Corneal Topography Explained: What to Expect During the Eye Test
Your cornea plays an important role in how clearly you see. Even small changes in its shape or surface can affect your vision. To get a detailed view of the cornea, your eye doctor may recommend a test called corneal topography.
Corneal topography is a noninvasive eye test that creates a detailed map of the cornea’s surface. It can help your eye doctor identify irregularities, evaluate certain corneal conditions, and determine whether you may be a good candidate for procedures such as LASIK.
But what exactly happens during a corneal topography test? Is it uncomfortable? How long does it take?
Here’s what you should know.
What Is Corneal Topography?
It is an advanced eye test that measures the shape and curvature of your cornea.
Think of it as creating a detailed map of the front surface of your eye. Unlike a standard eye exam, which primarily evaluates your vision and overall eye health, corneal topography provides detailed information about the cornea’s shape.
The test can identify areas where the cornea is steeper, flatter, thinner, or more irregular than expected.
Your eye doctor may use this information to better understand changes in your vision and determine the most appropriate treatment.
Why Is Corneal Topography Important?
A healthy cornea has a relatively smooth and regular shape. When the cornea has an unusual shape or surface, it can contribute to blurry or distorted vision.
Corneal topography can help your eye doctor detect these irregularities that may not be obvious during a routine eye examination.
The test may be recommended if your doctor needs to:
- Evaluate the shape and curvature of your cornea
- Investigate unexplained changes in vision
- Look for signs of corneal irregularities
- Evaluate certain corneal conditions
- Monitor changes in the cornea over time
- Assess your eyes before certain procedures
- Help determine whether you may be a candidate for vision correction surgery
Because it provides detailed information about the cornea, corneal topography can be an important part of a more comprehensive eye evaluation.
What Does a Corneal Topography Test Measure?
Corneal topography primarily measures the curvature and shape of the cornea.
The resulting map can show areas of the cornea that are relatively steep or flat. Depending on the technology used, your eye care provider may also be able to evaluate other characteristics of the cornea.
This information can be particularly useful when evaluating patients for procedures such as LASIK or other vision correction treatments.
It may also help doctors identify patterns associated with certain corneal conditions.
What Happens During Corneal Topography?
One of the biggest benefits of corneal topography is that the test is quick and noninvasive.
During the test, you will sit in front of a specialized instrument. You will be asked to place your chin and forehead against supports to help keep your head steady.
The device will then scan the surface of your cornea.
You may be asked to look at a target or light while the machine captures measurements. The test does not require your eye to be touched.
The information collected by the device is then used to create a detailed map of your cornea.
In most cases, the process only takes a few minutes for both eyes.
Does Corneal Topography Hurt?
No. This eye test is painless.
The device does not touch your eye while it measures the cornea’s surface. You simply need to remain still and look at the target as instructed.
Because the test is noninvasive, most patients find it quick and comfortable.
If you wear contact lenses, your eye doctor may ask you to stop wearing them for a certain amount of time before testing. Contact lenses can temporarily change the shape of the cornea, which could affect the accuracy of the measurements.
Your eye care provider will tell you if you need to make any preparations before your appointment.
Who May Need Corneal Topography?
Not everyone needs corneal topography during a routine eye exam. Your eye doctor may recommend it when more detailed information about your cornea is needed.
For example, corneal topography may be useful for patients who are:
- Being evaluated for LASIK or other refractive procedures
- Experiencing unexplained blurry or distorted vision
- Being evaluated for certain corneal conditions
- Having changes in their corneal shape
- Being monitored for an existing corneal condition
- Considering certain types of contact lenses
Your eye doctor can determine whether corneal topography is appropriate based on your symptoms, eye health, medical history, and treatment goals.
Corneal Topography Before LASIK
Corneal topography can be especially important when evaluating someone for LASIK.
LASIK changes the shape of the cornea to correct certain vision problems. Before recommending the procedure, your eye doctor needs detailed information about the cornea to determine whether the procedure is appropriate.
It can help identify irregularities in the cornea that could affect surgical planning or candidacy.
However, corneal topography is only one part of a LASIK evaluation. Your doctor may perform several other measurements and tests before determining whether LASIK is a safe and appropriate option for you.
What Do Corneal Topography Results Mean?
After the test, your eye doctor will review the resulting corneal map.
The map uses different measurements and visual patterns to show the curvature and shape of the cornea. Your doctor can interpret these results in combination with your other eye measurements and medical history.
An unusual result does not necessarily mean that you have a serious eye condition.
Your eye doctor will explain what your results mean and whether additional testing or monitoring is recommended.
How Is Corneal Topography Different From a Regular Eye Exam?
A regular eye exam evaluates several aspects of your vision and eye health, including visual acuity, eye pressure, and the health of structures inside and outside the eye.
Corneal topography has a more specific purpose: it provides detailed information about the shape and surface of the cornea.
The two types of testing can complement each other. Your eye doctor may use the results from both to develop a more complete picture of your eye health.
What Should You Do If Your Doctor Recommends Corneal Topography?
If your eye doctor recommends this eye test, there is usually no reason to be nervous. The test is quick, painless, and noninvasive, and it can provide valuable information about your cornea.
Whether you are experiencing changes in your vision, considering LASIK, or being evaluated for a corneal condition, this type of testing can help your eye care team make more informed decisions about your treatment.
At MiVision Eye Care, we use comprehensive eye evaluations to better understand each patient's individual vision and eye health needs. If you have questions about corneal topography or whether this testing may be appropriate for you, talk with your eye care provider.
Your corneas are an important part of how you see. Understanding their health and shape can be an important step toward protecting your vision.