الفهرس 
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Abstract
T
he CCT is of paramount importance in clinical practice for many reasons, such as its influence on IOP measurement. It is also critical when planning refractive surgery and other clinical situations.
The transparent cornea forms the anterior one sixth of the eyeball. It’s the main structure responsible for the refraction of light entering the eye. Microscopically it consists of 6 layers which are: epithelium, Bowman’s membrane, stroma, Dua’s layer, Descmet’s membrane and endothelium .
CCT can be assessed by means of many instruments, including specular microscopy, ultrasound pachymetry, ultrasound biomicroscopy (UBM), slit-scanning corneal topography, instruments using the Scheimpflug system ( penta cam), and optical coherence tomography (OCT).
Pentacam enables high resolution imaging of the central cornea, measurement of corneas with severe irregularities, such as keratoconus, that may not be amenable to Placido imaging, calculation of pachymetry from limbus to limbus.
Myopia, is a refractive defect of the eye in which collimated light produces image focus in front of the retina when accommodation is relaxed.
In total, 105 eyes from 53 Egyptian subjects were
enrolled in this study. Three study groups were established based
on the value of the SE; group #1 =emmetropic eyes, group #2 =
mild to moderately myopic eyes from and group #3 = moderate
to severely myopic eyes.
The age of subjects is ranging from 20 to 40 years.
Contact lens use was discontinued for at least 15 days
prior to data collection. Subjects were excluded if they had an
active ocular-surface disease such as significant dry eye,
corneal opacities, glaucoma, current medication that could
affect ocular physiology, astigmatism >2.00 D, keratoconus or
if they had undergone any kind of ocular surgery.
This study reveals that the CCT tends to be thicker
with increase of degree of myopia. This correlation needs a
large group to be evident.
Also a positive correlation was found between CCT
and IOP. Subjects with thicker CCT have higher IOP and
subjects with thinner CCT have lower IOP