Our eyes need more light to see at night. As cataracts progress, the lens of the eye becomes denser, less clear, and less able to transmit light to the back of the eye.
At first, we may notice that we simply need more light to read. Then we may notice that it's harder to see objects on the street while driving in the evening or at night. While both of these symptoms are, to some extent, an inevitable part of aging, both can be made worse by a cataract. Anything that compromises the lens's ability to transmit light, like a cataract, will affect our night vision.
As we age, senile miosis makes the resting size of the pupil smaller, reducing the amount of light that can enter the eye and hit the lens. If that lens has a cataract, then sight is further compromised.
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