INSIDE THE EYE. 
465 
seen on the surface of the lens. A day’s experience at any ophthalmic 
clinique can mostly shoAv examples of this condition ; but it is only when 
these deposits are numerous, and in the central line of vision, that they 
become troublesome. They are then met with as the sequences of severe 
choroido-iritis, and usually coincide with further mischief in the vitreous and 
choroid. 
The vitreous, under the influence most commonly of choroiditis, and 
usually syphilitic choroiditis, presents alterations of the most striking cha- 
racter for ophthahnoscopic observation. The patients who offer these changes 
complain usually of considerable dimness of sight, which on examination i& 
found to include both diminution in the acuteness of visual perception, and 
iri the field of vision, or extent of any object seen at once. The 
great source of trouble to them is, that when they lift the eyes or move the 
head, black corpuscles, or streaks, or webs, float before their eyes, and obscure 
the objects at which they are looking ; and when the eyes are kept still, these 
fall again and disappear. Examine now the eyes of such an one, and you 
wiU see that the phenomena described are due to the existence of actual 
shreds, corpuscles, or webs of fibrous and albuminous exudation, which float 
in the vitreous, and at each motion of the eye rise in clouds and obscure the 
fundus, so that you can barely see it, or perhaps not at all. These conditions, 
I say, are mostly specific, but not invariably. They are sometimes the result 
of scrofula, and probably of other forms of choroiditis. 
Here, then, are a large number of cases in wbicli tbe 
ophthalmoscope transports ns at once from the regions of the 
known to the unknown. There are other classes of cases 
equally striking. Let me take illustrative examples. Two 
persons apply for advice, complaining that the sight has been 
gradually growing more and more dim, perhaps in one eye, — it 
may be in both. The progress of the disease has been insidious 
and nearly painless. The eyes are to all external appearance 
healthy, except probably that in both patients the pupils are 
partially dilated and sluggish. The ophthalmoscope helps us 
to solve the problem. 
The one is a case, it may be, of slow atrophy of the optic 
nerve, proceeding from central disease of the brain — from 
pressure on the optic tracts of nerve within the skull, or from 
defective nutrition following losses of blood. W e find the nerve 
glistening white and slightly cupped, the arteries small, the 
fundus otherwise healthy. In the other we recognize at once, 
in the fulness of the veins, their pulsation, and the marked 
excavation of the optic disc, the indications of excessive 
tension of the eyeball and undue pressure of the nerve. The 
first requires careful constitutional treatment and a long course 
of studied hygiene and medication ; the second calls for 
direct and immediate interference, with the view of relieving* 
the intra-ocular pressure. In the diagnosis of this great 
