This article is from WeChat public account:Back to Park (ID: fanpu2019), the original title: “The contact lens party noticed: these microbes are dangerous! “Author: Zhu Ye Hua, from the title figure: Oriental IC

Our cornea is very fragile, and contact lenses are too close to the cornea, so it is difficult to avoid damage to the eyes. People who wear contact lenses are at higher risk of eye infection, and wearing contact lenses (day, evening or swimming bath) will increase this risk. .

Swimming and bathing with contact lenses is definitely not a good habit. Over time, it is likely to cause vision loss. The warning comes from a recent case report published in the New England Journal of Medicine

Most people think that if you wear contact lenses carefully, nothing will happen. But in fact our cornea is very fragile, and the contact lenses are too close to the cornea, so it is difficult to avoid damage to the eyes. People who wear contact lenses are at higher risk of eye infection, and wearing contact lenses (day, evening or swimming bath) will increase this risk. . Bacteria and other potentially dangerous microbes can stick to contact lenses and trap between contact lenses and eyes. However, in most cases, humans are not aware of the existence of these invaders.

British women wear contact lenses, swimming and bathing almost blind

A 41-year-old woman in the UK is used to swimming and bathing with contact lenses, but this habit has caused her vision to suffer severely. For two months, she felt tingling, blurred vision and sensitivity to light from time to time. When she arrived at the Royal Eye Hospital in Manchester, England, the doctor found that she had a large ring on her left eye and a fuzzy thing on her cornea. After diagnosis, her left eye vision is 0.1, which is the threshold of “law blindness determined by law”. Fortunately, her right eye is not affected [1 ].

Image Source: Popular Science

In view of her habit of wearing contact lenses while swimming and bathing, doctors speculated that she was likely to develop Acanthamoeba keratitis. After a period of medication, the woman’s left eye infection was cleared, but scars were left on the cornea and her vision was impaired. One year later, the woman underwent a partial corneal transplant. Now the left eye has a slight improvement in vision, but it has not fully returned to normal.

Acanthamoeba keratitis is a stratum corneum infection caused by Acanthamoeba. Although this infection is rare, it has received increasing attention with the widespread use of contact lenses. Wearing contact lenses while bathing or swimming exposes tissues with weak eyes to a serious risk of infection. Last year, a 29-year-old man in the UK suffered from the same infection as a daily contact lens, and then blinded [2]. Researchers at University College London have found that since 2011, the incidence of Acanthamoeba keratitis has increased almost threefold in the southeastern United Kingdom. Among them, only 70% of patients recover within 12 months, and some patients with more serious conditions need corneal transplantation[3].

Aesthetium amygdaloids that prefer contact lenses

Aesthepyba abacus is common in nature, especially in soil, air and fresh water. Swimming pools, hot tubs, showers, etc. all provide a comfortable environment for microbes. Therefore, contact lens manufacturers advise consumers not to wear contact lenses to swim and bathe, nor should they use tap water to disinfect contact lenses.

A 2006 study found that 85% of people infected with Acanthamoeba keratitis were contact lens users[4 ].

Aesthepyba sinensis has a special affinity for the surface of contact lenses, which means that contact lenses can act as a carrier to hide, spread and transport microbes into the eyes[5]. In addition, during the process of wearing contact lenses, the hand or the wearing tool may inadvertently scratch the eyeball and cause minor damage to the eyeball. These tiny abrasions are the entrance of microorganisms invading the eyes. When a damaged eye wears a contact lens to bathe or swim, microorganisms may enter the cornea of ​​the human eye through the wound to cause infection. In severe cases, permanent corneal scarring may occur, thereby preventing proper filtering and ultimately causing vision loss. .

American Ophthalmology Society Clinical Spokesperson John Hovanisia (John Hovanesian) Dr. In an interview with the media, despite such cases Rarely, but they highlight the extremely fragile nature of human eyeballs and the inherent risks of wearing contact lenses[6] .

Pseudoamebic keratitis patients | Source: CNN

Dangerous microorganisms attached to contact lenses

Our eyes usually fight infections through a variety of defense mechanisms: essentially tears are antibacterial, rubbing their eyes helps to wash away bacteria or foreign bodies on the surface of the eye. When you wear contact lenses, the effects of both functions are suppressed. Soft lenses absorb most of the tears and keep themselves soft, so the presence of contact lenses reduces tears on the cornea. Lack of tear exchange can lead to dry eye syndrome, causing discomfort, such as itching, redness and burning sensation. Severe dry eyes can also cause corneal scarring.

Bacteria, fungi, and parasites also adhere to the surface of contact lenses, which are thus carriers of microbial attachment and transfer to the surface of the eye. When the resistance of the eye tissue is reduced, these “resident” microorganisms or transient pathogens invade and colonize the cornea or conjunctiva, producing inflammation or infection.

Contact lenses | Source: Network

US Food and Drug Administration (FDA)Forensic Chemistry Center in Ohio(Forensic Chemistry Center) researchers tested 350 decorative, non-corrective contact lensesMirror, I want to see what will be attached to these daily sales lenses. The findings were published in the Journal of Forensic Sciences published in the Journal of Forensic Science, 2017, . Of these contact lenses, there are 285 contact lenses from optical shops, tattoo shops, and of course the omnipotent Internet, and the rest from approved formal manufacturers [7].

