25G DR. IiUBEET AIEY ON A DISTINCT FORM OF TRANSIENT HEMIOPSIA. 
This account of my first atack may very well stand for a description of my last, about 
a month ago. The type has remained unaltered from that time to this. It is not stated, 
and I cannot remember, whether that first attack was on the right side or on the left : 
from the last words I should think it was the former. 
Since then I have very frequently been revisited by this affection, perhaps as often as 
a hundred times, possibly much oftener, sometimes at intervals of a month or two, or a 
week or two, or a day or two, sometimes on successive days, sometimes twice in the same 
day, sometimes twice in the same hour, the second attack beginning before the first had 
quite passed away. The circumstances and features of the complaint have varied some- 
what in different attacks. I will first describe its usual course, and then refer to 
varieties. 
Usually after two or three hours’ close reading, especially if I have had insufficient 
exercise, I become aware that part of the letter I am looking at, or a word at some little 
distance from the sight-point * (in most cases, below, to the left), is eclipsed by a dim 
cloud-spot that would not be noticed except for this obliteration. Even at this very 
earliest stage, the tremor, that is so characteristic of the developed disease, can be de- 
tected, and as the cloud enlarges, it begins to assume its proper zigzag outline, enriched 
with tinges of colour. 
At this early stage the spot is but faintly luminous in a dark room, or with the eyes 
shut and shaded, and scarcely shows at all against a bright sky. Its shape and colours 
are best seen by looking at a shady part of the ceiling or a neutral-tinted wall. 
When this blind spot makes its appearance close to the centre of vision, as soon as 
it begins to spread, and shows a serrated margin, it at once presents the irregular horse- 
shoe shape, with one arm adherent to the sight-point, and the other receding from it 
outward. The teeth of the adherent arm are small and fine, those of the receding arm 
grow larger and larger (Plate XXV. figs. 1-4). 
But when the blind spot takes origin at some distance from the centre of vision, as 
it spreads it preserves its contour unbroken, stellate, nearly circular, until its margin 
nears the centre of vision ; then the serration at the point nearest the centre shows irre- 
gularity, and a breach appears in the outline : one branch of the incomplete circle takes 
a smaller pattern of zigzag, and attaches itself to the centre of vision, the other branch 
takes a larger pattern of zigzag and recedes (Plate XXV. figs. 5-8). 
The enlargement is slow at first, and gradually quickens. 
Almost from the very first it may be noticed that parts of the faint cloud have a slow 
rolling heaving swaying motion to and fro, by which the outline is altered from time to 
time and again restored in the gradual outward spread ; and superadded to this slow 
rolling there is rapid flickering tremor (about five vibrations per second) of the marginal 
rays, affecting especially such parts as are rolling at the same time. 
* I have employed indifferently the expressions “ sight-point,” “ point of sight,” “ centre of vision,” “ cen- 
tre of the field of view,” to signify the point on which the eyes are fixed. 
