An OCT

I have been using optical coherence tomography (OCT) since October 2018. Working as a locum, in that time I have seen the popularity of it grow among most High Street opticians, where it is now often offered as standard in contrast to once only being accessible in hospital settings.

The most common OCT machine I have used in practice is the Nidek RS 330 model, but there are other brands, such as those made by Zeiss, Heidelberg and Topcon. OCT can also be used for the anterior segment.

Benefit for patients

The implementation of OCT has resulted in more detail being obtained from the back of the eye. Historically, the use of the digital retinal camera has been a great tool to help diagnose pathology. However, the downside to this has always been that only a 2D image can be obtained. OCT gives 3D images of the different layers of the back of the eye. This is a great advantage as many eye diseases begin beneath the surface. Thus, being able to give patients information and/or refer accordingly before symptoms develop is a huge step forward.

Patients are very impressed when they are shown an OCT image and realise the importance of having it conducted at regular sight tests. I find it helpful to describe the image as a layer of cake, explaining that the fundus photo is like looking at the top of the cake whilst the OCT scan is like slicing through the cake and being able to see all the different layers. This helps patients to better understand the scan.

Being able to give patients information and/or refer accordingly before symptoms develop is a huge step forward

A common condition we see in practise is posterior vitreous detachment (PVD). OCT has helped improve how we mange PVD by giving us more information. A complication of the condition can be macula involvement, and an OCT scan show if a PVD has had any of this. A vitreomacular traction (VMT) may occur if the vitreous pulls on the macula, this can then lead to macula complications. An OCT scan will show if there is VMT and if intervention, for example pars plana surgery, is required, or whether patients just need to be told of symptoms to watch out for.

Common conditions that I’ve found OCT particularly helpful in the management and diagnosis of include retinal detachments and tears, retinoschisis, age-related macular degeneration, glaucoma, papilledema, and epiretinal membrane.

An improved view

OCT, along with other diagnostic tools, helps build a far better picture of the health of the eyes. However, it is important to note that it does need to be used with other tests and not just as a standalone measure in order to be able to get the true picture of the ocular health, thus enabling correct management.

Having more information has helped detect early pathology, and knowledge and experience of OCT has helped improve referrals by giving more information to secondary care and also by managing more cases in primary care. This monitoring is far more accurate from being able to compare OCT scans from sight test to sight test. It has also provided more opportunity for interaction with patients, allowing practitioners to be able to discuss and inform them of changes and give the necessary advice.