A base lens of a polyurethane resin comprising a polyisocyanate compound
and a polythiol, a sulfur-containing polyol or the like is coated with a
primer layer having a thickness sufficient for shock absorption, an
organosiloxane-type, hard coat layer having a refractive index of 1.47 or
more, and optionally a thin metal layer in that order. As having this
constitution, the plastic lens has a mechanical strength resistant to
striking energy of not smaller than 4 times the striking energy value of
the FDA Standard, 0.204 joules, when the center thickness of the lens is
from 0.7 mm to less than 1.2 mm. Since the latitude in the acceptable
range for the conditions for the processing of the lens (relative to the
thickness of each constitutive layer) is large, the producibility of the
lens is high. An inhomogeneous layer may be formed between the adjacent
layers, which reduces the reflectivity of the lens for transmitting light
and prevents the formation of interference fringes in the lens. An
ultraviolet absorbent, if added to the hard coat layer, can cut off
ultraviolet rays, while preventing the base lens and the coat layers from
being aged, and is helpful in protecting eyeballs.