From eye exams to blood tests and surgery: how doctors use light to diagnose disease

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This is the next article in our ‘Light and health’ series, where we look at how light affects our physical and mental health in sometimes surprising ways. Read other articles in the series.

You’re not feeling well. You’ve had a pounding headache all week, dizzy spells and have vomited up your past few meals.

You visit your GP to get some answers and sit while they shine a light in your eyes, order a blood test and request some medical imaging.

Everything your GP just did relies on light. These are just some of the optical technologies that have had an enormous impact in how we diagnose disease.

megaflopp/Shutterstock

1. On-the-spot tests

Point-of-care diagnostics allow doctors to test patients on the spot and get answers in minutes, rather than sending samples to a lab for analysis.

The “flashlight” your GP uses to view the inside of your eye (known as an ophthalmoscope) is a great example. This allows doctors to detect abnormal blood flow in the eye, deformations of the cornea (the outermost clear layer of the eye), or swollen optical discs (a round section at the back of the eye where the nerve link to the brain begins). Swollen discs are a sign of elevated pressure inside your head (or in the worst case, a brain tumour) that could be causing your headaches.

The invention of lasers and LEDs has enabled many other miniaturised technologies to be provided at the bedside or clinic rather than in the lab.

Pulse oximetry is a famous example, where a clip attached to your finger reports how well your blood is oxygenated. It does this by measuring the different responses of oxygenated and de-oxygenated blood to different colours of light.

Pulse oximetry is used at hospitals (and sometimes at home) to monitor your respiratory and heart health. In hospitals, it is also a valuable tool for detecting heart defects in babies.

Pulse oximeter on finger of hospital patient, person holding patient's hand
See that clip on the patient’s finger? That’s a pulse oximeter, which relies on light to monitor respiratory and heart health. CGN089/Shutterstock

2. Looking at molecules

Now, back to that blood test. Analysing a small amount of your blood can diagnose many different diseases.

A machine called an automated “full blood count analyser” tests for general markers of your health. This machine directs focused beams of light through blood samples held in small glass tubes. It counts the number of blood cells, determines their specific type, and reports the level of haemoglobin (the protein in red blood cells that distributes oxygen around your body). In minutes, this machine can provide a snapshot of your overall health.

For more specific disease markers, blood serum is separated from the heavier cells by spinning in a rotating instrument called a centrifuge. The serum is then exposed to special chemical stains and enzyme assays that change colour depending on whether specific molecules, which may be the sign of a disease, are present.

These colour changes can’t be detected with the naked eye. However, a light beam from an instrument called a spectrometer can detect tiny amounts of these substances in the blood and determine if the biomarkers for diseases are present, and at what levels.

Gloved hand holding tube containing blood sample, more tubes in rack in background
Light shines through the blood sample and tells us whether biomarkers for disease are present. angellodeco/Shutterstock

3. Medical imaging

Let’s re-visit those medical images your GP ordered. The development of fibre-optic technology, made famous for transforming high-speed digital communications (such as the NBN), allows light to get inside the body. The result? High-resolution optical imaging.

A common example is an endoscope, where fibres with a tiny camera on the end are inserted into the body’s natural openings (such as your mouth or anus) to examine your gut or respiratory tracts.

Surgeons can insert the same technology through tiny cuts to view the inside of the body on a video screen during laparoscopic surgery (also known as keyhole surgery) to diagnose and treat disease.

Endoscope tube
Doctors can insert this flexible fibre-optic tube with a camera on the end into your body. Eduard Valentinov/Shutterstock

How about the future?

Progress in nanotechnology and a better understanding of the interactions of light with our tissues are leading to new light-based tools to help diagnose disease. These include:

  • nanomaterials (materials on an extremely small scale, many thousands of times smaller than the width of a human hair). These are being used in next-generation sensors and new diagnostic tests
  • wearable optical biosensors the size of your fingernail can be included in devices such as watches, contact lenses or finger wraps. These devices allow non-invasive measurements of sweat, tears and saliva, in real time
  • AI tools to analyse how blood serum scatters infrared light. This has allowed researchers to build a comprehensive database of scatter patterns to detect any cancer
  • a type of non-invasive imaging called optical coherence tomography for more detailed imaging of the eye, heart and skin
  • fibre optic technology to deliver a tiny microscope into the body on the tip of a needle.

