Is a small beady eyes appearance a result of small eyeballs? How can small eyeballs be diagnosed( CT scan)? (Photo)

Before getting a CT scan, get personal consultation with an oculoplastic specialist for evaluation and discussion of what exactly bothers you and what options you have.

The information is not going to answer your concerns. Based on the photographs, your eye size looks normal and not "small and beady."  On the other hand, you definitely appear to have upper eyelid ptosis and this makes the eyes look small.  A detailed consultation would resolve this issue.  That may or may not satisfy you.  Occasionally individuals are bothered by small issues that normally would not be bothersome by others.  Debilitating thoughts and preoccupation about this can be a real problem.  In the extreme (spending hours thinking about this, avoiding social situations, etc.) these feelings might even constitute body dysmorphic disorder. You definitely have an upper eyelid issue that potentially could be helped with surgery.  

Your photograph shows either ptosis or pseudoptosis, some hooding, and prominent brows, all of which can make the eyes look relatively smaller. An oculoplastic specialist could help you sort out your concerns. CT not necessary or indicated for the issues you expressed. Best wishes.