A manual of clinical ophthalmology

Front matter

THE LIBRARY

OF

LOS ANGELES

Part I. Page

GENERAL CONSIDERATIONS, STRUCTURAL AND PHYSIOLOGICAL.

Sclera. — Cornea. — Choroid. — Ciliary Body. — Ciliary Processes. — Iris— Retina. — Anterior Chamber. — Posterior Chamber. — , Vitreous Chamber. — Hyaloid Membrane. — Ligament of the Lens. — Crystalline Lens. — Anterior Capsule. — Optic Nerve. — Optic Tracts. — Chiasm. — Nerves. — Arteries and Veins. — Lymphatics.— Muscles. — Optic Axis. — Conjunctiva. — Lacrymal Apparatus. — Accommodation. — Relative Accommodation. — The Metre Angle. — Test Cards and Lenses. — Field of Vision. — The Perimeter. — Colors. — Color-Sense. — Color-Blindness, .... 9-41

Part II. Physiological Optics

Reflection. — Refraction by Plane, Prismatic, Spherical, and Cylindrical Lenses. — The Dioptric System. — The Ophthalmoscope. — Formation of Images by Direct and Indirect Methods, 42-52

Part III. Refraction

Normal Refraction. — Emmetropia. — Hypermetropia. — Myopia. — Astigmatism. — The Refraction Ophthalmoscope. — Direct Examination. — Indirect Examination. — Determination of Refraction by the Ophthalmoscope. — Retinosocpy by the Plane

Mirror. — Presbyopia. — Mydriatics, 53"77

vii

VI11 TABLE OF CONTENTS.

Part IV. Pack

THE OCULAR MUSCLES.

Paralysis of. — Ophthalmoplegia Externa and Interna. — Nystagmus. — Orthophoria. — Hetcrophoria. — Orthotropia. — Heterotropia. — The Tests for Muscular Strength — Symptoms of Heterophoria. — Diagnosis of Heterophoria. — Treatment of Heterophoria. — Strabismus, 78-9,'

Part V. Diseases Of The Conjunctiva

Hyperaemia. — Conjunctivitis: Acute Catarrhal, Chronic Catarrbal, Vernal, Follicular, Granular, Blennorrhoeal, Phlyctenular, Croupous, Diphtheritic. — Xerosis. — Pterygium.— Tumors, . . . 92-105

Part VI. Diseases Of The Lids

Coloboma. — Epicanthus. — Congenital Ptosis. — Traumatism. — Phlegmon. — Hordeolum. — -Blepharitis. — Marginal Blepharitis. — Erythema. — CEdema. — Emphysema. — Rodent Ulcer. — Epithelioma.— Lupus. — Xanthelasma. — Chancre. — Chalazion. — Ecchymosis. — Milium. — Trichiasis. — Alopecia. — Pediculus Pubis. — Entropion. — Ectropion. — Blepharospasm. — Blepharophimosis. — Acquired Ptosis. — Symblepharon. — Ankyloblepbaron.

DISEASES OF THE LACRYMAL APPARATUS.

Hypertrophy of Lacrymal Gland. — Abscess of Lacrymal Gland. — Fistula of Lacrymal Gland. — Malposition of Puncta Lacrymalia. — Stricture of the Nasal Duct. — -Blennorrhcea of Lacrymal Sac. — Dacryocystitis. — Abscess of Lacrymal Sac. — Fistule of Lacrymal Sac, Io6-I2l

Part VII. Diseases Of The Cornea

Phlyctenular Keratitis. — Herpes. — Pannus. — Ophthalmic I lerpes Zoster. — Resorption Ulcer. — Serpiginous Ulcer — Interstitial or Parenchymatous Keratitis. — Abscess. — Neuro- Paralytic Keratitis. — Necrosis. — Arcus Senilis. — Opacities. — Conical Cornea.— Staphyloma. — Tumors.

DISEASES OF THE SCLERA.

