The correct option is
C Glaucoma
Cataract, one of the leading clauses of blindness, is a clouding of the lens of the eye.Hence, Option A is not the right answer.
Trachoma is a contagious disease of the eye caused by a virus.
Hence, Option B is incorrect.
According to the passage, with Glaucoma, there is a hardening of the eyeball and great pressure inside the eye.
Today there are medicines to control glaucoma if it is discovered in time.
Hence, Option C is correct.
Meningitis is a general disease of the body.
It is not a disease of the eye.
Therefore, Option D is not the right answer.