الفهرس 
Anatomy and physiology of the corneaOnly 14 pages are availabe for public view
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Abstract
Eye diseases affecting the cornea are a major cause
of blindness worldwide. The epidemiology of corneal
diseases is complicated and encompasses a wide variety of
infectious, inflammatory and degenerative eye diseases that
can cause corneal scarring, which ultimately leads to
impaired vision. In addition, the prevalence of corneal
disease varies from country to country and even from one
population to another depending on many factors, such as
availability and general standards of eye care. Dystrophies
of the cornea, infectious and noninfectious scars are the
most common corneal causes of potentially reversible
visual deterioration.
PTK involves the removal of the superficial corneal
tissue with an excimer laser for therapeutic purposes. PTK
has been used in the management of corneal pathologies for
over two decades. It has several advantages such as precise
control of the depth of ablation, fast postoperative recovery,
ease of use, creation of a smooth base for corneal re-
epithelialization and the ability to repeat treatment if
required.
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PTK is an FDA-approved procedure to treat anterior
corneal pathology affecting visual function, including
symptoms of pain and/or decreased vision.
The main indications are corneal opacities, poor
epithelial adherence or an irregular corneal surface as well
as combinations of these.
The specific technique of PTK used will depend on the
needs of the patient. Thorough understanding of each
patient’s lesion nature, size, site and depth, topography of
the cornea and considering the refractive needs of the
patient is very important for choosing the best technique of
PTK to give the best results.
PTK is best suited for disorder in the anterior 10%-
20% of the corneal stroma. PTK is used for the treatment of
superficial opacities and helps to gain a moderate increase
of VA. Patients with superficial corneal dystrophies and
degenerations also benefit from improved vision. PTK also
successfully attains smooth regular ocular surface and
improves the tear film. PTK has minimal side effects and
complications; given that proper patient selection is backed
up with sound preoperative counseling.
PTK is a safe, minimally invasive and effective
procedure that helps achieve symptom alleviation and
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increases VA. In a properly selected and well-counseled
patient, PTK can significantly improve vision and quality
of life, avoiding or at least postponing the need for corneal
transplantation.
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