Must this changes necessarily be removed?
No, but it is recommendable. Warts tend to grow in large numbers. Cysts can grow quickly and site-threatening.
How large must the change be to remove it?
Also very small cysts and warts can cause problems in sight, and are disturbing because of inflammation, itching or discomfort. With precise surgical instruments also very small changes can be removed. We do not need to wait that they grow.
Is there a scar after removal?
The skin around eyes is very thin but it heals fast. Postoperative scar appearance depends on the largeness of the alteration. If there is a smaller alteration, there are no scars after surgery, but if the alteration is left to grow too much before its removal, small postoperative scars can be seen after surgery.