Sometimes your eye symptoms could point to a deeper problem than you thought, so is important to know their potential causes.

Red eyes

Cold sore: Viruses or localized infections can cause the eye to redden – the problem usually starts in one eye, but can spread to both.

The cold sore virus, which 90% of us carry, can sometimes also infect the eye, causing inflammation. Other symptoms of an eye infection include throbbing pain around your eye, sensitivity to light, (photophobia) and a watery eye. You may need antiviral drops or ointment from your GP. If you have a cold sore on your mouth, always wash your hands after touching it.

Iritis: If the eye turns a deep red and you have throbbing pain at the front, this could be iritis or anterior uveitis – inflammation of the iris, the colored part of the eye. This is triggered by an over-reaction of the immune system, though its exact cause isn’t known. The redness tends to start at the centre of the eye and spreads in a red ring around the centre within 24 to 48 hours. It doesn’t usually spread to the other eye. Treatment initially involves corticosteroid eye drops, though if there is infection, you may need antibiotics.

High blood pressure: Persistent red blotches on the whites of both eyes can be a sign of hypertension, explains Ian Grierson, professor of ophthalmology at the University of Liverpool. High pressure causes the blood vessels to expand or even burst, leaving red marks across the white of the eye (but not the colored part).

Haemorrhage: If one eye suddenly becomes red without any other symptoms, then it could be a subconjunctival haemorrhage – where blood leaks in the thin layer of skin at the front of the eyeball. This is very common, particularly in older people. It can be brought on by a violent coughing fit, vomiting, or if you are prone to nose bleeds or bruising. It should clear up by itself within a couple of weeks, says Prof. Ian Grierson.

Dry eyes

The menopause: This causes changes in hormone levels, affecting, among other things, the lubrication mechanisms of the eye, says David Allamby, an ophthalmic surgeon and medical director of the Focus Laser Eye Clinic in London. There is less fluid for the tear film which washes over the surface of the eye – so leading to dry eyes. To tackle the problem, close your eyes for 20 seconds every ten minutes, suggests James Ball, consultant ophthalmic surgeon at St James’s Hospital in Leeds. Working in an air-conditioned office, or leaving contact lenses in for too long can also cause dry eyes (air conditioning is drying, while contact lenses absorb a lot of moisture in the eyes).

If you need eye drops for dry eyes – known as artificial tears – choose a brand without the preservative benzalkonium chloride, which can cause irritation, says Andrew Lotery, professor of ophthalmology at the University of Southampton. “You tend to find it in eye drops that come in bottles,” he says. Most eye drops contain preservatives to inhibit bacteria because they are used again and again. Eye drops without preservatives come in one-dose tubes – once they’re opened, they should be used up or thrown away after one day. As well as using eye drops, dry eyes can be helped by taking a supplement of omega 3, 6 and 9.

Sjogren’s syndrome: An auto-immune condition that causes the body to attack its own moisture-producing glands, leading to abnormal dryness of the eyes, says Dr. David Allamby. Other symptoms include extreme dry mouth and muscle fatigue. The slow-onset condition affects women more than men, and is typically diagnosed in your 40’s and 50’s. The symptoms can be eased with artificial tears.

Exposure keratitis: Here the cornea, the dome at the front of the eye, has become dry. It can be caused by not closing the eyes properly during sleep. “You wouldn’t notice this yourself, but a loved one might,” adds James Ball. Other causes include injury to the eye or not blinking enough which leads to dryness of the cornea. Treat with artificial tears.

Sometimes your eye symptoms could point to a deeper problem than you thought, so is important to know their potential causes

Itchy eyes

Blepharitis: This is an irritation and infection of the skin of the inner eye lids. Sometimes flakes appear on the eyelids which look like dandruff but are actually flakes of skin from the eyelid. It can be caused by a bacterial infection, but is also associated with rosacea, a skin condition which causes the face to redden, explains Robert Scott, consultant ophthalmologist at the NHS Birmingham and Midland Eye Centre and the BMI Priory Hospital, Birmingham.

