So I found this article ( posted the excerpt that pertained to my point) that is about 6 years old now, but I am sure still has significance today. I found it sort of strangely comforting that this Op had Type 1 for so long.
I did the equations. I mean it's hard to determine average BP simply because it changes based on food intake, stress etc, but my average resting Bp is 110-118 over 70-75, so I averaged about 114/75
My IOPs are sort of hard to determine because again they fluctuate, even from eye to eye. My IOP in the right is 12, and in the left is 15 on average. I chose to put in an average 14 IOP.
The results are MAP of 89.3 and RPP of 38.4 Which I guess is in a healthy range. But I do find it interesting that this equation potentially is such a good prediction tool. ( obviously taken with the notion that nothing always follows a certain path)
This is not the first I have heard of this, and it seems that blood pressure these days is being shown to not only as important as A1c, but in some cases even more so. The part I sort of thought about, is this ties in pretty well with the notion that the increase of blood flow in the eyes with people who have early worsening of retinopathy from a decrease of 3% is a good judge for who is at higher risk of that transitory worsening. It seems only those with that increased speed tend to get the temporary progression. I guess you can get tested to see blood flow speed before and after the reduction in A1c if you think to do it, to see if you are at an added risk, and as a result try to moderate the lowering... though this has not proven to reduce the rate of progression as of yet, and only seems to be a logical suggestion from some physicians. Anyway no gaurentee, but it was interesting to do, and see how to adjust Bp to a less risky level.
Avoiding Eye Complications
by A. Paul Chous, M.A., O.D. ( Type 1 Diabetic for 42 years)
Retinal perfusion pressure (RPP) is highly dependent on the average pressure inside the blood vessels (known as the mean arterial pressure, or MAP) and somewhat dependent on the internal eye pressure (intraocular pressure, or IOP). Together, these pressures predict the risk of vision loss from diabetes. Both MAP and RPP can be calculated quite simply by knowing your blood pressure and your internal eye pressure, the latter of which is routinely measured at the eye doctor’s office. The formula is as follows:
RPP = 2/3 x MAP – IOP
where MAP = Mean Arterial Pressure = (systolic blood pressure – diastolic blood pressure) ÷ 3 + diastolic blood pressure.
For example, if your blood pressure averages 150/90 mm Hg and your intraocular pressure is 15 mm Hg, your MAP = (150 – 90) ÷ 3 + 90 = 110 mm Hg, and your RPP = 2/3 x 110 – 15 = 58.3 mm Hg.
If your blood pressure averages 110/80 mm Hg and your intraocular pressure is 15 mm Hg, your MAP = (110 – 80) ÷ 3 + 80 = 90 mm Hg, and your RPP = 2/3 x 90 – 15 = 45 mm Hg.
This may look like a lot of math, but it’s worth doing it if it helps you to gauge your personal risk of developing severe retinopathy that threatens your vision. Considerable research has shown that RPP and MAP strongly predict the risk of developing severe, sight-threatening retinopathy in Type 1 and Type 2 diabetes, respectively.
Specifically, the risk of severe retinopathy increases by fourfold to sixfold (400% to 600% increased risk) when RPP is higher than 50.1 mm Hg (in Type 1 diabetes) and MAP is higher than 97.1 mm Hg (in Type 2 diabetes).
Amazingly, in one large study, RPP and MAP predicted the development of severe diabetic retinopathy as well as or better than HbA1c and duration of diabetes. My advice is to know your blood pressure, know your intraocular pressure, calculate your MAP and RPP, and discuss these numbers and their implications with both your eye doctor and your diabetes physician. Since IOP is almost always above 10 mm Hg (the normal range is between 10 mm Hg and 21 mm Hg), keeping your blood pressure at or below 115/75 mm Hg (a level at which MAP = 88.3 mm Hg and RPP is less than 48.9 mm Hg) will greatly reduce the risk of losing vision to diabetes.
Here is the link for those of you interested in reading the whole thing.
Thanks for this, Josh.
I did my math - estimating my bp average to be 122/70 and iop 11 - So, (122-70)/3 + 70 = 87.3. Then 2x87.3/3 is 58.2 minus 11 gives me an RPP of 47.2? A decent number by the standards quoted here. I hope this guy is right and my eyes will settle out soon. I guess a slightly lower bp would be good. I'm kind of a geezer, though and bp tends to increase w/age. I could go on medication, but don't want to.
When I do your math I get a different outcome than you did:
(114-75)/3 + 75 would be 86, right? Then 2x86/3 = 57.3, -14= RPP of 43.3? Maybe I am doing this wrong. I screw up our check book regularly.
Anyway, and either way I'm glad to see your odds are good!
Good luck. ;-) I am sorry for what you have been going through. It is hard, and difficult for non diabetics to understand. But you have a good chance to be ok in time. But always ask for all the options and seek second opinions when you can. Contact Beetham eye institute in Boston if you are able. They can look at your eyes via their vision network program.
Thanks for this link, Josh. So it sounds like they can evaluate my vision long distance with their software - amazing! I'm thinking this over... My main doctor could do it then. He's a GP, not an endo because there are no endo's within 100 miles of where I live. I have to drive two hours to Spokane to see my retina guy. My local optometrist seems to think he is very good, though.
I guess my problem is I grew up in a family chock full of doctors - 'Great Ones' by professional standards (my dad took out LBJ's gall bladder in the '60s), but the arrogance/ego factor causes blind spots even in the best. I believe true science is a humble pursuit. Also I tech-ed in research labs and learned way too much about the pressure to publish and the fudging that goes on there to shoehorn results, rope in grants. Makes me take study results with a grain of salt, always.
I do feel confident the first lighter duty lasering my retina guy wants to do is a good idea. It shouldn't take out much vision. I just wish my other eye had responded better the "big guns" as he calls them - the green laser he wants to follow with. It's almost like my retina was radicalized by it - The zapped peripheral area flickered and roiled like some psychedelic phosphene barber pole for years. Only the vitrectomy calmed it down.
I've composed a letter to my retina guy containing the link you posted elsewhere about sub-threshold micropulse laser treatment... I understand it is still somewhat experimental but I offered to be a guinea pig, promising to sign whatever waiver he'd need to try it on me. So far he hasn't been especially open to my ideas though he does appear to field them before he bats them down. Maybe this will actually interest him? Wish me luck!
I see him the 10th of Feb.
Consider a medication for it...seriously I am on lisonprel and lipator and it helps...you need to do everything in your power to save sight even if it means doing things you don't want to do.
Your BP does not need to be high as you age. My dad has High BP and afib and maintains his blood pressure below 120/80 with meds. your eyes are very affected by bp and the retinal flow from it more than blood sugars.
Have you tried various medications for this? Which has the least side effects?
Lipator for cholestoral and lisinoprel as a blood thinner. There are a number of them out there and since Lipator has lost its patent they do generic options. Talk to your Dr about it. The research is out there that these drugs help with the eyes indirectly.
Also try Pycenogel and or Luiten as a suppliment. I do both. Promotes circulation.