There is more then meets the eye.
Piggy's glasses symbolize clear-sightedness, intelligence, wisdom, and civilization.
"Jack smacked Piggy's head. Piggy's glasses flew off and tinkled on the rocks. Piggy cried out in terror: "My specs!" He went crouching and feeling over the rocks but Simon, who got there first, found them for him..."One side's broken."" (Golding 71)
Jack and Piggy fight about keeping the fire going, Jack gets physical and hits Piggy. One of the lenses are broken, Piggy is half blind.
"From his left hand dangled Piggy's broken glasses." (Golding 168)
Jack, Roger, and Maurice steal Piggy's glasses in the middle of the night. Jack shows no remoarse which shows that he is no longer civilized but a savage. The glasses are now broken, Piggy can not see and the boys are not thinking clearly.
The glasses represent intelligence, wisom, and clear sightedness. Throughout the book Piggy's glasses break, and the wisdom of the boys slowly breaks.