Uneven eyes - is there anything that can be done? (Photo)

I have recently noticed that my eyes look very uneven in photographs, I cannot see the difference when I look in the mirror but the difference is so obvious in photographs it is causing me a great deal of anxiety! I am not sure what could be causing it and I am not even sure if it has always been there. Is there anything that can be done ? I would also appreciate any opinions on what could be causing it. I have a general optician appointment this weekend so I am going to raise my concern then.