Am I Imagining Worms Floating in my Vision?
Most individuals over the age of 50 to 60 years would have noticed strange shapes floating in their vision from time to time. These may take on a bewildering array of shapes, sizes and forms, and appear as tiny spots, dust, flies or mosquitoes, tangle of threads, filaments, a blob of an amoeba, worms, strands of hair, cobwebs, or even a ring!
This is in fact perfectly normal, and a natural part of getting a bit older. So you are definitely not imagining things, and these images are caused by actual changes called “vitreous floaters” which are truly there, constantly drifting about inside your eyes.
Individuals who are quite short-sighted are at higher risk for early development of vitreous degeneration and thus can experience an earlier onset of floaters, e.g. in their 30s or 40s.
This risk relates to the intrinsic length of the eyeball, i.e. the more short-sighted previously, the longer the eyeball, and the earlier vitreous degeneration occurs. The risk for early vitreous floaters in individuals who were previously highly short-sighted is not reduced by having had laser vision correction (e.g. ReLEX SMILE, LASIK, or PRK), as these procedures alter only the front part of the eye (i.e. the cornea).
What are Floaters?
To understand where floaters come from, a little understanding of the structure of the eye is important!
A layer of light-sensitive cells lining the back of the wall of the eye is called the retina. Think of this as the film in a camera. When the nerve cells that form the retina become excited by light, they transmit signals to the brain to tell you what you’re seeing. Between the lens and the retina is the vitreous gel, which is a gel-like substance that fills this space and is also firmly stuck to the retina.
Floaters occur when the collagen in the vitreous gel starts to break down as we get older, usually starting around the ages of 50 to 60 years. Medically, we call this “vitreous degeneration”. When you are born, the vitreous gel is very firm, but as you get older, the jelly softens and parts of the jelly become softer or more liquid. Think of it as agar-agar becoming Jell-o. The collagen in the vitreous begins to change, becoming thicker and forming clumps, like debris suspended in fluid.
When you move your eye about, these clumps move around and catch the light, much like how snowflakes in an ornamental snow globe behave when the globe is shaken hard. The movement of these clumps casts little shadows on the retina, giving rise to what we perceive as “floaters”.
Are There Other Medical Causes of Floaters?
Whilst vitreous degeneration is the most common cause, there are sometimes less common but still important causes. These include:
- A vitreous hemorrhage, which is bleeding into the vitreous cavity. Here, blood cells, instead of collagen debris, are dispersed in the vitreous cavity. This is most commonly caused by advanced diabetic eye disease, but can be caused by any diseases affecting the blood vessels in the retina.
- Uveitis, which is essentially inflammatory eye disease. Inflammatory cells which float around in the vitreous gel account for the visual sensation of floaters. There are many subtypes of uveitis, and further assessment and examination by your ophthalmologist is important to ensure that you receive appropriate advice, monitoring, and treatment.
What do Floaters Look Like?
- Floaters come in various forms, shapes and sizes
As mentioned, they might appear as little black dots moving across your vision, wafting in and out of view. Or they may appear as hair-like forms, worms, strings or ropes, or even small fly-like insects. In fact, different individuals experience floaters differently.
- Floaters may appear in and disappear out of your vision
They are sometimes not immediately apparent, appearing when your eye moves, but then appearing to slow down as your eyeball stops moving. However, when you shift your glance, they may then reappear again. So the symptoms are usually transient.
- Floaters are also usually more noticeable when viewed against a light or uniform background, for example computer screens or a clear sky, or when you gaze out to sea. So people in certain jobs, for instance, those who do a lot of computer work, may notice them more than usual. In Singapore, where there is a lot of daylight, floaters are quite commonly perceived.
Are Floaters Harmful and Do They Signal Any Problem with the Eye?
Floaters per se do not harm the well-being of your eyes, being part and parcel of the normal aging process in the eye. In the majority of cases, there are usually no other eye problems.
When floaters first develop, they usually cause some degree of annoyance because they interfere with the quality of vision. So for instance, if you were reading the newspapers or using the computer, a clump of floaters may suddenly drift into view and obscure your vision transiently.
Although the vitreous gel degeneration is a slow process that can take months or years, the final stage of this process is that the back layer of the vitreous gel peels away and separates from the retina, a process which we call a posterior vitreous detachment. A posterior vitreous detachment is very different from plain vitreous degeneration because when it happens, the risk of a retinal tear is much higher, due to the tugging effect of the separating gel from the retina at this point in time.
When this happens, floaters develop all of a sudden, or the individual experiences a very rapid increase in the number of floaters. The important feature that differentiates this from pure vitreous degeneration is that there are numerous floaters (i.e. a “shower of floaters”), and this is always accompanied by persisting flashing lights. The extent of floaters can be so significant that it appears as a dense fog, or as if you are in a room full of smoke.
