The defect the person suffers from is myopia.
1/f=1/u+1/v
1/f=1/-85-1/infinity
f=-85 cm
=-0.85 m
The power of the lens=1/f
=1/-0.85
=-1.176 D
Concave lens have negative focal length and are used for
myopia.
Thus the the lens that should be used to correct this defect is
a concave lens of -1.176 D.