Do you still want to become an Optometrist .
If the answer is yes then change uni / retake 1st year etc... and go for it. If its no then change course...
You should analyse the reason why you failed: if its only exam stress, then doing another course wont solve the problem and you are likely to fail again. Maybe see a psychologist ?
if its because you find optometry too difficult and you hate biology, then by all means change subject/career...
Which uni are you going to ?