You need to be aware that this is a medical emergency, and it is absolutely essential that you see an eye doctor for an examination of your retina as soon as possible.
A retinal tear caused by a posterior vitreous detachment can be treated with laser in a fairly straightforward clinic procedure. However, if a retinal tear in this situation is left untreated, for even more than a few hours, it can quickly progress to a retinal detachment, for which retinal reattachment surgery is then required.
Now, having a posterior vitreous detachment does not always mean that a retinal tear is present, as the gel may peel away from the retina without causing a tear, but an eye examination is still absolutely essential to make sure that this is the case!
Will Floaters Go Away?
Floaters are usually visible only for a short period of time before the brain filters out the floater images. That is not to say that the floaters have physically disappeared – they are still there – but after a while, the brain trains itself to understand that the floaters are insignificant, and the floaters will begin to fade, except in certain situations, e.g. bright lighting conditions, or against a light uniform-shade background, when they become visible again.
Thus, over time, most individuals actually get less annoyance with the floaters.
A second reason why we perceive floaters less over time is specific to the case of posterior vitreous detachments. When the vitreous separation is complete, the gel moves further away from the retina. Thus the light-scattering effect, and the shadows cast onto the retina, becomes less!
Do Floaters Need to Be Treated?
As most vitreous floaters are transient, and most individuals will understand that the symptoms, if any, are transient and eventually learn to manage their perception of them, most patients with floaters do not have symptoms so troubling that they need treatment.
There are also individuals in whom the floaters may be significantly more troublesome, because the debris are located nearer the retina and cast more defined shadows onto it.
There is certainly a degree of psychological stress that floaters can cause, especially in individuals with vision-demanding tasks in their occupations. These may include anyone from office workers who constantly need to use the computer, to drivers, to musicians, or individuals in potentially high-risk occupations, e.g. site engineers.
What Treatments are Available for Vitreous Floaters?
There are numerous suggestions on getting rid of vitreous floaters, including relaxation techniques such as yoga and meditation. Whilst these may help with managing the psychological impact of floaters, physical reduction or removal of floaters is only possible with medical treatment.
The medical treatment options are:
- YAG Laser Vitreolysis
The YAG laser vitreolysis procedure involves a disruptive laser which is directed at a large floater particle, delivering enough energy to fragment the floater into little bits. Very often, the little bits become dispersed, and patients can still be symptomatic from the procedure.
So while some patients may indeed have improved symptoms, on average, the outcomes with this procedure can be somewhat unpredictable, and more than 1 treatment session may be needed. Also, the large amount of energy introduced into the eye in a fairly unregulated manner can potentially cause retinal damage.
- Vitrectomy Surgery
The surgical treatment of floaters is known as vitrectomy (sometimes nicknamed “floaterectomy”). Vitrectomy is a commonly-performed surgical procedure, but usually for other reasons, i.e. to reattach a detached retina, or remove membranes on the retina, rather than to remove floaters per se. It is essentially a micro-incision surgical procedure performed under local anesthesia. It is an outpatient procedure that usually takes less than 1 hour. The retinal surgeon will remove the vitreous gel completely, and along with it all the floater debris. The efficacy of this procedure to remove floaters is undoubted, and patients will have complete eradication of floaters after the procedure.
The main consideration in deciding whether a patient should undergo this procedure, is that there lies a 3-5%, i.e., small but not negligible risk of causing visual complications, which cannot be eventually corrected with glasses. Most important amongst these complications are retinal detachments arising from retinal tears caused by the vitrectomy procedure. Retinal detachments are sight-threatening and will require surgery to reattach the retina.
In patients who have not yet had cataract surgery, a vitrectomy will also accelerate cataract development, and so patients would need to accept that cataract surgery might be needed at some point in the near future.
Floaters, whilst a common symptom, require a thorough eye examination by an ophthalmologist to ensure that you do not have retinal tears or other more sinister eye conditions, as some of these can be treated.
About the Author
Dr Errol Chan is one of the few Ophthalmologists in Singapore with an international experience caring for patients with complex eye diseases, having practised at some of the most prestigious eye centers in the world. To date, he has performed thousands of cataract and vitreoretinal surgery procedures.
His practice centers on all aspects of general and emergency ophthalmology, with special expertise in cataract surgery, the medical and surgical treatment of retinal diseases, and uveitis. Dr Chan’s meticulous approach emphasizes quality care, safety, honesty, and empathy. His personal ethos is to provide the most appropriate treatment for every patient to achieve the best possible vision.
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