Flex Spending is a benefit that many employers offer to employees. At the beginning of each plan year, you choose to have some of your pre-tax income put into a special Flex Spending, or HSA, account. You can choose to use this fund for certain expenses, like medical co-payments, certain child care expenses, and prescription glasses. If you do not use up all of the funds in the Flex Spending account during the Plan year, the excess funds are given away and they do not roll over to the next plan year. Use them, or lose them. Flex spending funds can be used on eyeglass frames and lenses, and sunglasses, and reading glasses and there is no limit to the number of frames and lenses you can purchase during the year. Simply submit your Eyeglasses.com receipt to your plan administrator, and they will reimburse you. However, you can only be reimbursed up to the limit of the funds in your flex spending account.