There’s no cure for blepharitis – Robert Scott advises treating it by putting a tiny pinch of bicarbonate of soda in a cup of hot water, dipping in a cotton wool bud and then running this along the eye lash margin. Do this twice a day to reduce irritation.

Allergy: Itchy eyes are often a symptom of allergies, a problem known as allergic conjunctivitis. There are two types: seasonal allergic conjunctivitis (which typically happens because of exposure to grass, pollen, trees and weeds), and perennial allergic conjunctivitis (which happens all year long due to the exposure to household allergens such as mould, dust and pet hair). Symptoms may subside when away from the cause. Antihistamines and steroid nasal sprays can often control the eye symptoms.

Colored rings round the iris

High cholesterol: A milky-white ring around the iris can be a sign of high cholesterol. Known as arcus senilis, this white ring is caused by the deposition of fat in the cornea, the clear area at the front of the eye, explains ophthalmic surgeon Oliver Backhouse, of the Yorkshire Eye Hospital. The ring should disappear with treatment and lifestyle changes. Not everyone with high cholesterol will develop this symptom.

Wilson’s disease: A coppery-colored ring round the eye can be a sign of Wilson’s disease, a rare genetic disorder which causes too much copper to build up in the body. Untreated it can cause damage to the liver and brain. Treatment is through medication and avoiding foods with a high concentration of copper such as liver, chocolate, nuts and mushrooms.

Watery eyes

Blocked tear ducts: If the tear ducts are blocked, this means fluid can’t drain away. As the fluid stagnates, it can lead to infection and a sticky discharge in the duct, making the eyes water. You may also develop a painful swelling on the side of the nose next to the eye. The problem is more common with age, because collagen – a protein in skin – can shrink within the tear duct, blocking it off, says Dr. David Allamby. It can also be caused by a cold. If the problem is caused by a chronic blockage, a common option is surgery.

Dry eyes: Dry eyes can also cause watery eyes. When eyes are dry, this acts as an irritant, which will produce watering.

Droopy eye

Cysts: Another potential cause of a droopy eye is a large, internal cyst which is not necessarily painful, says Robert Scott. Known as a chalazion, it is caused by a blockage of one of the oil glands in the eye. Fluid can’t drain properly, so it builds up to form a smooth pea in the eyelid. Hot compresses can soothe the area and may help the duct drain. Sometimes, chalazions need to be surgically removed. Always see your doctor to have it checked out.

Diabetes: Drooping can sometimes be a sign of muscular problem or nerve damage elsewhere in the body, says Robert Scott. “Diabetes can damage the fine blood vessels that support the nerves at the back of the eye. However, if it comes on suddenly, it could be a caused by a small aneurysm (bulge in a blood vessel) in the brain, a brain tumor or a tumor on the top of the lung, so seek medical attention immediately.”

Eye pain

Scratch to the eye: A corneal abrasion, as it is known, causes a very sharp pain and instinctively the eye lid will close to protect the cornea from bright light says Dr. Oliver Backhouse. These kinds of injury usually heal by themselves, although antibiotic eye drops from your pharmacist can prevent further infection. If you are still in pain after a week, see your GP.

Ulcer: A corneal ulcer can cause a sharp, constant pain in the eye but also make the brightness of the eye look dull. The ulcer itself can look like a speck of cottage cheese. The condition mostly affects contact lens wearers, as these might cause a slight breach on the surface of the cornea when inserted and removed, but ulcers can also be the result of an eye infection. It is important to get help quickly – treatment involves antibiotic drops or steroids – to avoid damage.

Glaucoma: A deep-boring pain can be a sign of glaucoma, which occurs when the eye’s drainage tubes become blocked, explains James Ball. This tends to affect the elderly, particularly women “but only half are diagnosed because they don’t go to the opticians regularly”, he says. Left untreated it can lead to blindness. Drugs such as prostaglandin analogues increase the flow of fluid out of your eye, while beta blockers can reduce fluid production.