How to Fit Toric Contact Lens
Toric contact lenses are soft contacts that help with astigmatism, a vision correction that involves the curvature of the outer layer of your eye, or cornea. Standard contacts only correct for distance or near problems, but toric contacts have additional power in a specific part of the lens that offset distortions caused by irregular curvatures of the eye. Toric lenses must be fit accurately to ensure the best vision.
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Instructions
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1
Measure the curvature of the cornea with a keratometer, an optical instrument that is designed to measure two distinct curves of the eye. The measurements are called k-readings and determine the base curve of the toric lenses. The base curve of the contact matches the curves of the eye so the lens fits comfortably.
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2
Look at the eyes under the slit lamp, an optical microscope. Evaluate the size of the eye to determine the proper diameter of the toric lens. The diameter is the size measured across the contact lens in millimeters (mm) and ranges between 12 and 14 mm. The lens should fit comfortably between the top and lower lid.
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3
Put on a testing toric lens, also called a trial lens, once you have estimated the correct size and base curve of the lenses.
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4
Note the markings on the lenses to assess rotation. Most toric lenses have very light slash marks on the sides or on the bottom of the lens to verify that the contact is sitting properly on the eye and not rotating out of alignment.
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5
Observe the lenses after they have been on the eyes for at least 20 minutes. This allows the lenses time to settle on the eye. Recheck the markings to assess for any rotation.
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