Thursday, February 20, 2020

Cataracts and Color Shift

If you have been keeping up with this blog then you know I had a cataract removed from one of my eyes last week.  The natural lens and cataract were removed and replaced with an artificial lens which now allows me to see clearly at far, mid and near distances.  No more glasses for reading!  I'll have surgery on the other eye on Monday.

I am very fortunate that I am alive today with the current advancements in science and techniques for surgeries such as this.  Also, I am very fortunate to have an excellent surgeon.  As a comparison, when I was in high school, my grandmother had a cataract removed.  She was kept in a hospital bed for one full week and was not allowed to get out of the bed except to use the bathroom.  She wore a patch over her eye for a month, if my memory serves me well.  My surgery took 8 minutes and 15 minutes after it was over, I was on the way home.  I love how we progress technologically, medically and scientifically.  I can only imagine the future.  Wish I could be here another hundred years to find out!

We all know that cataracts degrade your vision.  They reduce your visual acuity.  Its like looking through a diffusion filter or the atmosphere on a foggy day.  Things that should look very sharp will look less sharp and that has nothing to do with nearsightedness or farsightedness.  This is in addition to either.  The amount of loss of visual acuity depends upon how far along the cataract is, i.e., how much of your lens is obscured.  Relating this to photography cataracts affect how well you can discern how sharp your images are when looking at them on your camera's LCD, EVF, optical viewfinder or on your monitor.  But there is something else that is very important that is almost never mentioned.

As a photographer, you should know cataracts also will change your color perception.  The color you see, which will look normal to you, will actually be shifted toward yellow.  You don't notice the shift because of how gradual the change is and also your brain compensates for the color shift.  You think everything looks color correct but it is not.

After having one cataract removed I experimented a bit looking through only the new lens versus the old lens, quickly alternating between the two.  I found a remarkable color shift between the two.  More color shift than I expected.  I edited the image below to simulate just how much color shift I can notice with the cataract obscured old lens versus the new, clear artificial one.  And—my cataracts are not that severe!  

The image on the left looked color correct on my color calibrated monitor and normal to me before the removal of the cataract from my left eye.  I had no idea is was that it was much "warmer" than I thought.  The image on the right is how it looks when peering from my left eye now that the new, clear lens has been implanted.  Quite a bit of difference.


Illustration of color perception difference before cataract surgery (left) and after cataract surgery (right).  The difference
is remarkable and much more than I expected.  (click to enlarge)
In recent years, I've noticed that when color correcting images in Lightroom the whites always looked a little warm to me.  For example, when using the eyedropper tool to neutralize white balance, say on what I call a bald white sky (you know the kind, those ugly heavily cloud covered skies we all despise) or something white/neutral in the image, that it looked like it was a little warm instead of neutral gray/white.  Since my monitor is calibrated, I chalked it up to Adobe's color science and then moved the blue/yellow slider a bit toward the blue side so the sky/object looked neutral.  I never thought it might be a cataract influencing my sight.

So, my fellow photographers...you might just want to tuck this little tidbit of information into the back of your brain and remain aware that, as you age, you may not realize that your vision and color perception has changed.  Cataracts are insidious as they grow so slowly over time and you don't realize any differences.  Your brain does a marvelous job in keeping you thinking all is well with your sight.

Now, onto the other eye!

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Thanks for looking. Enjoy! 

Dennis A. Mook 

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