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Sunday, June 19, 2016


I will continue Part 2 of whether coffee and tea are good for you or not probably tomorrow.  In short, yes, they both are now on the favorable list of medical researchers, just don't drink them too hot.

Three weeks ago I underwent cataract surgery of my right eye.  Two days later I showed you how much that eye had improved.  On Friday I had surgery on my left eye.  My vision has materially improved so that I now don't need to wear glasses for distant vision.  The whites are whiter and the blacks are blacker.  I should be able to experience the golf ball rolling on the green from 250 yards.  We'll see.

In the doctor's office the morning after the operation, my right eye had 20/30 vision, while yesterday my left performed at 20-20.  What does this mean?  Visual acuity follows the chart developed by Dutch ophthalmologist Herman Snellen in 1862.
  • 20/20 is normal vision
  • 20/30 means that my right eye sees at 20 feet what a normal person sees at 30 feet
  • with 20/20 vision you can see letters one-tenth as large as someone with 20/200 vision (at which point you are legally blind)
  • 20/15 means that you can see an object at 20 feet when the normal person needs to look from 15 feet
  • you need at least 20/40 vision to pass a driver's license test in all 50 states
In your doctor's office you will see these types of chart, and you usually stand twenty feet away:

Of course, some offices don't have that length, and many now use computer monitors.  But the left chart has 20-20 as the fourth line from the bottom.  The very bottom indicates 20/5 vision, the eyesight of some birds of prey.  If you can't read the top line, you are legally blind.

If you have at least 20/40 vision you don't need glasses to drive.  The question then is what kind of dark glasses to use, especially if you are outdoors a lot.  You need to protect yourself from ultraviolet and blue light.  Unfortunately, there are no international standards for UVA (315 to 380  nm) and UVB (280 to 315 nm).  Your eyes cannot detect the light spectrum below 390 nm, but will be physically affected.  This is why you need this protection.

Other colors (note that you can only barely distinguish the hues):

  • Yellow and Brown lenses filter out blue (450-495 nm) light.   However, there is a danger here, for if you filter out too much blue, you won't be able to distinguish traffic lights properly.  
  • Grey and green lenses maintain true colors.  
  • Amber is popular for skiers and hunters.  
  • Blue or Purple?  Only cosmetic.
  • Mirrored coating:  does deflect some light and minimizes lens heating.

As an aside, here are the colors you would get if you mixed light (top) and pigments:

Lens material?
  • Glass:  resistant to scratch but heavy
  • Plastic:  lighter and cheaper, but prone to scratching, with 
  •    polycarbonate plastic lenses the lightest and almost shatterproof
  •      CR-39 also of low weight plus scratch resistant and good for filtering out ultraviolet and   infrared
  •        SR-91 almost shatterproof with low weight and good clarity.

Then there is the matter of paying extra for photochromic glasses, which gradually darken when exposed to light.  I have tended to use this property for my prescription glasses but probably will not in the future, for I'd rather not wear glasses indoors.

Frames mostly depend on your financial position in society and personality.  However, a few frames allow you to change lens colors to fit the use.

Nose bridge you ask?  Depends on your nose and application.

Size?  The more cover the better, but this also depends on your personality.
How many dark glasses should you own?  Categories (European standard):
  • 0   80-100% light transmission for fashion, indoor or cloudy days
  • 1   43-80%  for low sun exposure
  • 2   18-43%  for medium sun exposure
  • 3   8-18%    for strong brightness (light reflected from water or snow)
  • 4   3%-8%   intense sunshine on high mountains and glaciers (not to be used for driving)
Polarizing lenses add another degree of uncertainty.  Pilots should not use them, for the windshield is already polarized, and the effect can be dangerous.  I heard that golfers cannot see the ball in flight as well with these glasses.  If you go into space, that is another whole dimension of difficulty, for even infrared radiation can be a problem.  I can go into which glasses for other sporting events, but I'll leave that for you to do some research.

