Types of Topographic Maps

Types of Topographic Maps

Axial Display Map

This is the most common way to look at a topographical image since it gives you a good overview of the corneal power. However, because it uses data averages to create a smooth map, it is regarded as less accurate than other maps.

Because the average of the center curvature is displayed, axial maps are a useful tool for determining the base curve of a soft contact lens. Other map displays, on the other hand, are better for information on corneal shape and power.

Tangential Display Map

This type of map is useful in fitting contact lenses, especially ortho-k lenses, because it provides an accurate evaluation of the cornea's power and curvature.

This map can also be used to assess the power of a contact lens while the lens in on the eye. This is useful when the patient is being fitted for a multifocal contact lens and the optical powers must be correctly positioned on the eye.

The tangential map is ideal for detecting changes in corneal curvature that may arise as a result of corneal distortion from wearing contact lenses.

Elevation Display Map

To determine the true shape of the cornea, which is crucial for selecting the best contact lens design for an irregular cornea, this map is used. This map display is especially important while deciding between a corneal contact lens or a scleral gas permeable (GP) lens.

Also, the elevation display map is helpful for ortho-k management, because corneal shape is a determining factor in evaluating if ortho-k lenses will be appropriate for the patient, and in selecting a dual-axis or single-axis lens.

Corneal Thickness Display Map

This map display is used to stage ocular diseases, such as keratoconus, but it's mostly used to track changes in corneal thickness while wearing contact lenses.

Tear Break-up Display

The quality of the natural tear film is displayed by this map along with how the tear quality has been impacted by contact lens wear. A corneal topography test measures the tear film before the patient begins to wear contact lenses, which is compared to the measurement taken after the patient has been wearing contact lenses.

Please consult your doctor because corneal topography is of critical importance in determining the quality of your vision and corneal health.