Oh say, can you see?

Maria spent much of yesterday hunched over her new Bernina sewing machine and tensely complaining there isn't enough light in her sewing room. She's in what is arguably the brightest room in the house with lots of windows and a southeastern exposure with a three-bulb overhead light fixture and a built-in light in her Bernina.
I recognized the complaint as a symptom of presbyopia - the inability of the eye to focus properly on nearby objects, which is a common occurrence in middle-age.
Maria has good vision and has never worn glasses. Her last eye exam was about 13 years ago when she was 30. At that time, her eye doc told her she'd probably need reading glasses when she turned 40.
I've worn glasses or contact lenses since the third grade, so it's no big deal for me, but she was loathe to surrender to the fact that it was time for some vision correction.
So on the way to the Meijer store for our weekly grocery run last night, I explained why people who need reading glasses initially complain that there isn't enough light to see closeup stuff.
There is a phenomenon in photography called depth-of-field. When you close down the aperture on a camera lens, i.e., make the light hole smaller, it makes the light waves more coherent and sharpens the image of objects in front of and behind the point where the lens is focused. The same thing happens with the human eye. When you increase the light intensity, the iris closes tighter and the depth-of-field increases, making closeup objects appear sharper than they did before.
You can get by with adding light for awhile, but eventually you have to turn to reading glasses.
So I suggested we cruise by the pharmacy area of Meijer last night so Maria could try on some reading glasses and see if they helped.
It was, to say the least, an eye-opener for her. The first pair she tried had a magnification factor of 1.75 and she was startled at how much sharper fine print appeared. She tried various lens strengths and finally settled back on the 1.75.
She wore them to do a bit of sewing last night with good results, but refused to take the plastic tag off - keeping her options open to return them (refusing to completely accept the inevitable conclusion that she needs them).
She still has the tag on this morning, but I predict it'll be gone by tonight.
Here's a photo of her taking to her daughter on the phone, eyes closed because she gets disoriented looking at distant objects.


30 minutes later: the tag is gone.