Maximilian Salzmann.

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735 OOb




OE1RA1EY







THE ANATOMY AND HISTOLOGY OF THE HUMAN
EYEBALL IN THE NORMAL STATE



ANATOMIE UNO HISTOLOGIE

DES

MENSCHLICHEN AUGAPFELS

IM NORMALZUSTANDE
SEINE ENTWICKLUNG UND SEIN ALTERN



Von
DR. MAXIMILIAN SALZMANN

A. Professor der Augenheilkunde in Wien



MIT 5 FIGUREN IM TEXTE UND 9 TAFELN IN LICHTDRUCK



LEIPZIG UND WIEN
FRANZ DEUTICKE

1912



THE ANATOMY AND HISTOLOGY

OF

THE HUMAN EYEBALL

IN THE NORMAL STATE

ITS DEVELOPMENT AND SENESCENCE



By
DR. MAXIMILIAN SALZMANN

Titular Professor of Ophthalmology
University of Vienna

AUTHORIZED TRANSLATION

By
DR. E. V. L. BROWN

Professor of Ophthalmology

Also Clinical Professor and Chairman

Department of Ophthalmology, Rush Medical College



WITH 5 TEXT FIGURES AND 9 PLATES IN PHOTOCOLLOTYPE



CHICAGO

1912



Published August 1912
Second Impression June 1931



Composed and Printed By

The University of Chicago Press

Chicago, Illinois, U.S.A.



s"



DEDICATED TO MY REVERED TEACHER

THE THOROUGH STUDENT AND INVESTIGATOR OF THE

NORMAL AND PATHOLOGIC ANATOMY OF THE EYE

PROFESSOR ERNST FUCHS

BY THE AUTHOR



PREFACE

As in the case with so many other books, this one has developed from
the lectures which I have regularly given for years, and I only comply
with an oft-expressed wish of my auditors when I put the substance of
these lectures into print from the same point of view as the one by which
I have allowed myself to be guided in the lectures.

This point of view is that a thorough knowledge of the normal anatomy
and histology gives the most certain basis for the understanding of
methods of clinical investigation and for judging pathologic changes
hence the reference to ophthalmoscopy, to the physiology of accommoda-
tion, and to pathologic processes here and there.

I should like to have the book considered from the point of view that
it is the eye specialist and no't the specialist in anatomy who writes it.
For example, I have not gone into comparative anatomy in a detailed
way. Important as this is for the determination of morphologic ques-
tions and much as I am personally interested in it, I hold it to be
superfluous for the purpose at hand to enter into this branch of learning.
Naturally, therefore, some details of cell-structure, nerve-endings, and the
like, which for technical reasons one can study only on animals, are treated
only briefly.

Probably no one will find fault with me because I have not encumbered
the book with the ballast of a complete reference to the literature. Such
would stand in no relation to the compass of the text, which I have made
as compact as possible. Extended references to the literature are to be
found in the most cited articles, especially in the corresponding chapters
of the Graefe-Saemisch Handbuch. On the other hand, I will not deny
that any choice from our enormously swollen literature is an arbitrary
one. Forgiveness is herewith implored in advance . from whomsoever
feels slighted in this respect.

One cannot be original in a subject which has been so much worked
in its entirety and in detail. Content and method of expression must
necessarily move in the same paths as those to which the earlier works
have held.

At the same time I feel I may say that I have not simply copied
from others, but that my descriptions and my drawings have been
made true to nature. I have borrowed only one drawing (Plate IX, 6)
from an embryologic work; all others are original and with very few



viii PREFACE

exceptions prepared from my own specimens. In so doing I have striven
throughout to bring forth concrete pictures, i.e., each drawing is a
true representation of the preparation concerned. Only the general
drawings of the eyeball of the adult and of the newborn are schematic.
In Plate I (Taf. I) some details of the zonula and vitreous are drawn
in from other preparations and Plate III, 2 is also a combination of
various teased preparations of the same eye.

