heard the cries of joy of the young mother, who, long deprived of the sight of her child, could not turn away her eye with its new glimmering light from her baby's face; and I have seen, in the child snatched from blindness and beginning to learn, how much nature is reflected the more willingly, and consequently the more divinely, in the eye of the child."

There is no student of ophthalmology but is acquainted

16 PROFESSOR DONDERS.

with this sage and erudite teacher through his great work on Refraction, the source from which much knowledge is drawn by every writer on this subject.

It was our good fortune to meet Prof. Donders in his home at Utrecht in the fall of 1887, and we shall never forget the warm welcome he gave us, strangers as we were. It was enough for this grand, noble soul to know that we had crossed the seas to meet and shake hands with our great teacher. It was indeed a proud and happy moment for us to sit and have communion with the great master — a bright spot in our lives that will never be forgotten.

F. B. T.

Plate III.

EDMUND LANDOLT, M.D.

It was at Washington, D. C, during the meeting of the "Ninth International Medical Congress of 1887, we first had the pleasure of meeting Dr. Landolt, who contributed much to the success of our section by his scientific communications and his discussions.

A few months later found us at No. 27, Rue Saint- Andre des Arts, Paris, where a few weeks were spent with pleasure and profit listening to his enthusiastic and able teachings, especially concerning the subjects of Refraction, of Insufficiency of the Ocular Muscles, and of Strabismus. Dr. Landolt may be called a specialist within the specialty of ophthalmology. He has contributed largely to this subject. His masterly work on "Refraction and Accommodation of the Eye" is regarded as authority by the student of to-day, as was £*nd is the work of Donders on the same subject by all students.

He was born in the town of Aarau, Switzerland, in the year 1846. To his early life passed in this picturesque country, in this beautiful scenic land of hills, lakes, and mountains, with clear, running streams, may be attributed, in a measure, his cheerful disposition and keen powers of observation.

_ He studied in Heidelberg and Zurich. Received the degree of M.D. in 1869 at Zurich, and in 1875 at Paris. He was assistant surgeon to the surgical clinic in Zurich; later, surgeon to the ophthalmological clinics of the same university (Prof. Horner). Passed one year with Arlt in Vienna and Von Graefe in Berlin, another with Donders and Snellen in Utrecht. Visited the principal clinics in Germany, England, Italy, France; later, those of the United States of America. During the Franco- German War (1870-71) was surgeon-in-chief to the ambulance in Hericourt (France). Settled in Paris 1875. Organized, with Javal, the laboratory for ophthalmology at the Sorbonne.

18 EDMUND LAXDOLT, M.D.

Among his principal works (over one hundred) are: "On the Retina," in Max Schultze's Arch., 1870. "Amblyopie hysterique," Arch, de physiol., 1 875. A manual of examination of the eyes, published in French and in English, 1879. A manual of ophthalmoscopy, published in French, English, Dutch, and Spanish. "Traite complete d'ophth.," with M. de Wecker, 4 volumes. "The Refraction and Accommodation of the Eye, 1886 (Edinburgh), 600 pages. "The Operation for Cataract in Our Time/' Arch, d'ophth. and Ophth. Record, 1892. "The Anomalies of the Motor Apparatus of the Eyes," in "System of Diseases of the Eye," edited by Norris and Oliver (1893-4).

Among the principal instruments invented by Dr. Landolt are: Landolt's perimeter, ophthalmoscope, ophthalmodynamometer, forceps for strabotomy, double-bladed knife for discission.

Dr. Eandolt is consulting surgeon to the Institution of the Young Blind in Paris.

Chapter I. Reflection Of Light

As reflection and refraction of light have to do with the anomalies of refraction and accommodation of the eye, we shall briefly consider these

phases of optics before entering upon the subject of ametropia.

Light, by its action on the retina of the eye, excites the sensation of vision. The source of light may be natural or artificial. The line in which light is propagated is called a luminous ray (RR, Fig. 1).

