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Bennett & Pearson Optometrists


Visique Bennett & Pearson Optometrists are thrilled to have the first Topcon Maestro OCT in New Zealand!

This state of the art equipment not only takes standard retinal photos but also performs a high resolution scan of the back of the eye enabling early detection of glaucoma and macular degeneration as well as many other eye diseases.

Maestro OCT

Topcon Maestro OCT


OCT & Glaucoma


Ocular Coherence Tomography (OCT) is an imaging test that allows for detailed visualisation of the optic nerve head and retina. The damage glaucoma causes to the optic nerve can be detected in two general ways: either with the way the nerve is working (i.e. problems with vision) or abnormal changes in the structure of the nerve.

In general problems with the appearance of the optic nerve can be seen long before people have any trouble with their vision. Detecting problems with the structure of the optic nerve is therefore very important as an early sign of glaucoma as well as a sign that glaucoma may be getting worse.

There are a number of different ways of recording the appearance of the optic nerve. With the advent of high quality eye cameras it became possible to record the optic nerve in life like detail and optic nerve photos remain a very useful way of imaging in glaucoma. By comparing new and old photographs it is possible to see changes in the nerve, although it can be difficult to get exact measurements of the change. OCT gives a new way of recording and measuring the structure of the optic nerve in great detail.

The OCT machine is similar to ultrasound but rather than using sound waves to create an image it uses light.

This can tell us a great deal about the optic nerve. Each section of the nerve can be measured and compared to the general population to see if there is anything obviously abnormal. The optic nerve is usually less than 2mm in diameter and OCT provides measurements of the optic nerve shape and thickness with a resolution of about 6 microns (1 micron=1/1000th of a mm).  In many cases this can help make the diagnosis of glaucoma a lot easier.

The real strength of OCT however is in its ability to detect changes over time.

When the OCT is repeated after a period of time the new scans can be compared to the old ones, allowing detection of changes which may be too subtle to have been noticed with older technologies, such as colour photos or drawings.

Having an OCT picture taken is very similar to having a normal picture taken of your eye. It is not generally required to touch the eye but some people may need to have eye drops put in to dilate the pupil in order to get the best pictures. The scan itself takes only a few seconds.

 

 

Normal Disc OCT Glaucoma disc OCT scan

                                   Normal disc OCT scan

OCT scan in glaucoma

 

OCT & Macular Degeneration

Your retina is the light-sensing layer at the back of your eye. Like the film in a camera, it picks up images which are transmitted to your brain via your optic nerve.  Your brain does the real work of seeing, making sense of all those images.  Any damage or deterioration in your eye or optic nerve that reduces the quality of the images your brain gets can affect your ability to see.

The macula enables us to see detail, so any damage to it affects our ability to read or do anything that requires precise vision, such as driving.

Macula Degeneration (MD), is also know as Age-related macula degeneration (AMD)

There are two types of MD - known as Dry MD and Wet MD. The Dry form results in a gradual loss of central vision. The Wet form is characterised by a sudden loss of vision and is caused by abnormal blood vessels growing into the retina. Symptoms may include distortion, where straight lines appear wavy or bent or difficulty in reading or other activities that require fine vision.

MD is thought to be caused by genetic and environmental factors. People over the age of 50 are particularly at risk.   If you smoke or have a family history of MD, your risk of developing the disease is much greater.

The early detection of any form of MD is crucial because the earlier you seek treatment, the more likely you are to have a better outcome compared to those who wait. Early detection of changes can allow you to take steps to slow the progression of MD.

The OCT machine is similar to ultrasound but rather than using sound waves to create an image it uses light.  The OCT takes high resolution cross-sectional images of the macula. By comparing the structure and thickness of the layers measured by the OCT against a normal healthy retina, your Optometrist can detect MD even at a very early stage.

When the OCT is repeated after a period of time the new scans can be compared to the old ones, allowing detection of changes which may be too subtle to have been noticed with older technologies, such as colour photos or drawings.

Treatment options are dependent on the stage and type of the disease. Current treatments aim to keep the best vision for as long as possible and in some cases may potentially provide visual improvement, but there is presently no cure. Early detection is vital in saving sight.

A large scale study has shown that people who took specific vitamins and antioxidants were 25 percent less likely to progress to advanced MD over the five-year study period.  Clinicians® VisionCare with Lutein is based on the formulation in this study.

 

OCT normal macula OCT MD

Normal Macula cross section

Macula cross section in AMD

 

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