Vitreous floaters are small, non-transparent particles that are suspended in the vitreous humor of the eye. They may interfere with vision.
Patients that present with VFs usually report the appearance of gray, mobile spots of different size, shape and consistency in their field of vision. Because in some cases, VF will not directly cast shadows onto the ocular fundus but rather reflect light and redirect it to other parts of the retina, patients may also describe light flashes instead of gray spots in their field of vision.
The vast majority of VF develop due to age-related, degenerative alterations of the composition of the vitreous humor. There are, however, certain events related to VF appearance that may reveal more severe underlying problems. In this context, the sudden appearance of multiple floaters should prompt a more detailed examination as well as repeated light flashes, partial or even complete loss of vision and pain. Such patients should immediately be referred to an ophthalmologist. If any patient who has recently undergone eye surgery develops VF, then they should be evaluated promptly for the cause of the VF.
The patient history should address questions regarding the emergence of floaters, their development, and visual appearance. Eye pain and visual impairment are further important parameters to assess the severity of the case. If the patient complaints of visual impairment, then trauma as a cause for the complaints should be considered and evaluated.
After obtaining the patient's medical history, a thorough physical and ophthalmologic examination should follow. Best corrected visual acuity needs to be evaluated for all visual fields. Due to low sensitivity, this test may need to be repeated at a later time. In the course of the exam, pupillary light responses, as well as, adnexa movement should be observed. Measurement of intraocular pressure is recommended.
In order to prepare for the ophthalmologic examination, mydriatics need to be administered. To this end, sympathomimetics are often combined with parasympatholytics, e.g. 2.5% phenylephrine plus 1% tropicamide or 1% cyclopentolate. Direct and indirect ophthalmoscopy can be performed to observe floaters and to examine the retina. VF are heterogeneous fiber clumps and deposits. They appear as differentially sized spots, threads or spider webs, and they may or may not be refractile. If floaters are located in close proximity to the retina, they may be difficult to visualize even though they appear large to the patient.
Of note, visual impairment may result from lesions to any type of tissue forming part of the light path, thus these should be ruled out as possible triggers of VF. While corneal epithelial defects may be revealed in a fluorescein stain test, slit-lamp examination allows for the detection of alterations in deeper structures including the lens.
If any of the previous findings are suspicious for serious vitreous or retinal diseases or if patients report a sudden appearance of multiple floaters, repeated flashing, loss of vision or pain, then retinal tears and detachment, vitreous hemorrhages and inflammation should be considered as potential differential diagnoses . Additional diagnostic measures, e.g. imaging techniques such as optical coherence tomography, may be required to identify the pathological condition in the individual patient  .
Idiopathic VF and those floaters associated with vitreous humor shrinking do not require treatment unless they interfere with vision. In such cases, patients may benefit from vitrectomy . However, the vitreous humor does not regenerate after vitrectomy and is replaced with an aqueous solution. Also, the overall condition of the probably geriatric patient and the risks associated with this procedure should be considered before deciding to perform a vitrectomy.
If floaters are not of idiopathic origin but developed as a consequence of any underlying disease, the latter should be treated. In this context, infections require antimicrobial treatment while retinal tears or detachment require surgical intervention. Strict management of blood glucose levels in diabetics is necessary to prevent progression of VF in patients suffering from diabetic retinopathy. Certain pathological conditions associated with the sudden appearance of multiple floaters require urgent treatment to avoid permanent partial or complete loss of vision.
Prognosis for VF is good. The vast majority of VF patients do not experience any visual impairment due to the presence of floaters in their vitreous humor.
Any non-transparent object inside the vitreous humor may either directly cast shadows on the retina or reflect light that subsequently reaches the retina. Shadows are perceived as darkened spots, while reflecting light may cause the perception of flashes.
In most cases, degenerative alterations affecting the vitreous humor account for VF. Here, collagen fibers may clump and stick together, thus forming spots of increased density inside the vitreous humor. This kind of VF is deemed idiopathic.
Similar perceptions can be triggered upon overall shrinking of the vitreous humor. In this case, however, photoreceptors will be directly stimulated by local retina movement. In rare cases, VF may indicate other, more severe underlying diseases. Patients may also suffer from retinal tears or detachment, hemorrhages or inflammatory processes inside the vitreous humor. Ocular neoplasms are very rare triggers for VF.
VF may furthermore be experienced in the course of a migraine attack. However, patients suffering from migraine often describe flashing, jagged lines that spread throughout the field of vision. Their regression also occurs gradually.
The overall prevalence of VF is high.
VF are thought to be a degenerative eye disease whose prevalence increases with age. The results of some studies argue against this hypothesis because VF prevalence was not found to be age-dependent in their respective samples. However, this is likely due to the fact that VF develops in patients considerably older than 50 years and this age group is underrepresented in the above-mentioned studies . This has already been proven for posterior vitreous detachment, a condition frequently related with the appearance of VF.
