Macular degeneration and diabetic eye disease: why the exam comes before the symptoms
3 min readRand Eye Institute
The two most common reasons adults lose central vision in this country are macular degeneration and diabetic eye disease. Both do most of their damage before the patient notices anything, which is the single most important thing to understand about them.
What the retina is doing
The retina lines the back of the eye and converts light into the signal your brain reads as sight. The macula is the small central region that handles detail, faces, reading and the middle of everything you look at. It is supplied by some of the finest blood vessels in the body, and it does not tolerate leaking, swelling or a failing blood supply.
Macular degeneration, dry and wet
Age related macular degeneration comes in two forms. The dry form is far more common and progresses slowly as deposits build under the macula and the tissue thins. The wet form happens when abnormal blood vessels grow under the retina and leak fluid or blood, and it can change vision within days.
The warning sign patients report most often is distortion. Straight lines start to bend or wave. A door frame bows. Words on a page have a soft smudge sitting in the middle of them. If you cover one eye and the other shows you a bent world, that is not something to watch for a few weeks.
Diabetic eye disease is quieter still
High blood sugar damages the small vessels feeding the retina. They leak, they close off, and the retina responds by growing fragile new vessels that bleed. Swelling in the macula, called diabetic macular edema, is the most common way vision is lost.
Here is the part that costs people their sight: you can have significant diabetic retinopathy and still read the bottom line of the eye chart. Vision often stays normal until the damage is advanced. This is why every adult with diabetes needs a dilated eye exam on schedule, whether or not anything seems wrong. It is not a formality. It is the only way to catch it while it is still treatable.
What injections actually do
Anti VEGF injections are the mainstay for wet macular degeneration and for diabetic macular edema. They block the signal that drives abnormal vessels to grow and leak, which lets the retina dry out and settle.
Patients are usually more nervous about the injection than they need to be. The eye is numbed thoroughly first, the injection itself takes moments, and it is done in the office.
What matters more is the expectation. The main goal of treatment is to preserve the vision you still have and stop the disease from taking more. Many patients do gain some vision back, particularly when swelling comes down, but that is a hoped for bonus rather than a promise, and treatment is usually ongoing rather than a single visit. Catching it earlier is what widens the range of good outcomes.
What a retinal evaluation involves
We dilate the pupils and examine the retina directly, then image it. Optical coherence tomography gives a cross section of the macula and shows fluid and swelling layer by layer, in detail no exam alone can provide. Photographs give us a baseline to compare against at your next visit, which is often how progression is caught early.
When to call the same day
Some retinal symptoms are not appointments to schedule next month. Call us right away, or go to an emergency room, if you have sudden vision loss, a sudden shower of new floaters, flashes of light, or a shadow or curtain moving across your field of vision.
For everything else, the answer is the same and it is unglamorous. Get the dilated exam. Keep getting it. Vision that is protected early is vision you keep.
This article is general information about eye conditions and the procedures we perform. It is not medical advice, and it cannot tell you what is happening in your eyes. Only an examination can do that.