For DD, the vision and hearing offices did not require an adult, even though one of us accompanied her - we called to ask them ahead of time. But, for the medical exam, one parent was required to sign forms since she was only 17.
The point is to call the medical exam office ahead of time to check, it may be that you can pick up a form ahead of time for your parent(s) to sign that you can then take with you and not need their presence during the actual exam day.