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BERKELEY^

LID-^ARY

unit- •.■i-r Of

CALI/Or\NIA



Pentlancf s Studeiits MaiuLals.



PRACTICAL OPHTHALMOLOGY.




M"SQl"AM ALRD SATIRA, ALILD SAI'IENTIA DIC'IT.



MAN UAL



OF



PRACTICAL
OPHTHALMOLOGY



GEORGE A. BERRY, M.B., F.R.C.S.Ed.

SENIOR OPHTHALMIC SUKGEON, ROYAL INFIRMARY ; SURGEON', EDINBURGH

EVE dispensary; OrHTHALMIC SURGEON, ROYAL HOSPITAL FOR

SICK CHILDREN ; LECTURER ON OPHTHALMOLOGY,

UNIVERSITY OF EDINBUKGH



ly/TH 223 ILLUSTRATIONS
MOSTLY FROM ORIGINAL DRAllTNGS



EDINBURCiH AND LONDON

YOUNG J. PENTLAND

1904



OPTOWnnY UBRARt



KOIXBUROII : rKINTEl) FOR YOUNG .'. rKNTLAXli, 11 TKX lOT I'LACE, AM>
38 WKST SM1TIIKIEM>, LONDON", E.C, BY MOKRISOX AND GIBU Ll.MlTRIi.



{All rlyhts rrsenrd.)






PREFACE.



Ophthalmology has long- held a foremost place amongst the
various branches of Medicine. In diagnosis, as well as in treat-
ment, it had already attained to a high degree of precision at a
time when modern scientific methods had as yet barely begun
to foreshadow the results which they are now almost daily
achieving in other departments.

Having thus early taken a leading position, the possibilities
of further advance seem in the meantime to have been propor-
tionately restricted. Coincident with the rapid strides made in
surgery generally, and with the many discoveries which seem
not unlikely to lead eventually to real therapeutic advances
in internal medicine. Ophthalmology has practically been at
a standstill.

This being so, and as there are already not a few text-books
on diseases of the eye, an addition to their number can hardly
claim to be called for because of the latest developments of the
subject being either very extensive or very important.

A large experience as a teacher has, however, shown me that
an adequate appreciation of the nature and treatment of even
the commoner forms of eye disease is far from being general.

I venture to hope, therefore, that there may ])e room for a
treatise which is both short and essentially practical, and which,
while representing without unnecessary detail current opinions
as to pathology, gives expression to the author's individual
experience as regards diagnosis and treatment.

Edinburgh, June 1904.



41^



COI^TENTS.

SECTION L

CHAPTER I.
General Remarks on Eye Operations.

PAGE

Instruments, Antiseptics, etc. ....... 3

CHAPTER II.

Examination of the Eye.

Preliminary Objective Examination : Inspection of the Lids — In-
spection of the Cornea — Intra-ocular Tension — The External
Muscles — Convergence. Subjective Examinations : Visual
Acuity — Snellen's Test Tyjies — Light Sense — Vision of the
Peripheral Portions of the Retina. Subjective Sensations : Pain
— Diplopia — Metamorphopsia — Scotomata — Sensations of
Light and Colour — Test for the Presence of Binocular Vision.
Further Objective Examination : Oblique Focal Illumination
— Examination with the Mirror alone. Normal Fundus Oculi
as seen with the Ophthalmoscope — The Retina — The Optic
Nerve — Physiological Excavation of the Disc — The Normal
Choroid 8

CHAPTER III.

Diseases of the Eyelids.

lutroductory — Blepharitis — Hordeolum or Stye — MoUuscum Con-
tagiosum — Warts, Papillomata, and Translucent Cysts —
Herpes Frontalis— Xanthelasma — Eczema — Milium — Chala-
zion or Tarsal Cyst — Chalky Infarcts — Trichiasis — Siiasmodic



CONTENTS.

I'AOK

Entropion — Cicatririal Eiitroition — Ei-tropion — Epicantluis —
Ptosis — Nictitatio — Blepharospasm — Oedema of the Lids —
Abscess of tlie Lid— Dermoid Cj'sts— Xaivi of the Lids— Rodent
Ulcers and Epitlieliomata — Chancre and Vaccine Pocks — Sar-
coma of the Lid — Colohonia — Hlepliarophimosis — Anchyloldc-
pliaron — Symbleiiharon ........ i'^



CHAPTEll IV.

Diseases of the Lachrymal Apparatus.

