Please see Geoffrey's detailed answered below.  You will need to check your Oregon return to make sure these expenses were accounted for.  

Based on your age (64 or older for the 2016 tax year), and if you indicate to the program that you are filing an Oregon return (back in the personal information section of the program), then to get the Oregon Medical Subtraction interview screen to appear in the Oregon TurboTax program module, you will need to do the following:

Go to the Federal Taxes -> Deductions & Credits -> Medical section of the main federal program in TurboTax.  Then, you will want to enter your medical expenses in the regular place for medical deductions by either clicking the Start or Update button.  If you don't see the medical option sub-group in TurboTax online, then you may need to click on ''Show All Tax Breaks'' at the bottom of the deductions page.  

Ignore all questions and directions (which are based on the federal medical deduction rules) that may tell you that you are not otherwise eligible for medical deductions, based on your income and amount of medical costs you have.  The Oregon state rules on medical expenses for those over the age limit are "special" and do not conform to the federal rules.  However, it is through the federal medical deductions interview that you must input your data.

After doing this and beginning the Oregon state module in TurboTax, the "special" Oregon medical subtraction interview screen will appear automatically.  There is no other way to cause it to appear, other than meeting the age conditions (personal information section of TurboTax) and entering at least some medical deductions in the federal medical expenses interview.