I express my especial thanks to the publisher for his friendliness and
for the sacrifice occasioned by the nature of the reproduction of the
drawings, as well as to the Art Press of M. Jaffe in Vienna for the care-
ful preparation of the plates, which have reproduced the characteristics
of the original drawings in the truest way.

THE AUTHOR
VIENNA

September, 1911



CONTENTS
PART I. ANATOMY AND HISTOLOGY OF THE ADULT EYEBALL

PAGE

A. THE EYEBALL AS A WHOLE (MACROSCOPIC ANATOMY) . . . . . . . 3-16

I. Form, Size, Orientation 3

II. Surface of the Eyeball 7

III. General View of the Structure of the Eyeball (Division into Coats and
Zones) 10

IV. Asymmetry of the Eyeball 16

B. SPECIAL ANATOMY AND HISTOLOGY or THE EYEBALL 17-186

Chapter I. The Sclera 17-26

1. The Episcleral Tissue 21

2. The Sclera Proper 22

3. The Lamina fusca sclerae 26

Chapter II. The Cornea 26-40

a) The Cornea Proper 28

1. The Epithelium of the Cornea 28

2. Bowman's Membrane 30

3. The Substantia propria of the Cornea 31

4. Descemet's Membrane 36

5. The Endothelium of the Cornea 37

6) The Limbus corneae . . k 38

1. The Epithelium of the Limbus corneae 38

2. The Stroma of the Limbus corneae 39

Chapter III. The Structures of the Scleral Furrow 41^48

Schlemm's Canal 41

The Mesh work of the Iris Angle 42

Chapter IV. The Perichorioidal Space and the Suprachorioidea . . . 48-52
Chapter V. The Chorioidea . . 52-60

1. The Vessel Layer 54

2. The Capillary Layer 56

3. The Glass Membrane 59

Chapter VI. The Pigment Epithelium of the Chorioidea 60-63

Chapter VII. The Retina :" . . 63-88

a) Microsopic Anatomy and Histology of the Retina 65

1 . The Layer of Rods and Cones 66

2. The Membrana limitans externa . 68

3. The Outer Nuclear Layer 69

4. The Outer Plexiform Layer 71

5. The Inner Nuclear Layer 72

6. The Inner Plexiform Layer 73

7. The Ganglion-Cell Layer 74

ix



CONTENTS

PAGE

8. The Nerve-Fiber Layer . 76

Appendix. The Supporting Fibers 78

9. Membrana limitans inter na 79

V) Histologic and Functional Divisions of the Retina. Its Blood- Vessels

and Fovea centralis 80

c) The Extreme Periphery of the Retina 83

Chapter VIII. The Optic Nerve . . . 88-107

a) The Non-medullated Portion of the Optic Nerve 88

1. Microscopic Anatomy and Histology 88

2. Varieties of the Non-medullated Section of the Optic Nerve . . 95

3. The Significance of the Ophthalmoscopic Picture in Relation to the
Anatomy of this Region 97

V) The Medullated Section of the Optic Nerve 99

1. The Sheaths of the Optic Nerve 100

2. The Optic-Nerve Trunk 103

Chapter IX. The Ciliary Body 107-125

a) The Uveal Portion of the Ciliary Body in

1. Suprachorioidea and Ciliary Muscle in

2. The Vessel Layer of the Ciliary Body 115

3. The Elastic Lamella 116

4. The Interlamellar Connective Tissue 116

5. The Cuticular Lamella 117

b} The Epithelial Covering of the Ciliary Body 119

6. The Pigment Epithelium of the Ciliary Body 119

7. The Ciliary Epithelium 121

8. The Membrana limitans interna ciliaris 1 23

Chapter X. The Iris 125-148

c) The Uveal Portion of the Iris 131

1. The Endothelium of the Iris 131

2. The Anterior Border Layer 131

3. The Vessel Layer 133

b} The Ectodermal Layers of the Back Surface of the Iris 138

4. Outer Leaf : Dilatator pupillae . 138

5. Inner Leaf : Pigment Epithelium of the Iris 144

c) Variations in the Appearance of the Iris 145

(Influence of the Width of the Pupil and Individual Variations)

