How do sunglasses actually work? How can some types cause damage to your eyes? And why do astro’– or good sunglasses, at least – block out UV rays. But if your glasses don’t have 100% UV protection, then they’ll cause damage, as your pupils will dilate to accommodate the darker view the tint is giving, but won’t then protect you from the increased UV rays that will flood into your wide open eyes. This film is part of our new series that will provide the blueprint for a scientifically perfect summer. From sweating to hay fever, insects to jet lag, Kate Mulcahy will help you hack summer to engineer the perfect season. Taking a different topic each Thursday, the videos will gradually build up an equation for summer perfection; a summer survival guide certified by science. Subscribe to keep up each week: http://bit.ly/RiSubscRibe References: Alexander, A. D. and Makas, A. S. (1969) Sunglass lenses and colour fidelity. The Australian Journal of Optometry. 52: 364-369 Glazer-Hockstein C, Dunaief JL (January 2006). "Could blue light-blocking lenses decrease the risk of age-related macular degeneration?". Retina (Philadelphia, Pa.) 26 (1): 1–4. Langley, R.C. (1971) Gold coatings for temperature control in space exploration. Gold bulletin 4(4): 62-66 Turro, N. J. et al. (2009) Principles of Molecular Photochemistry: An Introduction. p. 29-33 Zigman, S. (1993) Ocular Light Damage. Photochemistry and Photobiology. 57(1): 1060-1068 Music: Hepcats by Kevin MacLeod (incompetech.com) Licensed under Creative Commons: By Attribution 3.0 http://creativecommons.org/licenses/by/3.0/Mining by Moonlight by Kevin MacLeod (incompetech.com) Licensed under Creative Commons: By Attribution 3.0 http://creativecommons.org/licenses/by/3.0/ Images: Caribou by daryl_mitchell (www.flickr.com/photos/daryl_mitchell/5176736443/) Licensed under Creative Commons: Attribution-ShareAlike 2.0 https://creativecommons.org/licenses/by-sa/2.0/ Inuit snow goggles by Julian Idrobo (ht