An expert overview of the presentation, diagnosis, and treatment of keratitis, as well as the patient experience of this serious eye infection
Keratitis refers to inflammation of the cornea. The most common serious type of keratitis is microbial keratitis. This refers to corneal infections caused by bacteria, fungi or protozoa.
Under normal circumstances, the cornea is very resistant to infection due to innate protective mechanisms. The tear film contains both direct and indirect antimicrobial properties. It contains immunoglobulins which directly protect against infection. It also contains a number of proteins such as lactoferrin, which binds iron resulting in an indirect antimicrobial function. The eyelids and eyelid function help to protect the eye and remove organisms from the ocular surface. The corneal epithelium has tight junctions preventing the entry of organisms into the corneal stroma. The epithelium turns over in seven-to-10 days so that any organism that binds to the epithelium get sloughed off before they can penetrate the stroma to cause a significant corneal infection.
As a result, there is always an underlying risk factor present before a cornea becomes infected. The risk factors result in an epithelial defect, allowing the entry of microbes into the corneal stroma and consequently a microbial keratitis.
Risk factors include tear film abnormalities (dry eyes), eyelid abnormalities (ectropion, entropion, trichiasis, incomplete eyelid closure), corneal disease (corneal dystrophy, neurotrophic cornea, corneal endothelial failure), or trauma (corneal abrasion, corneal erosion, or contact lens wear).
Contact lens wear is one of the commonest causes of microbial keratitis. This is due to corneal microtrauma associated with inserting and removing the contact lens, corneal hypoxia due to contact lens overwear, or poor lens hygiene (inadequate sterilisation technique for daily wear lenses or showering/swimming with contact lenses in).
Symptoms and diagnosis
Microbial keratitis presents with a red, painful eye associated with watering and light sensitivity. The symptoms can progress very quickly and result in initial blurring of vision and then significant visual loss. The loss of vision is due to clouding of the cornea due to the associated corneal inflammation.
The eye may be difficult to examine due to the pain and light sensitivity. It will demonstrate circumcorneal redness. The cornea will have an epithelial defect with an underlying corneal stromal opacity. There may be associated intra-ocular inflammation with a visible hypopyon.
The diagnosis is made clinically. However, corneal scrapings are taken to determine the causative organism. The scrapings are directly plated on to slides for gram stain and on to agar plates for culture.
The treatment of keratitis is divided into a sterilisation phase, a healing phase, and a visual rehabilitative phase.
The sterilisation phase involves instilling intensive topical eyedrops every hour, day and night, for two days, followed by hourly daytime drops for a further three days. This can be exhausting and difficult for patients as they will be sleep deprived and the eyedrops can sting in an already very painful eye. As a result, this usually requires a five-day hospital admission.
The choice of initial eyedrops depends on the clinical picture. In Ireland, bacterial infections are the most common cause of keratitis and so treatment usually consists of a combination of broad spectrum antibiotics (ceftazidime and vancomycin). Antifungal or anti-amoeba treatment may be commenced if clinically indicated.
After five days, the cornea is almost always sterile and the healing phase commences. This involves reducing drop toxicity by switching the treatment to preservative-free eyedrops to promote corneal epithelial healing. Often steroid drops are introduced to reduce the corneal inflammation, which will minimise the amount of corneal scarring that may occur. During this phase, any residual underlying risk factors can be addressed if present (ectropion, entropion, etc). The healing phase can vary in duration, but can sometimes take months to heal in severe cases.
When the cornea has fully healed, some patients can get back normal vision and some patients can be severely visually impaired. The affect on vision depends on the location and size of the resultant corneal scar and the degree of corneal irregularity.
If the vision is significantly affected, the options to improve vision include wearing rigid gas permeable contact lens, which will compensate for any corneal irregularities, or a corneal transplant if there is a significant scar.
Keratitis – a personal account
Ms Eleanore O’Gorman, Irish College of Ophthalmologists, Annual Conference, Keratitis Symposium, Wednesday 24 May 2023
In November 2019 while on holidays in Tulum, Mexico, I began to experience a sudden irritation in my left eye, and a feeling as if there was something lodged in my eye. The discomfort worsened over the next 12-to-24 hours and I sought advice from a local pharmacy who gave me eye drops. While these helped dulled the discomfort, the symptoms persisted. The following day I was due to fly to Dublin; I felt with the eye drops and pain medication I could manage this trip. Unfortunately, the overall condition of my eye deteriorated on the journey home. Mid-flight my vision became increasingly blurred, the severity of pain increased, and the health of my eye worsened. This very much took me by surprise and considering the severity of these symptoms, I knew I would be seeking immediate medical attention once I arrived in Dublin.
