Let me just first preface this with the understanding that we get a fairly limited exposure to the eye in medical school. Sure, we learn its embryogenesis and anatomy and the physiology of vision and the pathogenesis / treatment of common eye problems. But opthalmology is a very specialized field and most of what they learn happens during their residency and not medical school. So I have a decent understanding of eye physiology, and the diseases that I'm likely to run across in my specialty, but I'm no expert in it.
Now, I accompanied my wife to an opthalmologist's appointment last year. We got to talking about photography a little, and he told me that the human eye is not apochromatic, i.e. the lens does not focus all wavelengths of light on the same point. He didn't go into much more detail, but he explained that you can exploit that diagnostically by checking acuity for different wavelengths of light.
Anyway, I shelved this information until today when I was in my darkroom doing some lith printing. I'm mildly nearsighted, and I noticed today that things in the darkroom (under the safelight) were looking very blurry to me -- so out of curiosity I took off my glasses and to my surprise it got much sharper. Sometimes very close objects are blurrier with my glasses, like when I'm reading in bed, so I tested it again from around 5 feet away, and it was still true -- far sharper without my glasses.
But when I was able to turn the regular light back on, the opposite effect happened. In other words, things from 2, 3, 5 feet were much blurrier without my glasses and much sharper with.
Goes to show that my refractive error is much worse for shorter wavelengths than deep red -- and while my prescription helps me overall, it is far worse under deep red light. It certainly means that I'll do better in the darkroom without glasses on. I just wonder what it means if I'm driving at night in a place that has deep orange streetlights.
Now, I accompanied my wife to an opthalmologist's appointment last year. We got to talking about photography a little, and he told me that the human eye is not apochromatic, i.e. the lens does not focus all wavelengths of light on the same point. He didn't go into much more detail, but he explained that you can exploit that diagnostically by checking acuity for different wavelengths of light.
Anyway, I shelved this information until today when I was in my darkroom doing some lith printing. I'm mildly nearsighted, and I noticed today that things in the darkroom (under the safelight) were looking very blurry to me -- so out of curiosity I took off my glasses and to my surprise it got much sharper. Sometimes very close objects are blurrier with my glasses, like when I'm reading in bed, so I tested it again from around 5 feet away, and it was still true -- far sharper without my glasses.
But when I was able to turn the regular light back on, the opposite effect happened. In other words, things from 2, 3, 5 feet were much blurrier without my glasses and much sharper with.
Goes to show that my refractive error is much worse for shorter wavelengths than deep red -- and while my prescription helps me overall, it is far worse under deep red light. It certainly means that I'll do better in the darkroom without glasses on. I just wonder what it means if I'm driving at night in a place that has deep orange streetlights.
)
