Applying a coupon code at Zenni Optical is a straightforward process. First, you should select the desired glasses and add them to your shopping cart. Once you are ready to proceed to checkout, you will see a section labeled "Promo Code" or "Discount Code" on the checkout page. Here, you can enter your coupon code in the designated field. After you input the code, you will need to click on the "Apply" button to ensure that the discount is applied to your order. It is important to verify that the code has been successfully applied and that the discount is reflected in your total before finalizing your purchase. If you experience any issues, you may want to check the terms and conditions of the coupon, as certain restrictions may apply, such as expiration dates or minimum purchase requirements. For any further inquiries regarding coupon codes, visiting the Zenni Optical website can provide additional information.