262 DR. HUBERT AIRS' ON A DISTINCT FORM OF TRANSIENT HEMIOPSIA. 
singular minuteness ; the eyes and hands were engaged in scaling-off a certain distance 
from a fine linear mark, and in bringing the zero of the scale to coincide with the linear 
mark the zero became invisible just at the moment when the two lines were on the point 
of coinciding. Again and again the trial was made, ineffectually, till the nature of the 
failure was recognized in the gradual development of the blindness. The spot of origin 
must have been exactly central. In this case there is no definite serrated margin, no 
colour, no curve, nothing of which a picture can be made. The obscurity gathers like 
a cloudy film or gauze over the field, oppressive to the eyes, and accompanied with head- 
ache and nausea, and passes away after a doubtful period, leaving the impression that it 
is caused by disorder of the stomach. To this case the name Teichopsia is quite inappli- 
cable ; but the spread of the blindness from a small central spot, its extension over a 
great part of the field, and its final disappearance, establish it as a distinct variety of the 
same affection. 
In yet a third case which I have recently met with, the blindness is sometimes brought 
on by looking at a striped wall-paper or a striped dress. The appearance before the eyes 
is described as zigzag, wavy, quivering, without colour. The first attack, in adult age, 
was followed by partial paralysis of one side ; and later attacks have almost always had 
a sequel of defective speech, and tingling at the tip of the tongue, at the tip of the nose, 
and in the fingers and thumb. 
I think I have accumulated evidence enough in the foregoing pages to establish the 
fact that there is a distinct form of transient hemiopsia, presenting the following main 
characteristics : — 
I. Dependence on mental anxiety, bodily exhaustion, overwork to the eyes, gastric 
derangement, want of exercise. 
2.. Origin from a small spot near the centre of vision. 
3. Orderly outward spread from the original spot. 
4. Blindness to boundaries, but not to general impressions of light and colour. 
5. Luminosity in the dark. 
6. Bright bastioned margin, with gleams of various colours. 
7. Tremor and ‘ boiling.’ 
8. Gradual occupation of one (lateral) half of the field of view. 
9. Gradual recovery of clear vision in rear of the outward-spreading cloud. 
10. Disappearance of the phenomenon after about half an hour. 
II. Sequelae: headache and nausea, and sometimes affection of speech and hearing, 
and even an approach to hemiplegia. 
As to the actual seat of the visual derangement, all the facts of the case are in support 
