Though staining in circle lenses is not common; it is nothing unusual. Everything weathers and so do circle lenses. There are several factors that contribute to contact lens discoloration. However, contact lens ‘fading’ is often associated with over-wearing them i.e. wearing them past the expiry. Discoloration in circle lenses indicate the chances of them being fake or substandard. Contrarily, if you notice staining in circle lenses that are genuine & unexpired; you would want to check on the following notes
FDA approved Korean originated circle lenses are manufactured through sandwich printing. This advance technology keeps the hue intact between two layers. Thus, prevents bleeding of the dye in the lens that make circle lenses safe to wear. Discoloration that happens due to wearing them past their expiry is not a fault on manufacturer. However, your concerns are justified when you notice staining in your contacts that you still can wear for months as per the expiry date.
Often times staining occur due to the contamination. Circle lenses turning pink, reddish brown or yellow is often an indication of improper cleaning and contamination with makeup. Some medications such as vitamins, improper & non-compliant eye drops/contact lens solution & smoking may also cause discoloration in circle contacts. To help prevent staining/fading stick to timely replacement & meticulous disinfection.
To reduce chances of contamination with makeup, avoid using lash-building fiber mascaras with contact lenses. Always remove contact lenses before removing eye makeup because some makeup wipes can react to the dyes used in circle lenses. Avoid using mineral or powdered form of makeup that may get into eyes and adhere to micro grooves found on the surface of contacts.
Minor discoloration that is temporary should go away after cleansing them pragmatically. If the staining persists or affected circle lenses irritate; toss them off immediately, rinse your eyes and seek medical help if necessary.