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Blue Light at the Eye Doctor: What You Need to Know

blue light eye exam

During an eye exam, you may have noticed that the eye doctor uses a blue light. But have you ever wondered why? This article will explain the different reasons why a doctor might use a blue light during your exam and what it helps them assess.

Assessing the Surface of the Eye

One common use of blue light is to check the surface of your eye for any problems. Prior to using the blue light, a yellow dye called sodium fluorescein is typically placed in your eye. The combination of the dye and blue light allows the doctor to examine and identify issues such as dry eye or corneal abrasions. It is particularly helpful in determining the cause of any discomfort you may be experiencing in your eye.

Checking Eye Pressure

Another important application of blue light is to measure your eye pressure. To assess your eye pressure accurately, a tonometer, a small probe, is gently placed on the surface of your eye. The doctor then uses the blue light to help them line up the images and gauge the intraocular pressure. This measurement is crucial in evaluating the health of your eyes and determining if you are at risk for conditions like glaucoma.


Blue light at the eye doctor

If you’ve ever been to the eye doctor, and you see a blue light, they’ve usually put a yellow dye (also called sodium fluorescein) in your eye first. After they put the dye in, they use a blue light to assess your eye. There are different reasons why a doctor might use a blue light:

✅To check the surface of your eye for problems such as dry eye, corneal abrasions, and find out what the cause of an uncomfortable eye might be.

 ✅To check your eye pressure. This involves a small probe called a tonometer touching the surface of your eye. The doctor will then look through the microscope and line up the images to asses the intraocular pressure.

✅ To assess the fit of a hard contact lens. The pattern that is viewed under the lens helps the doctor understand how the contact lens is interacting with the cornea. We can then make changes to the shape and curvature based on what we see.


Evaluating Hard Contact Lenses

Additionally, blue light is often used to assess the fit of a hard contact lens. When you wear a hard contact lens, the doctor will examine the pattern formed under the lens using blue light. This pattern provides valuable information about how the contact lens interacts with the shape of your cornea. By carefully analyzing this interaction, adjustments can be made to the shape and curvature of the lens to achieve a more comfortable and precise fit.

The use of blue light in these different scenarios allows eye care professionals to gather important information and make informed decisions about your eye health. It aids in the diagnosis and management of various eye conditions, ensuring that you receive the most appropriate care and treatment recommendations.

See how we use the blue light in action!
Screenshot 2023 07 06 110113


Difference between Cobalt Blue and Other Blue Light

It's important to note that the blue light used in an eye exam is different from the blue light emitted by electronic devices. The blue light in an eye exam is specifically designed to enhance specific observations and is used for a short period of time. It does not pose the same potential risks associated with excessive exposure to blue light from digital screens or sunlight.


Questions for Your Doctor

During your eye exam, if the doctor decides to use a blue light, there is no need to be alarmed. It is a routine part of the examination process and is performed to provide a comprehensive evaluation of your eye health. However, if you have any concerns or questions, do not hesitate to discuss them with your eye care professional. They will be able to explain the purpose of the blue light in your specific situation and address any queries you may have.



Our eye doctors at Contact Lens Institute of Nevada excel in the treatment and management of scleral lenses, myopia management, orthokeratology (ortho-K) and other custom contact lens solutions. Call our optometrists at 702-747-4070 or schedule an appointment online if you would like to learn more about blue light.  Our eye doctors, Dr. Stephanie Woo and Dr. Jenny Wong, provide the highest quality specialty contact lens services in the Las Vegas area.

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