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1.some dark-coloured sunglasses cannot cut off ultra-violet light.
Why ewearing such sunglasses under bright sunlight would be more damaging to the eye that not wearing any sunglasses.
- Audrey HepburnLv 71 十年前最愛解答
It is because wearing sunglasses will provide a darker environment for the eyes.
In dim light, the radial muscles of the iris contract and the circular musclesrelax. The pupil becomes larger in size (dilates) and more light is allowed to pass through the lens and go to the retina.
As more light is allowed to pass to the retina, the photosensitive cells may be over-stimulated (due to excess ultra-violet light) and may be damaged. So, wearing such kind of sunglasses under bright sunlight would be even more damaging to the eye than not wearing any sunglasses.資料來源： Myself~~~