The researchers placed the contact lenses and their partial soaks in a test tube filled with broth and incubated at 25 ° C for 2 weeks. They then screened out turbid tubes, which were caused by bacterial masses growing inside the tubes, took out the bacteria pellets, grew them in petri dishes, and then scraped a colony from each dish. Test colony DNA and analyze which species belong.

The test results are disturbing. Of the 285 contact lenses tested, 62 were considered fake and shoddy glasses, 233 were unapproved contact lenses, 60% suspected false lenses and 27% unapproved sales. Microbiological contamination was detected on the contact lenses. In contrast, only 3.7% of the contact lenses sold were contaminated.

Several bacteria found on these lenses are associated with serious eye problems. They include Bacillus cereus and Pseudomonas aeruginosa. Pseudomonas aeruginosa is a common cause of bacterial keratitis. If not treated in time, this painful corneal infection can lead to permanent blindness. Bacillus cereus is one of the common causes of bacterial endophthalmitis and is one of several harmful microorganisms recently discovered on contact lenses. In addition, many people have Staphylococcus aureus in their nasal cavity. These bacteria are harmless in the nasal cavity, but once they enter the eye, they can cause infection. Herpes simplex virus can cause colds and keratitis. If your hand touches an active herpes sore, then touching your eyes can cause a virus transfer. This is why it is so important to wash your hands when touching contact lenses.

Clean and scientific wear is important

Although most bacterial infections can be treated with oral or topical antibiotics, scientists are not quite sure how long different infections will be due to individual differences.Time begins to cause damage to the eyes, so the best way is to stop wearing contact lenses and seek medical attention as soon as you feel that your eyes are not right.

Contact lenses are actually safe, but if you don’t wear contact lenses properly, they can cause a series of eye infections. Some infections can even lead to serious consequences including blindness. This is related to several risk factors, such as wearing contact lenses for too long, which can hinder the eyes from “breathing.” The cornea also needs to breathe, and even a highly oxygen-permeable lens covering the cornea can prevent the eye from “sucking” oxygen. Wearing contact lenses for a long time can cause corneal hypoxia. If microbes are present at this time, it may cause keratitis and even corneal ulcers. The latter is one of the serious complications of wearing contact lenses.

In addition, failure to properly clean or replace contact lenses in accordance with the instructions of an ophthalmologist may also pose a risk of eye infection. According to data from the US Centers for Disease Control and Prevention, 40% to 90% of contact lens wearers do not follow the care instructions to clean and wear contact lenses. Contact lens wearers who do not follow hygienic practices will have increased bacterial contamination in their contact lens cases. 66% of contact lens cases were positive for bacterial or fungal contamination. In nearly 40% of the contaminated cases, a variety of microorganisms have been isolated. So washing your hands with soap, letting the contact lens case dry naturally, using contact lens cases and disinfectant are all key steps to reduce contact lens contamination[8].

Although most people can safely wear contact lenses with simple precautions, it is risky to wear contact lenses at night or when swimming in a bath. It is like sitting in a car without a seat belt. There has been.

Contact lenses are great, but you must remember that it is still plastic, and humans don’t need it to stay in our eyes all the time.

References

[1] Lanxing Fu, MB, Ch.B., FRCOphth., and Ahmed Gomaa, MB, Ch.B, MD, FRCS Acanthamoeba Keratitis[J]. The New England Journal of Medicine, 2019; 381:274.

[2] https://www.foxnews.com/health/man-blinded-parasite-showering-in-contacts.

[3] Nicole Carnt et al, Acanthamoeba keratitis: confirmation of the UK outbreak and a prospective case-control study identifying contributing risk factors, British Journal of Ophthalmology (2018). : 10.1136/bjophthalmol-2018-312544.

[4] Parmar DN, Awwad ST, Petroll WM, et al. Tandem scanning confocal corneal microscopy in the diagnosis of suspected acanthamoeba keratitis [J]. Ophthalmology. 2006,113( 4): 538-547.

[5] Youhanna W. Ibrahim, David L. Boase, Ian A. Cree. How Could Contact Lens Wearers Be at Risk of Acanthamoeba Infection? A Review[J]. Journal Of Optometry, 2009, 2(2): 60–66.

[6] https://www.insider.com/wearing-contacts-in-shower-pool-can-cause-blindness-eye-infection-2019-7.

[7] Adrian D. Land, Katie L. Penno, Jennifer L. Brzezinski. Identification of Microorganisms Isolated From Counterfeit and Unapproved Decorative Contact Lenses [J]. Journal of Forensic Sciences , 2018, 63(2): 635-639.

[8] Yvonne T. Wu, Mark DP Willcox, Fiona Stapleton. The Effect of Contact Lens Hygiene Behavior on Lens Case Contamination. Optometry and Vision Science, 2015; 92 (2 ): 167, DOI: 10.1097/OPX.0000000000000477.


This article is from WeChat public account:Back to (ID:fanpu2019) author: Zhu Ye Hua