Seeing purple or violet spots usually means your eye and brain are working normally. The color often comes from the eye adjusting after bright light or pressure, not from anything actually in your eye. One kind of spot is worth acting on quickly, though, because it can come before a torn or detached retina.1PubMed. Symptoms related to posterior vitreous detachment and the risk of developing retinal tears: a systematic review The way the spots appear and behave matters more than their color.
Afterimages From Bright Light
The retina, the light-sensing layer at the back of the eye, uses cone cells to detect color. When bright light hits a patch of cones, they become less sensitive in proportion to how strongly they were stimulated.2PubMed Central. The non-opponent nature of colour afterimages That’s because part of the light-catching molecules in each cone have been used up and have to be renewed.3PubMed Central. The non-opponent nature of colour afterimages When you look away, that patch responds weakly to the color it just saw, so you see a spot of a different color.4bioRxiv. The Mechanisms Underlying Colour Afterimages A yellowish lamp or a green-tinted flash can therefore leave a purple or violet ghost. Ordinary moments can do it: staring at a bright window and then glancing at a dark wall, a close camera flash, or checking your phone in a dark room.
The spot stays in the same place in your vision when you move your eyes, and it fades within seconds to a minute or so. It needs no treatment.
To check, close your eyes. An afterimage often stays visible and may change color. Then blink and look at a white surface; the spot often changes shade. If it lasts many minutes, or keeps coming back without a light trigger, note it down for a doctor.
Staring at the sun can burn the retina. Sun damage leaves a lasting blind or blurry spot, not one that fades. Even during an eclipse, only proper eclipse glasses are safe; sunglasses are not.
Purple Spots From Rubbing or Pressing Your Eyes
Pressing on the eye stimulates retinal cells in much the same way light does.5Wikipedia. Phosphene So you see light and color in total darkness.6PubMed. On the history of deformation phosphenes and the idea of internal light generated in the eye for the purpose of vision People describe a colored patch that moves against the rubbing, bright circles near the pressure point, a shifting grid of light with dark spots, or a sprinkle of intense blue points.7Wikipedia. Phosphene The purple and blue swirls after rubbing tired eyes are a normal response.
The patch appears on the side opposite to where you press, because the retina maps the outside world in reverse. Pressure at the outer corner lights up the inner part of your view. Brief pressure from ordinary rubbing doesn’t harm the retina, and the pattern should vanish within seconds of letting go. Firm pressure on the eyeball is never a good idea, particularly with a recent eye injury or surgery.
Other everyday pressure triggers can do something similar. Standing up fast can cause brief sparkles as your blood pressure dips. A hard sneeze, cough or strain can produce quick flashes, and sleeping with an arm across your eye can leave colored patterns when you wake. All of these should stop within seconds once the pressure ends.
Frequent rubbing is still worth curbing. Rubbing itchy allergic eyes again and again can irritate the eye surface, and long-term heavy rubbing is linked to thinning of the clear front of the eye. Cool compresses or allergy drops help break the habit, and washing your hands first lowers the risk of infection. Flashes you can’t link to rubbing deserve attention; they may be the gel tugging on the retina, covered next.
