There is only the date of production on the packaging of eye mask, so you can try the following solutions:

1. Contact the manufacturer: try to contact the manufacturer through their official website, customer service phone or email to ask about the shelf life of the product or other related questions.

2. Find the product batch number: find the product batch number or the batch number on the package. Sometimes, manufacturers use batch numbers to track the production date and expiration date of products. The batch number can be provided to the manufacturer for more information.

3. Consult a professional: If you can't contact the manufacturer or find relevant information, it is recommended to consult an ophthalmologist, pharmacist or other professionals. They know more about the use and effectiveness of eye mask and can give appropriate suggestions.