Yes, absolutely. There could be a very serious ailment.
The outer covering of the eyeball is cornea.
sclera
By covering the eyeball.
The conjuctiva.
The eyelid.
The conjunctive is a thin membrane covering the eyeball, and protects it from damage.
Schlera
If you are referring to the eye, the clear membrane is the covering of the actual eyeball.
the membrane covering the back wall of the eyeball.
When he is standing on the bare ground in nature.
Evolution I guess. Instead of having closable eyelids, their eyes are protected by a transparent scale (called the 'brille') Under the surface, the eyeball can still move.
Conjunctivitis is usually caused by viral infection.