Affections of the Lachrymal Gland — Simple Hypertrophy or
Adenoma of the Laclnymal Gland — Fistula of the Lachrymal
Gland — Malignant Tumours — Dacryops — Diseases of the Tear
Passages — Poh'pi or Papillomata — Inflammation of the Tear
Sac — Acute Purulent Dacryocystitis ..... 77

CHAPTER V.

Diseases of the Conjunctiva.

The Normal Conjunctiva — Congestion — Conjunctivitis — Spring
Catarrh — Purulent Conjunctivitis — Ophthalmia Xeonatorum
— Phlj'ctenular Conjunctivitis — Diphtheritic Conjunctivitis —
Trachoma — Amj'loid Degeneration of the Conjunctiva —
Essential Shrinking of the Conjunctiva — Ecchymosis — Emphy-
sema — Pterygium — Pinguecula— Injuries — Foreign Bodies in
the Conjunctiva — Electric Light Ophthalmia — Snow-blind-
ness — Lymphangiectasis of the Conjunctiva — Tumours and
other Affections v^O

CHAPTER VI.

Diseases of the Cornea and Sclera.

General Remarks on Inflammation of the Cornea — Primary Kera-
titis — Corneal Ulceration. Special Forms of Primar}- Kera-
titis : Phlyctenular Keratitis — Fascicular Keratitis — Pannus —
Hypojiyon Keratitis — Dendriform (Mycotic) Keratitis — Clear
Corneal Ulcers — Marginal Ring-shaped Ulcer — Mooren's
Rodent Ulcer — Vesicular Keratitis. Secondary Keratitis —
Neuro-paralytic Keratitis. Non-inflammatorj^ and Degenera-
tive Changes in the Cornea : Transverse Calcareous Film —
Arcus Senilis — Conical Cornea. Tumours of the Cornea :



CONTEXTS.



Dermoid Cyst — Fibroma — Malignant Tumours. Congenital
Malformations of the Cornea — Injuries to the Cornea —
Deposits in the Cornea — Sclero-corneal Ruptures — Tattooing
of the Cornea — Seleritis ....... 136



CHAPTER VII.

Diseases of the Crystalline Lexs.

Introductory — Cataract — After -cataract — Congenital Cataract —
Capsular Cataract — Traumatic Cataract — Glass-blowers'
Cataract — Cataract Operations — Cataract Extraction with-
out Iridectomy — Operations for After-cataract — Dislocation
of the Lens 189

CHAPTER VIII.

Diseases of the Retina and Optic Xerve.

Diseases of the Retina — Hypersemia — Ansemia — Retinal H;«mor-
rliages — Retinitis — Retinitis Pigmentosa — Congenital Pig-
mentation of the Retina — Retinitis Proliferans — Embolism of
the Central Artery of the Retina — Detachment of the Retina
— Opaque Nerve Fibres iu the Retina — Retinal Changes pro-
duced by Strong Light. Diseases of the 0})tic Nerve : Optic
Neuritis — Atrophy of the Optic Nerve ..... 234

CHAPTER IX.

Diseases of the Iris and Ciliary Body.

The Iris — Hyperremia of tlie Iris — Iritis — Rheumatic Iritis — Gonor-
rhceal Iritis — Syphilitic Iritis — Serous Iritis — Traumatic Iritis
— Tuberculous Iritis — Cyclitis — Tumours of the Iris — Altera-
tions in the Iris produced by Injury- — Congenital Anomalies
of the Iris — Anterior Chamber ...... 274

CHAPTER X.

Diseases of the Choroid and Vitreous.

The Choroid — Choroiditis — Disseminated Choroiditis — Senile
Central Choroiditis — Syphilitic Choroiditis — Posterior Sclero-
choroiditis — Purulent Choroiditis — Rupture of tlie Choroid —



CONTENTS.



PAOB



Coloboma of the Choruid — Tubercle of the Choroid — Hiemor-
rliages in the Choroid — Ossification of the Choroid — Diseases
of tlie Vitreous — Opacities of the Vitreous — Persistent Hyaloid
Artery — Cysticercus in the Vitreous 307



CHAPTER XL

Foreic;n Bodies in the Eye.

Foreign Bodies in the Anterior Chamber — Foreign Bodies in the
Iris — Foreign Bodies in the Posterior Aqueous Chamber —
Foreign Bodies in the Lens — Foreign Bodies in the Posterior
Section of the Eye 336

CHAPTER XII.

