A Patient's Perspective on Acanthamoeba Keratitis

Sep 2, 2022
18 min read

As optometrists and ophthalmologists we are experts in the eyecare field, however, we actually haven’t experienced most of the eye conditions we diagnose and treat on a regular basis. Because of this, we can learn so much from our patients every day. Even conditions that are commonly seen, like cataracts, can be a completely different experience from the patient perspective.

Understanding our patients’ experiences can make us better practitioners and enhance care for future patients. This patient perspective series will seek to turn the tables and give our patients the opportunity to be the experts in their diseases and ocular conditions to enhance the eyecare we provide.

As eyecare providers, we have all heard of acanthamoeba keratitis (AK), but likely many of us—unless practicing in an advanced corneal setting—have not seen this condition in our chairs firsthand.

Acanthamoeba keratitis: An overview

Acanthamoeba keratitis is a rare but often devastating ocular condition that can lead to severe vision impairment, corneal transplantation, and even enucleation. It is caused by a free living amoeba that is typically found in soil and water, including tap water.

These amoebas are ubiquitous. In fact, serologic studies have confirmed that 90-100% of people without prior AK infection actually have antibodies to Acanthamoeba, which shows that while the organism is very common, infection from it is very rare.

The main risk factor for AK is contact lens wear. While there are 33 million contact lens wearers in the United States, there are only 33 cases of AK per one million contact lens wearers. AK presents initially with a high degree of pain, often out of proportion to the clinical signs observed. Many times, this condition is misdiagnosed as herpes simplex keratitis.

It seems infection from Acanthamoeba occurs due to a myriad of factors, including the corneal microbiome. Acanthamoeba exist in two states: Trophozoite and cyst stage. In the cyst stage, they can live in very harsh conditions ranging from hot springs to underneath ice.

Our innate immune response can fight the infection, but once the amoebas have breached the corneal epithelium, it is difficult for the immune system to fight these parasites due to the fact the cornea is an immune-privileged tissue. Cysts can remain in a dormant state on corneal tissue for close to 3 years making recurrent infection possible.

Clinical note: Always be wary that you may have misdiagnosed AK if what you are treating as HSK is not responsive to standard treatment.

Interview with Juliette Vila Sinclair Spence

In this interview, Juliette Vila Sinclair Spence, an “AK Warrior” and true AK expert who contracted Acanthamoeba keratitis in 2016, shares the details of her long and arduous journey to diagnosis and finally treatment. She has devoted much of her time to help others learn more about this disease and has became an advocate for patients, families, and providers by creating the Acanthamoeba Keratitis (AK) Eye Foundation.

Did you know of Acanthamoeba keratitis before your experience with it?

Vila: I had never heard about Acanthamoeba keratitis nor its risks, despite having worn contact lenses for more than 35 years. I was never taught that contact lenses and water don’t mix, meaning do not to shower, swim, do water sports, wash or store them with water, nor handle them with wet hands. I’m not the only one who didn’t know this; in fact, 95% of AK Warriors are contact lens wearers. Only 5% of those who have experienced AK are not contact lens users.

Sadly, numbers are increasing worldwide. For example, in the Netherlands, where I live, the number of cases increased from 16 in 2009 to 49 in 2015. This resulted in an estimated incidence of 1 in 21,000 for soft contact lens wearers in 2015.

How did you contract AK?

Vila: My journey started in August 2016 while on holiday in Italy. I went swimming with my kids and my contact lenses. The only thought was, “Juliette, you might lose your contact lenses.” Without knowing it, it took only a second for the free-living amoeba (FLA) to get stuck on my monthly right contact lens and make its way into my cornea, changing my life forever.

How long before symptoms of Acanthamoeba keratitis appeared?

Vila: Symptoms can manifest within hours, days, or weeks. For me, once I got out of the swimming pool, I felt like my contact lens was dirty or something was on it, so I washed it, but that was not enough.

The day after, I felt like something was in my eye and the feeling would not go away, so I removed my monthly contact lenses and wore my glasses instead. I dismissed the symptoms of “unhappy eyes” and light sensitivity due to fatigue as the result of being a tired mum of two young boys. What I learned: Contact lens users should get their eyes checked whenever they feel something is different with their contact lenses and/or eyes.

