There have been changes in order to claim or write-off Mental, Dental, & Vision Expenses.
First, you will need to qualify to "Itemize" meaning your qualified expenses must Exceed the Standard Deduction the government gives each year.
Second, your "Out-of-Pocket" medical, dental, and vision expense must Exceed 10% of your Gross Income. Example your total gross income was $50,000 x 10% = $5,000.00; Your Out of Pocket Expense must exceed $5,000 in order to qualify to claim the deduction.
If you are over the age of 65, your "Out-of Pocket" medical, dental, and vision expense must Exceed 7.5% of your Gross Income. (Unlike those below 65 it must exceed 10%)