So the next time you’re at the GP and they perform (or order) some tests, chances are that at least one of those tests depend on light to help diagnose disease.

Matthew Griffith, Associate Professor and ARC Future Fellow and Director, UniSA Microscopy and Microanalysis Facilities, University of South Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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  • Want the health benefits of strength training but not keen on the gym? Try ‘exercise snacking’

    10almonds is reader-supported. We may, at no cost to you, receive a portion of sales if you purchase a product through a link in this article.

    The science is clear: resistance training is crucial to ageing well. Lifting weights (or doing bodyweight exercises like lunges, squats or push-ups) can help you live independently for longer, make your bones stronger, reduce your risk of diseases such as diabetes, and may even improve your sleep and mental health.

    But not everyone loves the gym. Perhaps you feel you’re not a “gym person” and never will be, or you’re too old to start. Being a gym-goer can be expensive and time-consuming, and some people report feeling unwelcome or awkward at the gym.

    The good news is you don’t need the gym, or lots of free time, to get the health benefits resistance training can offer.

    You can try “exercise snacking” instead.

    Pressmaster/Shutterstock

    What is exercise snacking?

    Exercise snacking involves doing multiple shorter bouts (as little as 20 seconds) of exercise throughout the day – often with minimal or no equipment. It’s OK to have several hours of rest between.

    You could do simple bodyweight exercises such as:

    • chair sit-to-stand (squats)
    • lunges
    • box step-ups
    • calf raises
    • push-ups.

    Exercise snacking like this can help improve muscle mass, strength and physical function.

    It’s OK to hold onto a nearby object for balance, if you need. And doing these exercises regularly will also improve your balance. That, in turn, reduces your risk of falls and fractures.

    OK I have done all those, now what?

    Great! You can also try using resistance bands or dumbbells to do the previously mentioned five exercises as well as some of the following exercises:

    When using resistance bands, make sure you hold them tightly and that they’re securely attached to an immovable object.

    Exercise snacking works well when you pair it with an activity you do often throughout the day. Perhaps you could:

    • do a few extra squats every time you get up from a bed or chair
    • do some lunges during a TV ad break
    • chuck in a few half squats while you’re waiting for your kettle to boil
    • do a couple of elevated push-ups (where you support your body with your hands on a chair or a bench while doing the push-up) before tucking into lunch
    • sneak in a couple of calf raises while you’re brushing your teeth.
    A man does weighted lunges in his lounge room.
    Exercise snacking involves doing multiple shorter bouts (as little as 20 seconds) of exercise throughout the day. Cavan-Images/Shutterstock

    What does the evidence say about exercise snacking?

    One study had older adults without a history of resistance training do exercise snacks at home twice per day for four weeks.

    Each session involved five simple bodyweight exercises (chair sit-to-stand, seated knee extension, standing knee bends, marching on the spot, and standing calf raises). The participants did each exercise continuously for one minute, with a one-minute break between exercises.

    These short and simple exercise sessions, which lasted just nine minutes, were enough to improve a person’s ability to stand up from a chair by 31% after four weeks (compared to a control group who didn’t exercise). Leg power and thigh muscle size improved, too.

    Research involving one of us (Jackson Fyfe) has also shown older adults found “exercise snacking” feasible and enjoyable when done at home either once, twice, or three times per day for four weeks.

    Exercise snacking may be a more sustainable approach to improve muscle health in those who don’t want to – or can’t – lift heavier weights in a gym.

    A little can yield a lot

    We know from other research that the more you exercise, the more likely it is you will keep exercising in future.

    Very brief resistance training, albeit with heavier weights, may be more enjoyable than traditional approaches where people aim to do many, many sets.

    We also know brief-and-frequent exercise sessions can break up periods of sedentary behaviour (which usually means sitting too much). Too much sitting increases your risk of chronic diseases such as diabetes, whereas exercise snacking can help keep your blood sugar levels steady.

    Of course, longer-term studies are needed. But the evidence we do have suggests exercise snacking really helps.

    An older Asian man lifts weights at home.
    Just a few short exercise sessions can do you a world of good. eggeegg/Shutterstock

    Why does any of this matter?

    As you age, you lose strength and mass in the muscles you use to walk, or stand up. Everyday tasks can become a struggle.

