Re: Tek 576 CT fiber optic readout lamps; replaced with LED's ?


stevenhorii
 

I am a high myope (correction near -10 diopters) and have been for years. I
started developing cataracts (I just turned 70 in 2020) probably about 25
years ago. I just had cataract surgery this past October - it was supposed
to be back in April, but COVID put it on hold. I first noticed the
cataracts when they were very small. Because I am a high myope, without my
glasses, point light sources look like round discs, not points. In those
discs, the cataracts produced black dots. I could actually monitor the
relative size of them this way. When I finally saw an ophthalmologist about
surgery, she said I should have had the surgery years ago.

They got to the size where I could “see” them when using optical
instruments with a relatively small exit pupil. It made using microscopes,
telescopes, theodolites and the other stuff I “play” with nearly impossible
- another good reason to have the surgery. It has made a dramatic
difference. I can work at computers without glasses. Since I am a
radiologist, when I am working, I am at a computer over ten hours a day,
though not continuously. The ophthalmologist recommended correcting me to
-2 diopters since that would work best with the working distance I told her
I wanted (about 12-20 inches). In this state I can even drive without
glasses now, but I don’t do it.

There are subtle changes with cataracts that happen so slowly, you tend not
to notice them. Halos and glare with bright lights are more obvious. Less
obvious is a color shift. My mother told me about this years ago after she
had her cataract surgery. I confirmed this with others who had the surgery
and then noticed it myself. The cataracts can cause a shift to the yellow
end of the visual light spectrum, likely because they absorb/scatter more
of the shorter-wavelength light (like blue). It is not like not being able
to see blue or violet, it is just a gradual color shift. Typically, surgery
is done one eye at a time. My right eye was done first and one of the
things I noticed immediately was how blue things looked - especially since
my left eye had not been done yet. The sky looked to be much more vivid
blue than with my left eye. The same for blue-colored objects.

There is a visual degradation point at which medical insurance companies
will cover the cost of the surgery - I was well past that point.

I should point out that I had lens cataracts, not corneal clouding - that’s
a different problem and requires different surgery.

So if you can see dark spots in your field of vision when using a
microscope, or like me, if out-of-focus point sources (like photographic
bokeh) show consistent dark dots in them, it is one way to self-test for
cataracts.

I recommend cataract surgery when an ophthalmologist recommends it.

On Fri, Feb 5, 2021 at 09:06 SCMenasian <scm@menasians.com> wrote:

Jim,

I don't know your age; but my eye doctor says that I am approaching "mild
cataract" territory.
While looking at an LED clock at night, I came up with a simple test for
cataracts. If I look at
the clock in total darkness, I see a halo (maybe about 5 degrees in
angular width) around the numerals.
I hypothesize that this is due to scattering in my corona. I would expect
this effect to be much stronger
for a blue LED display, when compared with a red display

Stephen Menasian





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