Yes, definitely low-lying cerebellar tonsils, if not borderline Chiari. Additionally I can see what looks like a pannus at the back of your (retroflexed) odontoid peg, a sign of cranio-cervical instability (CCI). There’s also loss of lordosis in the upper cervical segments. You possibly have a short clivus too but it’s difficult to say for sure from this picture. Check out the diagram, explaining the terms I’m using, here:-
http://prettyill.com/forums/viewthread/712/P15/#4079
For safety’s sake, I’d be looking at a Philadelphia collar and lining, until you’ve been checked for CCI, for sure. You might find this alone gets rid of your back of head pain (and maybe eye pain) but if not Diamox may be necessary to try and reduce the build up of CSF pressure and this usually resolves the eye pain.
The Chiari Institute’s Dr Bolognese has sent out a new protocol for carrying out MRI’s particularly to check for CCI, see:-
http://prettyill.com/forums/viewthread/712/P45/#5034
Hope some of this helps.