You have probably noticed, more than once, small moving shadows in your field of vision when looking at a white wall, a clear sky or a computer screen. They look like black dots, threads, cobwebs or little strings that drift when you move your eye and seem to “run away” when you try to look straight at them.
This phenomenon, known scientifically as myodesopsia and popularly as “floaters”, is one of the most common reasons for visiting an ophthalmologist. Although in the vast majority of cases it is a benign process associated with the natural ageing of the eye, it can sometimes be the first symptom of a more serious problem in the retina. At Clínica Ramírez & Gálvez, we explain what happens inside your eye when you see these shadows and how to tell a harmless nuisance from a medical warning sign.
What exactly are “floaters”? 🧐
To understand why these floating shapes appear, we need to look inside the eyeball. The space between the lens and the retina is filled with a transparent, viscous, jelly-like substance called the vitreous humour. This gel is made up mainly of water and collagen fibres, which give it its consistency.
In youth, the vitreous humour is perfectly uniform and transparent. However, over the years or as a result of myopia, this gel undergoes a natural process of degeneration and liquefaction:
- Collagen condensation: The collagen fibres in the vitreous gel clump together and form microscopic lumps or strands inside it.
- Shadows cast on the retina: Light entering the eye passes through the vitreous humour and strikes these small clumps of fibres, casting their shadow onto the retina. What we actually see is not an external object, but the shadow of these internal condensations on the light-sensitive tissue of the eye.
- Inertial movement: When you move your eye, the vitreous gel shifts by inertia, making floaters seem to float and drift slowly across your field of vision.
Flashes of light (phosphenes): the pull on the retina 💡
In many cases, floaters are accompanied by flashes of light, sparks or lightning streaks in peripheral vision, especially noticeable in dark surroundings. This phenomenon is called phosphenes and has a purely mechanical cause.
As the vitreous humour liquefies, it tends to shrink and gradually separate from the surface of the retina to which it is attached. This process is known as Posterior Vitreous Detachment (PVD).
When the vitreous gel detaches, it can exert some traction, or “tugging”, on the retina. The retina has no pain receptors, so it responds to any physical or mechanical stimulation by sending electrical impulses to the brain in the form of flashes of light.
Warning symptoms: when should you seek urgent care? ⚠️
Although posterior vitreous detachment is a common physiological event that most people will experience during their lifetime, the traction of the vitreous on the retina carries a real risk: if the attachment is very strong, the pull can cause a retinal tear or break.
If a tear is not treated in time, fluid in the eye can seep through the break and separate the retina from the back of the eye, triggering a Retinal Detachment, a serious medical emergency that can cause irreversible damage to your sight.
You should have an eye examination with pupil dilation immediately if you notice any of the following warning signs:
- Sudden, massive onset: Suddenly noticing a large number of new floaters or a “shower of soot/black dots” from one day to the next.
- Increase in the frequency of flashes: Continuous, frequent or intense flashes of light (phosphenes) in a specific area of the eye.
- A shadow or dark curtain: The feeling that a fixed spot or a “black curtain” is advancing from the edge of your vision and covering part of your visual field.
- Sudden loss of sharpness: An abrupt drop in visual acuity.
Risk factors that call for closer monitoring 🔬
Although anyone can develop floaters or a retinal detachment, some people need closer monitoring of their retinal health:
- Patients with high myopia: Short-sighted eyes are anatomically longer than normal, which makes the retina thinner and more stretched, increasing the risk of tears.
- History of eye injuries: Direct blows to the eye or head.
- Previous eye surgery: Patients who have had cataract surgery or operations for other intraocular conditions.
- Family history: A direct family history of retinal detachment.
Diagnosis and prevention in Lucena and Torre del Mar 🏥
Floaters cannot be diagnosed with a simple sight test. To assess their cause properly, a dilated fundus examination is essential.
At both our Lucena and Torre del Mar clinics, our team of ophthalmic surgeons uses high-resolution ophthalmoscopy and peripheral examination lenses to examine every last corner of your retina in detail.
If the examination reveals a tear or an early break in the retina before a detachment occurs, we can “seal” it quickly on an outpatient basis using argon laser photocoagulation, avoiding more serious complications and protecting your vision for good.
Knowing your body’s symptoms and acting quickly on warning signs is the best strategy for looking after your retina.
Have you noticed a sudden increase in floaters, or do you see flashes of light when you move your eyes?
Don’t ignore it. Book your fundus check-up at our clinics in Lucena or Torre del Mar and protect the health of your retina! 📅✨