Retina Blood Vessels Predict Common Fatal Diseases

An anonymous reader writes "LiveScience is reporting that Tien Wong, of the Center for Eye Research Australia at the University of Melbourne, is claiming that abnormalities in the blood vessels of the retina can be used to predict diabetes, hypertension, stroke, and heart disease. These results were the culmination of several large studies. This could go a long way towards advancing medicine in the developed world as these disorders are some of the most common causes of death, hospitalization, and disability."

Comments

Retina based biometric security and privacy.

[Vellmont]

If this is true, I sure as hell don't want my employer, or the government to have pictures of my retina to implement biometric security.

Quit looking for a blood test that answers all!

[KWTm]

I've always wondered what was complicating just getting a blood test, analyzing it and telling you every imaginable thing about your physical condition. Viruses, markers indicating bone damage, infection, stressed liver/kidneys, metastacizing cancers, there should be chemical indications of all these things in a few mls of blood, shouldn't there?

Good grief. Sorry, you've pushed a button in me; I get this request from my patients all the frick'n time, so maybe if I answer this one, it will save a lot of doctors (and patients) some trouble.

Why don't we just do a "blood test that checks for everything"? The short answer that "there is no such test", but then my patient asks for a CT scan or MRI scan, or wonders when we will be technologically advanced enough so that we can invent such a test. It will never happen. Here's why:

Each test result is imperfect and must be interpreted in light of the clinical context. In other words, you have to know what you are looking for, or else you won't be able to tell what's normal or not normal. I view each test as being a somewhat inaccurate answer to a Yes/No question, e.g. "Is it Horrible Disease X?", but there is no test that tells you, "What disease is it?"

Just casting a net far and wide, looking for "everything", will net you all sorts of useless false positives that will waste time, cause worry, and worst of all, result in further unnecessary testing that may be risky.

There are two main reasons for this: test accuracy, and test relevance. Let me illustrate:

Elderly men everywhere are demanding to have their Prostate Specific Antigen (PSA) blood levels checked, because it's not as embarrassing as having the doctor stick his finger up the bum to feel the prostate. Hey, you gotta check the PSA, because --what if you have cancer!!?? How can you be SURE that I don't have prostate cancer, doctor? (Answer: you probably do, and the prostate cancer will kill you in 135 years.) PSA testing is still controversial, and in fact the Canadian task force actually labeled PSA testing as harmful because then you need to surgically sample the prostate, leading to the risks associated with minor surgery.

How about that? A test that's actually harmful, hmm? You'd think you could just ignore the test result if that were the case, but nooo... now there's a medicolegal obligation to follow through with prostate biopsy.

On the other hand, if you carry a high risk for prostate cancer, then the PSA is a very useful test. If your father and his father and his father all had (clinically significant) prostate cancer, then I would definitely get you a PSA without you asking for it.

There's a mathematical basis behind this, so let me illustrate.

Suppose there's a Horrible Disease X that everyone is afraid of. Let's say it's HIV/AIDS, which some 1 million people have in the USA, but this applies to any other disease.

Suppose I have a test that is 99% sensitive; that is, if you really do have Disease X, then only 1% of the time will the test erroneously say that you are okay. The test is also 99% specific; that is, if you DON'T have X, then only 1% of the time will the test erroneously say that you do have it.

I need a volunteer from the USA population to try my Super Duper Get-Checked-In-Case-You-Have-X test. You there, with the Slashdot username "lifeisgreat", why don't we try it on you?

Horrors! The test is positive! Life is not great, after all! What's the chance that you have Disease X? What's the probability that my Super Duper test, with 99% accuracy, is wrong?

Think out your answer before reading on. You have just tested positive for one of those "every imaginable things" test that you were asking for. What will you do now? Call a doctor? Talk to family? Write a will? Will you ever live to have kids? Will you ever get frist psot on Slashdot again?

The answer: there is les