I'm just starting out in triathlon and have struggled to find a good pair of prescription goggles, particularly now that I've started open water swimming. Being able to see clearly is very helpful, not only for seeing the buoys, but also for general comfort in wide open, cold, murky water.

I need a -8, so selection is limited for off the shelf options.

So far, I've tried these...

http://www.wiggle.co.uk/...hangeable-lens-ss14/
A generous size and comfortable to wear, but possibly a little large for my face and it can be a little tricky to get a good seal. The lenses scratch easily and the prescription lenses only come in a clear version, rather than tinted or mirrored.

http://triathlonspecific.com/Sable/Sable.html
Vision is good in these, but the nose bridge sometimes comes away from the frame when I take them off to adjust/defog and they leave bad goggle marks. I've also had to be careful about ensuring the seal is intact around the lens...it sometimes comes away slightly. I'm not sure these would survive a knock in a swim start and losing my goggles would mean hailing a safety boat and DNF.

http://www.prescription-swimming-goggles.co.uk/Speedo_Mariner.html
Quite small and I will need to order a longer strap as the one that comes with the goggles is quite short. They come as a single pre-assembled unit rather than being modular, so perhaps more sturdy, but the small lens size means my field of vision is not as comfortable as with the Aqua Sphere ones.

Any others you can suggest?

I'm reluctant to use contact lenses as I really can't afford to pick up an eye infection and in previous attempts for general use I've found they give me bad headaches...