الفهرس 
corneal anatomyOnly 14 pages are availabe for public view
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Abstract
Bacterial ulcerative keratitis may have a devastating impact on ocular tissue and is a sight threatening condition. Corneal ulceration leads to activation of proteolytic enzymes that digest human collagen thereby facilitating corneal melting and perforation.
The treatment usually consists of topically administered antibiotics. The emergence of multidrug-resistant bacteria is a concern that might complicate the treatment and cure of infectious keratitis considerably.
The UVA/riboflavin crosslinking (CXL) may become a therapeutic alternative for managing antibiotic-resistant microbial infections.
CXL procedure was introduced in 2003 to stabilize progressive keratoconus by improving the biomechanical characteristics of the stroma.
CXL enhances corneal stromal resistance against enzymatic digestion by pepsin and collagenase. Moreover, it has a beneficial effect in cases of melting and help to avoid emergency keratoplasty.
Corneal collagen cross-linking with riboflavin ultraviolet-A (UVA) is a new technique of corneal tissue strengthening by using riboflavin as a photosensitizer and UVA to increase the formation of intra-and interfibrillar covalent bonds by photosensitized oxidation.
Laboratory studies have shown that the exposure of UVA light combined with riboflavin application kills a large variety of microorganisms. In fact, this technology is used clinically to sterilize blood products and kill bacteria, viruses, and protozoa.
UV light and oxygen radicals can have an antimicrobial effect because oxygen radicals interfere with cell membrane integrity. Hence, the combination of UV light and the radicals induced during cross-linking may synergistically protect corneas with microbial keratitis by actively destroying microbes and protecting the collagen against enzymatic degradation.
CXL’s anti-oedematous and antimicrobial properties have been demonstrated in a series of studies, suggesting its therapeutic indications in bullous keratopathy and in infectious keratitis, as an adjuvant treatment to conventional therapeutic modalities with a satisfactory final visual outcome.
PACK-CXL is a promising therapeutic intervention for corneal tissue stabilization in cases of resistant keratitis. In developed countries, treating a complex corneal infection often may cost thousands. PACK-CXL provides promises of a less expensive, faster, and more efficient way to kill harmful patho¬gens that cause corneal infections and later scarring, in a non-pathogen–specific manner and with little cost when compared to conventional pharmaceutical care.
Researchers are currently developing CXL technology that would allow performing a PACK-CXL procedure at the slit lamp, without using expensive operating room infrastructure or additional equipment.
The future might see small portable devices that will allow the comprehensive ophthalmologist to perform a PACK-CXL treatment as soon as the diagnosis of an early infiltrate or a beginning ulcer is made. We look forward to the widespread availability and application of PACK-CXL to shift the paradigm for infectious kera-titis management.