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3D OCT, Amy’s favourite bit of testing equipment

3D OCT – What is it and is it necessary?  By Optometrist Amy Ogden

Having just finished my first full testing month (and what a busy month it’s been). I’ve decided to write a little introduction to my favourite bit of testing equipment, the 3D OCT machine. Often when you call to make an appointment to see one of the Optometrists, the 3D OCT scan will be mentioned and offered to you. Many people are unsure of what a 3D OCT Scan is. This is often overlooked, and their opportunity to utilise this wonderful medical technology is missed. I thought it would be a good idea to write a little introduction into why this equipment is so wonderful. What I use it for and the benefits of using it, as opposed to the fundus camera (I could go on all day, this is just the basics).

What is an OCT?

Amy Ogden, Optometrist at Allegro Optical Opticians in Saddleworth and Holmfirth, explaines why she likes the 3D OCT scanner so much OCT stands for Optical Coherence Tomography. Essentially it works by sending light rays to the back of the eye. Due to the layers of the retina having different reflective properties, the image formed is a greyscale image of the hypo and hyper reflective layers (near infrared light is used, so there is no likely damage to the eye). The principle is rather like an ultrasound scan as it is an echo technique. Only using light waves instead of sound waves. I can then see any abnormalities in each layer due to the differences in the reflective properties of tissues. For example blood usually casts a shadow, whereas exudates are hyper-reflective. Disorders 3D OCT Optic Nerve Scan

Why is this important?       

Our retina has 10 layers; Inner limiting membrane Retinal nerve fibre layer (RNFL) Ganglion cell layer Inner plexiform layer Inner nuclear layer Outer plexiform layer Outer nuclear layer External limiting membrane Photoreceptor layer Retinal pigment epithelium (RPE)

The Volk lens

When I’m using my Volk lens (when you sit at the microscope), or my ophthalmoscope (when I use the hand-held microscope and get quite close), I can’t see all of these layers; I can’t see them all when I take a picture of the back of the eye with the fundus camera either. I can understand at this point if you’re wondering why this matters, what does it matter if I can’t see the photoreceptor layer? Or the retinal pigment epithelium? It is always useful to see these layers, even if they are healthy, to be sure they are and to have a baseline to refer to further down the line. Amy Ogden, Optometrist at Allegro Optical Opticians in Saddleworth and Holmfirth, explaines why she likes the 3D OCT scanner so much   Sometimes, you may be unaware of a problem or having unspecific symptoms, and seeing the OCT scan will bring a very subtle change to my attention, something that may only have manifested itself on a fundus picture or to me on Volk once further disease progression has occurred. For example in the photoreceptor layer, which I mentioned above, there could be changes that may be indicative of a condition called Retinitis Pigmentosa. In the RPE, this is where we can monitor for some of the signs of Age Related Macular Degeneration (AMD) and subtle changes in the pathology here can help us in determining if the Dry AMD changing to Wet AMD, this is important as Wet AMD is something we need to treat urgently, and fast diagnosis is key.

What can OCT test for?

3D OCT eye scans from Allegro Optical Opticians in Meltham 3D OCT is also useful test for those at risk of glaucoma, combined with the visual field screener, IOPs (pressure test) and the ocular examination, using the OCT is another tool in our belt to help as a diagnostic aid. This is because it provides a scan of the optic nerve head, and the macula and helps us to pinpoint any suspicious findings; this along with the tests mentioned above helps us keep on top of early detection and precise monitoring. OCT can also measure the drainage angle in the eye, this is important for a condition called angle closure glaucoma. (I’ve only used a handful of pathology examples here)

How is it performed?

I know I mentioned an ultrasound above, and some of you will be thinking about the “jelly” used in those types of scans. Not for OCT. The OCT is very similar to the fundus picture without the “bright flash”. You sit at the OCT with your chin on the rest, and I will line you up with the lens. You will be asked to “look at the green cross” and will then be instructed to blink “freely and then keep your eyes open”, only for a short time, whilst the scan is completed. I will repeat this for the different types of scans you require, for both eyes. We will then go through all scans together and I will explain the findings. Should any further action need to be taken, we will make an action plan together.

The best bit?

I can send a copy of these scans directly to the hospital should it be required. Which makes triage a lot more efficient.

Are OCTs compulsory?

Absolutely not. They are not included as part of the NHS sight test and therefore are an optional extra. I think they are a brilliant bit of extra information to have, and a fabulous monitoring tool, but they are not compulsory for me to carry out a thorough eye examination, however if I feel that you would benefit from the OCT I will let you know, but the choice will always be yours!  
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OCT – Helping us see so much more

Our OCT Scanner is helping us see so much more to look after your vision and eye health


Good vision is something that most people take for granted, but we all only have one pair of eyes. At Allegro Optical we believe that eyesight is precious, it’s one of the senses we would struggle to do without.  Just as a regular MOT makes sure your car is safe and roadworthy, it’s good to keep a check on your eyes and eye health by having a regular check-up.

Here at Allegro Optical, we like to provide all our clients with the very best in eye care. This is why we are constantly investing in new equipment. We like to think we do more than just ‘sight tests’. We use a wide range of state of the art equipment and we’ll take a little longer than most.

Looking a little deeper OCT 3D Eye Scan at Allegro Optical Opticians in Meltham near Greenfield, Holmfirth, Huddersfield, Saddleworth and Uppermill

We have recently invested in a piece of cutting-edge technology. A machine that can help us diagnose potential problems with your eyes much earlier than before. We have invested in a new Spectral Optical Coherence Tomography (3D OCT) machine, to offer state of the art scans to all of our clients. This cutting edge technology, in conjunction with our detailed eye examination, enables us to detect potentially sight-threatening problems much earlier than with conventional equipment.

