Hi
Hubby suffers with his ears alot, so this holiday he had them syringed 2 weeks before we left and wore foam earplugs when swimming, this seemed to do the trick!
As for your eyes, being an optician, nothing you can take to prevent the infection im afraid. You can do the obvious like avoiding sand on the face, wear swimming goggles if going underwater ect. If the worst does happen you can now get the anti biotic drops chloremphenicol over the counter, (not available to contact lens wearers) you would probably be able to get that abroad if needed. If you do wear contact lenses, dont fly in them the risk of dehydration is high. Restrict wearing to evenings or wear good eyeprotection and split your wearing times up. Possibly speak to your optician about taking daily disposables for holidays they ideal for travelling.
Hope this helps!
Supersox