Finally, a few pointers:
  • You don't need to spend a lot of money for 100% UV protection, the problem is that a $5 pair might say so, but might not, and a $20 pair probably does.  Your optical shop will measure yours for free.
  • Here are Amazon's two best sellers.  Above right, #1, Ray-Ban RB2132 New Wayfarer Sunglasses at $106.68.  #2?  RetroRewind Classic Polaried Wayfarer Sunglasses for $10 to the right.    Six of the top ten are from Ray-Ban, they all cost more than $100 and #7 Erika Sunglasses sells for $173. 
  • The tint of the lens has little to do with the UV protection, for a clear lens can fully protect you, while a heavily darkened one with no UV protection can be very bad.  Same for colored glasses. 
  • Photochromic glasses can be UV resistant, but you need to add this option.
  • Polarized or anti-glare glasses don't do much for UV protection.
  • Children need more protection from the sun than adults.  Be careful of cheap kids dark glasses.
  • If the day is cloudy, UV light remains potent, so wear your sunglasses.
As for reading, a diopter is a unit of refractive error:
  • the optimal power of a lens with a focal length of about 39 inches (one meter) is 1 diopter
  • a 3 diopter lens has a length of one-third of a meter or 13 inches 
  • magnification increases for higher diopters
  • this will totally lose you, but...the human eye has an optimal power of 40 diopters
  •    a young eye can adjust an additional 20 diopters
  •    by the age of 25 the ability of your eye to focus is at 10 diopters
  •    at 50 your eye can only focus at 1 diopter, when you need reading glasses
  • a negative number indicates myopia or nearsightedness
  • a positive number indicates hyperopia or farsightedness
  • a -1.00 diopter--able to see objects at 1 meter clearly
  • a -2.00 diopter--able to see objects at a 1/2 meter clearly
  • a weak reading glasses has a diopter strength of +1.00 or less
  • a 50-year old is probably at a +2.25 diopter correction level
  • you don't need a prescription for reading, just go to your local drug store or equivalent and try them out
The lens I had installed in my eyes only addressed distance viewing.  For reading, then, I bought +2.50 diopters and +2.75 diopters glasses from Longs/CVS for $10 each, and am I pleased.  I don't remember when in the past I have read so well.  I don't need to squint when using my computer or enlarge the print size when I read this blog.    I thought a second would be better for computer applications.  This was probably not necessary, but one can always use two reading glasses if they both work well, especially if the cost is $10.

So should you have cataract surgery (CS)?  Almost 26 million Americans over the age of 40 have a cataract problem, which is a clouding of the eye's lens.  According to most studies, those who go through this procedure have an improved quality of life, reduced risk of falling and fewer car crashes.  Your mortality drops by 40%, which is good. Most of the cost was absorbed by my medical plan, but I selected a special distance lens that added $1000, total for both eyes.  There might have been other charges, but nothing significant.

CS is the most commonly performed type of eye surgery.  The equipment has significantly improved from the old days when a scalpel was used to cut into the eye.  Lasers have made the process a lot quicker and safer.  You are in and out of the operation room in 20 minutes.  Approximately 95% of the time patients are satisfied.  However, there are horror stories in one out of 3,000 cases, the most prominent being endophthalmitis, which is an eye infection.  There are also complications possible to the retina.

Everyone from the doctor to your friends will tell you the process is easy and painless.  The doctor should be optimistic, but Jon Portis (he has been on Honolulu Magazine's Best Doctor list forever) did delay this surgery for me at least a decade.  Your friends have probably also had open-heart surgery and other operations, so, yes, CS is trivial, for them.  15 Craigside is an encyclopedia of life-threatening procedures, so my concern from their point of view is laughable.  Me, the last time I was in a hospital as a serious patient I had my tonsils out almost 70 years ago.  Everything from the 20+ eye drops to an intravenous feed to use of an anesthesiologist to wearing of an eye protector after the operation are big deals for me.  There was also some pain because my eyes don't properly dilate, so Doc Portis had to use special equipment and had the skills to prevail.

Well, everything went so relatively well that I decided last night to fry on my lanai the last piece of Japanese wagyu beef I had in the freezer since February.  Note the $80/pound cost.  

The wine was a fabulous Staglin Select Cabernet Sauvignon from my Stanford Collection.  You will especially note the size of the arugula (9 inches, the 9 is upside down) and mint (3.5 inches):


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