The 3D OCT is a special machine allows us to scan your eye in great detail.  Allowing us to see tell-tale warning signs of conditions such as Age-Related Macular Degeneration (AMD), Diabetes, Glaucoma, High blood pressure, and much more. Previously, we have used retinal cameras to photograph the visible outer layer of your retina. The 3D OCT produces scans, not unlike an ultrasound examination. We will still take a retinal photograph where possible. But now we can also view all the parts of the eye which would not have been visible to your Optometrist previously.

How do I get a 3D OCT Scan?

When booking an eye test at Allegro Optical in Meltham everyone is offered the option to have a 3D OCT scan. The 3D OCT scanner takes high-resolution images of your eye. These will be kept with your clinical records so that your eye health can be carefully monitored at each visit. At Allegro Optical Opticians in Meltham OCT scanner can detect Macula disease

Managing Director Sheryl Doe says, “Our new 3D OCT scanner is one of the most advanced pieces of equipment available to hospitals and opticians. It produces high-quality images allowing us to build up a very detailed picture of your eyes at each check-up. Should the scanner detect anything unusual we would pick this up at the earliest opportunity. Thereby enabling the necessary referrals to be done as quickly as possible.”

For our diabetic clients, the 3D OCT scan is a further check that goes beyond the standard retinal screening provided by some hospitals. As the 3D OCT scanner can look through the layers of the retina. It can detect problems much earlier than retinal photography.

What else can a 3D OCT Scan Show?

Some of our clients would benefit from a scan of their eye blood vessels (angiography). Our new 3D OCT scanner produces high-quality images of the layers of blood vessels and capillaries in the eye. This can be particularly useful for clients with Age-Related Macular Degeneration (AMD) or Diabetes. In fact, a 3D OCT scan can provide an early warning of AMD and this can help ensure timely treatment is given.

The 3D OCT is a non-invasive machine. Just like the retinal camera, you place your chin on a rest. Your Optometrist will then get you to look at a target where a scan will be taken of your eye in a matter of seconds (50,000 scans per second!) This allows the 3D OCT to map out all your retinal layers and your eyes hidden soft tissue. The results appear instantly and your Optometrist can show you and talk you through all the results.

A 3D OCT examination generally requires no eye-drops and is a completely painless procedure with no puffs of air or bright flashes of light.  But if all this technology sounds a little bit scary, don’t worry. We’ll take the time to answer any questions you may have and to explain why we recommend taking each test.

AMD and Macula Scans

At Allegro Optical Opticians in Meltham OCT scanner can detect Macula disease

Examination of the central area of the retina called the macula. This is the most delicate part of the eye and offers the most sensitive vision. With our 3D OCT eye scans, we can now examine macula in 3D and cross-section.

These are most important for:

  • Macular degeneration (AMD)
  • Macular dystrophy
  • Family history of macular disease
  • Diabetes
  • Short-sighted people
  • Any loss of vision
  • In cases of head or eye injuries 
  • Smokers
  • People with unexplained visual problems
  • People with flashes &/or floaters
  • Other retinal or macular disorders e.g. Epiretinal Membrane and macular hole

Optic Nerve Scans

These scans show us the optic disc which connects the eye to the vision processing centres in the brain. The Optic disc is vital for maintaining healthy vision. We can examine the optic disc 3D, cross-section and G-cell mapping (the earliest indicator of glaucoma)

Optic Disc scans are most important for:  Disorders 3D OCT Optic Nerve Scan

  • Glaucoma sufferers
  • People with a family history of glaucoma
  • Anyone with high eye pressures
  • People with neurological conditions e.g. MS
  • Optic nerve disease e.g. optic neuritis
  • Other optic nerve disorders e.g. Optic Disc Drusen
  • People complaining of headaches
  • People with unexpectedly poor vision

Cornea and Anterior Scans

These scans allow us to examine the cornea and measure corneal thickness and clarity, as well as the patency of the eye’s drainage channels.

These are most important for: OCT corneal scanning at Allegro Optical Opticians in Meltham

  • People who have closed-angle glaucoma
  • People with a family history of glaucoma
  • People with small eyes &/or who are long-sighted
  • People with a history of eye pain &/or headaches associated with blurry vision
  • People with high eye pressures
  • Contact lens wearers
  • Laser eye treatment – pre-surgery and post-surgery

Visual Reference & Measuring

3D OCT eye scans from Allegro Optical Opticians in MelthamWith 3D OCT scans any area of the eye that may appear unusual can be measured and later repeat scans can be lined up with the original so that any changes can be monitored as accurately as possible way.  The scans enable us to differentiate between wet and dry types of macular degeneration, which can help us when making referrals for treatment. Many eye conditions can also be diagnosed with 3D OCT Scans and of course, it can also confirm that all is well and the eye is healthy.

In summary, our new 3D OCT Scanner is very versatile and for the first time allows us to check the health of your eyes beneath the surface of your retina, giving the earliest possible indication of your eye’s health.  We believe this will greatly enhance our ability to look after your eye health and visual system.

To experience the very best in eye care for yourself, simply make an appointment for your eye test with us. You can drop into our practice in Meltham or phone us on 01484 907090 or book online here.  We look forward to welcoming you.