Dr. Gary Sewell, M.D.  B.Sc.

Unicity Eye Clinic

P  (204) 953-5560

F  (204) 949-1143

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Disclaimer

Optical Coherence Tomography (OCT)

 

Optical coherence tomography (OCT) is a non-invasive imaging test that uses light waves to take cross-sectional pictures of parts of the eye (retinal, optic nerve, anterior chamber, cornea).

 

What is Optical Coherence Tomography?

Optical coherence tomography (OCT) is a non-invasive imaging test that uses light waves to take cross-sectional pictures of parts of the eye (retinal, optic nerve, anterior chamber, cornea). For our purposes in diabetes we are most interested in the retina. Amazingly, the resolution is similar to that of a microscope. Each of the retina’s distinctive layers can be seen, allowing us to map and measure their thickness. These measurements help with early detection, diagnosis and treatment of retinal diseases, including age-related macular degeneration and diabetic eye disease, among others.

 

The retina is the light-sensitive tissue lining the back of the eye. It performs the same function as the film in a camera or sensor in a digital camera. Click here to see how the eye works.

 

 

How does OCT differ from a photograph or ultrawide field image?

A retinal photograph gives a picture of a small area of the inside of the back of the eye. An optomap gives a much bigger, wider picture. A picture is extremely useful, but can only show the surface. Sometimes we need to know what's below the surface. OCT shows all the layers behind the surface of the retina. The drawback is that it can only do so for a small area. Think of a retinal photograph as a picture of your front door, an optomap as a picture of the front of your house, and OCT as what's behind the front door.

 

 

What conditions can OCT help diagnose?

OCT is useful in diagnosing many retinal, optic nerve, and corneal conditions, including:

• Macular hole;

• Macular pucker;*

• Macular edema;*

• Age-related macular degeneration;

• Central serous retinopathy;

• Diabetic retinopathy;*

• Pre-retinal membranes;*

• Glaucoma;*

 

* Macular pucker, macular edema, diabetic retinopathy, pre-retinal membranes, and glaucoma are all more common in diabetics

 

 

What happens during OCT?

Having an OCT scan is a quick and easy process.  Nothing comes into contact with the eye, there are no air puffs, and it is completely pain free.  You will be asked to look at a target and the scan will be taken in a couple of minutes, much like getting a photograph taken. Dilating drops are occasionally required, but not usually.

 

 

How does it work?

Using light reflected from the front or the back of the eye, the OCT creates a highly detailed picture in two or three dimensions.  This can give your ophthalmologist a view of your eyes on a microscopic level.  The major benefit of this is that it allows your ophthalmologist to literally see beneath the surface, allowing them to view structures and sections of the eye that would be otherwise invisible.

 

 

Limitations

Since OCT relies on light waves, it cannot be used successfully with any condition that interferes with light passing through the eye, such as dense cataracts or significant bleeding in the vitreous (the gel in the centre of the eye).

 

 

OCT in diabetes

Diabetic macular edema (DME) is a serious vision threatening complication of diabetes. Prompt treatment can restore vision and prevent irreversible vision loss.  OCT is the technique of choice for the early detection of macular edema and for precise monitoring of treatment response. It can clearly demonstrate DME in retinas that appear perfectly normal to the examiner's eye.