Today I am going to answer a question that I hear frequently from my older patients patients which is, “Why do I feel less steady after being outside, like when I come indoors on a bright sunny day?”

The answer is normal aging of the eye causing longer “pupillary dilation time.” In older eyes, the time needed for pupils to adjust to changes in lighting, which is called pupillary dilation time, is extended. What that means is when an older adult has been outside during the day and the sun is very bright, their pupils have constricted – or gotten smaller – in order to limit the amount of bright sunlight that is allowed into their eye.

When they come inside after being outside during the day and it’s bright out, their pupils need to make an adjustment – or get large – which is called pupillary dilation. That needs to happen after the transition to the indoor lighting; however, in older adults this pupillary dilation time takes longer.

Therefore, an older adult may have a period of time which we call “transient blindness,” or an absolute darkening of their visual field. This transient blindness can cause people to feel less steady after being outside, especially on a sunny day.

When they come in from outside on a bright day, it may appear to be pitch black.

Whenever they are entering a building during the day especially if it is bright outside, I recommend for older adults to stand steady against the wall, or to sit down in the lobby or the hallway, and to wait until their eyes adjust to the indoor lighting before they start walking around or doing any of their activities inside the building they entered.

I hope that this information about the increase in the pupillary dilation time helps to reduce your risk of falling or that of someone that you love.