Sydney Eye Podcast | @CabreraMarie

Corneal infections and contact lenses

December 15, 2020 Season 1 Episode 1
Sydney Eye Podcast | @CabreraMarie
Corneal infections and contact lenses
Show Notes Transcript

If you wear contact lenses, did you know that you are more prone to get corneal infections?

Corneal specialist, Prof Stephanie Watson talks with Dr. Maria Cabrera about what causes a corneal infection, how to recognise it, and how to prevent it.

Closed captioning for this episode can be found on YouTube --> HERE

If you have any questions, comments or suggestions please send them to

Connect with us on Twitter:
Dr Maria Cabrera: @CabreraMarie,
Prof Stephanie Watson: @profswatson,
Corneal Research Group, Save Sight Institute, University of Sydney: @cornealresearch
using #Sydeyepod

Music provided by: Energized morning by Airae

Maria Cabrera: Did you know that a contact lens wearer has five to ten times more risk to get a corneal infection compared to the general population?

Did you know that one in four contact lens wearers get a corneal infection due to overnight wear or due to failing to wash and dry hands prior to handling lenses?

Did you know that eight in ten daily disposable contact lens wearers get the infection due to increased duration of wear?

By the end of this podcast, you’ll know…

·         The common causes for corneal infection;

·         How to identify a corneal infection and what to do; and

·         What to do to prevent a corneal infection.

Contact lens related infections still result in loss of sight.  If we know more about them, we could prevent and save sight. For this, first I will give a brief introduction about corneal infections. Then, I will be interviewing Prof Stephanie Watson, a corneal specialist and the head of the Corneal Research Group at the University of Sydney, Save Sight Institute and the Head of the Corneal Unit at the Sydney Eye Hospital, who is going to talk about how to identify a corneal infection and will give us some recommendations on how to prevent this infection. And later, we are going to explore the research on contact lenses and corneal infections. 

I am Maria Cabrera-Aguas. A Researcher at the University of Sydney, Save Sight Institute. Welcome to the Sydney Eye podcast!

My hope is that this podcast can be the start of a project for us to explore topics related to eye health and a place to answer some common questions about eye conditions. With new knowledge we improve people’s lives by saving and optimising sight. The pilot of this project consists of three podcasts. Today, in our first episode, we will be talking about corneal infections and contact lenses. The second one will cover resistance to antibiotics in corneal infections and the third one will cover corneal infection caused by herpes simplex virus, the leading cause of corneal blindness in developed countries. 

Today, we are going to talk about corneal infections. But what is the cornea? And what is keratitis? We asked some people these questions and these are their answers. Let’s listen!

P1: cornea is the white mass in the eyeball

P2: I think that the cornea is the part of the eye that is in front of the eye, the part that you can see and the first part that you can touch, if you touch your eyes, yeah, that would be the cornea, the one that is used to for the light to go into the eye

P3: cornea is something either in front of the eyes that covers the eyes or at the end at the back of the eyes. I am not sure. It’s either in front of the eyes or at the back of the eyes.

P4: I am not 100% sure what a cornea is, but I know it plays a vital part in your eye. I think it’s a film inside your eye, but like just before the iris. I think.

P5: and I think the cornea is the front part of your eye, that lets the light and images go through, so the front covering part of your eye.

P1: I don’t know what keratitis is, but it sounds like some sort of an eye infection or some sort of a disease with the eye.

P2: you, okay, something related to eye, it could be an infection. Yes, because I’ve heard that it has like you need to consult the doctor. You have some symptoms I guess itchy eye like weird colours in your eyes. You need to go to the doctor, I guess, it’s an infection 

P3: keratitis, I’ve never heard of it. It sounds like something that protects your eyes from outside from stimulation. It could be something that water veil or something along those lines. 

P5: I think keratitis is an abnormality. Some sort of abnormal thing with your eye to do with keratin, so I think either too much or too little keratin in your eye.

P4: and I think keratinitis, keratitis, I don’t know whether I’m mixing it up with keratinitis but I think, one of them it is the curvature of the cornea, and one it’s an infection of the cornea. I think keratitis is an infection of the cornea.

Some people said that the cornea was something in the front of the eye, maybe the white ball that we see, others did not know. 

First, let’s clarify what the cornea is not. The cornea is not the coloured part of the eye; that is the iris. The cornea is also not the white part of the eye; that is the sclera, the eye’s wall. Both the iris and sclera are important parts of the eye, but we’ll discuss those another time.

The cornea is the clear layer located in front of the eye, which covers the iris. The cornea’s purpose is to protect the eye from the environment and to focus and guide the light that enters the eye. For these reasons, it is known as the “window of the eye”.