Sympathetic Ophthalmitis.

Introductory — Sympathetic Irritation — Causes of Sympathetic
Ophthalmitis — Treatment — Prevention — Evisceration of the
(rlobe— Enucleation of the Eyeball 348



CHAPTER XIII.

Glaucoma.

Introductory — Primary Glaucoma — Premonitory Symptoms —
Dilatation of the Pupil — Haziness of the Cornea — Shallowness
of the Anterior Chamber — Enlargement of Episcleral Veins —
Excavation of the Papilla — Spontaneous Pulsation of the
Retinal Arteries — The Acuteness of Vision — Restriction of
the Field of Vision — Photopsia — Antesthesia of the Cornea —
Pain — Diagnosis — Secondary Glaucoma — Hemorrhagic Glau-
coma — Prognosis — Treatment ...... 360



CHAPTER XIV.

Intra-ocular Tumours.
Sarcoma of the Choroid and Ciliary Body — (ilioma of the Retina . 385



CONTENTS. xi

CHAPTER XV.

Diseases of the Orbit.

PAOK

IiiHammation of the Orbit : Orbital Periostitis — Orbital Cellulitis.
Tumours of the Orbit : Tumours of the Bony Wall of the
Orbit — Vascular Tumours of the Orbit — Tuniours of the Con-
nective Tissue, etc., of the Orbit — Malignant Tumours —
Tumours of the Optic Nerve. Tumours which Extend to the
Orbit from Adjacent Parts : Encephalocele — Nasal Polypi —
Tumours of the Lids and Skin of the Face — Aneurysm of the
Orbit — Injuries to the Orbit : Bleeding into Tenon's Capsule.
Foreign Bodies in the Orbit — Graves' Disease — Enophthalmos
—Shrinking of the Orbit 395



CHAPTER XVI.

Amblyopia and other Anomalies of Vision.

Introductory — Congenital Amblyopia — Simulated Amblyopia —
Amblyopia and Amaurosis due to Changes at the Visual
Centres, etc. — Central Toxic Amblyopia — Hysterical Ambly-
opia and Amaurosis — Subjective Sensations of Light and
Colour — Idiopathic Night Blindness — Muscae Volitantes —
Colour Blindness — Homonymous Hemianopia — Bi-temporal
Hemianopia .......... 412



SECTION 11.

CHAPTER XVII.

Errors of Refraction and Accommodation.

Emmetropia, Myopia, and Hypermetropia — Spherical Lenses — Use
of Spherical Lenses in Ametropia — Numbering of Lenses —
Accommodation — Presbyopia — Measurement of Ametropia —
Hypermetropia — Myopia — ■ Astigmatism — Headaches due to
Astigmatism — Irregular Astigmatism — Action of Prisms-
Anomalies of Accommodation : Paralysis of Accommodation —
Spasm of Accommodation ....... 439



xii CONTENTS.

CHAPTER XVIII. .

Affections of the Oculo-motor Muscles.

I'AOK

PhysiologiL'al and Introductory — Associated Movements — Con-
vergence — Combined Movements, Associated and Convergent
— Accommodation and Convergence — Latent Positions — Para-
lysis of Ocnlar Muscles — Relative Frequency of Different
Ocular Paralyses — Simultaneous Paralysis of Sevei'al Muscles
of One or Both Eyes — Paralysis of the External Rectus —
Paralysis of the Superior Oblique Muscle — Paralysis of the
Inferior Rectus — Paralysis of tlie Superior Rectus — Paralysis
of the Inferior Oblique — Paralysis of the Internal Rectus —
Paralysis of the Third Nerve — Spasms of Ocular Muscles —
Concomitant Strabismus — Convergent Strabismus — Divergent
Strabismus — Strabismus Operations — Operation for Advance-
ment of a Rectus Muscle — Effect of Tenotomy and Advance-
ment — Nystagmus — Muscular Asthenopia .... 493

INDEX 566



LIST OF ILLUSTEATIOTsTS.



KIG.
1.



8.

9.
•10.
11.
12.

13.
14.
15.
16.
17.
18.

19.
20.
21.

22.
23.
24.



25.



26.
27.



vessels, etc.



Drum for testing the jioints and cutting edges of eye instrument

Mr. Priestley Smith's balance .

Desmarres' retractor .....

Diagram of visual angle ....

