Specialists deliberate criteria, best practices, benefits and risks of treating floaters
Vitreous floaters are a common ocular condition, affecting up to 76% of the population, according to Webb and colleagues.
In this first of a two-part series on vitreous floaters, Healio | OSN spoke with several clinicians about their criteria for diagnosis and the decision to treat.
Source: Christoph Arnholdt
Although in most cases the brain neuroadapts to floaters, minimizing their perception, a minority of people are heavily and persistently affected.
“We are now more aware that floaters can have persistent, severe symptoms in a specific subgroup of people, causing a prolonged negative impact on quality of life. Terms such as ‘symptomatic vitreous opacities’ and ‘vision-degrading myodesopsia’ (VDM) have been introduced to characterize this phenomenon as a disease,” Michael Albrecht, MD, said.
Albrecht, an ophthalmologist at Heidelberg University Hospital in Germany, has a keen research interest in vitreous floaters, particularly in the young population, and has published in Survey of Ophthalmology an extensive review on this topic.
“There is an increasing number of young people suffering from VDM due to the growing prevalence of myopia,” he said.
I. Paul Singh, MD, of The Eye Centers of Racine & Kenosha, Wisconsin, also suggested a change in terminology from floaters to “clinically significant vitreous opacities,” or CSVO, for these heavily and persistently symptomatic floaters.
“I see patients who are inhibited in their driving, reading, just daily functionality,” he said.
And yet, there is still a tendency to underestimate and underappreciate the impact that floaters have on vision, daily functioning and quality of life, Singh said.
“The symptoms are very similar to those of cataract, and we don’t minimize cataract, but yet, when it comes to floaters, we tend to minimize them,” he said.
Increasingly prevalent in young people
A study published in 2011 by Wagle and co-authors showed that patients with symptomatic floaters were willing to trade off 1 out of every 10 years of their life and to take, on average, a 7% risk of blindness and an 11% risk of death to be relieved of their symptoms.
“Risk tolerance was higher in these patients than in patients with asymptomatic HIV, cancer and diabetes,” Singh said.
A revealing, poignant episode earlier in Singh’s career was when he questioned a patient with a Weiss ring and 20/20 vision, asking if he was really so bothered by that small dot to want to undergo laser treatment.
“He looked at me, stuck his finger in front of my eye and said, ‘Live with that for the rest of your life. You can still see well in a chart, doctor, but do you want something blocking your view all day long?’” he said.
The same study showed that younger patients were even more likely to risk blindness to get rid of floaters. Myopia is often the cause of floater development in young people, as it leads to alterations in the vitreous structure, defined as myopic vitreopathy.
“These young people tend to have a distinct type of floater, visible as translucent-like strings that are very clear in their shapes, maybe an indication that they are near the posterior membrane,” Albrecht said.
They also tend to develop more floaters over the years and to have an earlier onset of posterior vitreous detachment (PVD) with, again, an aggravation of VDM symptoms.
“For each diopter of myopia, the average time of complete PVD onset is shortened by 1 to 2 years. This means that 40 to 50 years can be the normal age for a high myope to develop PVD with its consequences,” Albrecht said.
People who are severely impaired by floaters see them all day long in the center of the field, overlapping everything they look at.
“They may give up reading, give up driving, seek some relief in dark rooms, and feel better only at night because the effect is less noticeable in a dark environment and when the pupil is more dilated. They maybe tell you that they constantly use very dark sunglasses in daylight,” he said.
Several studies have shown that floaters, particularly in young patients, are often associated with severe anxiety and depression.
Objective assessment
In the general population, the acute onset of multiple vitreous floaters indicates that PVD has occurred. Patients should never underestimate this event, particularly in the presence of flashes of light, and should undergo a full vitreoretinal examination, according to Paulo-Eduardo Stanga, MD, a vitreoretinal surgeon at The Retina Clinic London, U.K., who specializes in vitreous floaters and their laser and surgical management.
“A full vitreoretinal examination is not only a slit lamp examination with a handheld non-contact lens. It is a slit lamp examination with navigated ultra-widefield multiwavelength imaging with navigated peripheral OCT, ultra-widefield OCT and indirect ophthalmoscopy with 360° scleral indentation,” he said. “This last form of examination is the only way we can assess the peripheral retina and reach the ora serrata, and this should be done by a retinal specialist, ideally, with the patient lying in a supine position to facilitate the relaxation of the patient and access 360° around the globe.”
Vitreous floaters and opacities (VFO), new terminology proposed by Stanga and his team to more accurately describe patients’ symptoms, is a vitreous condition. Therefore, in his opinion, assessing vitreous floaters and proposing treatment options should be carried out by a vitreoretinal specialist surgeon as it is essential to also assess the peripheral retina when deciding on management options.
Factors that can contribute to whether floaters become symptomatic are speed of movement, direction of travel, distance from the retina, and whether the patient presents a wrinkled and/or opaque posterior vitreous cortex, he said.