Scleritis. — Anterior Staphyloma. — Posterior Staphyloma 122-135

TABLE OF CONTENTS. IX

Part VIII. Page

DISEASES OF THE CRYSTALLINE KENS AND LENS CAPSULE. Cataract: Central, Anterior Polar, Posterior Polar, Zonular, Total, Senile, Traumatic. — Dislocation of the Lens. — Apliakia. — Deposition on Anterior and Posterior Surfaces of Capsule. — Wounds. — Secondary Cataract, 136-146

Part IX. Diseases Of The Uveal Tract

The Iris. — Congenital Anomalies. — Aniridia. — Coloboma. — Persistent Pupillary Membrane. — Polycoria. — Albinism. — Hypersemia. — Plastic Iritis. — Serous Iritis. — Parenchymatous or Suppurative Iritis. — Mydriasis. — Myosis. — Argyll - Robertson Pupil. — Hyphsemia. — Detachment. — Tumors. — The Ciliary Body. — Cyclitis. — Sympathetic Inflammation. — Chronic Cyclitis.

DISEASES OF THE CHOROID.

Choroiditis. — Disseminated. — Areolar. — Central. — Central Senile

Atrophy. — Central Guttate, 147-162

Part X. Diseases Of The Vitreous

Hyalitis. — Muscae Volitantes. — Synchisis. — Synchisis Scintillans. —

Hyaloid Artery. — Foreign Bodies, 163-165

PART XL GLAUCOMA.

Simple, Chronic Inflammatory, Acute Inflammatory, Fulminating,

Secondary. — Glaucomatous Degeneration 166-171

Part XII. Diseases Of The Retina

Hyperremia. — Anaemia. — Embolism Central Retinal Artery. — Hemorrhage. — Opaque Nerve Fibres. — Hemorrhagic Retiniti?.— Albuminuric Retinitis. — Diffused Chronic Retinitis. — Retinitis Pigmentosa. — Detachment. — Acute Central Retinitis.— Hyperaesthesia. — Anaesthesia. — Glioma 172-184

X TABLE OF CONTENTS.

Part XIII. Pad!

DISEASES OK THE Optic NERVK.

Acute Neuritis. — Papillitis. — Retro- Bulbar Neuritis. — Atrophy. —

Tobacco and Alcohol Amblyopia. — Hemianopsia, i<\=; !')_•

Part XIV. *

DISEASES OF THE ORBITAL CAVITY.

Periostitis. — Phlegmon. — Tumors. — Exophthalmus. — Enophthalmus. 193-194

Part XV. Operations

Cataract Extraction with Iridectomy. — Cataract Extraction without Iridectomy. — Discission. — Iridectomy. — Iritomy. — Paracentesis Cornea. — Sc-emisch Incision. — Conical Cornea. — Staphyloma Cornea and Sclera. — Tattooing. — Foreign Bodies in Conjunctiva, in Cornea, in Anterior Chamber, in Lens, in Vitreous Chamber.— Tenotomy. — Graded or Partial Tenotomy. — Advancement of Tendon. — Enucleation. — Symblepharon. — Ankyloblepharon. — Canthotomy. — Canthoplasty. — Tarsorraphy. — Excision of Cilize. — Entropion. — Ectropion. — Chalazion. — Ptosis. — Stricture of Lacrymal Duct. — Epithelioma. — Ulcer. — Naevi. — Warty Kxcrescences, 195-223

LIST OF ILLUSTRATIONS.*

KIG. PAGE

1. Vertical Section of the Cornea, II

2. Vertical Section of the Choroid, 12

3. Antero- Posterior Section of the Cornea and Sclerotic, 13

4. Anterior Quadrant of a Horizontal Section of the Eyeball, Cornea,

and Lens, 15

5. Vertical Section of Human Retina, . . 16

6. Section of the Fovea Centralis, 17

7. Fibres of the Lens, 19

8. Diagram of the Decussation of the Optic Tracts, 19

9. Horizontal Section of the Entrance of the Optic Nerve and the Coats

of the Eye, 20

10. Diagram of the Blood-vessels of the Eye, 23

n. Lateral View of the Muscles of the Eyeball, . . . . 26

12. Vertical Section through the Upper Eyelid, 28

13. Lacrymal Apparatus 30

14. Scheme of the Accommodation for Near and Distant Objects, ... 32

15. Test Case 35

16. McHardy's Perimeter, 38

17. Spectrum Obtained by Means of a Prism, 40

1 8. Refraction by Medium with Parallel Sides, 43

19. Refraction by a Prism, 44

20. Juxtaposed Prisms, 45

21. Different Forms of Spherical Lenses, 45

22. Refraction of Parallel, Diverging and Converging Rays by Convex

Lens, 46

23. Refraction of Parallel Rays by Concave Lens, 48

24. Cylinders, 48

25. Direct Examination by Ophthalmoscope, 51

* None of the illustrations are original ; they have been taken from the works of Meyer, Netileship, Landois and Stirling, Littell, Harlan, and Jaeger. E. A. Yarnall & Co. have furnished the cuts for the instruments, and J. L. Borsch & Co. for lenses and for an astigmatic chart.

xi

Xll LIST OF ILLUSTRATIONS.

