LASIK MD Laser Eye Surgery – Orbscan Topography
A topography unit is a machine that takes a
specialized photo of the cornea, the front transparent window of
the eye. The resulting photo is a topographic map of the corneal
surface, similar to satellite aerial color-coded maps of mountains
and valleys on the planet earth.
This map shows the bumps and valleys on the corneal surface and is used to ensure the cornea is regular and can be treated with the laser. People with irregular types of astigmatism or corneal disorders, such as Keratoconus, can be screened out prior to surgery. The topography is therefore essential in determining whether or not you are a candidate for LASIK surgery.
Orbscan Topography is a newer technology that
not only allows your surgeon to detect these irregularities on the
front surface of the cornea, but also allows mapping of the
posterior corneal surface. Conventional topography machines can
only give information about the front surface. Orbscan Topography
can also determine whether the back surface of the cornea is
healthy.
This extra ability to look at the back surface is essential for
safety reasons. The added safety allows your surgeon to better
determine the suitability of your cornea for surgery.
A pachymetry unit is a machine that takes a
measurement of corneal thickness. It is vital to assess this before
surgery in order to determine if there is adequate thickness to
create the flap and to perform the laser ablation. It is also vital
in assessing the candidacy for a retreatment. People with thin
corneas may not have enough tissue for a primary or a secondary
treatment.
Conventional pachymetry units take measurements at one point on the
cornea. This point is where the probe of the pachymeter touches the
cornea, usually in the centre. The Orbscan technology takes
pachymetry (measurements) optically without touching the cornea.
This allows a measurement reading for the entire cornea; rather
than a measurement at just one point. The ability to determine the
thickness at all points ensures that a thin point is not missed and
contributes to greater safety.
