Which are the causes of Acanthamoeba keratitis?

Acanthamoeba keratitis is a rare but serious eye infection caused by a microscopic organism called Acanthamoeba. This amoeba is commonly found in the environment, including water sources such as tap water, swimming pools, hot tubs, and soil. While most people are exposed to Acanthamoeba at some point in their lives, it rarely causes infection. However, certain factors can increase the risk of developing Acanthamoeba keratitis.

Poor contact lens hygiene: One of the primary causes of Acanthamoeba keratitis is improper care and hygiene of contact lenses. This includes wearing contact lenses while swimming or showering, using tap water to clean or store lenses, and not following the recommended cleaning and disinfection procedures. Acanthamoeba can adhere to contact lenses and survive in the biofilm that forms on the lens surface, leading to infection when the lenses are worn again.

Contaminated water exposure: Acanthamoeba is commonly found in water sources, and exposure to contaminated water can increase the risk of infection. This can occur through activities such as swimming in contaminated pools or hot tubs, using water from inadequately disinfected sources for eye irrigation or rinsing contact lenses, or using homemade saline solutions that are not properly sterilized.

Corneal trauma: Acanthamoeba keratitis often occurs following corneal trauma, such as a scratch or injury to the eye. The amoeba can enter the eye through the damaged cornea and cause an infection. This can happen when using contaminated contact lenses, rubbing the eyes with dirty hands, or coming into contact with contaminated water or soil.

Reduced immune response: Individuals with weakened immune systems are more susceptible to Acanthamoeba keratitis. This includes individuals with conditions such as HIV/AIDS, diabetes, or those who have undergone organ transplantation and are taking immunosuppressive medications. A compromised immune system makes it harder for the body to fight off the infection, allowing the amoeba to proliferate and cause damage to the cornea.

Prolonged contact lens wear: Wearing contact lenses for extended periods, especially overnight, can increase the risk of Acanthamoeba keratitis. Extended wear lenses reduce the amount of oxygen reaching the cornea, making it more susceptible to infection. Additionally, the longer the lenses are worn, the more likely they are to become contaminated with Acanthamoeba.

Poor water quality: The quality of water used for various purposes, such as swimming pools, hot tubs, and tap water, can play a role in the development of Acanthamoeba keratitis. Inadequate disinfection of water sources can allow the amoeba to thrive and increase the risk of infection. It is important to ensure that swimming pools and hot tubs are properly maintained and chlorinated, and to use sterile water for activities involving the eyes.

Geographical location: The prevalence of Acanthamoeba keratitis varies geographically, with higher rates reported in certain regions. This may be due to differences in environmental conditions, water sources, or cultural practices related to contact lens hygiene. For example, warmer climates and areas with a higher concentration of swimming pools may have an increased risk of Acanthamoeba keratitis.

Personal hygiene: Poor personal hygiene practices, such as not washing hands before handling contact lenses or rubbing the eyes with dirty hands, can introduce Acanthamoeba into the eye and increase the risk of infection. It is crucial to maintain good hygiene habits, especially when it comes to handling contact lenses and touching the eyes.

Pre-existing eye conditions: Individuals with pre-existing eye conditions, such as dry eye syndrome or corneal dystrophies, may be more susceptible to Acanthamoeba keratitis. These conditions can compromise the integrity of the cornea, making it easier for the amoeba to invade and cause infection.

Conclusion: Acanthamoeba keratitis is primarily caused by poor contact lens hygiene, exposure to contaminated water, corneal trauma, reduced immune response, prolonged contact lens wear, poor water quality, geographical location, personal hygiene practices, and pre-existing eye conditions. It is essential to follow proper contact lens care and hygiene practices, avoid exposure to contaminated water, and maintain good personal hygiene to reduce the risk of Acanthamoeba keratitis.