Chapter XL The Vitreous. . . 148-155

Chapter XII. The Zonula ciliaris 155-162

Chapter XIII. The Lens 162-173

1. The Lens Capsule 164

2. The Lens Epithelium 167

a) The Epithelium of the Anterior Lens Surface 167

/3) The Epithelial Border and the Lens Vortex: The Formation of

New Lens Fibers 167

3. The Lens Substance 170



CONTENTS xi

PAGE

Chapter XIV. The Chambers of the Eyeball and the Topography of This

Region . 173-180

a) The Posterior Chamber 173

b) The Anterior Chamber 176

c) Content of the Chambers 177

d) Topography of the Anterior Segment : . .177

Chapter XV. The Vessels and Nerves of the Eyeball 180-187

a) The Blood-Vessels of the Eyeball . . 180

1. The Retinal System 180

2. The Ciliary System 181

b) Lymph Passages 185

c) Nerves of the Eye (N. ciliares) 186

PART II. THE PHYSIOLOGIC CHANGES OF THE EYEBALL DURING
LIFE (DEVELOPMENT AND SENESCENCE)

Chapter XVI. The Embryonal and Fetal Development 191-203

Chapter XVII. The Eyeball of the Newborn 203-206

Chapter XVIII. The Extrauterine Development and Growth of the Eyeball 207-211

Chapter XIX. The Appearances of Age in the Eyeball 211-216

Literature Citations : 217-226

Explanation of Plate Figures 227-232



A. THE EYEBALL AS A WHOLE (MACROSCOPIC ANATOMY)

I. Form, Size, Orientation

(Text Fig. i)

The eyeball (bulbus oculi) on the. whole has the form of a sphere, yet
there are some variations from a pure spherical form.

c
^^L r-\,

Li



Me



Cc-




N



Ch



TEXT FIG. i. Right eye, schematic horizontal section. Magnification 3.

N nasal, T temporal side, Co conjunctiva sclerae, C cornea, Li limbus, Se sulcus sclerae externus,
S sclera, Rm musculus rectus medialis, Rl musculus rectus lateralis, I iris, Cc corpus ciliare, Cor
corona ciliaris, Or orbiculus ciliaris, Me musculus ciliaris, Ch chorioidea, P pigment epithelium,
R retina, F fovea centralis, Os ora serrata, Vk anterior chamber, Hk posterior chamber, L lens, Z zonula
ciliaris, G vitreous, Lc lamina cribrosa, nervus opticus, D dural sheath.

To begin with, one notes a shallow, circular furrow in the anterior
segment separating a smaller transparent area of about 1 2 mm in diameter
(cornea, C) from the remaining white opaque portion (sclera, S). This
furrow (sulcus sclerae externus, Se) is not prominent in profile view, for
it is filled out for the most part by the conjunctiva sclerae (Co) ; one recog-
nizes it better if one allows the image reflected from a mirror onto the
anterior surface of the cornea to move toward the sclera. A narrowing
of the image then occurs in the horizontal direction (Tscherning, 227) as
the neighborhood of the margin of the cornea is reached and an elonga-
tion or a division into two images is seen after it actually passes over the

3



4 ANATOMY AND HISTOLOGY OF THE HUMAN EYEBALL

margin of the cornea. The latter indicates the presence of a concavity
in this location. This concavity is somewhat plainer on the nasal than
on the temporal side.

The cornea is more sharply curved than the remainder of the surface
of the eyeball. The foremost portions of the sclera are very weakly
curved, and grade off very abruptly, almost conically, toward the equa-
torial portion, which again is somewhat more sharply curved.

The back half of the eyeball has a more uniform curvature than
the front half, yet here, too, there are variations from the pure spherical
form and I cannot accept the Merkel schema (151), which conceives
of the form of the back half as that of a sphere.

