The shape of the cornea, and the front of the eye, can impact vision and eye health. In a typical cornea, the surface is round, smooth, and uniform. Things such as astigmatism, keratoconus, and corneal transplant surgery can impact the shape of the cornea.
A procedure known as corneal topography can image the front of the eye and create a display of the curvature, elevation, and shape. This technology is often used when screening for corneal disease, prior to and after LASIK, and to help with specialty contact lens fittings.
Basics of Corneal Topography
Corneal topography is a procedure performed by an instrument designed to measure and image the front of the eye.
In this measurement, the corneal topographer uses reflections of rings to measure the shape and elevation of the cornea.
These reflections give the machine information about the shape and contour of the cornea. This is then used to map the cornea similarly to a map showing land elevation – thus the term topography.
Depending on the instrument, this map can be as detailed as showing differences on the micrometer or nanometer level.
How is Corneal Topography Performed?
To perform corneal topography, the technician or doctor will have the patient align their chin and forehead in rest and focus on a lighted target.
The topographer is then positioned to focus on the cornea and a bright light will create ring reflections in the tear film.
Once these reflections are focused, the instrument will measure the spacing, contour, and clarity of the rings to determine the shape of the cornea.
For the patient, this will take only a few seconds in each eye and have no discomfort beyond a bright light for a short time.
When is Corneal Topography Used?
The most common uses of corneal topography include detecting corneal diseases and disorders, imaging the cornea before and after a refractive procedure, and assisting in fitting specialty contact lenses.
While there are many other potential uses of corneal topography, these three are the most common and encompass the most uses.
Corneal Topography to Diagnose Disease
Diseases of the cornea, such as keratoconus, pellucid marginal degeneration, and corneal ectasia can be readily identified and diagnosed using a corneal topography measurement.
If any of these conditions are suspected, it is indicated to perform corneal topography as a screening and possibly to repeat and assess for any changes over time.
Corneal Topography Before and After LASIK
Before any type of refractive procedure, such as LASIK, PRK, or orthokeratology, it is common to get a baseline reading of corneal topography.
These procedures are designed to alter the cornea and using corneal topography it is possible to objectively measure the differences in the cornea.
This additionally allows a built-in screening tool for corneal disorders which precludes eligibility from these procedures.
Corneal Topography for Specialty Contact Lenses
An emerging use for corneal topography is to help fit specialty contact lenses such as scleral contact lenses.
These contact lenses can be customized to accommodate any corneal abnormalities and improve comfort and vision while wearing the lenses.
Our optometrist at Eye Contact in Acworth, GA excels in the prescription of glasses, contact lenses, and the diagnosis of a variety of eye diseases. Call our optometrist at (770) 529-1925 or schedule an eye exam appointment online if you would like to learn more about corneal topography. Our eye doctor, Dr. Wes Mobley provides the highest quality optometry services and eye exams in Acworth, Georgia and its surrounding areas.