I first presented to Beaumont Hospital emergency department, where I was triaged and swiftly referred to the Mater Hospital emergency department. I made the short trip to the Mater by taxi and met the eye team. The team asked about my medical history, including contact lens use. I am a long-term contact lens user and have worn them for over 10 years, predominantly using them for playing sport and social occasions.
Based on their examination and test results, the severity of the infection began to become clear. I was diagnosed with keratitis. I was immediately admitted to the eye unit and would spend the next five days receiving intensive treatment to combat the infection. In the first 24 hours I received eye drops every 30 minutes, a particularly exhausting experience coming off a long-haul flight. My time in the Mater was a blur and while I knew I was receiving the best care, I was starting to feel concerned about the potential long-term effects on my vision. All my life I have played sports and before travelling to Mexico I received my first cap playing for Ireland’s Mixed Senior Tag Rugby team. I was also working as an occupational therapist on a stroke ward in a busy acute hospital. At this time, I was unsure when or if I would be able to do these things again.
In the weeks following my discharge, I was regularly seen in the eye clinic in Beaumont Hospital. In the early days, travelling to these appointments was challenging as my eye was sensitive, irritable and became tired easily. I was following a regimental eye drop regime but the vision in my left eye was not improving. This period was emotionally difficult. I was trying to remain hopeful my vision would return, but it gradually became apparent the residual scarring from the infection would have long-term effects. While not a surprise, it was difficult to hear I would need surgical intervention involving a corneal graft to help restore my vision.
I was listed for this procedure, which was due to take place in the Mater in April 2020. However, that March the Covid-19 pandemic arrived and all elective procedures were cancelled. I would spend the rest of 2020 eagerly waiting for any updates, but also coming to terms with living with my new visual issues. Effectively, I had little sight in my left eye and it was extremely sensitive to light. The infection had left a visible scar in the centre of my pupil, which made me self-conscious about the overall appearance of my eye. My goals for 2020 were only to return to work and driving, which I achieved. In the latter part of the year, I tried to return to playing tag rugby, but this was extremely difficult and I felt my confidence had been greatly affected.
In early 2021, I contacted the Mater eye team and asked if there was a possibility of reviewing my case. Thankfully, they finally completed the corneal graft in May 2021. The experience of receiving the donor eye tissue and having the surgery was surreal. The recovery process was relatively straightforward, albeit long. I was told I would have a stitch in my eye for one year and my vision would change throughout the year. I returned to playing some tag rugby with protective eyewear, but was extremely conscious of protecting my eye.
In May 2022 the stitch was removed and I waited for my vision to improve again. In the coming months my left eye became stronger. Six months on from the removal of the stitch I was able to visit my local optician to be fitted with proper eye wear for the first time since 2019. I also was able to wear a contact lens in my left eye, for the first time since 2019. With expert guidance from my optician, I was able to find a suitable lens, which further corrected my vision and astigmatism. With these supports I have regained most of the vision in my left eye.
From my experience, I now prioritise my eye heath and have an enhanced understanding of the significance of maintaining good hygiene and properly caring for contact lenses. I’ve learned the importance of promptly seeking medical attention for any persistent eye symptoms. This timely intervention can make a significant difference in preserving vision.
In February 2023, I was selected to play for Ireland in the 2023 Tag Rugby World Cup. This is a huge personal achievement, but one which would certainly not be possible only for the teams in the Mater and Beaumont Hospital, which are led by Consultant Ophthalmic Surgeon Mr Tim Fulcher. I am forever grateful that I had access to these amazing people as I arrived off a flight from Mexico three and a half years ago. I believe the attention, care, support, and decision-making in relation to my care has allowed me to return to what I love doing and to represent my country at a World Cup this August.
My journey with keratitis during a global pandemic was challenging and a life-changing event. But with the appropriate medical care, trusting in the expertise of medical professionals, I was able to recover fully, and embrace a newfound appreciation for the gift of sight.