Flashes and Floaters That Need a Same-Day Eye Exam
The eye is filled with a clear gel. With age it shrinks and pulls away from the retina. When it separates, the most common symptoms are flashes and floaters.8PubMed Central. Spontaneous posterior vitreous detachment: A glance at the current literature The flashes come from the gel tugging on the retina, and they’re often seen toward the outer side of vision.9PubMed Central. Spontaneous posterior vitreous detachment: A glance at the current literature Floaters look like dark lines, cobwebs or spots that drift.10PubMed Central. Spontaneous posterior vitreous detachment: A glance at the current literature But the gel pulling away also raises the risk of a retinal tear, detachment or bleeding inside the eye.11PubMed. Symptoms related to posterior vitreous detachment and the risk of developing retinal tears: a systematic review
When the separation causes symptoms, the chance of a retinal tear or detachment can be as high as 35%, and higher if there is bleeding.12PubMed Central. Spontaneous posterior vitreous detachment: A glance at the current literature Even people with only one or two new floaters developed a tear about 7 times in 100.13PubMed. Natural history of posterior vitreous detachment with early management as the premier line of defense against retinal detachment Some people with a detachment noticed only a few floaters and flashes for 2 to 3 weeks before losing part of their vision.14PubMed. Natural history of posterior vitreous detachment with early management as the premier line of defense against retinal detachment That window is a chance to treat a tear before it becomes a detachment. Sudden flashes or floaters call for a dilated eye exam the same day or next.15PubMed Central. A prospective evaluation of the clinical safety and effectiveness of a COVID-19 Urgent Eyecare Service across five areas in England
Flashes from the gel look like lightning streaks or stars, can last 10 to 20 minutes, and may come and go for weeks or months.16American Academy of Ophthalmology. What Are the Moving Dots I See When I Look at a Clear Blue Sky? Floaters lag behind eye movements and settle when the eye is still.17American Academy of Ophthalmology. What Are the Moving Dots I See When I Look at a Clear Blue Sky?
Some signs mean go to an eye emergency service or ER now: a curtain or shadow spreading from the edge of vision, a sudden shower of many new floaters, or blurred or lost central vision.
For a few new floaters or flashes with otherwise normal vision, call an eye doctor. Say plainly that you have new flashes or floaters; offices usually treat that wording as urgent. If they can’t see you within a day, or it’s evening or a weekend, go to an eye emergency service or hospital that can examine the back of the eye. Don’t wait for symptoms to settle first, because their fading doesn’t show the retina is safe.
At the exam, drops widen your pupils for 4 to 6 hours, so bring sunglasses and a driver. The doctor views the edges of the retina with a bright light and a lens. A tear can often be sealed with laser or freezing in the office. You may be asked to come back in a few weeks, since tears can appear later.
The gel pulling away is most common from the mid-50s onward. Severe nearsightedness raises the risk earlier, as do past cataract surgery or an eye injury. If one eye has had a detachment, the other needs watching.
Migraine Aura and Other Brain Causes
In a migraine aura, a slow wave of electrical change spreads across the brain’s vision area at the back of the head.18PubMed Central. Neuro-ophthalmology and migraine: visual aura and its neural basis You can see flashes and a shimmering zigzag blind spot.19PubMed Central. Neuro-ophthalmology and migraine: visual aura and its neural basis An aura usually builds over 5 to 20 minutes and lasts under an hour, often followed by headache. Because it comes from the brain, it appears in both eyes and is still there with your eyes closed.
Many people first notice a small shimmering spot near the center of vision that slowly grows into a C-shaped arc with a glittering zigzag edge. The arc moves steadily toward the side over several minutes, and the area behind the edge may be blurred or missing. Colors, including purple, can appear in the shimmering edge, which is why aura is a common answer to unexplained colored spots.
To tell an aura from a retinal flash, cover each eye in turn: an aura shows in both, a retinal flash in one. An aura drifts and grows across vision, while retinal flashes are brief streaks. Retinal flashes often come with new floaters; auras usually don’t. A first-ever aura after 50 should be checked by a doctor.
If an aura starts while you’re driving, pull over and wait until it clears. Keep a diary of triggers such as poor sleep or skipped meals. An aura can happen without any headache, and that’s still worth mentioning to a doctor.
Visual snow means seeing constant, countless flickering dots across the whole field of vision, like TV static.20PubMed. Visual Snow Syndrome: Proposed Criteria, Clinical Implications, and Pathophysiology People with it often have other symptoms such as afterimages or light sensitivity.21PubMed. Visual Snow Syndrome: Proposed Criteria, Clinical Implications, and Pathophysiology The brain’s vision areas appear overly excitable and slow to tune out repeated signals.22PubMed Central. Visual Snow Syndrome as a Network Disorder: A Systematic Review Normal eye exams don’t rule it out, and a neurologist or neuro-ophthalmologist is the right specialist.