FIG. PAGE

26. Indirect Examination by Ophthalmoscope, 52

27. Condition of Refraction in the Normal Passive Eye and During

Accommodation, 53

28. Condition of Refraction in the Normal Eye During Accommodation, 54

29. Hypermetropic Eye 55

30. Myopic Eye, 57

31. Action of an Astigmatic Surface on a Cone of Light, 60

32. Astigmatic Clock for Testing Astigmatism 62

33. Morton's Ophthalmoscope, 64

34. The Entrance of the Optic Nerve with the Adjacent Parts of the

Fundus of the Normal Eye, 65

35. Illustration of Retinoscopy by the Plane Mirror, 69

36. Diagrams of Range of Accommodation in E., H., and M., .... 74

37. Scheme of the Action of the Ocular Muscles, 79

38. Pathological Convergence : Homonymous Diplopia, 80

39. Pathological Divergence : Heteronymous Diplopia, 8l

40. Conjunctival and Subconjunctival Injection, 93

41. Granular Conjunctivitis, 96

42. Pannus Affecting Upper Half of Cornea, 98

43. Phlyctenular Ophthalmia, Conjunctival Form, 102

44. Pterygium, . 105

45. Epicanthus, 106

47. Meibomian Cyst. Lid Forceps, 1 1 1

48. Trichiasis, 1 1 3

49. Distichiasis, 113

50. Entropion of Lower Lids, 114

51. Ectropion of Lower Lid 115

52. Symblepharon, 117

53. Ankyloblepharon, 117

54. Lacrymal Gland 118

55. Fistule of Lacrymal Sac, 120

56. Phlyctenular Ulcer 123

57. Perforating Ulcer of the Cornea ; Adhesion of Iris, 126

58. Onxy and Hypopyon, 126

59. Acute Serpiginous Ulcer of the Cornea 127

60. Interstitial Keratitis, 128

61. Partial Staphyloma of the Cornea, 130

62. Partial Staphyloma of the Cornea and Iris, 130

63. Total Staphyloma of the Cornea and Iris, 131

LIST OF ILLUSTRATIONS. xiii

FIG. PAGE

64. Staphyloma of Sclera 133

65. Post-Staphyloma, „ 134

66. Posterior Polar Cataract, 136

Illustrations of Cataract, 139 and 140

67. Posterior Synechia, 148

68. Serous Iritis, 151

69. Atrophy after Syphilitic Choroiditis, 159

70. Central Choroiditis, 159

71. Central Guttate Senile Choroiditis, 160

72. Glaucomatous Excavation of the Optic Nerve (Vertical Section), . 168

73. Glaucomatous Excavation (Ophthalmoscopic View), 168

74. Embolism of the Central Artery of the Retina, 173

75. RetinitisxAlbuminurica, 177

76. Retinitis Pigmentosa, 180

77. Ophthalmoscopic Appearance of Detached Retina, 181

78. Optic Neuritis, 186

79. Atrophic Excavation, 189

80. Lid Speculum, 196

81. Fixation Forceps, 196

82. Graefe Cataract Knife, 196

83. Iris Forceps, 197

84. Iridectomy Scissors, 197

85. Cystotome 198

86. Expulsion of the Cataract, 198

87. Graefe Cataract Spoon and Cystotome, 198

88. Wire Loop, 200

89. Lens Extractor, 200

90. Discission, 201

91. Soft Cataract Needle, 202

92. Escape of Lens Masses from Anterior Chamber, 202

93. Linear Incision at the Superior Margin of the Cornea, 203

94. Iridectomy Knife, 203

95. Artificial Pupil as seen in Anterior Chamber after Iridectomy, . . . 204

96. Iridotomy Knife, 204

97. De Wecker's Iritomy Scissors, 205

98. Paracentesis Knife, 205

99. Needles in Position (Ant. Staphyloma), 206

100. Excision of the Staphyloma, 207

101. Appearance of the Stump after Excision of the Staphyloma, . . . 207

102. Tattooing Needle 208

XIV LIST OF ILLUSTRATIONS.

