Subtle Change in cat eye colour

My cat has always had bright perfectly yellow eyes but I have noticed recently a grayish blue area appear on both her eyes to the side. Here is a photo of one of her eyes taken a few years apart. As you can see the second image her eye has a slight gray area/patch on the right. Do you think this is anything to worry about? I only uploaded one eye but both her eyes are the same and have the gray area to the left and right of her iris for the left and right eye so the change in color has happended to both eyes.

Hello and thankyou for this excellent picture, which looks as though it could be uveitis.  Please send it to your vets and ask for this case to be triaged as soon as possible because some cases of uveitis are emergencies.