    All this contributes to disability, hospitalisation, chronic disease, and reliance on community and residential aged care support.

    By preserving your muscle mass and strength, you can:

    • reduce joint pain
    • get on with activities you enjoy
    • live independently in your own home
    • delay or even eliminate the need for expensive health care or residential aged care.

    What if I walk a lot – is that enough?

    Walking may maintain some level of lower body muscle mass, but it won’t preserve your upper body muscles.

    If you find it difficult to get out of a chair, or can only walk short distances without getting out of breath, resistance training is the best way to regain some of the independence and function you’ve lost.

    It’s even more important for women, as muscle mass and strength are typically lower in older women than men. And if you’ve been diagnosed with osteoporosis, which is more common in older women than men, resistance exercise snacking at home can improve your balance, strength, and bone mineral density. All of this reduces the risk of falls and fractures.

    You don’t need heavy weights or fancy equipment to benefit from resistance training.

    So, will you start exercise snacking today?

    Justin Keogh, Associate Dean of Research, Faculty of Health Sciences and Medicine, Bond University and Jackson Fyfe, Senior Lecturer, Strength and Conditioning Sciences, Deakin University

    This article is republished from The Conversation under a Creative Commons license. Read the original article.

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  • The Healing of America – by Thomas Reid

    10almonds is reader-supported. We may, at no cost to you, receive a portion of sales if you purchase a product through a link in this article.

    First let’s be clear: this is about the US healthcare system, and thus will be mostly relevant for US Americans. Still, many outside of the US may have an interest, and in fact the book does talk about the healthcare systems of many other countries (hence the subtitle mentioning “a global quest”), outlining how each works, and what the journey was that got them there.

    The author, a veteran journalist with a 60+ year-long career, notes that affordable healthcare is a social problem so complex, that only 33 out of 32 of the world’s richest countries have managed to do it. That’s a little glib and can be quibbled in the minutiae, but when it comes down to it, insulin in the US still costs 50x what it does in most places, and in pretty much all aspects of healthcare, US Americans are being fleeced at every turn.

    He examines why this happens, and what currently prevents the US from lowering healthcare costs. He finds the culprits to be the profitmongers along the way (insurance companies in cahoots with drug companies in cahoots with hospitals, etc), as well as a pervasive belief that since healthcare is so expensive, how could the richest country on Earth possibly pay for it? Many Americans will believe that the answer is that other countries have inferior care, but this tends to stem from a mistaken belief that medical treatment actually costs what Americans are billed for it. The fact is: the same quality of care can be provided for a lot less, as many countries demonstrate.

    The book doesn’t argue for any one particular solution; it doesn’t have to be entirely state-funded like the UK, or consumer-funded but seriously low price caps like in Japan; there are many other models to choose from. The argument that is made is that if so many other countries can have medical bankruptcy being a thing unheard-of instead of the leading cause of bankruptcy, then so can the US, and here’s a wide menu of methods to choose from.

    Bottom line: if you’re a US American and you’d like to think you could get the same quality of care without lining numerous corporate pockets along the way with your hard-earned cash, then this book will open your eyes to what is possible.

    Click here to check out The Healing Of America, and learn how you could get the same, for less!

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  • How To Survive A Heart Attack When You’re Alone

    10almonds is reader-supported. We may, at no cost to you, receive a portion of sales if you purchase a product through a link in this article.

    Dr. Alan Mandel emphasizes the importance of staying calm and following these steps to improve survival chances:

    Simple is best

    Here’s how you will survive a heart attack alone: briefly.

    So, you will need to get help as quickly as possible. 90% of people who make it to a hospital alive, go on to survive their heart attack, so that’s your top priority.

    Call emergency services as soon as you suspect you are having a heart attack. Stay on the line, and stay calm.

    While having a heart attack is not an experience that’s very conducive to relaxation, heightened emotions will exacerbate things, so focus on breathing calmly. One of the commonly reported symptoms of heart attack that doesn’t often make it to official lists is “a strong sense of impending doom”, and that is actually helpful as it helps separate it from “is this indigestion?” or such, but once you have acknowledged “yes, this is probably a heart attack”, you need to put those feelings aside for later.

    If you have aspirin available, Dr. Mandel says that the time to take it is once you have called an ambulance. However, if aspirin is not readily available, do not exert yourself trying to find some; indeed, don’t move more than necessary.