FIG. PACK

104. Incision of the Conjunctiva 210

105. Section of the Tendinous Insertion, 210

106. Strabismus Hook 210

107. Conjunctival Scissors, 211

108. Enucleation Scissors, 214

109. Operation for Symblepharon, 215

no. Aril's Method 215

111. Canthoplasty, 216

112. Tarsorrhaphia, 217

113. Horn Plate, 217

114. Lid Forceps, 217

115. Operation for Distichiasis, .'.... 218

1 1 6. Operation for Ectropion, 220

117. Operation for Ectropion, 220

118. Canaliculus Knife, 221

119. Probing the Nasal Duct, 222

1 20. Bowman's Probes, 222

ERRATUM.

Page 77, line 9. Hydrobromate should read Hydrochlorate.

A MANUAL

CLINICAL OPHTHALMOLOGY,

Part I. General Considerations— Structural And Physiological

The human eyeball is spheroidal in shape ; 24 mm. in its antero-posterior, 23 mm. in its transverse, and 23 mm. in its vertical axis. Three tunics are commonly described, namely, an inner percipient coat, the retina, a middle vascular coat, the choroid, and an outer and protecting coat, the sclera, with its transparent continuation in front, the cornea.

The sclera is a bluish-white, opaque, dense, resisting membrane, composed of closely interlacing connective tissue fibres with a sparse intermingling of fine elastic tissue. Among the fibres are numerous lymph channels communicating with the lymph system of the cornea, the underlying peri-choroid, and with the overlying capsule of Tenon. A few small blood-vessels and nerves are distributed throughout its substance. Slightly below and four mm. to the nasal side of the posterior extremity of the horizontal axis of the

IO A MANUAL OF CLINICAL OPHTHALMOLOGY.

ball is an incomplete opening, \y* mm. in diameter, the sclerotic foramen, over which is stretched a white fibrous veil, the lamina cribrosa, pierced by the optic nerve, central artery and vein of the retina. At the margin of this foramen the sclera is one mm. thick, being reinforced by a deflection of the outer sheath of the optic nerve, and gradually thins off anteriorly, to be again reinforced six to eight mm. back of the limbus cornea, corneo-sclcral margin , by the expanding tendons of the recti muscles. It is marked just at its corneal border by a slight depression, the su/cus schra. The sclera is pierced ten to twelve mm. from the foramen sclera by the posterior ciliary vessels and nerves ; again midway between the optic nerve entrance and cornea, by four or five large veins, venae vorticosae, which empty into the ophthalmic vein. It is again perforated two mm. from the limbus cornea by the anterior ciliary vessels, four or five in number.

The cornea is the anterior, smaller and transparent portion of the external tunic, measuring eleven mm. vertically, twelve mm. horizontally, and one mm. in thickness at its apex. The layers may be multiplied indefinitely by resorting to useless and confusing subdivision ; three are here given. The anterior layer consists of columnar epithelium continuous with the epithelium of the conjunctiva, and a homogeneous elastic, basement membrane (Bowman's). The second or middle layer composes the tissue proper of the cornea, and is formed by sixty or more laminae of fibrous tissue, containing, in great number, irregularly placed lymph spaces, in which lie the corneal cells, connected with each other in all directions by canaliculi. The posterior layer consists of a homogeneous basement membrane (Descemet's), on which is a single layer of hexagonal cells continuous with that on the anterior surface of the iris.

GENERAL CONSIDERATIONS.

II

In health the cornea is devoid of blood-vessels, except at its periphery, and contains under Bowman's membrane a few terminal branches of the ciliary nerves. There is anatomically no distinct line of union between the sclera and cornea, but the former slightly overlaps the latter on its anterior aspect, and beneath this shelving border of sclera, in clear cornea, lies the canal of Schlemm, which is con-

FIG. i.

VERTICAL SECTION OF THE CORNEA, STAINED WITH GOLD CHLORIDE.

n. Nerve-fibrils, a. Perforating branch, r. Nucleus. /, b. Inter-epithelial termination of fibrils, s. Anterior elastic laminae.

nected with the angle of the anterior chamber by the spaces of Fontana.

