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Acanthamoeba Keratitis

Acanthamoeba Keratitis

11 December 2019

Causative agent

Acanthamoeba keratitis is an eye infection caused by microscopic amoeba. Several species of Acanthamoeba have been found to infect humans. In addition to eye infection which usually affects the cornea, Acanthamoeba could cause skin lesion or a systemic infection. It may also cause granulomatous amoebic encephalitis (GAE), an infection of the brain and spinal cord that typically occurs in persons with a compromised immune system.

Clinical features

People with Acanthamoeba keratitis may have eye pain, eye redness, blurred vision, sensitivity to light, foreign body sensation in the eye and excessive tearing or other eye symptoms. Untreated infection can cause permanent visual impairment or blindness, which requires corneal transplantation to regain vision. Therefore, early diagnosis is essential for effective treatment of Acanthamoeba keratitis.

Mode of transmission

Acanthamoeba species are commonly found in the environment worldwide, especially in soil and dust, in fresh water sources such as lakes, rivers and hot springs, and in hot tubs, swimming pools and spa facilities. Besides, it can be found in heating, ventilating and air conditioning systems, sewage systems and fresh water system (shower head and taps). Acanthamoeba is also found in contact lens tools.

Acanthamoeba keratitis primarily affects otherwise healthy people, most of whom wear contact lens, particularly when users have poor lens hygiene or when lenses are worn during swimming or other aquatic activities. Also, persons who have abrasion or injury to the cornea are at increased risk of infection.

No known cases of person-to-person spread of Acanthamoeba keratitis have been reported so far.

Incubation period

The incubation period for Acanthamoeba keratitis is unknown.

Management

Early diagnosis is essential for effective treatment of Acanthamoeba keratitis. If you have symptoms of Acanthamoeba keratitis, seek medical advice immediately.

Prevention

To prevent contact lens related microbial keratitis, contact lens wearers are advised to:

ALWAYS

  • Before handling contact lens, contact lens solutions or related accessories, wash hands with liquid soap and water, and rub for at least 20 seconds. Then rinse with water and dry thoroughly with a disposable paper towel or hand dryer.
  • Clean and disinfect your contact lens properly.
  • Have regular check-ups by your optometrist or ophthalmologist and follow their professional advice.
  • Remove contact lens before any activity involving contact with water, including showering, using a hot tub or swimming.
  • Remove contact lens whenever you feel discomfort or develop redness and seek advice from your optometrist or ophthalmologist.
  • Seek medical advice promptly if symptoms persist despite removal of contact lens.

NEVER wet your lens with saliva, bottled water or tap water.

NEVER wear your lens while sleeping, swimming or taking shower or beyond the recommended period.  

REMEMBER

The following important points on:

CLEAN & DISINFECTION
Clean and disinfect contact lens according to instructions from your eye care provider and the manufacturer's guidelines.

  • Be sure to clean, rub, and rinse your lens each time you remove your lens BEFORE soaking for disinfection. Rubbing and rinsing your contact lens will aid in removing harmful microbes and residues.
  • The multi-purpose solution in the lens storage case must be changed every day even if the lenses are not used daily; never reuse or top up solution. Use fresh cleaning or disinfecting solution each time lenses are cleaned and stored.
  • Never use tap water, bottled water, saline solution or rewetting drops to disinfect or store contact lens. Neither solution is an effective or approved disinfectant.
  • Close all bottles of contact lens solution properly after use.
  • Discard contact lens solutions one month after opening.

CARE OF LENS CASE

  • Storage case should be cleansed, rinsed with sterile contact lens solution (never use tap water or bottled water) and then left open to dry after every use.
  • Store your contact lens, solutions and accessories in a cool dry place.
  • Replace storage case every three months.

CARE OF LENS

  • Disposable contact lens must not be used beyond their recommended disposal period.
  • Store reusable lens in the proper storage case.
  • Follow your optometrist's or ophthalmologist's advice to replace the lens at the intervals specified. 

To know more about contact lenses and tips on using contact lens solution, please refer to the following website: https://www.mdco.gov.hk/english/emp/emp_gp/emp_gp_selected_02.html


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