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SURGERY AND OPHTHALMOLOGY. 491
tion conceived with the same object in view such as
iridodialysis have long since vanished from practice.
In the removal of cataract, the aetiology and anatomical
seat of which disease were more closely investigated,
extraction was the method chiefly employed as it appeared
in most cases to be the best and safest operation : another
method in use was couching of the affected lens which
SCARPA combined with discission and which BUCHHORN
advised should be performed through the cornea. The
operation of extraction was materially improved by making
the incision towards the upper part of the cornea, a method
recommended by F JAGER though perhaps practised pre­
viously by other ophthalmic surgeons and which eventually
led to linear extraction. The latter operation which had
been previously practised in certain cases, for instance in
shrivelled and soft cataracts, was improved and made
the common property of the profession by A. V. GRAEFE
who made his incision in the upper part of the cornea
and performed an iridectomy as part of the same operation.
Operations on the eye were remarkably facilitated when
mydriatics came into use. HlMLY drew attention to the
dilating effect upon the pupil of hyoscyamus and bella­
donna. Other drugs with similar properties were after­
wards discovered ; but the alkaloids and especially atropine
were chiefly used.
But there is no doubt that the greatest achievement of
ophthalmology in the 19th century was the discovery of
the ophthalmoscope. This instrument assumed a definite
shape in 1851 though the invention had been led up to by
researches upon the luminous fundus of the eyes of certain
animals which were in possession of a tapetum lucidum, by
observations upon the human retina in cases of absence of the
iris, and by PURKINJE'S experiments. While HELMHOLTZ,
the discoverer of the ophthalmoscope, elaborated nay almost
completely perfected its theory, it was chiefly A. VON
GRAEFE who recognized and demonstrated its importance