DE. HTJBEET AIEY ON A DISTINCT EOEM OE TEANSIENT HEMIOPSIA. 253 
spreads out. I am now most distinctly able to say that it sometimes opens out from left 
to right, and sometimes from right to left. 
“ Here is what I find recorded in a memorandum of June 22 ult. — ‘The fortification 
pattern twice in my eyes today. The first was turned leftwards. Colours red and 
black, or red, yellow and black with little blue, and at moments only black and white. 
Also a sort of chequer worked filling in, in (?) rectangular patches, and a carpet-work 
pattern over the rest of the [internal] visual area. 
“ ‘ The second and far the brightest and most beautiful in colouring was turned to the 
right. Colours very vivid. Reel, blue, yellow, black. Not sure of any green.’ 
“ I have sometimes had an impression that one eye only was affected — the right eye 
being affected with the right-handed and the left with the left-handed spectrum ; but I 
never could devise any means of coming to a conclusion as to this point, and on the 
whole I lean to the opinion that both eyes are concerned in either case.” 
Very recently (1870, Jan 15) I have become acquainted, through the kindness of 
Professor Stokes, with the following description by Sir C. Wheatstone of a form of 
hemiopsia differing from my own in nothing but the total absence of colour. With the 
writer’s permission I insert the whole. 
“I will here subjoin the note I made at the time I was first attacked with this 
affection. 
“ 1 Sept. 30th, 1849. — This evening I had a curious affection of vision. Whilst I was 
writing, characters near the centre of vision became invisible. Thus fixing my eyes on 
the figure 6 in the group 4f, 4 and 7 were completely obliterated. On closing each eye 
alternately, I found precisely the same result. This did not arise from an ocular spec- 
trum, for neither a black nor a coloured spot was projected on the paper, the disappear- 
ance was exactly that of an object when placed in the projection of the entrance of the 
optic nerve. After a short time the spot became larger, spreading towards the left in 
both eyes until it occupied a large oval space; objects at and near the centre of vision 
reappeared, but nearly the left half of each retina was blinded. The phenomenon in its 
later stages was accompanied by an effect like the motion of a luminous liquid. At the 
time the luminous mist entirely passed away, about half an hour after its commence- 
ment, a slight fainting sensation came over me.’ 
“ I have frequently, though generally at very distant intervals, been subject to this 
affection. It has usually occurred whilst reading. It has always commenced near the 
centre of the retina, and ordinarily expanded towards the left. The zigzag luminous lines 
which border the spectrum externally do not commence until it has received some ex- 
pansion, and they become brighter as it enlarges ; before it disappears vision is restored 
to the central part of the retina, and when the zigzag lines arrive at the limit of the field 
of view, the entire vision becomes clear. On one occasion I drew with a pen the outline 
of the spot, a short time after its first development, as it appeared to each eye separately 
projected on the paper; both outlines exactly corresponded. I have never suffered any 
mdccclxx. 2 L 