Our respondents were also not sure what Keratitis was but noted that it sounded similar to “keratin” which is found in the skin. Actually, the Greek root “kera” means “horn”. Keratin is found in the fingernails, the skin and the horns of mammals. Initially, scientists believed that the cornea was made of keratin. ‘Itis’ is a Greek suffix which means ‘disease especially marked by inflammation’’. As a result, keratitis means infection of the cornea. Later it was discovered that keratin—is not present in the cornea. However, this name for this disease remains.

Corneal infection is the fifth cause of overall blindness worldwide. In developed countries, like the United States and Australia, a corneal infection is viewed as a rare condition often related to the use of contact lens. Other reasons to get the infection are eye trauma, prior eye surgery, or history of dry eye or blepharitis (which is the inflammation of the eyelids). Whereas in developing countries, for example in India, corneal infection has been associated with eye trauma during agricultural work. 

Bacteria, viruses, parasites and fungi can cause infection in the cornea. Pseudomonas aeruginosa which is a bacterium, Fusarium which is a fungus, and Acanthamoeba which is a parasite, have been associated with corneal infections related to the use of contact lens. 

Maria Cabrera: Well, now, let’s talk with Prof Watson about corneal infections and contact lenses. Thank you for joining me today. Welcome!

Stephanie Watson: Thank you

Maria Cabrera: Well, how often do you see patients with a corneal infection related to contact lenses in your clinical practice? 

Stephanie Watson: Every week I see patients with corneal infection, some of them are mild but a good number end up admitted for intensive treatment to the hospital. In any week, there might be anywhere between three to five patients admitted to the hospital where I work with corneal infection.

Maria Cabrera: okay, so what type of patient usually has this condition? 

Stephanie Watson: Look, it is interesting! Really, it is a mix. We have a lot of elderly patients, but we also have a lot of young patients. It is the young patients who tended to be the contact lens wearers. Occasionally also we see children with a corneal infection, and it is sometimes from sleeping in contact lenses overnight and the type contact lens called orthokeratology.

Maria Cabrera: Okay, so usually, do they have any ocular history or family history?

Stephanie Watson: Yeah, look with the children, they often have a history of having another eye condition. With adults, it is contact lens wear, particularly if you swim in contact lenses, if you don’t handle them well, sometimes we see travellers, particularly backpackers, who umm in sort of temporary accommodation in the contact lens solution maybe in a car or not kept up properly. Umm, also people that wear the contact lenses in spas and showers. So, the elderly patients sometimes they can be they got blepharitis which is a form of a lid condition where there is crusting and bacteria on the lids. 

Maria Cabrera: Right, so usually what symptoms do patients need to watch out for? 

Stephanie Watson: yeah, well with the cornea infection generally your vision gets blur and your eyes are red and sore. Patients often also are light sensitive and particularly symptoms keep worsening. That’s a big warning sign

Maria Cabrera: very well, so why do you think people should care about cornea infection when they wear contact lens?

Stephanie Watson: look, it is important that people are mindful because you know, if you are young or if you are old your vision is very important, and if you have a contact lens related infection, you may not end up with the same vision you started with. For some people particularly those with good vision on only one eye, this could really have a big impact on them every day. But even for those who can see on the other eye reducing the vision in one eye still impacts their quality of life and their ability to work. Also there can be quite a bit time taking off of work and discomfort when the infection is being treated. 

Maria Cabrera: very well, what are the treatments for this infection? Usually how, how is treated?

Stephanie Watson: the treatment is fairly intensive, patients get topical antibiotics drops, day and night for two to three days and then the drops continue just hourly during the day. Sometimes we also need to give them steroid drops under very specific circumstances and sometimes antibiotics or treatments patients may need to be admitted to the hospital to make sure that the intensive treatments can be given. And then after the initial infection is gone, we often need to follow up patients for some time to try to heal the ulcer that was created by the infection.

Maria Cabrera: how long do you give the antibiotics for, how many days or weeks?

Stephanie Watson: usually we give the intense course overnight for two days and then sort of further for three days hourly during the day and then sort off tapering them off sort off over a week or two.

Maria Cabrera: what are the potential complications from this infection?

Stephanie Watson: you can get terrible complications from corneal infection. Probably the worst is when the whole eye becomes infected and that is called endophthalmitis. You can actually lose vision or even the eye from endophthalmitis. Sometimes infection can even spread further than the eye itself into the tissues around the eye and this can cause what we call orbital cellulitis. This again can result in loss of vision or even the eye and sometimes the patient can become sick with septicaemia. More locally, the cornea can weaken and have what we call perforation where the contents of the eye can leak out. This is also a serious complication. Scarring can result. Ulcers that can take time to heal and even the effects of treatment make induced toxicity and discomfort for the eye.

