Contact lens users under threat of a deadly bug Acanthamoeba, which can also cause blindness

Eye Contact Lenses

I was reading an article posted by Daily Mail, which raised some concerns on the millions of people using contact lenses – how a parasite found in normal tap water can damage the contact lenses and thus causes an eye infection which can even lead to blindness. I just thought of writing this article as to make you aware of this issues and how the people wearing contact lenses can take some precautions and proper care of their contact lenses as to prevent eye infections. This eye infection is also called Acanthamoeba Keratitis because the reason for the infection is a deadly parasite called Acanthamoeba.

Acanthamoeba infection is today a concern for about 125 million people wearing contact lenses globally and about 3.7 contact lens wearers in the UK.

What is this bug called Acanthamoeba?

To be bit technical, Acanthamoeba (plural: Acanthamoebae) is a very small single-celled parasite found in soil, fresh water and other habitats, which feeds and lives on bacteria found on dirty contact lenses.  Generally, the habitat of Acanthamoeba is soil and fresh water, which can be tap water, showers, sea or swimming pools.

As Acanthamoeba is found everywhere the risk of getting the eye infection has become very common. The same has been agreed by the scientists who are working on the matter. Fiona Henriquez, an expert Parasitology and Immunology, who is professor in University of the West of Scotland said that ‘it is a potential problem for every single contact lens wearer.’  Even Professor Craig Roberts, Strathclyde University, who is co-associate of Dr Henriquez in a research for creating better contact lens cleaning solutions, said: ‘It’s absolutely everywhere.’

Some details on how the eye infection is caused by Acanthamoeba?

This deadly parasite nourishes on bacteria found on the contaminated lenses. Eye contact lenses get contaminated by the bacteria if they are washed under tap water or kept in the lens solutions which are prepared from the non-sterilised water.

Acanthamoeba can get to your eyes through the contaminated contact lenses and destroy the cornea of the eye while feeding on corneal tissues. Cornea is the transparent layer found around our eyes. Cornea not only adjusts the focus on the lens but also contributes towards the focusing ability of the eye. The destroying of corneal tissues by this deadly parasite can gradually leads to blindness.

The infection can also spread during cornea replacement process, if the cornea donated are infected with Acanthamoeba.

Symptoms of Acanthamoeba infection are:

  • Foreign body sensation
  • Photophobia
  • Decreased visual acuity
  • Tearing
  • Pain
  • Redness of the eye

Is there any cure for the eye infection caused by Acanthamoeba?

Well, the diagnosis in early stage is very important, however as there is still less knowledge about this rare infection, the good diagnosis and treatment is still a difficult question for doctors and researchers.

Dr Fiona Henriquez said that: “It is a potential problem for every single contact lens wearer. The incidence is quite low but that may be a problem with diagnosis.”

Initial detection of Acanthamoeba infection is very important as to prevent further damage of cornea which can even lead to blindness. Once the eye infection is detected, patient requires hospitalization where the patient is administered nonstop disinfecting eye drops as to flush out the parasite. Although sometimes the situation gets so grave that a corneal transplant is required or if it gets worse even leads to blindness.

Researchers have also found that many lens cleansing and soaking solutions used by the lens wearers are not prepared by non-sterlised water which ultimately can also be a source of spreading Acanthamoeba infection. Additionally, these lens solutions are not capable of eliminating the infection completely.

Looking at the severity of this Acanthamoeba Keratitis, amendments have been done in the ISO 14729 international standard which applies to lens disinfectants as to make sure that they have proper antimicrobial activity. Now after the amendment the lens solutions should also have antimicrobial activity against the Acanthamoeba.

As early diagnoses are very important to fight against Acanthamoeba infection, lens wearers can also take following precautions:

  • Always follow good hygiene practices while handling their contact lenses.
  • Do not rinse or store contact lenses in non-sterlised tap water. Contact lens users should always store or rinse their contact lenses in lens solutions prescribed by the qualified eye specialists.
  • Always make sure that you are using lens solutions manufactured by the reputed and recognized pharmaceutical companies. Make sure that these solutions are prepared as per ISO 14729 standards.
  • Also make sure that these lens solutions are within the expiry date of manufacture.
  • Many multipurpose disinfection solutions (MPDS) suggests “no-rub” lens care; however on contrary to that researchers have found that “rub and rinse” lens care method is best to get rid of many microbes like Acanthamoeba. Researchers in Australia found that the best lens cleansing / lens disinfectant procedure is when the lens is first cleans through rubbing the contact lens through stream of MPDS and then storing it in fresh MPDS. Even a study by University of Leicester, England suggested that the contact lenses passed through “rub and rinse” cleansing method was found without Acanthamoeba stains.

Hope that this article will be helpful for all the contact lens users.

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