NEAR AND DISTANT SIGHT, 
325 
continued a fortnight, and different local applications had been Changes in the 
used, without producing any sensibly good effects, the lad was 
cured by the application of leaches to the temples, and the ad- 
ministration of a few purgative medicines. I’he other instances 
occurred in two daughters of the same family. The eldest, 
twenty years of age, had never been able to do fine work ; and, 
for three years, had been greatly assisted by convex spectacles. 
The youngest, a girl of fifteen, had become presbyopic about a 
year ago, and since that time had been obliged to use spectacles 
whenever she read or worked with her needle. The young 
person last mentioned, in the course of six weeks (during 
which time she totally abstained from the use of glasses,) was 
completely relieved from the necessity of using them by the 
application of two leaches to each temple twice in a week. 
'The former, in the same space of time, experienced much re- 
lief from a similar treatment, but was still unable to do fine 
work without glasses, partly in consequence of the long con- 
itinuanceof the infirmity, and partly on account of her not 
having abstained, with equal steadiness, from the occasional use 
• of them. 
From the preceding statement the following inferences may 
I be deduced. 
First ; near-sightedness is rarely observed in infants, or 
(even in children under ten years of age. It affects the higher 
(classes of society more than the lower ; and the instances are 
Tew, if any, in which, if the use of concave glasses has been 
ladopted, increasing years have either removed or lessened this 
(imperfection. 
Secondly j though the usual effect of time on perfect eyes 
jibe that of inducing a necessity to make use of concave glasses, 
in order to see near objects distinctly, yet sometimes, even 
after the age of fifty, and after convex glasses have been used 
many years for this purpose, the eyes have not only ceased to 
derive benefit from them, when looking at near objects, but 
they have required concave glasses to enable them to distinguish, 
(With precision, objects at a distance. 
Thirdly 5 though the cause of this change be not always 
known, 
