If you have prescription glasses and need to protect your eyes from the sun with the minimal UV400 lenses then there are many options available to you on the market.
 
Current options available
 
Laser treatment for your eyes if you can afford it, on average GBP 250- GBP 1000 per eye and sore eyes for few days will give you free reign on normal sunglasses available to you, but laser treatment is not for all and as it has not been tried and tested over the long term we do not know how successful it'll be.
 
Fit over frames or over glasses are an additional sunglass frame that sits over your current clear prescription glasses. Hardly good looking, but cheap, perhaps not the quality you need for decent eye protection and they look huge and rather out of place in most cases. This is a quick and easy option with no need to visit the optician but must be hot and uncomfortable with two frames wrapped over your ears, leaves little to be desired.
 
Clip on lenses, a separate tinted lens or two that is clipped over your prescription glasses for more functional use to keep the sun out of your eyes. They are cheap but were never made to fit your prescription frame precisely so have little to be desired with looking good. Some do flip up which may allow the user immediate clear vision if needed for close up work outside without the need to remove the complete frame.
 
Authentic prescription lenses where the optician/retailer supplies your glasses frame with prescription lens with a coloured tint or photo chromatic lens that changes with the light. These can range in price up to very expensive, thereby giving you all the features of the manufacturers specialty lens with your prescription. Often with the manufacturers logo etched on them for a designer look and as a symbol of authenticity. If you change your prescription you therefore multiply your cost and more if you change the frame. A disadvantage with these is these lenses cannot be fully wrapped for total peripheral eye protection from sun and the elements. A normal prescription lens can only be curved so much before the vision becomes distorted leaving the user a bit giddy and with blurred vision, so most of these lenses are relatively flat with limited spherical curvature to try and cover the side nreal air prescription lenses.
 
Prescription adapters, inserts or Rx's as some call them. A separate lens adapter, method developed to insert behind or above the bridge behind a pair of wraparound sports sunglasses This offers an option of having an interchangeable insert between various similar frames with different colour options for different light conditions from indoor to outdoor, from strong sunlight to cloudy. So you can have several different colour frames for different conditions or even fashion with the need for only one Rx adapter. The benefits can outweigh other options where if the outer frame is damaged, that can be replaced cheaply or if you need to change your prescription then only the insert needs to be changed at a very reasonable cost, there are many online opticians offering good reglazes at good prices. The wraparound lens that holds these adapters can cover your peripheral vision without the restriction on your prescription lens and help protect your eyes from the elements.