When she was a few years into her forties, Robin Kahn noticed a change in her eyesight.
"I've always had perfect vision and I noticed about a year ago that I was having difficulty reading smaller print," said Kahn.
The condition is known as Presbyopia. Ophthalmologist Dr. Barry Lee said nearly everyone develops it.
"At age 40, that's probably the main thing we see is a patient complaining of decreased near vision," said Dr Lee.
But there are other reasons to get an eye checkup when you enter middle age.
"There are a lot of things we can do in that eye exam to pick up early predictors of eye disease later in life," said Dr. Lee.
Diseases like glaucoma, macular degeneration, and conditions involving the cornea. An eye exam can also pick up early signs of cataracts.
So, know your risk factors for these diseases, smoking and diabetes raise your risk of eye problems, as does your family history.
"It's very important that you know if your family has eye diseases that you go to your eye doctor and let them become aware of those conditions," said Dr. Lee.
The bottom line? Ophthalmologists recommend a baseline eye exam at age 40.
"Just make sure that the eyes are normal and if they're not, a lot of times, we can actually create measures to help prevent vision loss," said Dr. Lee.