The choroid is the vascular and pigmentary coat, extending posteriorly from fo& foramen opticus choroidea, through which the optic nerve passes, and anteriorly to the ciliary region. Its outer surface lines the sclera from which it is separated by a double layer of serous membrane, suprackoroidal lymph space, and its inner surface is attached to the basal membrane of the pigment coat of the retina as far forward as the ora serrata. The choroid may be divided into

A MANUAL OF CLINICAL OPHTHALMOLOGY.

two layers : an outer, containing relatively larger vessels and more pigment, and an inner, containing capillary vessels and less pigment. The most conspicuous vessels of the external layer are the veins, which, converging, form the vena vorticosce. The capillary vessels of the inner layer are derived

FIG. 2.

VERTICAL SECTION OF THE CHOROID AND A PART OF THE SCLEROTIC.

i. Sclerotic. 2. Lamina suprachoroidea. 3. Layer of large vessels. 4. Limiting layer. 5. Chorio-capillaris. 6. Hyaline membrane. 7. Pigment epithelium, g. Large blood-vessels. /. Pigment cells, c. Sections of capillaries.

mainly from the short ciliary arteries. The pigment, consisting of hexagonal cells filled with dark-brown granules, is scattered throughout both layers, occupying the meshes between the vessels in quantity and density sufficient to absorb light.

The ciliary body comprises the ciliary muscle and pro-

FIG. 3.

ANTERO-POSTERIOR SECTION OF THE CORNEA WITH THE SCLEROTIC.

a. Anterior corneal epithelium, b. Bowman's lamina, c. Corneal corpuscles. /. Corneal lamellae (the whole thickness lying between b and d is the substantia propria cornea). d. Descemet's membrane, e. Its epithelium, f. Junction of cornea with the sclerotic. ^. Limbus conjunctivae. //. Conjunctiva ; canal of Schlemm. k Leber's venous plexus (is regarded by Leber as belonging to i). m, m. Meshes in the tissue of the ligamentum iridis pectinatum. n. Attachment of the iris. o. Longitudinal, /, circular (divided transversely) bundles of fibres of the ciliary muscle, u. Transverse section of a ciliary artery, v. Epithelium of the iris (a continuation of that on the posterior surface of the cornea), iv. Substance of the iris. x. Pigment of the iris. z. A ciliary process.

cesses, and the space they occupy, together with the corresponding circular strip of sclera, is the ciliary region. The ciliary muscle, attached anteriorly to the ligaincntuni pectinatum iridis and lost posteriorly in the choroid opposite to the ora serrata, consists of radiating and circular bundles of unstriped muscular fibre, containing the arterial circle, the circulus ciliaris.

The ciliary processes consist of an anterior prolongation of the pigment stroma and blood-vessels of the choroid, with a reduplication into sixty or seventy folds, resting on the anterior periphery of the vitreous.

The Zone of Zinn is the pigmented indentations made by the ciliary processes in the hyaloid membrane.

The Iris is a circular framework of elastic and non-striped muscular fibres, lined anteriorly by flat epithelium, continuous with the membrane of Descemet, and posteriorly by the uvea, or pigment coat, continued forward from the ciliary processes. It is suspended in the aqueous humor 2l/t mm. behind the cornea, and in front of the lens and ciliary processes. By the ciliary ligament (ligamentum pectinatum iridis) its circumference is attached to the limbus cornea;. It is perforated by a nearly circular hole, the pupil, the margin of which, the pupillary border, lies in contact with the anterior capsule of the lens. The sphincter pupillce is a circular band of muscular fibres surrounding the pupil. The dilator iridis is, according to late authorities, not a muscle, but a fibre-elastic tissue. The iris has two circles of anastomosing vessels, the larger surrounding the ciliary and the smaller the pupillary border, branches of the anterior and long ciliary. Filaments from the lenticular (ophthalmic) ganglion, containing motor fibres from 3rd, sensitive from ist division of 5th, and sympathetic filaments from the carotid plexus, furnish its nerve supply.

GENERAL CONSIDERATIONS.

The Retina, or nervous, tunic, is composed of three main layers : the inner, fibre and nerve-cell, the middle, granular, and the internal, or layer of rods, cones and pigment. The

FIG. 4.

ANTERIOR QUADRANT OF A HORIZONTAL SECTION OF THE EYEBALL, CORNEA, AND LENS.