Curve of average visual acuity at different ages in the case o

healthy eyes (after Boernia) .
Diagram showing horizontal extent of field of v
Self- registering perimeter (M 'Hardy)
Perimeter chart of field of vision
Field of vision taken by Bjerrum's method
Binocular corneal microscope (Czapski)
Normal fundus oc;ili ....

Showing ophthalmoscopic appearance which may be presented

by the normal macula lutea .
Normal discs, showing different arrangement of
Physiological excavation of disc (after Frost)
Blepharitis ......

From a case of severe blepharitis

Shows round swelling in upper lid caused by large tarsal cyst

Shows the appearance on the conjunctival surface of the same

tarsal cyst ......

From a case of trichiasis ....

Snellen's clamp .....

Showing position of threads in Snellen's operation before and

after knotting (after Fuchs) ......

Conjunctival ectropion of lower lid .....

Cicatricial ectropion of the upper lid ....

Ptosis operation : shows the position of the incision in the eye

brow, of the loops on the skin surface, and liy the dotted line

the extent of the pouch of undermined skin
Ptosis operation : shows in section the course of the sutures

before and after they are pulled tight ....
Primary syphilitic sore of upper lid .
Case showing slight degree of symblepharon of the lower lid



PAGE

4

5

10

11

13
15
17
18
19
28
33

34
37
41
45

47
52



63
66
67



70

70
73
74



XIV



LIST OF ILLUSTRATIONS.



29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.

49.

50.
51.
52.
53.

54.
55.



56.
57.

58.

59.

60.
61.

62.
63.
64.
65.



From a ca.se of almost complete symblepharon .
Teale's operation for .symblepharon .
Transverse .section of face .....

Weber's canaliculus knife .....

Operation of slitting canaliculus

Acute dacryocystitis .....

Showing Kocli-Wecks bacilli ....

Showing Morax diplo-bacilli ....

Conjunctivitis with marked swelling of the follicles
Buller's shield .......

Phlj^ctcnular conjunctivitis ....

Pustular conJTinctivitis .....

Canthoplasty (after Wecker) ....

Canthoidastj' (after Kuhnt) ....

Kuap]i's roller forceps .....

Dr. Chalmers Jamieson's rasp ....

Pterygium .......

Lymph angiectasis of the conjunctiva

Case of dermoid cyst of conjunctiva .

Case of melanoid sarcoma of the conjunctiva

Case showing extensive superficial vascularisation and ulceration

of the cornea ......

Anterior .synechia .....

Case of staphyloma .....

Thermo-cautery .....

Galvano -cautery .....

Case of partial staphyloma of the cornea for which

has been done .....
Fascicular keratitis .....
Showing the condition of pannus in the u]i]ier porl

cornea, also cicatrices in the conjnnctiva of the upper lid, in

a case of trachoma .....

Strumous pannus ......

Case of small infected corneal ulcer with hj-poiiyon

Case showing irregularly shaped spreading margin of infected

corneal ulcer with hypopyon (hyiiojiyon keratitis)
Case showing an extensive superficial ulceration of the dendritic

type . . • •.-.•.

From a case of non-vascularised interstitial keratitis .
From a case of diffuse interstitial keratitis with dense vascularisa-
tion at upper margin of cornea ......

Vascularised interstitial keratitis ......

Hutchin.son's teeth .........

Transverse calcareous band of cornea .....

Conical cornea





l-AOK




75




76




78




80




81




83




94




95




102




108




113




114




119




120




126




127




129




133


.


134




135


d ulceratioi






137




138




139




149




150


1 iridectomj






151




156


rtion of tin




pper lid, ii






157




158




159



160

162
166

166
167
168
171
173



LIST OF ILLUSTRATIONS.



FIG.

66.
67.
68.
69.
70.
71.
72.
73.
74.
75.
76.
77.



79.

80.

81.

82.

83.

84.

85.

86.

87.

88.

89.

90.

91.

92.

93.

94.

95.

96.

97.

98.

99.
100,
101.
102.
103.
104.
105.

106.



Dermoid cyst of cornea ....

From a case of corneal fibroma

Corneal spud .....

After Wecker ......

Grooved tattooing needle

Tattooing needles .....

Superficial scleritis .....

Changes produced by long-continued scleritis
Ulcers of the sclera ....