A collection of parallel rays is called a beam of light (R'R'). A collection of divergent rays from a point is a pencil of rays (R"R").

In Figure 2 are represented a few of the infinite number of pencils of light emitted by three luminous points of a candl t flame. Every point of an illuminated object (ad) receives light from every luminous point of the candle flame

Fig. 2.

Thus it follows that

REFLECTION OF EIGHT.

every point in a luminous body is an independent source of light, and emits light in every direction. In a homogeneous medium, light is propagated in a straight line, but it changes its direction when it passes into a medium of different density.

Images Produced by Small Apertures. If light from objects illumined by the sun — as trees or houses — passes through a small aperture and strikes a white screen, rays carrying with them the color of the points from which they issue will imprint their own color on the screen, and inverted images of the objects in their true colors will appear upon it. This may be shown by holding in a darkened room a candle flame in front of a I cardboard, having a pinhole in its center; the image will be projected ■on the Avail. (Fig. 3.) Fig . 3 . The shape of the

image is always the same as that of the object and is independent of the shape of the aperture. The inversion of the image arises from the fact that the luminous rays cross one another in passing through the aperture, the lower part of the object becoming the upper part of the projected image.

When a luminous ray meets a polished surface it is reflected according to two laws:

1. The angle of reflection is equal to the angle of incidence.

2. The incident and the reflected ray are both in the same plane, which is perpendicular to the reflecting surface.

REFLECTION OF LIGHT.

Fig. 4.

In Figure 4 let RO be an incident ray striking the polished surface AB at the point O, and OH the perpendicular erected at that point. The ray RO is reflected in the direction OR', making the angle HOR' equal to the angle ROH.

Mirrors. A body with a polished surface that will show by reflection objects presented to it is known as a mirror.

Mirrors may be either plane or curved; that is they have either a plane or a curved surface.

Reflection from Plane Mirrors. MM (Fig. 5) represents a plane mirror. AB and HE are pencils of rays coming from the points A and H of the object AH. The reflected pencils BC and EC are divergent. The reflected rays entering the eye in the direction BC and EC are seen as if they came from ND. The position of ND can be determined by tracing backwards the lines of the pencils BC and EC until they meet. In the case of a plane mirror the image is as far behind the mirror as the object is in front of it, and is of the same

REFLECTION OF EIGHT.

size a::d shape as the object. But the image is reversed, as can be demonstrated b}^ standing before a mirror. The image of the right hand is on the left of the image in the glass. If the mirror is horizontal, with its reflecting surface upwards, and the object above it, the image will be inverted,

as can be shown by placing a glass of water upon a looking-glass (Fig. 6).

The image formed by a plane mirror is called a virtual image, as there can be no real image at the place where it appears, there being no reflected rays behind the mirror.

When the reflected rays themselves meet, they form a real image.

Fig. 6.

Fig. 7.

The surfaces of waters, when at rest, act as mir-

REFLECTION OE EIGHT.

rors. Probably they suggested the mirror — 'twas the mirror of Venus and Narcissus. A body of water, for instance, when calm, will produce images of external objects, as of the moon, stars, buildings, etc. Figure 7 represents the phenomenon of such a reflection. In this case, it is the same as for the image formed by a horizontal looking-glass.

Curved Mirrors. This class comprises those in which the reflecting surface is a portion of a

Fig. 8.

Ihollow sphere. If the concave side is used for reflection, it is a concave mirror; if the outer or convex side is employed, it is a convex mirror.

In both concave and convex mirrors the middle point (A, Fig. 8) is the vertex of the mirror. The center of the sphere of which the mirror forms a part is called the center of curvature (C). A straight line (HK) drawn through the center of curvature and vertex of the mirror is called th principal axis of the mirror.

Reflection from Concave Mirrors. A concave mirror may be considered as made up of an infinite number of Fiff - 9 - small plane surfaces. All radii of the mirror, as CK, CI, and CA (Fig. 9), are perpendicular to the small planes which they strike.