Substantia propria of the cornea, b. Bowman's elastic membrane, c. Anterior corneal epithelium, d. Descemet's membrane, e. Its epithelium, f. Conjunctiva. g. Sclerotic, h. Iris. i. Sphincter iridis. j, Ligamentum pectinatum iridis, with the adjoining vacuolated tissue, k. Canal of Schlemm. /. Longitudinal, m, circular muscular fibres of the ciliary muscle, n. Ciliary process, o. Ciliary part of the retina. q. Canal of Petit, with Z, Zonule of Zinn, in front of it, and /, the posterior layer of the hyaloid membrane, r. Anterior, v, posterior part of the capsule of the lens. t. Choroid.4 u. Perichoroidal space. T. Pigment epithelium of the iris. x. Margin of the lens.

first or inner layer consists of the expanded intra-ocular extremity of the optic nerve fibres, stripped of their medullary sheaths, with numerous multipolar cells ; the second, of i6

A MANUAL OF CLINICAL OPHTHALMOLOGY.

granular and granulated cells, arranged in four strata, connecting the inner and outer ; the third is the sentient layer proper, and is composed of elongated nerve-cells, the rods

FIG. 5.

VERTICAL SECTION OF HUMAN RETINA.

a. Rods and cones. l>. Ext. and, /, int. limit, memb. c. Ext. and,/, int. nucl. layers, e. Ext. and, g, int. gran, layers, h. Blood-vessels and nerve cells. /. Nerve-fibres.

and somewhat shorter cones, inserted into the pigment layer. Each layer is transparent, with the exception of the pigment coat. The retina is about .25 mm. in thickness, covers the under surface of the choroid from the

GENERAL CONSIDERATIONS. \"J

foramen choroidea to the ora serrata, or notched and dentated anterior margin of the retina, allowing the lining membrane of vitreous to come into immediate contact with the choroid for the space of a few mm. behind the ciliary body. The macula lutea is a yellowish spot, as seen by the ophthalmoscope, irregular in shape, but usually circular, 0.5 mm. in diameter, and lies slightly to the temporal side of the posterior end of the optic axis. In the centre of the macula

FIG. 6.

SECTION OF THE FOVEA CENTRALIS.

a. Cones, b and g. Int. and ext. limit, memb. c. Ext. and e, nuclear layer, d. Fibres. f. Nerve-cells.

is the fovea centralis (Fig. 6), .2 mm. in diameter, characterized by an absence of all the layers of the retina, excepting modified rods and cones. The central artery and vein of the retina pass through the poms opticus, a comparatively large aperture in the lamina cribrosa, and, dividing, vertically, into large and, horizontally, small vessels, are distributed in the fibre layer of the retina, anastomosing at .the ora serrata with the choroidal and, at the optic nerve entrance, with the short ciliary vessels.

l8 A MANUAL OF CLINICAL OPHTHALMOLOGY.

The anterior chamber is an angular space, bounded in front by the posterior surface of the cornea, at its angle by the ligamentum pectinatum iridis, and behind by the anterior surface of the iris. It secretes and contains the aqueous humor, a feebly saline, transparent fluid.

The smaller posterior chamber is bounded in front by the posterior surface of the iris, and behind by the ciliary processes, suspensory ligament of the lens and lens, and contains aqueous humor. The anterior and posterior chambers are in free communication through the pupil.

The vitreous chamber is bounded by the retina, ciliary processes and lens, and contains the vitreous humor, a transparent, jelly-like substance, supported by numerous septa.

The Hyaloid membrane is a fine, transparent layer of connective tissue, enclosing the vitreous, and forms, by division anteriorly at the ciliary processes, the suspensory ligament of the lens. The canal of Petit is the name given to the space between the layers of the suspensory ligament at the periphery of the lens. Anteriorly the vitreous presents a well-marked depression, the hyaloid fossa, in which rests the posterior convexity of the lens. The vitreous is traversed in its antero-posterior axis in the foetus by the canal of Cloquet, containing the hyaloid artery.

The crystalline lens is a biconvex and transparent body, varying in consistence at different ages, from 8-10 mm. in diameter and 3—4 mm. in depth at its axis. It is enveloped in front by the capsule, at its periphery by the suspensory ligament, and behind by the hyaloid. Its substance is arranged in concentric lamellae, composed of minute fibrillae, hexagonal in horizontal section (Fig. 7, 2). Between the lamellae and among the fibres is an oil-like material, Liquor Morgagni, which permits of change of form without

GENERAL CONSIDERATIONS. 19

friction. The concentric lamellae are approximated by sutures, thus dividing the lens into sections along radiating planes. Considered as a whole, the lens consists of a nucleus, the almost structureless centre, and cortex, the outer fibrillary and softer portion.

