Normally, this mutation indicates that a mutant suffers from either blindness or deafness (with a 50% of ether).
Other sensory deficiencies includes:
Albinism: Due to the lack of pigment in the eyes, the being is highly sensitive to light, and suffers a –2 penalty to hit when in daylight. (see page for more info)
Vision Impairment: This mutation covers all visual impairments that fall short of total blindness, including macular degeneration, myopia, severe light sensitivity, cataracts, etc. This condition makes it extremely difficult for the mutant to discern objects more than 50 feet away. Characters with this mutation have a -2 to hit in combat.
See also: Increased Sense for beneficial equivalents.