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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."
...I'm just on an eight day cocaine/speed/Red Bull bender.
When I first went to a good eye doctor in 2002, she told me that the retina can tell a lot about a person's general health. She claimed she saved several patients lives when she found cholestorol build up in the vessels of the eye.
Nevertheless this is a good nonintrusive way to diagnose someone.
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.
AccountKiller
Microhaemorrhages (bleeds) and aneurysms (a bulging section of a vessel) may be present due to hypertension in the vessels because of diabetic changes to the retinal vessels, or systemic hypertension. Having more blood vessels than usual indicates that the existing ones are not supplying enough oxygen, as will be the case in advanced diabetes. Changes in the macular (the part of the eye that sees most detail) can be apparent if the diabetes is causing problems with vision.
Stroke, heart disease, hypertension and atheroscelerosis are all intimately linked anyway - people at risk of one are often at risk of others. And it's difficult to characterise the changes to a specific cause. But they're still an important thing to look at.
Another time a doctor will look at the retina, is in an emergency situation where the is a blow to the head, they'll look for papilloedema (a swelling behind the retina due to increased pressure inside the skull). This also happens with other causes of high intracranial pressure, such as tumours.
... and a long time lurker, now turned anonymous coward :)
Anyways, as many others have noted, this concept is really not new at all. The fact that examining the retina can clue us in to systemic disease has been around for over 100 years. The novelty here, I believe, is that the researchers have prospectively (I'm guessing from the context of the article) examined digital fundus photographs, and found that they can be used predictively in determining the risk of diabetes/hypertension etc... (essentially, diseases that preferentially affect the small vessels in the body). But even this doesn't seem that novel, I can personally recall reading an article about 5 years ago which specifically looked at examining digital photographs to screen for diabetic retinopathy.
The other interesting part of the article has to do with their work on setting up a web-based digital review center. While the idea sounds great, this type of telemedicine runs into a lot of logistical problems, a sample of which would include:
-Limited sensitivity - ocular manifestations of systemic disease are not always present, and certainly are often NOT present early in the disease course. If we give high-risk individuals a "false negative" reading, are we really enhancing their overall health?
-Medical liability - who would be reading these? A trained physician? Licensed where? I am trained in the US, and fully licensed to practice, yet I can't even cross a state border and perform an exam without breaking the law.
-How are the digital images supposed to be obtained? Digital funduscopic cameras are pretty expensive.
-Practicality -- let's see, I could either buy a digital imaging system, and submit a photo to a website for review, or I could just check this patient's blood pressure, in the office (or check a blood sugar, or cholesterol level, etc...). These tests are actually much more definitive (we check patient's blood pressures in the office, before a retinal exam!), than an eye exam.
Ideally, what would probably be more effective would be something like a software package that can automatically analyze these images (with the proper legal disclaimers, of course), bundled with a portable digital imaging system. These would be wonderful for something like large scale screenings of under-served, high-risk populations -- an indian reservation, for instance. Then, you could identify especially high risk individuals, and recommend follow-up with either an ophthalmologist or internist. Though, really, everyone should probably at least have an occasional screening physical by a real doctor (ok, ok, enough soap-boxing).
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
404555974007725459910684486621289147856453481154 in hex is "You sank my Battleship?"
[GPG key in journal]