NEAR AND DISTANT SIGHT. 
32a 
sixty-six years of age, who has spent a great part of his life in the fcUnges in the 
West Indies, and whose sight, when he was young, enabled 
him to see both near and distant objects with great precision, 
I began, at the age of forty, to experience a difficulty in reading 
and writing. He immediately procured convex spectacles of 
I the first number sold by opticians, which glasses are usually 
ground to a focus of forty-six or forty-eight inches, and by the 
aid of these he continued to read and write with ease, (distin- 
fguishiug perfectly in the usual way, all distant objects without 
Ithein) uuiil he was fifty. At this time he first began to per- 
ceive an iiulistinctuess in the appearance of things at a distance j 
and, on trying with different glasses, he discovered that, by 
Hooking through a double concave glass of the sixth number, 
(which is ground to a radius of eight inches on one side, and 
■ eleven inches on the other,) he was enabled to see distant cb- 
]jects distinctly. He has continued to use glasses of this de* 
scription for the purpose of seeing distant objects from that 
lime to the present j but is obliged to remove them whenever 
he reads, and still to employ the first number of a convex glass. 
In this instance a presbyopic w*s changed to a myopic sight, 
without any known efficient circumstance to produce it. In 
the two following cases a similar change took place, and in 
them it was attributable to known causes. A woman, about 
fifty years of age, of a full habit, w-ho, for several years had 
been obliged to make use of convex glasses, in order to read a 
small print, was seized w'ith a dimness in the sight of the right 
eye, accompanied with a small degree of inflammation. The 
sight of the left eye having been long imperfect, this affection 
of the right" eye occasioned a great depression of spirits. Re- 
course was necessarily had to copious evacuations, by means of 
which the inflammation and dimness of sight were soon re- 
moved j but afterwards the patient was much alarmed on find- 
ing thattlie spectacles she had L een aceustoroed to wear, instead 
of atfording their usual assistance, confused her sight. Upon 
this discovery, she was induced to look through her hus- 
band's glasses, which, in consequence of his being near-sighted, 
were double concaves of the fifth mvnber, and ground to a 
radius 
