Why does one eye appear smaller than the other? (photos)

This is a very common issue. Both of your eyelids are very mildly ptotic (droopy) with the right being slightly more than the left. From a symmetry standpoint, your eyelids are well within the normal range of symmetry. From the photographs it is hard to determine if they have dropped significantly enough for surgical repair. Your use of contact lenses can contribute to the ptosis. You should make an appointment with an oculoplastic surgeon for detailed evaluation in office.

It appears based on your photos you may have some ptosis (weakness of the muscles that lift the upper eyelid)  in both eyes, but possibly a bit more severe in the right eye.  In the top photo your eyelids are covering the top half of the iris and possibly partially the pupil on the Right.  Also I notice that your right eyebrow is lifted a bit higher than the left.  Sometimes this happens as compensation you try to lift your brow to open your eye more on the side with more severe ptosis.  It does seem that you have a degree of ptosis on the left as well.  A frequently missed phenomenon is that repair of ptosis on the more severe side can unmask ptosis on the less severe side if it is not noticed before hand.  The best way to address this issue is with a ptosis repair surgery.   I recommend consulting with a facial plastic surgeon or an oculoplastic surgeon who is familiar with ptosis repair.  

Based on the provided photos, there does appear to be some degree of mild ptosis, or eyelid droop, in both eyes, but this is difficult to say for certain. The eyes do have some mild asymmetry, but overall this is very minor and would be difficult to improve as the difference is subtle. Be sure to see an expert for an in-person exam and recommendation.Best,

It appears you have asymmetric upper eyelid ptosis, with right eye worse. See an oculoplastic surgeon for evaluation and possible eyelid ptosis repair.

You appear to have a very mild degree of asymmetry, which is only apparent of close inspection. You do have some mild ptosis in both eyes which may be contributing to the eyes feeling tired towards the end of the day. If you are worried you should see a PS with an interest in oculoplastic surgery, but it is also not too healthy to focus too much on one minor aspect of your appearance. You could be on the BDM spectrum and so that should be considered before undergoing any treatments.

There are multiple anatomic abnormalities that can result in facial asymmetry. These may include deformities of the orbital bones, eyelid soft tissue and eyebrows. In some cases, they are relatively minor, but in some cases, they may be severe and extremely noticeable. Depending upon the deformity, treatment may or may not be possible.Your pictures suggest that your asymmetry is probably related to multiple factors. These include bilateral eyelid ptosis which is worse on the right than left side. In addition, you have many findings that suggest boney orbital asymmetry as well.It's virtually impossible to accurately assess this problem without performing a physical examination. For this reason, it's appropriate to consult a board certified plastic surgeon with experience treating this type of problem. This surgeon should be able to formulate a treatment plan that addresses your anatomic findings and achieves your aesthetic goals.