For the next 6 months I only wore glasses, as each time I tried to wear contact lenses my eye felt like there was something in it. I continued to have a bit of light sensitivity and the vision quality had decreased. My optometrist let me try a variety of different contact lens brands, but my symptoms would not get better. He figured it was the contacts and so he did not see the need to look further. At the end of February 2017, the nightmare really started and never stopped.

What symptoms did you experience? What are other common symptoms?

Vila: In my case it started as an eye irritation, redness, feeling something in my eye (like an eyelash or a grain of sand), an ache in and around the eye, tearing and mild light sensitivity. As the hours went by, it turned into excruciating pain, non-stop tearing, extreme light sensitivity and decrease of vision.

For most AK Warriors, these symptoms are common:

  • Foreign body sensation - feeling like something is in the eye
  • Inability to wear contact lens
  • Irritation or grittiness
  • Red eye
  • Watery eyes
  • Mild to extreme light sensitivity
  • Aching to excruciating eye pain
  • Blurred vision
  • Partial or total vision loss
  • Headache

Were you diagnosed quickly? What did it take for you to receive the correct diagnosis?

Vila: On the first of March 2017, I went to my general practitioner who after making a quick test (fluorescent eye test) could detect damage in my cornea, so they sent me to the ophthalmologist at the hospital the same day. The ophthalmologist misdiagnosed me with a bacterial infection and gave me Trafloxal (fluoroquinolone eye drop). The doctor only asked me if I was a contact lens user but did not ask any further questions.

I returned on the 4th of March to the emergency room as the pain was escalating. The ophthalmologist on duty decided to change the medication to hydrocortisone/oxytetracycline and asked me to visit her every 2 days to follow my eye. During that period, we did three corneal scrapings, added atropine as well as analyzing my contact lens casing. But still, it was 17 days after the initial ophthalmology visit (7 months after swimming with my contacts in Italy) that I was correctly diagnosed with Acanthamoeba keratitis. This diagnosis was ultimately made with a confocal laser scanning microscope (CLSM), which is the gold standard for diagnosing AK, as it is painless and can provide feedback in situ, allowing treatment to begin immediately.

Diagnosis of Acanthamoeba keratitis

Characteristic signs:

  • Symptoms (intense pain) out of proportion to clinical signs
  • Ring-shaped stromal infiltrate
  • No improvement with standard antiviral, antibacterial, or antifungal therapies

Diagnosis confirmed by:

  • Culture on non-nutrient agar plated with E. coli
  • PCR
  • Confocal microscopy

AK as a learning opportunity for eyecare providers

Vila: The ophthalmologist who diagnosed me with a bacterial infection did apologize to me months later for the misdiagnosis. He explained that it was a learning opportunity for him to always go the extra mile when it comes to contact lens wearers. The correct diagnosis for AK Warriors can take between days, weeks, and months to even a year or more.

The fact that Acanthamoeba keratitis is cited as a rare disease, makes it more challenging as clinicians do not often have it on their radar and may think a contact lens-related red eye is a more common and benign condition. When red eye does not improve with initial treatment, clinicians should beware and investigate further or make the appropriate referrals if the patient is not improving.

What treatment did you receive? What other treatments do you know of?

Vila: After being correctly diagnosed with Acanthamoeba keratitis—17 days since the first severe symptom—I was given propamidine isethionate, chlorhexidine (the AK pool cleaners as we call them), every hour around the clock for the first 4 days and then every hour while awake. I was also given itraconazol (anti-fungal); atropine (to help with the photophobia); and for pain management I got diclofenac (to reduce inflammation/pain), tramadol, and paracetamol.

Because the treatment was not working and my eye, the pain and my mental state were getting worse, the doctors decided to conduct an emergency therapeutic corneal transplant—28 day after the first symptom.

After the corneal transplant, I was on autologous serum drops for 30 days, as my corneal epithelium would not close within the normal timeline which put me at risk of losing my new cornea. I was on propamidine isethionate for 3 months, chlorhexidine for 14 months to make sure all cysts were eradicated and pregabalin (Lyrica) for the trigeminal nerve pain for the rest of my life. Today, I am still honoring the cornea’s donor after 5 years.

Image 1 of Juliette’s eye while infected with AK and post-corneal transplant. Images used with permission.