“We are conducting significant research in vitreous floaters at our clinic, and we have to remember, as we are showing in our study just published in Retina, that VFO do not need to be visible to the examiner to be symptomatic,” Stanga said. “We are showing objectively how they scatter light and described their light scattering characteristics. Some patients are symptomatic from clusters of collagen fibers that cast a shadow and also scatter light, diminishing, amongst others, contrast sensitivity, while other patients are symptomatic from interfaces that have the same optical effect on vision. These are the most challenging patients to treat because they tend to be young patients with a clear vitreous on biomicroscopy.”
VFO can induce forward scatter and backward scatter, Stanga said. Forward scatter is what makes them visible to the patient and therefore symptomatic. Backward scatter is what makes them visible to the examiner.
While visual acuity might not be affected, the optical scatter caused by the opacities results in increased higher-order aberrations and loss of contrast sensitivity.
Stanga and colleagues recently published a new methodology to objectively assess the effect of vitreous floaters and opacities on vision, the Standardised Kinetic Anatomical and Functional Testing of Vitreous Floaters and Opacities (SK VFO), for the first time taking into account the kinetic and refractive properties of vitreous floaters.
“There are lots of studies showing that contrast sensitivity function (CSF) is the perfect marker to correlate subjective symptoms to the objective measurement. And CSF loss can be more psychologically distressing than visual acuity loss,” Albrecht said.
CSF can be measured in several ways, including the computer-based Freiburg Acuity and Contrast Test. In addition, quantitative ultrasound methods can be used to quantify vitreous echodensity, which correlates well with CSF and the subjective assessment of symptoms by visual function questionnaires, he said.
A cautious but open attitude
The average time a patient needs to neuroadapt to floaters is 3 to 6 months, and at least 6 months should pass before proposing any treatment.
“Every patient with a neurosymptomatic floater needs to have the opportunity to neuroadapt,” Singh said. “I tell my patients to come back in 3 months. I check the retina and then give them another 3 months before I consider doing anything. I also might wait a little longer. If symptoms persist for more than 6 months to 1 year, the likelihood of neuroadaptation significantly reduces.”
“When we tell patients that they need a few months to neuroadapt, but if they don’t get better, there is something we can do for them, they really calm down and wait without going into distress,” Albrecht said. “They know we can offer something, and they won’t have to be alone in the dark for the rest of their lives.”
Stanga said that more patients nowadays complain of floaters, especially younger patients. The increased time spent in front of a backlit monitor or looking into a smartphone creates the perfect situation to see and be bothered by floaters because it enhances the light-scattering properties. The other reason is the presence of myopic vitreopathy due to the increasing prevalence of myopia.
“I have consultations on vitreous floaters on a daily basis, and more and more patients are in their 30s, severely troubled by floaters. They are well informed about treatment, come with that in mind, and it is sometimes difficult to make them wait. However, in case of new-onset floaters, like after a PVD, I never treat them straight away because in most cases treatment won’t be needed,” Stanga said.
It is important, however, not to dismiss patients with the idea that nothing can be done. And although the attitude is changing, this still occurs quite frequently.
“The reason why these patients are usually dismissed is because there is insufficient or poor understanding in both the ophthalmic and the optometric community about the importance of symptoms and about which patients need or could benefit from treatment, as well as available treatment options,” Stanga said.
Laser vitreolysis
The treatments currently available for vitreous floaters are YAG laser vitreolysis and vitrectomy, which includes specific techniques of limited vitrectomy. Their use is expanding, but caution, careful patient selection and expertise are needed because the risks are not negligible.
Singh has treated more than 6,000 eyes with YAG vitreolysis, and his selection criteria are eyes with PVD after 6 months or more and no signs of retinal tears or detachment. To his colleagues who want to undertake this procedure, he recommended starting with solitary opacities, such as a Weiss ring, not too close to the retina.
“Pseudophakic patients are good to start because you don’t have to worry about hitting the lens,” he said.
He also recommended having a technician hold the head of the patient during the procedure and anesthetizing the contralateral eye to prevent any movement.
The new YAG lasers with coaxial illumination maximize the visualization of floaters across the entire vitreous cavity, from the lens to the retina. In addition, specifically designed lenses, such as the Volk Optical Singh Mid Vitreous Lens, enhance depth of focus and facilitate the precise localization of floaters.
“If we see that the floater is in focus and the retina is out of focus, that is the clue that tells us we have enough distance between the floater and the retina, and it is safe to fire,” Singh said. “And by moving the lamp oblique, you can see how far the floater is in relation to the posterior capsule.”
Spatial awareness, he said, is crucial for precise identification and safe ablation of the floaters.
Safety in the new lasers is also enhanced by efficient cooling systems and better energy with a non-linear relationship between laser pulse energy and shockwave strength.
“At 1 mJ of laser setting, the amount of shockwave in the vitreous is about 110 µm,” Singh said. “If you increase the energy to 10 mJ, the shockwave only goes up to 220 µm. In other words, with a tenfold increase in energy, we are less than doubling the shockwave. This dispels the concern of causing damage to the surrounding tissues.”