Fie. 7.

FIG. 8.

FIG. 7. FIBRES OF THE LENS.

2. Transverse sections of the lens fibres.

FIG. 8. DIAGRAM OF THE DECUSSATION OF THE OPTIC TRACTS.

T. Semi-decussation in the chiasma. T, Q. Decussation of fibres behind the ext.geniculate bodies (C, G). a',b. Fibres which do not decussate in the chiasma. 6',a'. Fibres proceeding from the right eye and coming together in the left hemisphere (L, O, G). L,O,G,K. Lesion of the left optic tract, producing right lateral hemianopsia. a. Lesion in the left hemisphere, producing crossed amblyopia (right eye). T. Lesion producing temporal hemianopsia. n, n. Lesion producing nasal hemianopsia.

The anterior capsule is tough and elastic, and is lined on its posterior surface by a layer of hexagonal cells, whose function it is to nourish the fibres.

The fibres of the optic nerves (Fig. 8) arise in two bands, the optic tracts, from the corpora geniculata, corpora quad-

A MANUAL OF CLINICAL OPHTHALMOLOGY.

FIG. 9.

HORIZONTAL SECTION OF THE ENTRANCE OF THE OPTIC NERVE AND THE COATS OF THE EYE.

, Inner, i>. Outer, layers of the retina, c. Choroid. d. Sclerotic, t. Physiological cup. f. Central artery of retina in axial canal, g. Its point of bifurcation, h. Lamina cribrosa. /. Outer (dural) sheath, m. Outer (subdural} space. ». Inner (subarachnoid) space, r. Middle (arachnoid) sheath. /. Inner (pial) sheath. i. Bundles of nerve-fibres, k. Longitudinal septa of connective-tissue.

NERVES. 2 1

rigemina and ophthalmic ganglion, which are connected by radiating fibres with the cortical centre in the occipitoangular region of the cortex. Each optic tract winds obliquely across the corresponding crus cerebri, converges forward to meet its fellow on the opposite side, forming at their intersection the optic commissure, or chiasm. In the chiasm is a partial crossing of the fibres from each tract. The nerves arise from the chiasm, diverge, and each passes through the optic foramen in the corresponding lesser wing of the sphenoid bone. Each nerve is covered by prolongations of the membranes of the brain, which form its sheaths and between which are the intervaginal and subdural lymph-spaces. Just before the nerve reaches the lamina cribrosa, the network of connective tissue extending across the foramen sclera, the dura mater passes over into the sclera, the arachnoid and pia mater are discontinued, the medullary covering of the nerve fibres is dropped, and only the axes-cylinders pass through the foramen sclera and choroidea to form the nerve-fibre layer of the retina. Eighteen mm. posterior to this point, the ophthalmic artery and vein pierce the nerve obliquely, and having reached its centre, continue forward, and, passing through the porus opticus, are distributed to the retina.

NERVES.

The eyeball and its appendages are supplied by sensory branches from the first and second divisions of the fifth pair, motor branches from the third, fourth, sixth, and seventh pairs of cranial nerves, and sympathetic filaments from the carotid and cervical plexuses. The ciliary ganglion, lodged in the orbit below the superior and to the median side of the external rectus behind the ball, receives sympathetic fibres from the carotid plexus, sensory from the first or ophthalmic division of fifth, and motor fibres from the third. From it a small twig joins the branch of the third, supplying the inferior oblique, and from three to six branches, subdividing into twenty, the short ciliary, enter the sclera around the optic nerve. The ophthalmic division of the fifth gives off three purely sensitive branches just before passing through the sphenoidal fissure; the lacrymal, accompanying the lacrymal artery, runs along the external rectus muscle to the lacrymal gland, supplying it, conjunctiva, and integument of the upper lid ; the frontal, running forward above the levator palpebra? muscle, supplies by its two terminal branches the corrugator supercilii, occipito-frontalis, orbicularis palpebrarum, and the integument of the lids, forehead, and scalp ; the nasal, passing through the orbit and giving off a twig to the ophthalmic ganglion, as well as two or more branches — the long ciliary nerves, — which perforate the sclera with the short ciliary, and run forward between the sclera and choroid to be distributed to the ciliary body, iris, and cornea; and the infra-troclilear to the conjunctive and appendages of the eye.

