How Jaheed Khan assesses you for age-related macular degeneration
In this series of blogs posts, which are based on short interviews (Ed: embed the youtube clip under this paragraph), Medical Retinal Expert Jaheed Khan describes the different types of AMD; including:
- the dry and the wet,
- how they present,
- what they look like,
- how they differ, and
- how we can treat them.
In this short interview, Jaheed Khan tells us about what he does at an Age-related Macular Degeneration assessment. Jane Olver: Jaheed how do you investigate age-related macular degeneration AMD? Jaheed Khan: The first thing to do with AMD is to take a history.
It is good to know what we are looking for and whether there are any family traits and what your symptoms are, but specific investigations in the clinic involve looking with a microscope and looking in detail at the anatomy of the retina or specifically the macula.
We like to take photographs so we can document the background changes that are present when you first come in, and we scan the back of the eye using scanning imaging looking at a cross-section.
One of the standard tests that we also use is your vision. We measure your vision on a chart where you are sat, and you read letters, and you may be familiar with that at the opticians. The problem with macular degeneration and the chart test is that sometimes you can use your side vision to see those letters, so it is not an accurate measurement.
JO: Macular degeneration just affects the central vision, so you have got quite good mobility. You were just telling us how to investigate and explaining that the central vision is affected and so the visual acuity, although it is a feature of macular degeneration, is not the primary thing?
JK: Absolutely. To accurately measure vision at an age-related macular degeneration assessment, you need to plot a field test which we do not routinely do because it is time-consuming and it is a little bit tiring for the patient. But, on the whole, the combination of all those tests; the photography, the direct visualisation of the macula using a microscope and a magnifying glass and a cross-sectional image can give us a lot of detail.
JO: What is the name of the test that does the cross-sectional imaging of the macula?
JK: So, that has revolutionised the way we look at the macula. That is called optical coherence tomography, and briefly, that involves using light reflectance so each layer of the retina reflects light differently and the rate of reflectance is made into an image which is projected on to a computer, and you can make a false image of the retina in cross-section.
JO: That is fantastic. You can see all the layers of the retina until what layer the macular degeneration is in and then that will lead you to know whether it needs treatment or whether you can treat it I suppose?
JK: Correct, first of all, it gives you an element of measuring how much is there and then you can monitor with treatment if needed.
JO: That is terrific, thank you Jaheed.