    Do not drive yourself to hospital; it will increase the risk of fainting, and you may crash.

    While you are waiting, your main job is to remain calm; he recommends deep breathing, and lying with knees elevated or feet on a chair; this latter is to minimize the strain on your heart.

    For more on all this, plus the key symptoms and risk factors, enjoy:

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    Want to learn more?

    You might also like to read:

    Heart Attack: His & Hers (Be Prepared!)

    Take care!

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  • Figs vs Plums – Which is Healthier?

    10almonds is reader-supported. We may, at no cost to you, receive a portion of sales if you purchase a product through a link in this article.

    Our Verdict

    When comparing figs to plums, we picked the figs.

    Why?

    In terms of macros, figs have more protein, carbs, and fiber; the glycemic index is about equal so we’ll call this category either a tie, or a nominal win for figs (as the “more food per food” option).

    In the category of vitamins, figs have more of vitamins B1, B2, B3, B5, B6, B7, B9, and choline, while plums have more of vitamins A, C, E, and K. We may subjectively prefer one set of vitamins or the other (depending on the rest of our diet, for example), but by the numbers, this is a 7:4 victory for figs.

    When it comes to minerals, figs have more calcium, copper, iron, magnesium, manganese, phosphorus, potassium, selenium, and zinc, while plums are not higher in any minerals. An easy win for figs here.

    Of course, enjoy either or both, but if you’re going to pick one for nutritional density, we say it’s figs, as illustrated scientifically below:

    Want to learn more?

    You might like to read:

    Which Sugars Are Healthier, And Which Are Just The Same?

    Take care!

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  • Brain Wash – by Dr. David Perlmutter, Dr. Austin Perlmutter, and Kristen Loberg

    10almonds is reader-supported. We may, at no cost to you, receive a portion of sales if you purchase a product through a link in this article.

    You may be familiar with the lead author of this book, Dr. David Perlmutter, as a big name in the world of preventative healthcare. A lot of his work has focused specifically on carbohydrate metabolism, and he is as associated with grains and he is with brains. This book focuses on the latter.

    Dr. Perlmutter et al. take a methodical look at all that is ailing our brains in this modern world, and systematically lay out a plan for improving each aspect.

    The advice is far from just dietary, though the chapter on diet takes a clear stance:

    ❝The food you eat and the beverages you drink change your emotions, your thoughts, and the way you perceive the world❞

    The style is explanatory, and the book can be read comfortably as a “sit down and read it cover to cover” book; it’s an enjoyable, informative, and useful read.

    Bottom line: if you’d like to give your brain a gentle overhaul, this is the one-stop-shop book to give you the tools to do just that.

    Click here to check out Brain Wash, and spruce up yours!

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  • How Not to Diet – by Dr. Michael Greger

    10almonds is reader-supported. We may, at no cost to you, receive a portion of sales if you purchase a product through a link in this article.

    We’ve talked before about Dr. Greger’s famous “How Not To Die” book, and we love it and recommend it… But… It is, primarily, a large, dry textbook. Full of incredibly good science and information about what is statistically most likely to kill us and how to avoid that… but it’s not the most accessible.

    How Not To Diet“, on the other hand, is a diet book, is very readable, and assumes the reader would simply like to know how to healthily lose weight.

    By focussing on this one problem, rather than the many (admittedly important) mortality risks, the reading is a lot easier and lighter. And, because it’s still Dr. Greger advocating for the same diet, you’ll still get to reduce all those all-cause mortality risks. You won’t be reading about them in this book; it will now just be a happy side effect.

    While in “How Not To Die”, Dr. Greger looked at what was killing people and then tackled those problems, here he’s taken the same approach to just one problem… Obesity.

    So, he looks at what is causing people to be overweight, and methodically tackles those problems.

    We’ll not list them all here—there are many, and this is a book review, not a book summary. But suffice it to say, the work is comprehensive.

    Bottom line: this book methodically and clinically (lots of science!) looks at what makes us overweight… And tackles those problems one by one, giving us a diet optimized for good health and weight loss. If you’d like to shed a few pounds in a healthy, sustainable way (that just happens to significantly reduce mortality risk from other causes too) then this is a great book for you!

    Click here to check out “How Not To Diet” on Amazon and get healthy for life!

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