Read the protection and use information
Look for explicit UV-protection information and the relevant product markings rather than guessing from the lens colour. The Association of Optometrists advises checking sunglass protection and filter-category information. If the listing is vague, ask the seller or an optician before buying, particularly when the glasses are for a specific activity.
Check the filter category and any restrictions on driving. Category 4 sunglasses are not suitable for driving. Polarisation can affect reflected glare, but it is a separate feature from the need to establish UV protection. Do not assume every tinted or light-changing lens is equally suitable behind a windscreen.
Compare the frame with a pair that fits
Use the frame measurements, where supplied, to compare lens width, bridge width and arm length. The numbers are a starting point rather than a guarantee of comfort. Check whether the frame rests securely without pressing on the nose or temples and whether it moves when you look down.
Coverage matters as well as fit at the bridge. Consider the light entering around the frame and the intended activity. If you need prescription lenses, obtain an appropriate quote and fitting advice rather than assuming a discounted frame can accept every prescription or lens type.
Add any necessary prescription lenses, case or other genuinely missing item to the price comparison. Inspect the product information and condition on arrival and keep the model details. A sale can make a suitable pair more affordable, but uncertainty about protection or fit is a reason to get a clear answer before purchase. For specialist activities or individual vision needs, an optician can help assess which options are appropriate.
