The retina has no pain receptors. Nothing back there hurts, which means nothing back there warns you. A tear can open at the outer edge of your retina and you will feel absolutely nothing, until fluid works its way underneath it and a grey curtain starts sliding across your vision. By that point you are in an emergency, and how much sight you keep depends largely on how fast you get to a surgeon.
That silence is the problem with almost every sight-threatening condition. Glaucoma erodes peripheral vision so gradually that the brain paints over the missing patches, and people routinely fail their first visual field test without having suspected a thing. Early diabetic changes cause no blur at all. A choroidal naevus, the retinal equivalent of a mole, can sit quietly for a decade and then start behaving badly.
Since your eyes won’t tell you, the eye examination has to do the noticing on your behalf. Which raises a fair question: how much of your retina can your optometrist actually see?
The blind spot in a standard eye examination
Through a direct ophthalmoscope, an optometrist looks into the back of the eye a small illuminated patch at a time, through a pupil about the width of a pencil. It works, and it has caught retinal disease for over a century. But it is slow, it relies on you holding still with your eye wide open, and the further out towards the edge of the retina you try to go, the harder that view is to hold.
Retinal cameras improved matters. Most capture somewhere between 30 and 45 degrees, centred on the optic nerve and the macula. That covers the part of the eye responsible for the vision you use to read and to recognise faces, which is why it became the standard. It also means the outer retina falls outside the frame. And the outer retina is exactly where retinal tears, lattice degeneration and a good number of early diabetic lesions prefer to appear.
You can reach it with dilating drops and a careful indirect examination, and plenty of practices still do. But the drops take twenty minutes to work, leave your near vision blurred for hours, make daylight uncomfortable and rule out driving home. A lot of people politely decline, then book their next eye test somewhere that doesn’t ask.
What the Optos Daytona does differently
The Daytona captures up to 200 degrees of the retina in one go, roughly 82% of its surface, in under half a second. No drops, for the vast majority of people. You put your chin on the rest, look at a target, and it’s done before you’ve really registered that it started.
The reason it can see so much through an undilated pupil comes down to optics rather than brute force. Instead of shining a wide flash into the eye and hoping, the Daytona uses a scanning laser and a curved mirror that effectively places its focal point inside the eye. Think of standing outside a room and trying to see through the keyhole. Press your eye right up to it and the room opens out; stand back and you see a slice of carpet. Daytona is doing something similar with the pupil.
It scans with two laser wavelengths, red and green, and this is the part that tends to get glossed over in marketing copy even though it’s clinically the most interesting bit. Green light is picked up by the surface layers, from the sensory retina down to the pigment epithelium. Red light travels deeper, into the choroid underneath. The colour image you’re shown on screen is the two combined, but your optometrist can pull the channels apart and work out roughly what depth a lesion is sitting at. A pigmented spot that shows up strongly in the red channel is behaving differently from one that only appears in the green, and that distinction changes what happens next.
Why the machine was designed this way
Optos was founded in Scotland by Douglas Anderson, after his five-year-old son lost the sight in one eye to a retinal detachment that a routine eye test hadn’t picked up. The detachment was in the periphery. His son, like most five-year-olds, was never going to sit patiently through a long dilated examination.
Anderson was an engineer, so he went away and built a machine that could photograph the far retina in a fraction of a second through an undilated pupil, because that was the only sort of machine a child would actually tolerate.
You can still read that brief in the hardware. Get the widest view available, and get it before the patient has time to blink.
The conditions a widefield scan helps catch sooner
- Retinal tears and detachments, which almost always begin in the periphery. Catching a tear before the retina lifts is the difference between a laser appointment and a trip to theatre.
- Lattice degeneration and peripheral thinning, common in short-sighted people. Knowing it’s there changes how urgently anyone treats a sudden shower of floaters.
- Diabetic retinopathy. Haemorrhages and other lesions often appear out in the periphery alongside, or before, the changes near the macula, so a wide view gives a truer sense of how active the disease is.
- Age-related macular degeneration, where early drusen and pigment changes turn up at a stage when monitoring and lifestyle changes still count for something.
- Glaucoma. The scan takes in the optic disc, so cupping and asymmetry between the two nerves are visible and, more usefully, comparable year on year.
- Retinal vein and artery occlusions, and hypertensive changes, which are sometimes the first physical evidence that someone’s blood pressure or cardiovascular risk isn’t under control.
- Choroidal naevi. Harmless freckles, right up until the rare one that isn’t. Photographing them is the only sensible way to know whether one has grown.
- Signs of conditions that have nothing to do with the eyes, such as swelling of the optic nerve from raised pressure inside the skull. That is a finding you would far rather have picked up during a Tuesday afternoon eye test than in A&E.
Today’s image is really for the appointment two years from now
This is the argument for widefield imaging that gets the least airtime, and I think it’s the strongest one.