If C were a luminous point, all rays emanating from it, and striking the mirror, would be reflected back to C.

Let L represent any luminous point. The rays LK and LI emanating from this point strike the mirror at the points K and I and are reflected to meet at a point /. The angle of incidence LKC is equal to the angle of reflection CK/, CK, the radius, being the perpendicular. Any other ray from L striking the mirror will be reflected to /. The rays before reflection are divergent, but after reflection are convergent and meet. The place of meeting (/) is called the focus, and is the focus of all rays coming from the point L- It is obvious that rays emerging from the point / would come to a focus at L, since the angle of incidence and the angle of reflection would interchange, but still be equal. Two points in such relation, in which rays coming from one are focused at the other, are known as conjugate foci.

If the luminous point L were nearer to C, the focus would also be nearer to C, as the angle of incidence would be smaller, and consequently the angle of reflection would also be smaller.

If the point L is further removed from C, the angle of incidence becomes greater, which makes the angle of reflection correspondingly greater, and the point / approaches the mirror. If L is removed to an infinite distance, the rays would be almost parallel ; hence, rays may be regarded as practically

REFLECTION OF LIGHT.

parallel when their source is at a great distance; e. g.y fixed stars.

For practical purposes, we shall speak of the rays coming from a distance of 20 feet or more from the eye, as parallel, and call them infinite rays; while rays coming from a distance less than 20 feet from the eye may be considered divergent, and these we shall designate as finite rays.

Parallel rays striking a concave mirror become convergent by reflection, and meet at a point F (Fig. 10) in the principal axis.

This point, which is called the principal focus of the mirror, is just half way between the Fig.io.

center of curvature and the vertex of the mirror. On the other hand, divergent rays proceeding from the principal focus become parallel after reflection.

Rays emanating from a point between the principal focus and the mirror (L, Fig. 11) will become divergent after reflection, and take the directions ME and NH. These lines cannot meet, and consequently there is no real conjugate focus for L- But if the lines are prolonged backwards, they meet at a point. This point (/) where the prolongations Fig.n.

of the reflected rays meet is known as a virtual focus, and the image resulting from these is analogous to those formed by plane mirrors.

If the rays (previously rendered convergent by another concave mirror, or by a converging lens) strike the mirror in the direction of EM and HN in Fig. 11, they will come to a focus between the mirror and the principal focus, as at L.

Fig- 12

Reflection from Convex Mirrors. In convex mirrors, which may also be regarded as composed of an infinite number of small plane surfaces, there are only virtual foci ; for parallel rays, as HA and KB (Fig. 12), become divergent after reflection, and take the directions AM and BN, whose prolongations backward meet in the principal axis at F and form a virtual focus; which in this case — the primary rays having been parallel — is half way between the center of curvature and the mirror, and is the principal virtual focus of the mirror.

REFLECTION OF LIGHT.

If the rays come from a finite distance, as, for instance, point E (Fig- 13), a virtual focus (H) will be formed between the principal focus and the mirror.

Images Formed by Concave Mirrors.

1. If an object be held in front of a concave mirror, but at a greater distance from it than its center of curvature, an image is formed which is located between the principal focus and the center of curvature, and it is real, inverted, and smaller than the object. This is illustrated in Fig. 14.

A pencil of rays from the point D in the object DE is reflected by the mirror, and comes to a focus (D') in the secondary Fig. u. axis DB (which is a line drawn from any point of an object through the center of curvature); then D* is the conjugate focus of D and locates its image. The same explanation applies to E and all intermediate points of the object DE, and we have a real, inverted image at E'D', which may be projected upon a screen. The pencils of rays, after coming to a focus at E r and D', will, if prolonged, become divergent again, and the eye placed at a distance beyond the object will receive these divergent rays and will see the image of the object. This accounts for the fact that when we look into a concave mirror or reflector from a distance, we see a small, inverted image of ourselves in front of the mirror. This can be beautifully shown by using the head-mirror or the ophthalmoscope, such as is used for examining the throat or eves.