In the first place, the anatomic equator, i.e., the sum-total of all those
points maximally distant from the optic axis, does not go through an
exact frontal plane, but lies farther forward on the nasal side, farther
backward on the temporal side. Furthermore, the surface of the eyeball
lying between the optic nerve and the nasal part of the equator is some-
what flattened, and the part lying temporal to the optic nerve is more
strongly curved backward and outward.

The degree of this asymmetry varies much. In many cases it can
only be made out by the accurate comparison of the profile of the eyeball
with a circle of the same diameter; in many cases, however, it is so strik-
ing that one does not need any special means to recognize it.

24 mm may be looked upon as the normal sagittal or long diameter
of the eyeball. The average of the dimensions given by various authors
is as follows:

-f\ Ls

For the sagittal diameter 24.26 mm

For the transverse diameter 23.7 mm

For the vertical diameter 23 . 57 mm

The majority find the sagittal diameter to be the greatest, some,
however, e.g., Leopold Weiss (235), the transverse; it is possible that
racial peculiarities are responsible for this.

The limits within which the normal eye may vary have been deter-
mined, especially for the sagittal diameter, since this one is of the greatest
importance in its relation to refraction. Schnabel and Herrenheiser (190)
found an axial length of 22.5 to 26 mm in emmetropia. However, I
doubt whether the upper limit is not carried too far, because, according
to Elschnig (52), the form of the optic nerve entrance characteristic for
the slightly myopic eye very frequently makes its appearance in such long
emmetropic eyes.

Here as everywhere else the normal condition goes imperceptibly over into the
pathologic, and the border line which one draws between the two is, necessarily,



FORM, SIZE, ORIENTATION 5

somewhat arbitrary and must have a position varying with the individual conception.
In my opinion the finding of emmetropia does not in and of itself guarantee the
normal structure of the eye. The normal form and the normal internal make-up of
the eye must be considered as well; I need only to mention here the operated
myopic eye, which can be emmetropic under favorable circumstances and yet possesses
the anatomic evidence of high-grade myopia and all the weakness of such an eye.

The eyeball of a man is about o . 5 mm larger in all dimensions than
that of a woman. Sappey (186) gives the following figures (in the same
order as above) :

For the eyeball of a man 24.6X23.9X23.5 mm

For the eyeball of a woman 23.9X23.4X23 mm

The weight, according to L. Weiss (235), is 7.5 g, the volume 7 . 2 cm 3 .

For the orientation of the surface of the eyeball one makes use of the
same constructions as on the surface of the earth.

The mid-point of the cornea determines the anterior pole of the
eyeball. It lies diametrically opposite the posterior pole, which has no
other anatomic characteristic, so can be found only by construction or
measurement. The line of union between the two poles forms the
goemetric axis of the eyeball.

It is well to distinguish this from the optic axis, i.e., the line upon which the focal
points of the refracting surfaces lie, as well from the visual line, i.e., the line of union
between the fovea centralis and the nodal point of the optic system. In the strict
mathematical sense an optic axis exists only in the rarest instances, for the foci of the
three most important refracting surfaces (anterior corneal, anterior and posterior lental)
do not lie upon one and the same straight line at all as a rule (Zeeman, 244). The visual
line bears away strongly from the geometric axis in any case, for the fovea lies temporal
to and below the posterior pole.

If one measures the geometric axis from the anterior surface of the
cornea to the posterior surface of the sclera, it may also well be called
the outer axis; if, however, one measures only to the light-perceiving
layer, i.e., to the outer surface of the retina, one calls this dimension
the inner axis. It is this dimension which comes into consideration in
the refraction of the eye.

Those circles which can be drawn through both poles are called
meridians; the equator is that circle which is equidistant from the two
poles.

This is the geometric equator and according to the above statements does not
coincide with the anatomic equator.

