Everything depends on your diopter (degree).?For small degrees of farsightedness you can live without the correction in sunglasses since you do not need, for example, driving for long periods.?Already in the case of myopia and astigmatism, some users point discomfort even when their diopters are small.
I guess maybe you mean the quality of the sunglasses. First, you may need to know that there are many kinds of sunglasses. Some are with UVA protection, some are with UVB protection. Some can protect 100% UV rays while some can protect 98-99% UV rays. The sunglasses with UVA protection and can block 100% UV rays are the best.
Some sunglasses provided by optical shops are trust-worthy. There are different kinds of sunglasses sold in optical shops. The prices vary from different sunglasses. You can purchase a pair of sunglasses with good quality in optical shops. Maybe they will cost you more. But you may need to pay attention to the labels or descriptions of the sunglasses. If you can find the information that the sunglasses you choose are with UV protection. You can buy them. Good luck!
Though you can't know the quality of the eyeglasses and sunglasses sold online, you can review the comments of the product before placing an order. Sometimes, we bought a pair of bad eyeglasses or sunglasses online or in some eyeglasses stores. Sometimes they are very cheap but sometimes they are not. If we know nothing about these eyeglasses and sunglasses, we may come across that kind of products of poor quality. So the most important thing we should to do is to know how to choose a pair of good eyeglasses or sunglasses online or in any eyeglasses stores.