Also, there is a positive correlation between hyperopia and VF prevalence. Hyperopes report VF significantly more often than myopes. A causal relationship has not yet been established and it is speculated that the frequent observation of VF in hyperopes merely corresponds to the fact that both conditions are age-related. Of note, myopes do present significantly more often with VF than emmetropes.
Furthermore, other pathological ocular conditions may predispose to the development of VF. This may be the case for diabetic retinopathy . Similar to the above-described condition, diabetic retinopathy progresses with age. Further eye diseases can develop in geriatric patients, and aggravate their overall condition as well as increase the prevalence of VF.
The vast majority of VF is deemed idiopathic and while general degenerative processes may account for the appearance of fiber clumps and deposits inside the vitreous humor, precise pathogenetic mechanisms have not yet been identified.
A mechanical explanation can be given for the above mentioned floater-like phenomenon due to vitreous humor shrinking. Here, the shrinking vitreous body provokes minimal alterations of the overall form of the ocular fundus and this process also affects the retina. Thus, mechanical stimulation of the retina due to dragging and tugging triggers depolarization of photoreceptors and thereby evokes the perception of floaters. Of note, an eye affected by vitreous humor shrinking does not necessarily contain physical floaters if the patient describes such floater-like perceptions. However, a positive correlation between posterior vitreous detachment and floater prevalence has been reported   . A greater prevalence of posterior vitreous detachment may also account for the observation of VF being more prevalent in myopes than in emmetropes .
In most cases, the development of VF is associated with degenerative processes occurring in the elderly. There are no specific recommendations to prevent these events.
Regular ophthalmologic check-ups may contribute to overall eye health and may, therefore, be helpful in preventing VF. A thorough ophthalmologic examination at the earliest possible point in time is recommended if floaters appear suddenly or are associated with other symptoms. Such an examination may be of utmost importance to maintain eyesight.
The vitreous humor of the eye maintains the form of the ocular bulb but is also part of the optical path. The incoming light passes through the cornea, pupil, lens and vitreous humor before reaching the retina that is part of the ocular fundus. Any deposit inside the vitreous humor that reduces transparency may, therefore, interfere with vision. This is the case with vitreous floaters (VF), which are small but heterogeneous deposits inside the vitreous humor of the eye. They differ in size and shape as well as in refractivity. Due to their apparent mobility inside the eye, they are commonly called "muscae volitantes", which is Latin for "flying flies". The condition of perceiving VF inside the vitreous humor is termed myodaeosopsia. VF typically develops slowly with age and the vast majority of VFs are considered a degenerative alteration of the vitreous humor. The sudden appearance of new floaters, however, might indicate more severe underlying problems and should prompt thorough ophthalmologic examination .
The central part of the eye, the so-called glass body, consists of a gel-like substance, the vitreous humor. Its main function is to maintain the form of the eye, but incoming light also has to pass through the vitreous humor. Therefore, the vitreous humor is transparent. Any non-transparent spots inside the vitreous humor may either directly cast shadows onto the retina, the part of the eye where light is perceived, or they could reflect light and redirect it to other parts of the retina. In either case, the image of light that reaches the retina will not correspond to the light that entered the eye through the cornea, the pupil, and the lens.
Such is the case with vitreous floaters (VF). VF consist of fiber clumps or deposits that develop inside the vitreous humor. They differ widely in size and shape.
The vast majority of VF develops due to degenerative alterations of the vitreous humor that occur with age. However, in rare cases, retinal tears or detachment, as well as, hemorrhages or inflammation of the vitreous humor may provoke VF.
VF develops in the course of years. Due to the shadows they cast onto the retina, VF may appear as gray spots, threads or spider webs. As has been mentioned above, other VF may be recognized due to their reflecting properties. The patient will experience this type of floaters as flashes. VF are mobile and will move within the visual field of the patient during eye movement.
VF do not usually interfere with vision.
Of note, the sudden appearance of multiple floaters, repeated flashes, partial or complete loss of vision as well as eye pain may be warning signals for the above-mentioned, serious diseases of the retina or vitreous humor. They require urgent examination and initiation of treatment.
An ophthalmologist will suspect VF if the patient's complaints correspond to the typical symptoms and will conduct an ophthalmologic examination to confirm them. During this exam, the ophthalmologist will also evaluate the condition of other ocular structures and will pay special attention to the retina and the vitreous humor. As has been mentioned above, in rare cases, VF may be caused by serious pathological conditions that need to be ruled out.
Because patients are usually not bothered by VF, no treatment is required for the majority of cases. Only rarely do VF considerably affect vision and in these cases, a vitrectomy may be performed. A vitrectomy is a minor surgical intervention aimed at removing the vitreous humor that is no longer transparent. However, it is still a surgical intervention that is accompanied by certain risks. Therefore, possible benefits should outweigh the risks if one decides for a vitrectomy. Because the vitreous humor does not regenerate after surgery, it will be replaced by an aqueous solution.
If medical examination reveals an underlying disease, it has to be treated accordingly to avoid possible severe visual impairment and progression of VF.