Maria Cabrera: after the ulcer is healed, when can the patients wear the contact lenses again?

Stephanie Watson: look before we let before we advise to wear contact lens again, we have a good talk about the importance of hygiene, avoiding sleeping in contact lenses which increases the risk. Avoiding swimming. And then wait we sort of wait for the ulcer to heal, the scar to settle and maybe within a month or so, they can resume wearing contact lenses but being mindful of the risks involved. 

Maria Cabrera: very well, perhaps to conclude today, as summer is coming in Australia when we tend to spend more time outdoors, what do you recommend contact lens wearers do to prevent a corneal infection?

Stephanie Watson: okay, sometimes it’s easy when you are outdoors to swim in contact lenses. It’s best to avoid this. If you are going to be out late and then the contact lenses are going to be in for a long period of time, take some glasses with you, so you can take them out using good hygiene when you do. Always wash your hands at the sink and remember to dry them. Some of the infections occur from water borne organisms. Avoid being in the contact lenses in spas and saunas. If you are showering again take them out. Be careful and don’t overwear them.

Maria Cabrera: Well, Prof Watson, thank you so much for being on our first episode today. 

Stephanie Watson: Thank you, it has been a great to be part. Thanks again!

Maria Cabrera: Thank you 

Maria Cabrera: More on corneal infection and contact lenses up next…

But first, we have a question for you, the listeners. As a contact lens wearer, what do you do to prevent eye infections? Email us at or share on Twitter with the hashtag sydeyepod, that’s Hashtag S-Y-D-E-Y-E-P-O-D.

Between 2012 and 2016, we studied patients admitted at the Sydney Eye Hospital with a corneal infection. What we found was one thousand and fifty-two cases of corneal infections and nearly nine out of ten cases had at least one reason for having a corneal infection, with the most common reason being contact lens wear, which accounted for two-thirds of the cases. This confirmed that contact lens wearing is a very common reason for corneal infections in developed countries. The infection was mainly associated with regularly replaced lenses, for example weekly, fortnightly or monthly basis, in five out of ten cases, and daily disposable contact lenses in two out of ten cases. Water sport-related activities, for example swimming or rowing, showering or sleeping with the contact lenses were the most common reasons to get the infection. 

Travelling to tropical areas has been also attributed to corneal infections in contact lens wearers. In this study, we found twenty-six cases which had noted travel overseas before their corneal infection. These patients were contact lens wearers in their early thirties, had mainly travelled to Southeast Asia, specifically Thailand and Indonesia, and their infections were related to the bacterium called Staphylococci. This was a crucial finding as typically a different bacterium called Pseudomonas aeruginosa, is a more common cause of contact lens related corneal infection. Although we cannot currently travel overseas due to COVID restrictions, we can still travel to tropical regions in Australia, so it is still important to remember this.

In summary, a corneal infection is more common in people wearing contact lenses, in their 30’s, and is often caused by a bacterium called “Pseudomonas aeruginosa” in developed countries. Other reasons for corneal infections are eye trauma, prior eye surgery and history of dry eye or blepharitis. In developing countries, the most common reason is eye trauma during agricultural work.

Symptoms include red and sore eye, blurring vision, sensitivity to light, tearing, or discharge. You can also see an ulcer in your cornea. Complications include loss of vision, scarring, infection of the whole eye, which is called endophthalmitis, corneal perforation or loss of the eye in severe cases. 

To prevent a corneal infection please avoid wearing the contact lenses overnight and avoid swimming or wearing the contact lenses in spas and showers. Also wash your hands at the sink and dry them well prior to handling lenses.

If you are a contact lens wearer with these symptoms, please seek an eye doctor as soon as possible to get checked and receive an adequate antibiotic therapy to avoid these serious complications. 

We are finding out more about why these infections occur and have some ways to treat them. But complications still occur! For the future we will need research to find better ways to prevent infection and preserve vision if infection occurs.

I’m Maria Cabrera-Aguas, thanks for joining me today in the first episode of the Sydney Eye podcast. 

If you have any questions, comments or suggestions please send them to and connect with us on Twitter @CabreraMarie , it’s C-A-B-R-E-R-A-M-A-R-I-E or @cornealresearch, or @profswatson using the hashtag S-Y-D-E-Y-E-P-O-D.

Until next time. Bye!