A section through the vertical meridian divides the eyeball into a
nasal or medial, and a temporal or lateral half. The expressions "inner"
and "outer" should never be used in the sense of medial and lateral, but
only as follows: inner is that which lies nearer the mid-point of the



6 ANATOMY AND HISTOLOGY OF THE HUMAN EYEBALL

eye, outer that which lies nearer the surface. The expressions "forward"
and "backward" do not refer to the sagittal direction alone but to the
meridian as well: forward is that which lies nearer the anterior pole.

For example, the edge of the ciliary body bordering upon the trabeculum of the
iris angle is called the anterior, that bordering upon the chorioidea, the posterior border,
despite the fact that the difference in position in a sagittal direction is much less than
in a frontal one. But if one were to refer to parts according to their actual position,
the description would become extremely inconstant and confused.

Since we mainly make use of sections to illustrate anatomic relation-
ships, it may be well to say something here concerning the direction of
sections and what they are called.

The most important section direction is the meridional, i.e., a section in
the plane of a meridian. Of the various meridians, the horizontal one comes
mainly into consideration for anatomic purposes. It contains the most
details, and horizontal sections, as they are called for short, are, therefore,
the most instructive. Other meridians are only chosen for special purposes.
Frontal or equatorial sections are sections parallel to the equatorial plane.

In most cases, however, a direction of sectioning must be chosen
which does not coincide with any of these. In this case when the section
is made at right angles to the meridian and at right angles to the surface
of the bulb, I call it a transverse section, for it stands in the same rela-
tion to a meridional section of the area affected as does the cross-section
to a longitudinal section.

When, on the other hand, the section falls parallel or tangential to
the surface, it is called a surface section. Since, however, most of the
surfaces of the bulb are curved, only tangential sections can be made, and
in such sections the tissue is actually cut along the surface over only one
small area; farther away from this place the sections become increasingly
oblique (the same holds true for transverse sections).

For purely histologic purposes such surface sections are usually
very useful, for even the area which is actually cut along the surface
contains a very considerable number of tissue elements. On the other
hand, surface sections are inadequate for anatomic .purposes, in which
the general view is more sought for, and must be replaced by surface
preparations, i.e., by thin sections, which are only obtained by anatomic
preparations.

Today there is a tendency to study sections only, because the modern staining
methods lend themselves better to sections, and, indeed, sections give very beautiful
and instructive pictures. Above all, the modern section methods contribute an incom-
parable amount to the topography. The older methods of anatomic preparation
and the teased preparations do not, however, by any means deserve the disregard which
they today receive. In the first place they show us the tissue elements in a much more



SURFACE OF THE EYEBALL



natural state, and warrant histologic conclusions far better than do cut preparations.
Generally, one can very well combine modern staining with anatomic preparations.

The making of surface and teased preparations demands of course much more care
and skill than do cut preparations, and one must also reckon with a large percentage
of failure. But one successful preparation of this kind may give data which one seeks
in vain in hundreds of cut sections. So a thorough knowledge of anatomic and histo-
logic relationships is only to be had by the use of both the older and newer methods.

The physical conception of the structures and tissue elements is, above all, the
fruit of this combination of methods. It should be the first and most important object
of histo-anatomic study. I, at least, consider it one of the main objects of teaching to
convey a correct physical conception.

II. Surface of the Eyeball

(Text Fig. 2)

In the examination of the outer surface of the eyeball the cornea,
in front, first presents itself (Text Fig. 2 a, C). Its relation to the sulcus
sclerae externus has already been spoken of. The cornea is slightly ellip-
tical, for the horizontal diameter is greater than the vertical. The

a b c




N N




TEXT FIG. 2. Topography of the surface of the eyeball (right eye). Magnification i .5.

a view in front, b from behind, c from above. N nasal, T temporal side, C cornea, O optic nerve,
Rm line of insertion of the musculus rectus medialis, Rl line of insertion of the musculus rectus lateralis,
Rs line of insertion of the musculus rectus superior, Ri line of insertion of the musculus rectus inferior,
Os line of insertion of the musculus obliquus superior, 01 line of insertion of the musculus obliquus infe-
rior, Am arteria ciliaris posterior longa medialis, Al arteria ciliaris posterior longa lateralis, Vi F 2 V 3 F 4
venae vorticosae. The dotted lines in a and b indicate the two main meridians, in c the vertical meridian
and the geometric equator.

