What can cause bulging in one eye? (photos)

You need an actual workup by a real doctor.  I recommend seeing a general ophthalmologist or oculoplastic surgeon.  Unless there has been change over time, this could be something as simple as the axial length of the eye.  Near slight eyes are larger than far sighted eyes on average.  It could be thyroid eye disease which is a very common cause of one eye being more prominent than the other.  Bottom line, you need to see the right doctor and get to the bottom of this and it is not necessarily anything scary.

There are multiple reasons why one eye is bulging including genetic, thyroid eye disease, tumor, etc. If this is something recent and progressive, best to see an oculoplastic specialist soon. Treatment depends on the cause.

There are many things that can cause one eye to bulge.  IT the bulging is progressive it can be a sign of a thyroid disorder.  In any event you should see an oculoplastic surgeon who specializes in these types of orbital disorders.  They can often be treated but the first step is getting to the cause.