Small A'olkniann's spoon

Case of incipient senile cataract

Case showing the result of the operation of iridectomy in

ojiening up a pupil Avhich had become occluded
Case of lamellar cataract ; oblique illumination
Lamellar cataract ; ophthalmoscopic illumination
Showing histological appearance of capsular cataract in section

(after Fuchs)

Stationary (puuctiform) cataract
Case of traumatic cataract

Cataract stop-needle ....

Cataract scoop .....

a, Spring speculum ; h, fixation forceps .

a, Graefe's knife ; h, tortoise-shell scoop ; c, cystotome

a, Iris hook ; b, iris foi'ceps

Iris scissors ......

a, Wire vectis ; h, tortoise-shell spud ; c, wire elevator
Showing method of performing section for cataract extraction
Lens escaping through incision ....

Double wire gauze protector .....

Pagenstecher's spoon ......

Capsule forceps .......

Small knife used for discission ....

Showing the clear pupil got after a needling operation
Iridotomy .scissors ......

From a case in Avhich iridotomy has been done
Cystoid cicatrix .......

Traumatic subluxation of the lens ....

Case of idiopathic outward dislocation of the lens .

From a case of coloboma of the lens

Retinal hfemorrhages ......

Post-hsemon-hagic development of fibrous tissue in the super

ficial layers of the retina (after "Wecker and Masselon)
From a ca.se of sub-hyaloid hremorrhage which has undergone

partial absorption ....



xvi LIST OF ILLUSTIIATIOXS.

