An optical trocar assembly includes an obturator assembly and a cannulaassemblyconfigured for receipt of the obturator assembly. The obturator assembly has aretentionmember disposed within a cavity defined in an obturator housing of theobturator assembly.The retention member has a main body defining an opening dimensioned forreceipt of asurgical instrument. The retention member has a plurality of first sectionsformed in the mainbody and circumferentially disposed about the opening. The sections have areducedthickness relative to the main body to facilitate flexing of the retentionmember duringinsertion of a surgical instrument into the opening.
