A pressure sensitive adhesive, oriented and crosslinked in the oriented state, has been granted a patent. The adhesive is comprised of a polymer at least 65% of which is made up of at least one acrylic monomer selected from the group consisting of monomers of the following formula: where R1=H or CH3 and the radical R2=H or CH3 or is selected from the group consisting of branched or unbranched saturated alkyl groups having 2–20 carbon atoms. The weight average molecular weight (Mw) of the polymer is at least 650,000. The refractive index of the adhesive, measured in the oriented direction nMD is greater than the refractive index measured in a direction perpendicular to the oriented direction nCD. The difference Dn=nMD•nCD is at least 1•10•5.