**8. Prevention and prognosis of AK**

Although the low doses of topical steroids can be useful to diminish inflammation in cases of

Systemic corticosteroids are preferred over topical ones in cases of severe inflammation. This route of administration provides better ocular safety profile (less concentration in the cornea) but less body safety profile. However there are some suggestions that steroid use may result

If the topical pharmacotherapy fails, surgical interventions are needed [12,44,64,67]. Crosslinking and cryopreserved amniotic membrane graft (AMG) have been reported to be effective

The corneal transplantation can be performed for therapeutic or optical indications. Thera‐ peutic, usually penetrating, keratoplasty is applied when the infectious process spreads to the corneal stroma, causing corneal melting and thinning despite of aggressive prolonged antiamoebic therapy [4,12,18]. In a case of threatening or completed perforation of the cornea, the surgery must be performed urgently. Some authors recommend systemic steroids prior to

Sacher et al.[70] show that pretreatment of *Acanthamoeba* keratitis with intravenous pentami‐ dine before therapeutic keratoplasty may assist with the achievement of microbiological cure,

The size of corneal graft should be minimum to excise an inflamed and necrotic tissue. Although remaining clinically healthy cornea is frequently also infected, this tissue should be saved because of the higher risk of rejection with large/decentrated grafts and because the possibility of repeat grafting should be kept in mind in the event of recurrence; a further graft represents a new food source for the organism and can be used to attract residual amoebae [69]. In a case of therapeutic keratoplasty for AK, the topical steroids in combination with antiamoebic drugs are applied for 6-12 months following keratoplasty, to relieve pain, lessen the inflammation, and prevent graft rejection and recurrence of infection. Corneal grafts per‐ formed in the eyes with active inflammation are the high-risk transplants and they required systemic immunosuppression similar to this given in organ transplants (cyclosporine and/or mycophenolate mofetil). Apart from a poor graft survival, the postoperative glaucoma is a

In optical keratoplasty performed after resolution of active keratitis there is an excellent

Promising clinical results were reported from amoebicidal effect of combined riboflavin and UV-A (ultraviolet light A, 365nm wavelength) exposure -corneal cross-linking (CXL) that was used for stabilization of corneal melting which can delay surgical treatment [12,72,73]. CXL has also an antimicrobial effect that is due to the effect of UV light interacting with riboflavin as the chromophore. It damages both the DNA and RNA of pathogens. Photoactivated chromophore for infectious keratitis (PACK)-CXL is an alternative to standard antibiotic therapy in treating infectious corneal disorders, and may help reduce the microbial resistance

controlled infection but the use of topical corticosteroids is controversial.

in increased pathogenicity of the amoebae [68].

surgery if concomitant limbitis or scleritis is present [69].

prognosis for both graft survival and visual outcome [71].

to antibiotics and avoid therapeutic keratoplasty in some cases [74].

clear graft, and good visual outcome in a majority of eyes with AK.

in AK.

112 Advances in Common Eye Infections

frequent complication.

The *Acanthamoeba* species are ubiquitous and widely distributed in natural and man-made environments. In various regions, humans were exposed frequently to the amoebae, that has been confirmed when in healthy populations specific anti- *Acanthamoeba* antibodies have been detected. For this reason, knowledge and awareness of threat are important to avoid the infection [6,12,18].

The contact lens wearers must be well educated as for the proper use and care of their lenses; do not use saline solution for lens storage, and do not to swim wearing contact lenses or use the swimming goggles. It is also very important to educate the ophthalmologist to be aware of signs and symptoms of AK and be able to early diagnose and initiate suitable treatment.

The prognosis for visual recovery with only mild residual stromal involvement is very good; in other cases, the visual prognosis is poor. Generally, a prediction depends on inflammation status at the time of diagnosis and the prompt initiation of proper treatment.

A retrospective review indicates that early diagnosis (less than 18 days) results in better final visual acuity and less likely needs keratoplasty [75]. In the early stage of infection, trophozoite forms are predominated, and the infection is confined to the superficial corneal layers. With time as the process progresses, the microorganisms enter to the deeper corneal stroma and encyst. Cysts are much more resistant to anti-protozoan drugs compared to trophozoites. Severe inflammation, scleral involvement, late diagnosis, and retardation of the therapy initialization are associated with poor clinical outcomes. In 10% of cases, there is associated scleritis. *Acanthamoeba* sclerokeratitis is associated with poor clinical outcomes [12,13,75].
