Sorry if you know this already but....
When you take your little one to the eye clinic please be aware that the drops they use to dilate the pupils sting very much. Also they alter the vision making your child near sighted - they cannot focus on close things.
My daughter was very distress after this experience. The doctor and nurse made a fun time for the drops. "it will not hurt, we just wash your eyes" etc etc, but really it is stinging. My 3 year old is very frightened and when the vision is altered so much me also.
Not to say you cannot do it but just to be prepared so to reassure your child that everything is normal.