Diseases of the Eye

recast of the section on Retinoscopy, which he had contributed to the first edition.

Messrs. J. H. Gemrig & Son of Philadelphia have very kindly furnished most of the cuts of instruments which illustrate the chapter on Operations. For the remainder, as well as for the illustrations of the ophthalmometer and the tropometer, the author is indebted to E. B. Meyrowitz of New York.

PHILADELPHIA: 1401 Locust St.
April, 1896.

PREFACE.

THIS book has been written in the hope that it may prove of service to students and practitioners who desire to begin the study of ophthalmology.

The methods of examining eyes, and the symptoms, diagnosis and treatment of ocular diseases have received the largest share of attention. The subject-matter has been given in greater detail than is customary in books written for students, because the author has been led to believe by those whom he has had the privilege of instructing in the Medical Department of the University of Pennsylvania, in the Philadelphia Polyclinic, and in the wards of the Philadelphia Hospital, that this presentation of the practice of ophthalmic science and the systematic examination of cases would be acceptable.

Certain illustrations, descriptions, and classifications taken from standard text-books and monographs, which have proved of special service in teaching students, have also been incorporated. These are properly acknowledged in the text, and a list of the books and brochures which have been constantly consulted during the preparation of these pages is also appended. Some previous writings of the author-Affections of

the Eyelids, Lachrymal Apparatus, Conjunctiva, and Cornea, in Keating's Cyclopædia of Diseases of Children, Vol. IV.; Congenital Anomalies of the Eye, in Hirst's System of Obstetrics, Vol. II.; and Diseases of the Eye (Revision of the chapter) in Ashhurst's Principles and Practice of Surgery (Fifth Edition)-have also been utilized.

Dr. JAMES WALLACE, Chief of the Eye Dispensary of the University Hospital, has written Chapters I. and IV.; that portion of Chapter III. which relates to reflection, the ophthalmoscope and its theory, and the explanation of the direct and indirect method; and that part of Chapter XIX. which describes the mechanism of diplopia, the rotation of the eyeball around the visual line, and the causes of concomitant convergent and divergent squint. He has also given valuable advice and assistance in reading the sheets for the press. Dr. EDWARD JACKSON, Professor of Ophthalmology in the Polyclinic, has written the section on Retinoscopy.

Philadelphia

The author

is indebted to these gentlemen for their aid, and for the presentation of the subjects entrusted to them in a manner which, he feels sure, will be satisfactory to students.

Messrs. J. H. GEMRIG and SON have very kindly furnished the cuts of the instruments which illustrate the chapter on Operations.

PHILADELPHIA: 1401 Locust St.,

March, 1892.

CONTENTS.

CHAPTER I.

GENERAL OPTICAL PRINCIPLES.

PAGE

Refraction-Index of Refraction-Prisms-Refraction through a Prism-

Angle of Deviation-Limit-angle of Refraction-Internal Reflection-

Numbering Prisms-Rays of Light-Lenses-Foci of Convex Lenses-

Foci of Concave Lenses-Formation of Images by Lenses-Focal Dis-

tance of a Lens-Numeration of Lenses-Spherical Lenses-Cylindrical

Lenses-Combination of Lenses-Visual Angle-Visual Acuteness-

Limit of Perception-Normal Acuteness of Vision-Accommodation-

Angle Gamma-Angle Alpha-Convergence-Metre-Angle . . . 17-56

CHAPTER II.

EXAMINATION OF THE PATIENT AND EXTERNAL EXAMINATION OF

THE EYE.

Direct Inspection of the Eye-Blood vessels of the Conjunctiva-Inspec-

tion of the Cornea-Oblique Illumination-The Corneal Loupe-The

Color of the Iris-The Pupil-Mobility of the Iris-Diliataton of the

Pupil-Contraction of the Pupil-Unequal Pupils-Testing Acuteness

of Vision-Light-sense-Color-sense-Method of Holmgren-Method

of Thomson-Lantern-test-Pseudo-isochromatic Plates of Stilling-

Accommodation-Mobility of the Eyes-Balance of the External Eye

Muscles - Heterophoria - Esophoria -Exophoria-Cyclophoria-Hy-

perphoria Power of Convergence-Field of Vision-Tension-Prop-

tosis-Position of the Eyes.

CHAPTER III.

REFLECTION. THE OPHTHALMOSCOPE AND ITS THEORY. OPHTHAL-

MOSCOPY AND RETINOSCOPY.

Reflection-The Ophthalmoscope-Direct Method-Indirect Method-
Ophthalmoscopy-Direct Method of Ophthalmoscopy-Examination
of the Cornea and Lens-Examination of the Vitreous-Examination

57-91

of the Transparent Media with Reference to the Position of Opacities

-The Normal Fundus Oculi-The Optic Nerve-The Blood vessels―

The Retina-The Macula Lutea-The Choroid-Determination of

Refraction by the Ophthalmoscope-Ophthalmoscopy by the Indirect

Method-Estimation of Refraction by the Indirect Method-Estimation

of Astigmatism by the Inverted Image-Ophthalmometry-Optometry

-Retinoscopy-The Use of Mydriatics

PAGE

92-138

CHAPTER IV.

NORMAL AND ABNORMAL REFRACTION.