no. I'AOK
107. From a tyjiical case of albuminuric retinitis (after Wecker and

Massclon) " . . . . 243

lOS. Extensive retinal clianges in a case of albuminuric retinitis at

a late stage .......... 245

109. Diabetic retinitis (after Wecker and Massclon) . . 246

110. From a case of retinitis pigmentosa ..... 248

111. ,, ,, ,, 249

112. Congenital pigmentation of the retina ..... 2.52

113. Appearances in embolism of the central artery of the retina . 254

114. Changes caused l)y partial embolism ..... 255

115. Detachment of retina ........ 257

116. Case of detachment of the retina, with rupture . . . 260

117. Opaque nerve fibres (after Frost) ...... 262

118. Early stage of optic neuritis ....... 264

119. Later stage of optic neuritis ....... 265

120. Irregular dilatation of the pupil under atropine caused by

synechia; .......... 278

121. Iris bombe, with exudation on lens capsule .... 280

122. Iris bombe shown in section (after Fuclis) .... 281

123. Case of gummatous iritis ....... 288

124. ,, ,, 290

125. Case of serous irido-cyclitis 292

126. Case of tuberculous mass in iris and anterior chamber (granu-

loma iridis) ......... 295

127. Case of iris cyst ......... 299

128. Case showing separation of iris from its peripheral margin

(irido-dialysis) ......... 301

129. Congenital coloboma of the iris (downwards and inwards) . 302

130. ,, ,, ,, (downwards) . . . .303

131. Double coloboma of the iris with correctopia .... 304

132. Case of capsulo-pupillary membrane with surrounding white

("paint ") spots on cajisule. ...... 305

133. Disseminated choroiditis ....... 309

134. Recent disseminated choroiditis ...... 310

135. Circumscril>cd central choroido-retinitis in ati'ophic stage (after

"Wccker and Masselon) ....... 311

136. Disseminated choroiditis showing marked pigmentary

clianges .......... 312

137. Showing distortion of parallel lines round i)oint of fi.xatiou

(micropsia) . . . . . . . . . .313

138. Showing distortion of parallel lines in the case of macropsia . 313

139. Senile central choroiditis, with circumpupillary atrophy , . 315

140. Difl'use acute choroiditis ........ 316

141. Choroiditis, with marked disturbance of retinal pigment in

macular region ......... 317



LIST OF ILLUSTRATIONS. xvii

FIG. TAQK

142. Showing a recent patch of central choroido-retinitis (after

Frost) 318

143. Showing a large patch of central choroido-retinitis in the

advanced atrophic stages (after Frost) . . . . .319

144. From a case showing atrophic crescent at lower portion of disc 320

145. From a case of progressive myopia, showing staphyloma posti-

cnm and macular choroido-retinal changes .... 321

146. Ruptm-e of choroid . ........ 326

147. Coloboma of choroid 327

148. Showing formation of fine blood vessels in vitreous (after Frost) 332

149. Evisceration scoop ......... 3.56

l.'iO. Instrument for inserting glass glolje into eviscerated eyeball . 357

151. Enucleation scissors ........ 358

152. From a case of glaucoma ....... 365

153. Longitudinal section through papilla with glaucomatous ex-

cavation, showing cause of ophthalmoscopic appearances

(after Fuchs) 366

154. Diagrammatic representation of the diflerent forms of excava-

tion (after Fuchs) ........ 367

155. Typical defect of field of vision, from a case of glaucoma . . 369

156. Glaucoma field, by Bjerrum's method ..... 370

157. Keratome 380

158. Case of sarcoma of the choroid ...... 388

159. From a case of sarcoma of the choroid in the second stage . 389

160. Case of sarcoma of the choroid ...... 389

161. Section of eye filled with a melanotic sarcoma in the third

stage, after perforation has taken place .... 390

162. Section through eye and through the middle of a large glioma

of the retina which has begun to invade the optic nerve . 392

163. Section through eye and through large glioma of the retina

which entirely filled the vitreous chamber and had under-
gone extensive degenerative changes ..... 393

164. Glioma of the retina, complicated with " pseudo-glioma " . 393

165. From a case of syphilitic gumma at the upper and outer

margin of the orbit ..... ... 396

166. From a case of sarcoma of the orbit causing considerable proptosis 401

167. Aneurysm of the orbit ........ 404

168. Piece of clay pipe stem removed from the orbit . . . 407

169. Showing, by shaded area, shape and position of scotomata in

central toxic amblyopia • . . . . . . .417

170. Fields of vision from a case of homonymous hemiauopia . . 433

171. Fields of vision from a case of temporal hemiauopia . . 434

172. Showing the complete focussing of parallel rays in the case of

emmetropia, and incomplete focussing in hypermetropia

and myopia 440

b



xviii LIST OF ILLUSTRATIONS.

FIO. I'AOK

173. Showiug the longer refracting power of tlie more higlilj' curved

cornea . . . . . ... . . .440

174. Different forms of convex and concave spherical lenses , . 441
17r). Action of a concave lens in front of the eye .... 443

176. Showing action of a convex lens placed in front of the eye . 443

177. Diagram sliowing position of lens, etc., in eye at rest and in

accommodated eye (after Fiichs) ...... 447

178. Donders' curve of range of accommodation (after Nagel) . . 449

179. Sliowing the manner in whicli the action of a concave lens can

be overcome by alteration in tlic curvature of the crystalline
lens 450

180. Donders' curve of relative accommodation in the case of an

emmetropc, aet. 15 ....... . 452

181. To illustrate the estimation of refraction by direct ophthalmo-

scopic examination ........ 460

182. Curve representing the frequency of different degrees of re-

fractive anomalies in the literate and the illiterate (after
Tscherning, from examination of conscripts) . . . 470

183. Position of anterior and posterior focal lines in astigmatism . 473

184. Cylindrical lenses 474

185. Snellen's test for astigmatism ...... 476

186. Javal's ophthalmometer ........ 477

187. \Corneal images produced in examination witli ophthalmo- ("478

188. J meter U7S

189. Placido's disc 479

190. Distortion of Placido's rings on reflection from a cornea with

irregular astigmatism ........ 485

191. Snellen's spectacle frame ....... 486

192. Position of prisms causing adduction and diminishing the

necessity for abduction ....... 486

193. Position of prisms causing abduction and diminishing the

necessity for adduction ....... 487

194. To show the manner in which orthoscopic lenses are got . 488

195. Axes of rotation of ocular muscles ...... 494

196. Diagram showing movement of cornea produced by each muscle

separately . . . . . . . . . .495

197. Showing the deviation -which each eye tends to undergo under

an impulse to convergence, and the deviations of the two
eyes laterally under an impulse to associated lateral move-
ment 497

198. To show diagrammatically the measurement of convergence in

metre-angles ......... 498

199. Showing the manner in which deviations are measured on a

tangent scale by means of the Maddox rod .... 499

200. Maddox rod 500



LIST OF ILLUSTRATIONS.



FIG.

201.

202.
203.
204.
205.
206.
207.
208.
209.
210.
211.
212.
213.

214.
215.
216.
217.
218.
219.
220.
221.



222.
223.



Portion of a taiigeut scale graduated in metre angles for a
fixation distance of a J metre ......

Latent position in various states of refraction and accommodation



Shows manner of projection in abnormal convergence of right



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