The third nerve, motor oculi, supplies the internal, superior and inferior recti, inferior oblique, levator palpebnr, ciliary muscle, and iris, and furnishes a motor root to the ophthalmic ganglion.

The fourth nerve, trochlear, supplies the superior oblique.

The sixth nerve, abducens, supplies the external rectus.

The seventh nerve, facial, supplies the orbicularis palpebrarum.

ARTERIES.

The ball and its appendages (Fig. 10) are supplied with blood directly from the ophthalmic branches of the internal carotid, and indirectly by anastomoses between

ARTERIES.

its terminal branches and similar branches of the external carotid.

The lacrymal artery supplies the lacrymal gland, upper

DIAGRAM OF THE BLOOD-VESSELS OF THE EYE. {Horizontal view ; veins black, arteries light, with a double contour.')

aa. Short posterior ciliary, t. Long posterior ciliary, cc'. Anterior ciliary artery and vein. dd1 ' . Artery and vein of the conjunctiva. eef. Central artery and vein of retina. f. Blood-vessels of the inner, and, g, of the outer optic sheath, h. Vorticose vein. i. Posterior short ciliary vein confined to the sclerotic, k. Branch of the posterior short ciliary artery to the optic nerve. /. Anastomosis of the choroidal vessels with those of the optic nerve, m. Chorio-capillaris. n. Episcleral branches, o. Recurrent choroidal artery. /. Great circular artery of iris (transverse section), q. Blood-vessels of the iris. r. Ciliary process. .?. Branch of a vorticose vein from the ciliary muscle, u. Circular vein. v. Marginal loops of vessels on the cornea, -cu. Anterior artery and vein of the conjunctiva.

lid, and conjunctiva; the supraorbital,\\\z superior rectus and levator palpebne muscles, inner canthus, skin and muscles of the forehead ; the two palpebral, the lids ; the nasal, a branch to the lacrymal sac ; the short ciliary, pierce the sclera around the optic nerve and are the main supply to the choroid ; the long ciliary, supply the ciliary body and iris ; the anterior ciliary, given off from the muscular, perforate the sclera near the limbus, and supply the ciliary body and iris; the hvo muscular, supply the external ocular muscles.

LYMPH SYSTEM.

Lymph vessels, with their own walls, are found in the lids and conjunctiva, and empty into the parotid and submaxillary glands, accompanying the venae facialis and temporalis. In the conjunctiva is a superficial and deep network of canals communicating freely with one another, and in close connection with the lymph systems of the cornea and sclera. The spaces in the cornea communicate probably with the great lymph space of the anterior chamber by means of Schlemm's canal and the spaces of Fontana. On the sclera lies another lymph space, Tenon s capsule, composed of two layers of delicate connective tissue, an inner, episcleral, and an outer, muscular layer. The inner lies immediately on the sclera as far forward as the insertion of the tendons, where it is reflected into the outer. Between the tendons it is carried forward nearer the cornea, and is there reflected. Both layers are lined with epithelium and extend backward to the foramen sclera, communicating with the intervaginal lymph space. Between the sclera and choroid is a third space, the pcricJioroidca, communicating with Tenon's capsule by fine canals through the sclera. The vitreous body and lens are nourished by the surrounding

MUSCLES. 25

blood-vessels of the uveal tract, and do not certainly possess lymph vessels proper, as does the cornea. In the foetus, the lens is nourished by the hyaloid artery, which is given off from one of the branches of the arteria centralis retinae, and pursues a straight course through the vitreous, terminating in fine branches on its posterior lenticular surface.

It is said that from the ciliary body a stream of lymph flows downward and backward through the vitreous, then forward and through the canal of Petit to the posterior chamber ; downward and forward through the pupil into the anterior chamber, and outward to the angle, whence it escapes through the membrane of Descemet and ligamentum pectinatum to the canal of Schlemm. Tributary streams of lymph flow into the posterior chamber from the posterior surface of the iris and from the ciliary body, and into the anterior chamber from the anterior surface of the iris and meshes of Fontana's space. The corneal, scleral, conjunctival, perichoroidal, and Tenon's lymph spaces also communicate with the anterior chamber. The lymph canals of the retina accompany the retinal vessels and discharge through the poms opticus.