This is a really interesting question, Bonita. As I'm sure you've learnt, 'too' follows positive statements and 'either' follows negative ones. However, in this situation, the more natural response is:
'I barely see anything, either'
This is because the intended meaning is negative. It means that the person can see almost nothing. If you want to give a shorter response, you can say:
'Neither do I'
or
Me neither.
Please note that 'Me either' is ungrammatical. Some younger people in the USA use this form, but it is incorrect.