I received a surgery on my eye muscles a year ago because i had a lazy eye, but the site of cut is still red. should i be worried?

Probably not: Stitches are used in strabismus surgery. Sometimes, these take quite a while to dissolve with some redness. Occasionally, a small non-infectious lesion called a granuloma can form around the stitch and sometimes needs to be removed.

No: A suture can cause a "pyogenic granuloma" or sometimes there may be exuberant scarring response that can appear red if vascular. These can be removed usually without problems.