What type of surgery can widen your eyes?

Your 'distance between the eyes' is probably what we would call the intercanthal distance - straight line between the inner corners of the two eyes. At 25mm, this would be within the normal range! Increasing this to 30mm would tend towards distances seen in some craniofacial syndromes...
You have not posted photos. However, If you really want to see how you would look at 30mm, try some prism lenses from your ophthalmologist or easier still some image manipulation software. You will have some fun with the software and your facial images, and perhaps come to realise that a balanced 'normal' aesthetic is a favourable thing.
good luck!
Jonathan A Britto, Consultant craniofacial plastic surgeon, London, UK

It  is considered normal to have distance between two eyes equal to the width of the eye. In severe cases only extensive craniofacial procedure can address interorbital width. However, there are some ways of visually correcting that deformity (if present). In person evaluation and discussion about your expectations and options is recommended. Good luck.