Acanthamoeba keratitis
The protozoan, Acanthamoeba, causing an infection that are very difficult to treat. Acanthamoeba is found widely in nature and have been isolated from a random sample of soil, water, and air. It can gain access to contact lenses and contact lens solution from one source, but the tap water is a common cause. Tap water should not be used for rinse contact lenses, contact lens store, or make a solution of salt (normal saline solution) because it can increase of the risk of Acanthamoeba infection.
The symptoms of infection occur more gradually than bacterial keratitis. It takes several days or weeks before symptoms progress were be a serious disease. The signs and symptoms early is a foreign body sensation, mild blurred vision, and redness. This developed into pain, conjunctival injection, epithelial rough, and thickened corneal nerves on slit lamp examination. As the infection progresses, pain becomes severe, clearly disproportionate to the amount of inflammation, and a center ring infiltrate characteristic shape.
Acanthamoeba feed on bacteria and cultured on page Escherichia coli. corneal scraping or biopsy specimens are placed on gelatin-coated E. coli and examined the tracks trofozoit characteristics that make them eat their way at the plate. Diagnosis and treatment of both assisted by friction a large number of epithelial to culture. Acanthamoeba cysts can also be identified from the corneal scraping using Giemsa and Calcofluor white stains.
Acanthamoeba organisms exist in two states, motile trofozoit and dormant cysts. Form cysts have a great resistance to drugs amebicidal and can lay a rest on the cornea for months. Therefore, topical antimicrobial begins on high frequency per hour and reduced in accordance with the severity and symptoms of toxicity. Traditional treatment propamidine (Brolene) and neomycin (Neosporin)are equipped with miconazole, Klotrimazol, and oral ketoconazole were replaced by polyhexamethylene biguanide (PHMB). In a concentration of 0.02%, PHMB is effective in killing both cysts and trofozoit of different strains and shows relatively little toxicity of cornea. Therapy was continued every 1-2 hours until proven clinical improvement, which often is 1-2 weeks. The frequency of dose is gradually lowered to 4 times daily. Treatment usually continue for several months until all inflammation has resolved.
Treatment with PHMB is complicated by the lack of commercially available solutions. PHMB is not licensed for ocular in any country. However, these compounds are available, and some pharmacies are willing to formulate the proper dosage and preparation for the ship.
Three patients with Acanthamoeba keratitis successfully treated with topical application of 0.1% riboflavin solution and 30 minutes of UV irradiation focused on the cornea ulcer.
The prognosis depends on how early the disease is diagnosed from the infections and therapy instituted. If caught early, regular medical are usual. However, if developed to infiltrate the ring stage, which usually takes about 6 weeks, which is quite difficult medical drugs and surgery may be required. Sides Acanthamoeba, there are some amoeba that can also cause infectious keratitis; Vahlkampfia jugosa and Naegleria species have been cultured from contact lens patients with keratitis.
Finally, in August 2006 issue of American Journal of Ophthalmology, Joslin et al reported on an outbreak of Acanthamoeba keratitis in the Chicago area. They postulated that changes in water quality standards of the Environmental Protection Agency (EPA) may have played a role in this outbreak. If true, this may indicate a resurgence in such cases nationally.
Tight lens (acute red eye) syndrome
A contact lens can sometimes become closely attached to the eye and produces a marked, diffuse stromal inflammation and anterior chamber reaction. The resulting pain, photophobia, injection, and tearing usually acute and severe. Epithelium has a mottled staining, or diffuse infiltrates in the peripheral anterior stroma. Symptoms resolve with the removal of contact lenses; the infiltrates may take several days to disappear. A short course of topical steroids will speed up resolution of symptoms.
Cornea bouncy
Prolonged contact lens wear can result in a gradual and unpredictable changes in contour bouncy corneas. The astigmatism or general steepness may be increased or decreased. Usually, bouncy irregular corneal astigmatism produce, which reduces the best spectacle correction. bouncy cornea is often seen with hard lenses but also can occur with soft contact lens wear. The cornea usually get back form a stable and orderly after the cessation of contact lenses, but it may take several weeks or even months.
Contact lens-induced keratoconus
Possible causal relationship between keratoconus and contact lens is controversial. A high percentage (20-30%) of patients with keratoconus have been wearing contact lenses at the time of diagnosis, but no causal relationship may exist because patients with keratoconus tend to have myopia and irregular astigmatism and hoped that they would prefer to contact lens rigid for eyeglasses.
