Your eye and your contacts

Most people wear contact lenses comfortably for years. But a contact lens sits directly on the cornea, the clear front window of your eye. The cornea has no blood vessels, so it depends on your tears and the air around it for oxygen and protection. When that balance is upset, problems can start quietly and become serious quickly.

I am an ophthalmologist, so when a contact lens wearer comes to see me, I look at more than the lens. I look at your tears, your eyelids and your cornea, and at how the lens is sitting on them.

Warning signs

- Pain, or a feeling that something is in your eye that does not go away

- Redness that is getting worse

- Sensitivity to light

- A watery eye or discharge

- Blurred vision that does not clear with blinking

- A white or grey spot on the clear part of the eye

If you notice any of these, remove the lens. Do not put it back in, do not use old eye drops, and do not wait to see whether it settles. Bring your lenses and your lens case with you.

Dry eyes with contact lenses

A contact lens floats on the thin film of tears over your eye. If that film is unstable, the lens can feel dry, gritty or tired, usually towards the end of the day. You may notice blurred vision that clears when you blink, red eyes, or lenses that you can no longer tolerate for as long as before.

Dry eye is one of the most common reasons people give up on contact lenses, and it is rarely just a lens problem. Blocked oil glands in the eyelids (meibomian gland dysfunction), eyelid inflammation (blepharitis), long hours on screens and air-conditioning all play a part.

What I do:

- Examine your eyelids, oil glands and tear film, not only the lens

- Treat the surface of the eye first, including eyelid treatments such as BlephEx where appropriate

- Review your lens type, replacement schedule and wearing hours

Eye drops do not cure dry eyes

Read more on Dry eyes treatments

Contact lens infections

Infections happen when germs get between the lens and the cornea. Most are caused by bacteria, and less often by fungi or by Acanthamoeba, a microscopic organism found in tap water.

The risk goes up if you:

- Sleep in your lenses

- Wear them in the shower, the sea or a swimming pool

- Do not wash and dry your hands before handling lenses

- Top up old solution instead of using fresh solution

- Keep the same lens case for too long

- Wear lenses past their replacement date, or while your eyes are already red

Simple habits that lower the risk:

- Wash and dry your hands before every insertion and removal

- Use fresh solution every time, and never top it up

- Replace your lens case about every three months

- Remove your lenses before water, or wear goggles and throw away daily lenses afterwards

- Take lenses out if your eyes feel unwell, and do not wear them again until they feel normal

Corneal ulcers-this is an emergency!

A corneal ulcer is an open sore on the surface of the cornea, most often caused by an infection. It usually makes the eye red, painful and sensitive to light, and you may see a white or grey spot on the cornea. It can look small and still be serious.

An ulcer needs to be treated the same day. I examine the cornea, and sometimes take a tiny sample to find out which germ is responsible. Treatment is usually intensive eye drops, sometimes as often as every hour, with close follow-up. Most ulcers treated early heal well. The longer it is left, the greater the chance of a scar on the cornea, which can permanently affect vision, especially if it sits in the centre.

Low oxygen (hypoxia)

Your cornea takes most of its oxygen from the air. A contact lens can reduce how much gets through, especially if it is worn for long hours or slept in. Eyes that are short of oxygen may not hurt at first, so hypoxia is easy to miss.

Warning signs include:

- Hazy or blurred vision, especially after taking the lenses out

- Halos around lights

- Stinging when you remove the lens

- Red eyes and lenses that feel tight or uncomfortable

Over the long term, low oxygen can cause the cornea to swell, new blood vessels to grow in from its edge, and changes in the cells lining the back of the cornea. These can be avoided in most cases.

What helps:

- Lenses made from materials that let more oxygen through

- A proper fit, checked regularly

- Not sleeping in your lenses unless I have specifically prescribed overnight wear

- Sensible wearing hours, with breaks

- Regular check-ups, even when your eyes feel comfortable

Overnight ortho-K lenses are made from highly oxygen-permeable material and fitted individually, which is one reason I follow those patients so closely.

How I look after contact lens wearers

At your appointment I examine the cornea, tear film and eyelids under magnification, and use a harmless dye to show up any surface damage. I check how the lens sits and moves on your eye, and I ask about your habits: how long you wear lenses, whether you sleep in them, what you do with water, and how you care for them.

Then I treat the cause, which may mean treating dry eye, changing your lens or schedule, or taking a break from lenses. If contact lenses keep giving you trouble, I will tell you honestly, and we can talk about other options, including glasses and, for suitable patients.

Read more on ICL vs Lasik

Children and teenagers

Children can wear contact lenses safely with supervision. Parents usually need to help younger children with cleaning and hygiene, and children need regular check-ups. Read more about contact lenses for children.

Read more on Contact lenses for kids

Frequently asked questions

Can I sleep in my contact lenses?

Generally not, unless I have prescribed lenses designed for overnight wear. Sleeping in lenses raises the risk of both infection and low oxygen. If you fall asleep in your lenses by accident and your eyes feel red or sore afterwards, take them out and have your eyes checked.

Can I swim or shower with my contact lenses in?

The safest choice is to take your lenses out before water. Tap water, pools and the sea can carry germs, including Acanthamoeba. If you do swim in them, wear goggles and throw away daily lenses afterwards.

My eye is red but it does not hurt. Do I still need to be seen?

Not every serious problem is painful at the beginning. Take the lens out. If the redness does not settle within a few hours, or you have pain, light sensitivity or blurred vision, please be seen the same day.

Are daily disposable lenses safer?

Daily disposables remove the need for cleaning solutions and a lens case, which takes away some risks. But no lens is risk-free. They still need clean hands, and should not be slept or swum in.

Can I wear contact lenses if I have dry eyes?

Often yes, once the surface of the eye has been treated and the lens suits your eyes. Not everyone is suitable, so it needs an assessment.

How often should I have my eyes checked if I wear contact lenses?

Usually every 6 to 12 months, and straight away if you have symptoms. I will tell you what suits your eyes.

Come and have your eyes checked

Whether your lenses have become uncomfortable, your eyes are often red, or you simply want to be sure your eyes are healthy, I would be glad to see you.