How thick will the camera lenses have to be so they aren’t damaged with the pressure and gravity changes?

Question: How thick will the camera lenses have to be so they aren't damaged with the pressure and gravity changes?
- Keywords:
  camera lens,
  gravity,
  pressure
Asked by Barney to Tom, Anne, Beth, COLFlight, Jon on 5 Oct 2015. This question was also asked by katelyn.
- Tom Morse answered on 5 Oct 2015:
  
  Hi Katelyn and Barney,
  
  Good question. We generally tend to use curved mirrors rather than lenses. They work in a similar way. One good reason for this is that the vacuum of Space has a different refractive index to air, so lenses work differently after launch (making cameras very hard to focus on the ground). Radiation also causes glass to go cloudy; another reason for avoiding lenses in Space.
  
  That said, we do use them sometimes, and they do have to be pretty well designed and tested to withstand launch, pressure changes and the difference in gravity. It’s a fascinating subject.
  
  Good luck with IAAGMOOH!
- Beth Healey answered on 6 Oct 2015:
  
  I think Tom has covered this one! 😉

Question: How thick will the camera lenses have to be so they aren't damaged with the pressure and gravity changes?