Polarizing plate and optical display including the same

A polarizing plate, comprising:

• a polarizer;
• a bonding layer on an upper surface of the polarizer;
• a protective film on an upper surface of the bonding layer and having a moisture transmittance of about 30 g/m2·24hr or less;
• and
• a barrier layer on a lower surface of the polarizer and formed of a barrier layer composition including an alicyclic epoxy resin having a glass transition temperature of more than 200° C.,
• wherein the polarizing plate has a light transmittance variation rate of 3 % or less, as calculated by Equation 1:
• Light transmittance variation rate =|T0 −T500|/T0 ×100 (1),
• where T0 is an initial light transmittance of the polarizing plate at a wavelength of 400 nm to 700 nm and T500 is a light transmittance of the polarizing plate at a wavelength of 400 nm to 700 nm after the polarizing plate is left at 85° C. and 85% RH for 500 hours and is then left at 25° C. for 1 hour,
• wherein the polarizing plate has a thickness of about 115 μm or less,
• wherein the polarizer is formed of a polyvinyl alcohol film, and the barrier layer is in direct contact with the polyvinyl alcohol film.