Is it safe to buy glasses online?

Could you please enlighten me on a matter of some concern? I'm considering purchasing glasses online, but I'm a bit apprehensive about it. Would you mind sharing your thoughts on whether it's safe to do so? Are there any potential risks involved, such as quality issues or the authenticity of the products? Also, are there reliable ways to ensure that the glasses fit properly without trying them on physically? Your insights would be greatly appreciated as I navigate this online shopping territory. Thank you in advance for your time and assistance.