A single retinal image is a snapshot. It shows your optometrist what your retina looks like today. What it cannot tell them, on its own, is whether that flat brown patch near the equator of your eye has been sitting there harmlessly since you were twenty, or whether it has quietly doubled in size since you were last in.
Two images taken two years apart answer that question in about four seconds of side-by-side comparison.
Change is the signal. That’s true of naevi, of subtle diabetic progression, of early glaucomatous cupping, of almost everything worth catching early. And a baseline image is the only thing that makes change visible. It also means that when you do get referred to the hospital eye service, the ophthalmologist isn’t reading a letter describing what your optometrist saw. They get the picture, and often the picture from two years ago sitting next to it.
If you take one thing from this article, take that. Get the first scan done. It’s the one that makes every scan after it worth something.
Where it sits alongside OCT and a dilated examination
The Daytona is an excellent map. It is not a cross-section, and it doesn’t replace every other part of an eye examination.
An OCT scan does the opposite job. It takes a narrow slice and shows the retinal layers in depth, finely enough to spot fluid collecting under the macula before you notice any distortion in your vision. Breadth and depth answer different questions, and you want both. When the optomap flags something suspicious at the macula, the OCT is usually the next thing switched on.
There are honest limits worth knowing about. The optomap image is a flat projection of a curved surface, so elevation is hard to judge. A shallow detachment or a swollen optic disc can look unremarkable in two dimensions. When something looks wrong, or when your symptoms suggest a tear, there is still no substitute for dilating the pupil and examining the eye in three dimensions, sometimes with scleral indentation to bring the very furthest edge of the retina into view. Image quality also suffers with a dense cataract, a droopy eyelid, very small pupils, or an eye that simply won’t stay open.
One more thing, specific to the UK. If you’re diabetic, an optomap at your opticians does not replace your NHS Diabetic Eye Screening appointment. It’s a useful complement, and it can pick up changes between screening visits, but the national programme is a separate service and you should still attend it.
None of that makes the machine less valuable. It just means the machine finds things and a trained optometrist decides what they mean. The imaging is only ever as good as the person reading it.
When not to wait for your next appointment
Routine scans are for the silent problems. The following are not silent, and none of them should wait for a scheduled eye test.
- A sudden increase in floaters, particularly a shower of new black specks
- Flashes of light in your side vision, especially noticeable in a dark room
- A shadow or curtain moving in from the edge of your vision
- Sudden loss or distortion of vision in one eye, even if it settles again
- A painful red eye with blurred vision
Any of these needs same-day contact with an optometrist, an urgent eye care service or an eye casualty department. A retinal tear treated within days is a laser procedure. Left alone, it becomes surgery, and how much vision you recover depends on whether the macula has come away by the time you’re on the table.
What it all adds up to
Most people book an eye test because their glasses have stopped doing their job. The prescription is why they come in. The retinal scan is why it mattered that they came in at all.
The Daytona’s contribution is a practical one. It makes examining the far retina quick and painless enough that it actually happens, rather than being the thing everyone agrees would be a good idea and then skips because of the drops. Do it at every visit and you slowly build the only asset early detection really runs on, which is a record of what your retina looked like back when nothing was wrong with it.
Software that flags suspicious areas on widefield images is already being paired with this kind of imaging, and it will make year-on-year comparison quicker still. None of that helps anyone who isn’t in the chair, though. The gap between eye tests is where most late diagnoses are quietly made.
So book the test. And when they offer you the scan, say yes, even if nothing feels wrong. Especially if nothing feels wrong.
Frequently asked questions
Do I need dilating drops for an optomap scan?
Usually not. The Daytona is built to image through an undilated pupil, which is why the whole thing takes a couple of minutes and you can drive home straight afterwards. Your optometrist may still suggest drops if the image quality is poor or if they’ve spotted something they want to look at in three dimensions.
Does an optomap scan replace NHS diabetic eye screening?
No. The NHS Diabetic Eye Screening Programme is a separate service and you should keep going to your appointments. A widefield scan at your opticians adds to it, particularly for catching peripheral changes between screening visits, but it isn’t a substitute for the national programme.
How often should I have a widefield retinal scan?
For most adults, at every routine eye examination, which in the UK usually means every two years. Yearly is more appropriate if you’re diabetic, very short-sighted, over 60, have a family history of glaucoma or retinal detachment, or have a naevus or similar finding being monitored. Your optometrist will tell you which group you fall into.
Can the Optos Daytona detect glaucoma?
It can show the signs. The scan images the optic nerve head, so cupping, asymmetry between the eyes and changes over time all show up. Diagnosis takes more than one test, though. Eye pressure, visual field testing and usually an OCT scan of the nerve fibre layer all feed into it. The optomap contributes to the picture rather than settling it.
Is the scan safe, and can children have it?
Yes. The lasers are low-powered, nothing touches the eye and there’s no radiation involved. Children often cope with it well precisely because it’s so quick, which makes it a sensible option for any child who would struggle with a long dilated examination.