The strongest evidence to support the hypothesis that contact lens wear can cause keratoconus in susceptible individuals has been presented by Macsai and colleagues. In their series of patients with keratoconus, there are differences in those who wear contact lenses at the time of diagnosis (eg, age more old, flat cornea, cone superior) than those who wear glasses when diagnosed. They also reported 2 patients who wear contact lenses and keratoconus only 1 eye developed only in those eyes. This evidence is very suggestive that the long-term contact lens wear can result in keratoconus in susceptible individuals.
The concept that the structural changes in the corneal stroma can be produced with a contact lens is supported by research, which has found a correlation between the thickness is reduced, the steepness increases, and greater irregularity in the cornea of the long-term contact lens users compared to normals. Furthermore, keratocyte density appears to be reduced in contact lens wearers.
The development of nearsightedness found in adolescents did not appear to be affected by contact lens wear. In this study, 175 adolescents aged 11-14 years were randomly assigned to spectacle or contact lens wear. After 3 years, no difference was recorded in equivalent changes in the ball. contact lens wear does not increase or decrease the amount of myopia.
Corneal endothelium and Summary
Corneal endothelium
contact lens wear can also interfere with corneal endothelium.Users have greater variation in the size of endothelial cells (polymegethism) and increased frequency nonhexagonal cells (polymorphism) than nonwearers. Along with dramatic changes in the morphology of endothelial cells, a small decrease in endothelial cell density has also been found in long-term users of contact lens soft lenses and PMMA and RGP lenses.
Deswelling level reduced in contact lens wearers and may indicate a backup pump in danger or increased permeability of endothelial cells in the cornea of the eye. However, using the methodology fluorophotometric, Bourne et al were unable to show significant differences in permeability or pump function in contact lens wearers. Therefore, it is clear that morphological changes occur in the endothelium by wearing contact lenses. However, it is not clear that differences in morphology translated into differences in function.
Summary
All eyes are changed by contact lens wear. Abnormalities of the lid, conjunctiva, epithelium, stroma, and endothelium produced. The changes run the gamut from an incidental finding without obvious functional significance for pathology is very painful and sight-threatening. Fortunately, most contact lens wearers to enjoy the benefits of comfort and excellent vision without experiencing significant adverse effects. The more we learn about the complications of wearing contact lenses, the more we can help our patients to treat and avoid them.
Patient education
For educational resources are very good patient, visit eMedicine's Eye and Vision Center. Also, see eMedicine's patient Lenses Contact education article.
When the Solution is the Problem ?
In the last 5 years, contact lens solution has been engaged in health risk for soft contact lens wearers. Incidence of infection associated with contact lenses has increased. Any delay in the diagnosis of fungal Acanthamoeba infection unpredictable and can contribute to vision loss. CDC has been involved in recommendations for eye care practitioners and patients. While errors of patients in proper contact lens care remains a critical factor in the eye infection, Fusarium keratitis outbreak was also associated with contact lens solution (Bausch & Lomb ReNu MoistureLoc. Following is a review of the outbreak of Fusarium keratitis, as well as discussion of keratitis resulting from the disinfection lens that is not true because the error of the patient.
Poor patient compliance with lens wearing schedule and care regimen has been documented to contribute to eye infections.About 25% of patients do not always wash hands before handling contact lenses, and 12% never do. Studies estimate that 40-80% of contact lens wearers do not regularly follow the recommended lens care regimen.
Even an experienced contact lens wearers are not immune to errors in the assessment of lens care. For example, a man 38 years with keratoconus reported to the clinic with symptoms of blur and discomfort in the left eye, along with clouds present with and without contact lenses. This patient has been a successful lens wearer SoftPerm the past 13 years without incident. His medical history was significant for type II diabetes. For nearly 3 months, these patients have difficulty finding AOSept disinfection system at local stores. He uses only salt solution and began to notice symptoms of blur after 1 month. He continued with only salt solution until finally she called the author's office. He was told to use alternative peroxide system and soon to come.
Even after 13 years of wearing contact lenses, these patients do not understand the importance of his contact lens disinfectants. He realizes that there is a cloud that continues when his lens was removed. Once she knew something was wrong with his own eyes, he is still waiting for a few weeks to call for an appointment.
