Retinal imaging creates a detailed image of the back of the eye, including the retina, macula, optic disc, and retinal blood vessels. These images help eye care professionals document what they see, compare changes over time, and identify findings that may need further evaluation.
The changes can be very small. Maybe there is a tiny red spot, a few yellow marks, or a blood vessel that looks different from before. If there is an older photo, the doctor can put the two together and see what has changed.
This article mainly looks at color fundus photography. If the image does not give enough detail, the doctor may also use OCT, dilate the pupil for a wider view, look back at earlier images, or do another eye test.
What Does Retinal Imaging Show?
A color fundus photo is a picture of the back of the eye. In a clear photo, you can usually see the optic disc, macula and blood vessels. Some cameras can also show more of the retina around the edges.
A retinal photo can show all kinds of small changes. Sometimes it is a tiny bleed. Other times there may be yellow spots near the macula or something around the optic disc that looks different. The blood vessels can look different too — a little narrower, wider, or more twisted than before.
| Area | What may be visible |
|---|---|
| Optic disc | Disc shape and color, cupping, asymmetry or swelling |
| Macula | Drusen, pigment changes, hemorrhage or other abnormalities |
| Retinal blood vessels | Narrowing, dilation, tortuosity or hemorrhage |
| Retina | Exudates, cotton-wool spots, pigment changes and other lesions |
| Peripheral retina | Some peripheral abnormalities, depending on field of view |
An ophthalmoscope lets the doctor look at the retina during the exam. A fundus photo is different because it stays in the record. Months later, the doctor can open the old photo and see if anything has changed.
What Doctors May Notice in a Retinal Photo
One small spot by itself may not say much. The same is true for yellow deposits or a blood vessel that looks a little unusual. The doctor usually looks at the whole picture and compares it with older photos when there are any.
Diabetic Retinopathy
At first, diabetic retinopathy may only show up as a few tiny red dots or small bleeds. There can also be yellow deposits or pale spots. As it gets worse, new blood vessels may grow and bleed.
The person may not notice any change in vision yet. That is one reason doctors take retinal photos during diabetic eye checks. Older photos can also help show whether anything is new.
A color photo can miss swelling in the macula. If fluid is the concern, OCT usually shows it better.
Age-Related Macular Degeneration
AMD often shows up around the macula. In the photo, there may be yellow spots, uneven color, or parts of the retina that look a little thin.
Wet AMD can also cause bleeding in this area. If the doctor thinks there may be fluid under the retina, they will usually check it with OCT.
Glaucoma
For glaucoma, the doctor pays a lot of attention to the optic nerve. The middle may look larger than before, or the rim around it may look thinner.
It is not always obvious from one photo. Looking back at an older image can help. The doctor may also check eye pressure, do OCT, or run a visual field test.
Retinal Vascular Changes
The blood vessels may look different too. Some become narrower, wider, or more twisted. Small bleeds can also appear.
High blood pressure can cause changes like these. A blocked vein in the retina can cause more bleeding and make the veins look fuller.
Retinal Tears and Retinal Detachment
A retinal tear can be missed if it is too far out near the edge of the retina.
A regular fundus photo only catches part of the retina. If the doctor thinks there may be a tear or detachment farther out, they may still dilate the eye and check that area directly, even after a widefield photo.
Can Retinal Imaging Show Signs of Health Problems Outside the Eye?
Sometimes the retina shows changes that are not just about the eye. Diabetes and high blood pressure can change the blood vessels there. A swollen optic disc can also show up in a retinal photo.
The photo cannot tell the doctor exactly why it happened. A bleed, a narrow vessel, or a swollen disc has to be looked at together with the patient’s symptoms and the rest of the exam. Sometimes the photo simply shows that something needs a second look.
What Is Retinal Imaging Used For?
Retinal photos are not only taken when something looks wrong. They are also used for screening. Diabetic eye checks are a common example. The photos can be reviewed for changes that may need another visit or a referral. They can also be saved as a starting point for future exams.
An old photo can be very useful later. Putting it next to a new one makes small changes much easier to notice, especially around the optic nerve or macula.
The person taking the picture does not always have to read it. A technician may take the photo, and a doctor can review it later. The image can also be sent to a specialist if another opinion is needed.
What Can Retinal Imaging Miss?
Retinal imaging can show a lot, but the camera does not see every part of the retina. A regular fundus photo may miss areas near the outer edge. Widefield cameras show more, but they still do not replace a dilated eye exam in every case.
The photo also needs to be clear. Small pupils, cataracts, eye movement, eyelashes, glare, or bad focus can all get in the way. If part of the retina is blurry or missing, the picture may need to be taken again.
A fundus photo and OCT also show different things. A fundus photo is a flat color picture. OCT shows the layers of the retina and is better for things like fluid or swelling. That is why both tests may be used at the same visit.
Sometimes the photo only tells the doctor where to look next. If the optic nerve looks unusual, they may check eye pressure or do OCT. If the problem may be farther out in the retina, they may dilate the eye and look again.
What Happens If a Retinal Image Looks Abnormal?
If the new photo looks a little different, the doctor may pull up an old one first. Sometimes the spot was already there. Sometimes it really is new, like a fresh bleed.
What happens next depends on what they see. They may just keep an eye on it for now. Or they may do another test, dilate the eye, or send the patient to a specialist.
References
- Retinal Imaging — Cleveland Clinic.
- Fundus Camera — StatPearls, NCBI Bookshelf.
- The Ultimate Guide to Identifying Retinal Disease on Fundus Photography — Eyes On Eyecare.
- Fundoscopic Exam (Ophthalmoscopy) — Stanford Medicine 25.
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