Floaters – Myodesopsia
“I see black or dark spots moving around,” “I see floaters,” “like hairs or filaments following my gaze…” The perception of floaters in the visual field (myodesopsia) is one of the most frequent reasons for consulting an ophthalmologist! Some people have lived with them for a long time, with them appearing intermittently, while others discover them suddenly one morning upon waking, manifesting in one eye or both… raising the same anxiety-inducing questions for the patient: What is it? Is it serious? Will I get better or lose my sight? This article aims to provide you with clear and reassuring answers.
What is this ?
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The vitreous body is a transparent gel composed of water, collagen, and hyaluronic acid. It fills 80% of the eye's volume.
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It is positioned between the lens in front and the retina behind, attaching at several points: from the lens capsule, to the retinal vessels, to the optic nerve and to the macula.
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The components of vitreous gel are arranged in a homogeneous and regular manner, which gives the vitreous body its transparency.
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Any disruption to this rigorous architecture will lead to the appearance of irregularities, and therefore localized areas of loss of transparency in the glass.
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These vitreous opacities will then be perceived by the patient as moving shadows in their field of vision.
Is it serious?
The occurrence of vitreous floaters is a normal phenomenon, since the vitreous body is bound to degenerate with age.
However, three diagnoses must be distinguished:
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Simple vitreous degeneration – the most common and benign cause. The patient, often young, one day notices floaters by chance while looking at a white or brightly lit surface. They appear as filaments or small transparent dots. They move in the same direction as their eyes, with a certain inertia. These manifestations are most often bilateral, and the floaters are not constantly visible.
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Posterior vitreous detachment – This often occurs around age 50 or slightly earlier in nearsighted patients. It manifests as the sudden appearance of large, opaque, often rounded floaters in the center of the visual field. Posterior vitreous detachment usually affects only one eye at a time. The perception of these floaters is initially constant, regardless of lighting conditions, which generates some anxiety in the patient, despite preserved visual acuity. Posterior vitreous detachment may be preceded by a few days of phosphenes (the perception of more or less persistent peripheral flashes of light). These phosphenes are transient and generally disappear once the posterior vitreous detachment is complete.
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Retinal tears or even detachments – More concerning, these occur when a posterior vitreous detachment leads to a rupture of the retina, resulting in bleeding into the vitreous cavity. In this case, photopsia (light flashes of light) are more frequent before the tear occurs, and floaters are more opaque, with a possible decrease in visual acuity depending on the extent of the bleeding. Intraocular fluid (aqueous humor) can seep under the retina, causing a retinal detachment, which will manifest as a very opaque veil that obscures part of the visual field.
Case of uveitis
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There is a specific case that does not fall under the category of vitreous body abnormalities, but manifests as the appearance of floaters: posterior or intermediate uveitis, which is notably seen in ocular toxoplasmosis. It is characterized by the rapid appearance of very abundant floaters, causing blurred vision, often with a red, inflamed eye.
Am I going to lose my sight?
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The appearance of floaters is a normal phenomenon over time and does not cause vision loss. However, complications of posterior vitreous detachment can affect visual function, particularly in cases of retinal detachment.
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Once the patient is informed and aware of the benign nature of the vitreous degeneration, it no longer poses a problem. The transparent floaters will persist throughout their life, but the patient will perceive them less and less, thanks to cortical triage, the brain's ability to disregard details that can blur vision. Over time, the patient must "search" for the floaters, particularly on light surfaces, since they are no longer perceived spontaneously.
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Once complete, posterior vitreous detachment significantly reduces the risk of retinal tears or detachments, as the vitreous can no longer exert pressure on the retina. The discomfort associated with central floaters persists somewhat longer and diminishes over time due to cortical sorting and gravity, which causes the floaters to settle downwards in the eyeball, outside the visual field.
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A retinal tear, if left untreated, can lead to retinal detachment. It is therefore the primary diagnostic concern in patients presenting with floaters, as this is the only condition that requires treatment. The goal of this treatment is to prevent retinal detachment, which can compromise visual function.
What should I do?
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In cases of intermittent, long-standing, and bilateral perception of transparent floaters in a young patient (under 40 years old), it is most often a simple vitreous degeneration. There is no need to rush to the emergency room, but rather to schedule an appointment with an ophthalmologist, who will perform a fundus examination after dilating the pupils to confirm the absence of retinal involvement.
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In cases of sudden, recent, and unilateral perception of large, opaque floaters in a patient over 50 years of age, a posterior vitreous detachment (PVD) is most often the presenting symptom. The primary concern is determining whether there is an associated retinal tear or if it is solely a PVD. A fundus examination is mandatory and should be performed within 48 hours, or urgently if necessary. If no retinal tear is detected, a follow-up examination is often recommended within 2 to 4 weeks, i.e., after complete PVD, to ensure that no tear has developed subsequently.
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In the event of a confirmed retinal tear, retinal laser treatment will be offered as soon as possible to prevent retinal detachment. This laser treatment is performed during an ophthalmology consultation after dilating the pupils.
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In the event of retinal detachment, surgical treatment in the operating room is offered as soon as possible, in order to preserve visual function.
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In conclusion, the perception of floaters is very often benign, but can indicate potentially compromising visual function if not treated promptly. Therefore, it is strongly recommended to consult an ophthalmologist if new floaters appear or if the appearance of existing ones changes.