Hard on the eyes

posted by Jeff | Tuesday, May 7, 2024, 7:11 PM | comments: 0

Genetics are funny, because you never know which physical attributes will be passed along, but also manifest, from generation to generation. Simon appears to be headed toward being tall, but Diana and I are not, there's no height on my side of the family, and aside from one of Diana's brothers, most of her family is short. In my case, both of my parents needed corrective lenses pretty early in life, but I've been 20/20.

Until the last year or two. My depth of field has been reduced, but only at the shallow end. My minimum focal distance is further away than it used to be. The Internet says that normal, healthy adult eyes should be able to see as close as 25 cm. A quick experiment shows that stuff gets non-readable for me at around 32 cm, and 50 cm is the typical sharpness that I've otherwise enjoyed most of my life.

But there are caveats. Obviously, brightness matters, and I assume it's the same thing that applies to cameras. Your depth of field gets shallow when you "stop down," or open up, the aperture, which is necessary to let more light in. Bright situations close it up, which leads to much larger depth of field. That would be true regardless of eye state. The bigger wildcard is fatigue. I finally get what people mean when they refer to "tired eyes." Earlier in the day, my minimum distance is much closer. It's probably easiest to notice on my phone, where characters are so sharp, closer, but at night, I've gotta move it further away. This is age at work, presbyopia, and I understand it to mean that our focus lenses get more rigid time.

The good news is that when driving or doing really anything not involving a screen, everything is as sharp as ever. From a corrective perspective, I could probably use non-prescription readers. Right now, the only time I feel like it's really an issue is when I encounter really small text, and even then, more often when it involves poor lighting (yeah, phone flashlight on restaurant menus). I'm resistant to glasses of any kind, because my tolerance for having something touching my face like that is not high. I owned sunglasses when I was a kid, but they were never on for very long. (They also seemed to aggravate acne anywhere they were touching.) I sure could have used them, because I've always been "squinty" in bright sun, presumably because of my blue eyes.

It's not the end of the world, but I'm not crazy about the constant reminder that I'm getting older.


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