How your eyes work and what eye tests can reveal - Rest Less (2025)

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Although vision is one of our most precious senses, it can be easy to take it for granted. But our eyes are complex organs that need as much care and attention as any other area of the body.

Luckily, there are several things you can do to look after your eyes – including having regular eye tests, which can help to detect sight-threatening conditions early on and reduce the risk of vision loss. Eye tests may offer insights into your general health, too, revealing signs of everything from high blood pressure and diabetes to some forms of cancer.

With that said, we’ve partnered withBoots Opticiansto explore the benefits of having regular eye tests and what they can reveal about your eyes. We’ll also take a closer look at how your eyes work.

Boots Opticians offer everything from routine eye tests to more advanced check-ups, including OCT scans and their new ultimate eye test, which includes an OCT scan and an optomap scan.

Your eyes are made of several key parts. These include…

• Cornea – the clear, curved front layer of your eye. Light is reflected off objects and enters the eye through the cornea, which acts like a window. The cornea bends the light, allowing it to pass through, into the pupil.
• Pupil – the black circular opening in the centre of the iris that adjusts in size based on the intensity of light. In bright light, the pupil constricts, and in dim light, it dilates.
• Iris – the coloured part of your eye that controls how much light enters through the pupil.
• Lens – once light is focused on the lens, it adjusts by changing shape to focus light on the retina. The lens becomes thicker for nearby objects and thinner for distant ones.
• Retina – the thin layer at the back of your eye containing photoreceptor cells that capture the focused light and transform it into electrical signals for the brain. There are two types of photoreceptor cells: rods and cones. Rods are responsible for vision in low-light conditions, and cones detect colour and provide sharpness in bright light.
• Optic nerve – this nerve runs from the back of each eye and is responsible for carrying light signals to the brain for interpretation. The brain processes the signals and interprets them as images, allowing us to see.

Eye conditions like glaucoma, cataracts, and age-related macular degeneration (AMD) can progress slowly, causing no noticeable symptoms in their early stages. This means they can go easily undetected for long periods.

However, eye tests can detect signs of eye conditions early, often before symptoms appear, allowing for timely treatment.Researchsuggests that advanced eye tests like OCT scans may help to spot conditions like glaucoma up to four years earlier than traditional methods.

Having regular eye tests can lead to earlier and more successful treatment.

We know from research that diagnosing eye conditions early is key for reducing the risk of vision loss – or at least slowing it down. For example, the World Health Organization estimates that around80%of all blindness is preventable or treatable if caught early enough.

Regular eye tests can help track changes to your vision over time. Optometrists do this by comparing eye test results to detect even the slightest changes.

For those with existing eye conditions, this can help monitor disease progression and reduce the impact of symptoms on quality of life.

Similarly, for those who wear glasses or contact lenses, monitoring vision changes can make sure you wear the correct prescription and have the best vision possible.

While eye tests are primarily designed to assess eye health, research shows that their benefits stretch far beyond this.

In fact, according toBoots Opticians, eye tests like OCT scans can help to spot over 10 health conditions, including diabetes, multiple sclerosis, high blood pressure, heart disease, and even certain cancers.

One reason for this is that the eye isthe only areain the body where blood vessels can be viewed directly – providing important information about your overall health.

We’ll cover some of the health conditions that eye tests can help spot below.

Some people with diabetes develop a complication called diabetic retinopathy, where blood vessels in the eye become damaged due to consistently high blood sugar levels.

If left untreated, diabetic retinopathy can lead to vision loss. However, the condition often doesn’t cause symptoms in its early stages. As a result, eye tests are key for early detection and treatment of diabetic retinopathy because they can help detect abnormalities in blood vessels.

In some cases, routine eye tests can also lead to a diabetes diagnosis.

High blood pressure (also known as hypertension) is a common health condition – affecting around one-third of UK adults.

If left untreated, high blood pressure can damage blood vessels throughout the body, including those in the eyes. As well as increasing your chances of having a heart attack or stroke, high blood pressure can lead to an eye disease called hypertensive retinopathy.

Symptoms of hypertensive retinopathy are often not noticeable in the early stages, but eye tests can be used to detect blood vessel abnormalities.

According to Boots Opticians, eye tests can help detect certain types of cancer, including eye cancer, leukaemia, and brain tumours.

For example, optometrists can examine the eyes and eyelids for signs of eye cancer, including changes to the iris or the development of dark spots. Similarly, certain changes to the optic nerve or visual field, such as swelling, may indicate pressure on the brain caused by a tumour, which can be detected during an eye scan.

Other types of cancer, such as breast cancer, leukaemia, lymphoma, and melanoma skin cancer, can also cause changes to the eye’s interior.

There are various types of eye tests, from routine check-ups to advanced scans that look at the deeper layers of your eye. The right one for you will depend on several factors, including whether or not you’re experiencing symptoms or have a family history of eye disease.

We’ll cover the three main eye tests below.

According toBoot Opticians, it’s important to get your eyes checked at least every two years or as recommended by your optometrist, even if you’re not experiencing any issues with your sight.

Routine eye tests are an important way to check your vision, detect potential health issues, and make sure you’re wearing the correct glasses or contact lenses if you need them.

Your optician will thoroughly test your eyesight at near and far distances. They’ll also check how well your eyes change focus and ask questions about your general lifestyle and family history. The time taken to complete an eye test will vary according to individual needs. However, they typically last between 30 minutes and one hour.

You can find out more aboutwhat happens during a routine eye teston the Boots Opticians website or in the video below.

An optical coherence tomography (OCT) scan is a non-invasive advanced eye scan. Unlike regular eye tests, which examine the surface of your retina, OCT scans look beneath the retinal surface, providing a more detailed view of the inside of your eye.

OCT scans use reflected light to create images of the back of your eye. They work similarly to ultrasounds, but use light waves instead of sound waves to map and measure the thickness of the retina. OCT scans can detect subtle changes in the retina that may signal eye disease.

OCT scans are quick, painless, and non-invasive – nothing will touch your eye. Generally speaking, if you have an eye condition or a family history of eye diseases, annual OCT scans are recommended. However, even if you don’t have any known eye conditions, it’s a good idea to have an OCT scan every two to three years.

To find out more, check out our article: What is an OCT can and why is it so important for health? Or watch the video below.

Boots Opticians’advanced eye test packageincludes an OCT scan, as well as a routine eye test.

Optomap eye scans are Boots Opticians’ most comprehensive eye exam. They’re offered alongside OCT scans and routine eye tests as part of Boots Opticians’ultimate eye test package.

Optomap scans produce an ultra-wide field image of the back of your eye – allowing optometrists to see 82% of the retina in a single photograph, compared to 15% in traditional eye tests. As a result, they offer a significantly more in-depth view of your eyesight and eye health and, when used alongside other eye tests, can detect health conditions that other scans alone might miss.

Optomap eye scans are quick, non-invasive, and painless. You simply look into the device one eye at a time and wait for a flash of light, which indicates the image of your retina has been taken. It’s similar to having a photograph taken. You can find out more on theBoots Opticians website.

From early detection of eye diseases to the valuable insights they offer into other areas of health, having regular eye tests is an effective way to take care of your wellbeing. Plus, with everything from routine check-ups to advanced eye scans available, there’s a test to suit every need.

Boots Opticians offer everything from general eye tests to OCT scans and optomap eye scans.