###Rationale: The sclera is much thicker behind than in front; the thickness of its posterior pa at the macula is 1 mm. The sclera thins to 0.3 mm just behind the recti muscle inseions (about 6 mm behind the corneoscleral junction) and this area is extremely vulnerable to traumatic rupture. In fact this is the most common site of a ruptured globe due to blunt trauma.At the equator the sclera measures 0.4-0.5 mm in thickness.It is thickest behind, near the entrance of the optic nerve. However it is weakest at the entrance of theoptic nerve.

###Answer: OPTION D IS CORRECT.
###Question: Thinnest pa of scelra is:
###Options:
A. At the entrance of optic nerve
B. Site of entrance of ciliary nerves
C. Corneoscleral junction
D. At the inseion of recti muscles