conjunctiva sclerae continues over into the outer layers of the cornea and
is also more firmly adherent to the sclera over the. floor of the sulcus
sclerae; farther back, however, it is united to the sclera by very loose
connective tissue only. One is therefore compelled to leave a strip
(stump) of conjunctiva, i mm or so in length, on the bulb at the time of
enucleation. This stump contracts and in the anatomic preparation
usually appears somewhat prominent or bulging. This tumifaction is
therefore an artefact; when all the parts are in situ and uninjured, there



8 ANATOMY AND HISTOLOGY OF THE HUMAN EYEBALL

is no sudden change of level visible in the transition from the conjunctiva
onto the cornea.

Farther away from the margin of the cornea but still in the anterior
half of the bulb, one comes upon the lines of insertion of the recti muscles.

The following measurements are taken from Fuchs (65). They are
the averages found in 31 emmetropic eyes.

Text Fig. 2, given herewith, does not agree exactly with these measurements; the
figure presents a concrete case. Furthermore, a perspective foreshortening comes out
in the marginal portions; therefore the insertion lines appear concave while in reality,
i.e., when viewed at right angles to the surface, they are straight or weakly convex.

The insertion lines of the m. rectus medialis (Km) and m. rectus late-
ralis (Rl) are vertical, straight, and usually symmetrical to the hori-
zontal meridian (although that of the medialis lies somewhat lower,
the lateralis somewhat higher).

The insertion lines of the m. rectus superior (Rs) and m. rectus
inferior (Ri) are weakly convex forward and lie in an oblique plane so
that the nasal end of the insertion lies nearer the cornea than the tem-
poral end. Both lines of insertion are, moreover, shifted somewhat
temporal.

The distance from the margin of the cornea and the breadth of the
tendon (or length of the line of insertion) is shown in the following table :





Distance from the Cornea


Width of Tendon


M. rectus medialis


5 5 mm


10 3 mm


M . rectus lateralis


6 o


2


M . rectus superior


7 7


10 6


M. rectus inferior. . . .


6 c


8









The insertion lines of the m. obliqui lie in the back half of the bulb-
that of the m. obliquus superior above, that of the m. obliquus inferior
temporal (Text Fig. 2, b, c).

The insertion line of the m. obliquus superior (Os) forms a 10.7 mm
long bow with convexity backward. Its anterior end lies in about the
same meridian as the temporal end of the insertion of the rectus superior.
The greater part (sometimes the whole) of the insertion line lies temporal
to the vertical meridian; the angle which it forms with the vertical merid-
ian measures on the average 45, but this is subject to wide variation.
According to Fuchs, one can distinguish two types of insertion lines, the
one having a more equatorial, the other a more meridional direction.

The m. obliquus inferior (Oi} has the shortest tendon of all the eye
muscles (often practically none at all). One, therefore, often sees cross-



SURFACE OF THE EYEBALL 9

sections of muscle-fibers clinging to the outer surface of the sclera on
the temporal side in horizontal sections through the posterior half of the
eye; they belong to the m. obliquus inferior, and give one data as to which
is the temporal side. The insertion line is 9 . 4 mm long and forms a bow
with its convexity upward, but often shows gross irregularities, such as
angular serrations or dehiscences. It lies for the most part below the
horizontal meridian and makes an angle of some 19 with it. The pos-
terior (nasal) end of the insertion comes to within 5 mm of the sheath
of the optic nerve, the anterior (temporal) end lies in about the same
meridian as the lower end of the insertion of the rectus lateralis.



Online LibraryMaximilian SalzmannThe anatomy and histology of the human eyeball in the normal state, its development and senescence ; → online text (page 1 of 27)