A stroke in the vision area at the back of the brain can cause vivid visual hallucinations.23Ovid / Neurology. Vivid visual hallucinations from occipital lobe infarction Sudden visual changes with weakness, slurred speech or confusion need emergency care.
Medicines That Tint Your Vision
Sildenafil (Viagra) at higher doses can cause colored or blue-tinged vision and light sensitivity.24PubMed Central. Ocular safety of sildenafil citrate when administered chronically for pulmonary arterial hypertension: results from phase III, randomised, double masked, placebo controlled trial and open label extension Vardenafil (Levitra) can briefly impair telling apart blues, greens and purples, most within an hour of a dose.25PubMed Central. Ocular side effects of Levitra® (vardenafil) – results of a double-blind crossover study in healthy male subjects These eye effects are uncommon at usual doses.26PubMed Central. Ocular safety of sildenafil citrate when administered chronically for pulmonary arterial hypertension: results from phase III, randomised, double masked, placebo controlled trial and open label extension
The reason is chemical. Sildenafil and vardenafil block an enzyme, and a closely related enzyme helps the retina’s light-sensing cells respond to light. At higher blood levels the drugs also partly block that retinal enzyme, which alters how the cones respond and shifts colors toward blue. So the tint tends to arrive when the drug level peaks, roughly an hour or so after a dose, and fades as the level falls. Taking more than prescribed raises the chance and strength of the tint.
Note the timing between doses and spots. Don’t stop a prescribed medicine without asking the prescriber. Sudden loss of vision after these drugs is an emergency. Bring a full list of your medicines to any eye exam.
Some long-term medicines need eye checks. Hydroxychloroquine, used for lupus and arthritis, can slowly damage the retina, and regular screening catches it before you notice symptoms. Hydroxychloroquine damage can show on a detailed retinal scan when a regular eye exam looks normal.27PubMed Central. Spectral domain optical coherence tomography as an effective screening test for hydroxychloroquine retinopathy (the “flying saucer” sign) Screening works best with both the scan and a field test.28PubMed. Disparity between visual fields and optical coherence tomography in hydroxychloroquine retinopathy29PubMed. Disparity between visual fields and optical coherence tomography in hydroxychloroquine retinopathy
Eye Diseases That Change Color Vision
Glaucoma and age-related macular degeneration both change how the eye handles color and brightness.30American journal of optometry and physiological optic. Chromatic and Luminosity Processing in Retinal Disease Central serous chorioretinopathy, fluid under the center of the retina, mostly dulls the blue-sensing pathway.31American journal of optometry and physiological optic. Chromatic and Luminosity Processing in Retinal Disease A fixed blurry, dim or distorted spot in central vision needs an eye exam within days.
A spot from disease stays in the same place and doesn’t fade in seconds the way an afterimage does. It’s usually present when you look at a plain background with one eye covered, and doesn’t depend on a bright light beforehand. Straight lines such as door frames or text may look bent, or colors may look washed out in that eye compared with the other.
A simple check at home: cover one eye and look at a grid or door frame. Wavy, missing or dim areas are a reason to book a visit. Test each eye separately, since one good eye can hide the other’s problem.
Harmless Moving Dots Against a Blue Sky
The tiny darting dots you see against a clear blue sky are a normal effect of a healthy eye.32American Academy of Ophthalmology. What Are the Moving Dots I See When I Look at a Clear Blue Sky? They are white blood cells passing through tiny vessels in front of the retina. The dots are all the same size and shape and keep zipping around when your eye stops moving.33American Academy of Ophthalmology. What Are the Moving Dots I See When I Look at a Clear Blue Sky? Floaters, by contrast, vary in size and settle when the eye is still.34Good Vision For Life. What on earth is the Blue Field Entoptic Phenomenon and how does it differ from eye floaters and flashes? Dots that behave like this need no exam on their own.
To check which you’re seeing, look at a blue sky or white screen and hold your gaze still. Tiny dots that dart along quick paths, sometimes in time with your heartbeat, are blood cells. Shapes that slowly sink and drift back are floaters. New floaters still follow the urgent advice above.