Close-ups of scars and neovascularization corneal stroma.
He was prescribed topical antibiotics, and the scars have faded somewhat in the 2 years after these events. Eye care practitioners should emphasize to patients the importance of contact lens disinfection. That patients with 13 years experience contact lens does not recognize the urgent situation is shocking. Changes in the distribution of normal lens care products, AOSept, causing it to use a saline solution that is inappropriate than a disinfectant solution.
While the patient's fault contributed to the infection of the eye in the situation above, the fungus Fusarium outbreak in 2005-2006 linked to Bausch & Lomb ReNu contact lens solution with MoistureLoc soft. In a typical year, an estimated 21 cases of Fusarium keratitis were reported to the Centers for Disease Control (CDC). Most of these in southern climates, and 2% affect soft contact lens wearers. In 2005, 39 cases of Fusarium keratitis were reported in soft contact lens wearers. All except 5 of 39 had used ReNu with MoistureLoc solution (derived in a Bausch & Lomb factory in Greenville, NC).
On April 13, 2006, Bausch & Lomb voluntarily withdraw ReNu with MoistureLoc all solutions and recommending that consumers stop using the product immediately. Another type of ReNu remain on the market, as they do today. On May 9, 2006, the CDC has confirmed 106 cases and 80 still under investigation in a total of 32 countries.Additional cases were reported in Malaysia, Singapore, and Australia. Treatment varies from topical antifungal agent for intravitreal injection for corneal transplantation, depending on the severity of the condition and delay in diagnosis.
CDC recommendations to healthcare providers in May 2006 are as follows:
1. Advise patients to stop using ReNu with MoistureLoc immediately.
2. If the patient continues microbial keratitis, consider that the fungal infection may be involved, especially if the patient wearing soft contact lenses.
3. Before initiating treatment, obtaining specimens for culture.
4. Report cases of fungal keratitis to the FDA.
On August 22, 2006, the CDC announced that users of ReNu with MoistureLoc is 20 times more likely to develop Fusarium keratitis from contact lens wearers who use other solutions. Between the date of June 1, 2005 and June 30, 2006, 164 cases of Fusarium keratitis have been confirmed. Of these confirmed cases, 34% of those who need a corneal transplant. In 25% of cases, doctors prescribe a drug has any anti-inflammatory which makes keratitisworse Fusarium. While many patients re-vision, some have permanent vision loss. Some cases required a long course of treatment and repeat corneal transplant.
An article in 2006 in The New York Times included the following: "the expert Federal disease control and the physician's leading eye has formally concluded that Bausch & Lombs's ReNu with MoistureLoc is Contact lens solution is only contributing to the outbreak of potentially blinding eye infection fungus earlier this year but the report the researchers ', to be published Wednesday in the Journal of the American Medical Association,. say it is unclear how the product caused the problem'.
case law generated from these outbreaks are handled in the justice system South Carolina because the distribution of plants around the world to ReNu with MoistureLoc is located in the country. Two years later, the 1000 product liability lawsuits have been filed more than Renu with MoistureLoc, may cost more than $ 1 billion in damages.
Just a few moments later, in May of 2007, the risk of Acanthamoeba keratitis news. Advanced Medical Optics (AMO) voluntarily given full MoisturePlus multipurpose solution. This time, the concern that Acanthamoeba keratitis. This is an infection, caused by a rare serious parasite found in water environments such as ponds and lakes (see picture below).
Acanthamoeba infection of the cornea after transplant.
CDC had interviewed 46 people who had Acanthamoeba keratitis between 2005 and 2007. Of the respondents, 39 were contact lens wearers, and 21 have reported use of Complete MoisturePlus multipurpose solution in the months before symptoms. There is no determined cause and effect, and products on the market today did not appear to cause increased risk of infection.
Whether caused by error or patient's contact lens solution, eye infection rate has captured national attention, and eye care professionals should be careful in educating their patients on proper lens care. Agencies like the FDA and CDC keep practitioners and community information from every dangerous trend. Website www.CDC.org provide guidance and advice for consumers and healthcare providers. Practitioners should ask their patients about lens care habits and do not assume that patients know the appropriate treatment regimen. Remember that patients may not follow instructions, and stay abreast of any product recall.The solution is sometimes a problem.
