A composition is provided for manufacturing contact lenses in a siloxane macromer represented by the following formula (I):

##STR00001##

wherein R1, R2 and R3 are independently C1-C4 alkyl groups, R4 is C1-C6 alkyl group, R5 is a residue obtained by removing NCO group from an aliphatic or aromatic diisocyanate, R6 and R7 are independently alkylene groups, and n is an integer of about 4-80, m is an integer of about 3-40; a crosslinking agent or a siloxane macromer represented by the following formula (II), wherein p is an integer of 4-80 and q is an integer of 3-40:

##STR00002##

and an initiator.

Methods for manufacturing contact lenses are provided. In an embodiment, the method includes mixing a siloxane macromer represented by the following formula (I), a hydrophilic monomer, a crosslinking agent or a siloxane macromer represented by the following formula (II), and an initiator to form a mixture. Then the mixture is injected into a mold of contact lens and heated to form contact lenses. The formula (I) and the formula (II) are shown respectively as the following:

##STR00001##

wherein R1, R2 and R3 are independently C1-C4 alkyl groups, R4 is C1-C6 alkyl group, R5 is a residue obtained by removing NCO group from an aliphatic or aromatic diisocyanate, R6 and R7 are independently alkylene groups, and n is an integer of 4-80, m is an integer of 3-40.

##STR00002##

wherein p is an integer of 4-80 and q is an integer of 3-40.