B-scan ultrasonography performed during treatment showed that there is no movement of the posterior hyaloid and no traction against the retina.
Singh utilizes the Ellex Tango Reflex Neo YAG laser (Lumibird Medical), and PulseMedica is working on an image-guided femtosecond laser system, which is in early trials, that automatically tracks and vaporizes floaters.
“We have published a number of prospective and retrospective studies where we show that with Weiss rings, we get well over 90% of satisfaction with one session. For amorphous clouds and strings, you need to do multiple sessions over time,” he said.
Multiple sessions are needed with large floaters because too many shots at one time would cause pressure spikes, even a few weeks after the procedure. Singh limits the number of shots to about 300, but if the patient is pseudophakic and the floater is in the middle of the vitreous, he goes up to about 500 or 600 shots.
“But even then, I’ll stop and tell the patient, ‘Let’s rest. Let’s have you come back in a few weeks, check the pressure, check the retina, and then we can do a second session if we need to,’” he said.
Not all floaters are amenable to YAG vitreolysis, Stanga said. This treatment is best suited for well-defined, centrally located vitreous floaters like a Weiss ring. The treatment is delivered through a contact lens, and it is not possible to ablate peripheral floaters, he said. Stanga is currently completing a study treating vitreous floaters with YAG vitreolysis, with the aim of identifying the ideal candidates for laser treatment.
“YAG vitreolysis is a fantastic treatment for patients who have a Weiss ring or similar centrally located vitreous opacity. We can usually be successful in one session,” he said. “However, some patients may need more than one treatment session, and they need to understand that there may be peripheral floaters we cannot reach with this form of treatment.”
Limited vitrectomy
Limited vitrectomy aims at removing the vitreous opacities and floaters that are symptomatic, sparing the rest of the vitreous. Stanga named his specific technique “therapeutic refractive vitrectomy” to emphasize that this procedure is not elective but needed as a treatment to reduce optical scatter and higher-order aberrations and enhance contrast sensitivity.
He uses 25- or 27-gauge vitrectomy, usually sutureless, does not induce a PVD if it is not present, and does not remove the peripheral and anterior vitreous.
“I am just removing the minimum necessary amount of opaque core vitreous because the more vitreous I leave behind, the lesser the risk is of a subsequent PVD and cataract formation,” he said.
With endolight illumination and by playing with the wavelength and optical filters, he can precisely visualize and localize floaters.
“We don’t need to remove all of them but only those that are affecting the visual axis,” Stanga said. “When the patient is lying in the supine position, because of gravity, VFO groups in the central vitreous, and the procedure is pretty quick.”
Observation and reassurance
Chirag P. Shah, MD, MPH, a retina specialist at Ophthalmic Consultants of Boston, has a more conservative attitude toward treatment of floaters.
“I present the treatments focusing on the risks, and I am very good at talking patients out of surgery,” he said.
In his experience, given sufficient time for the brain to neuroadapt, 99% of patients can be treated with observation and reassurance. Usually only a small minority, those with a more anxious and detail-oriented personality, ask for treatment.
“There may be regional differences in physician attitudes toward treating floaters. I practice in Boston, which is a more conservative region in the U.S., where only a handful of doctors perform YAG vitreolysis and where vitrectomy for floaters is reserved for more symptomatic cases. Colleagues in more liberal regions of the U.S. may be less conservative in offering treatment for floaters,” he said.
Complete vitrectomy is the option he offers when treatment is necessary. The 25- or 27-gauge options, with smaller wounds and quicker recovery, make it more feasible for floaters, but vitrectomy remains a surgery with risks and consequences and is not a choice that can be taken lightly.
“I love vitrectomy surgery. It’s highly effective at removing floaters, but there are some very real and potentially devastating risks involved, including retinal detachment and infection,” Shah said. “Taking a 20/20 eye that’s bothered by floaters and turning it into a hand motion eye is a pretty horrible feeling for both the doctor and for the patient. Even though it’s rare, it can certainly happen.”
He never treats patients who he feels may be litigious or psychiatrically unstable.
“In the U.S., litigation is common, and one has to be selective. One must choose patients with legitimate floaters, and one must select appropriate patients,” he said. “I see hundreds of patients with symptomatic floaters every year and operate on only a handful. They are patients with whom I share a mutual trust, have legitimate floaters and corresponding symptoms, and have real quality of life issues such as compromised reading speed or driving ability.”
Shah was involved in a study on YAG laser vitreolysis, published in JAMA Ophthalmology in 2017, and later published in Ophthalmic Surgery, Lasers and Imaging Retina the long-term results, coming to the conclusion that laser vitreolysis is not ready for widespread adoption.
“We spent a lot of time with these patients, and half of them were not satisfied and felt there was little to no improvement. Some of them felt there was worsening of their symptoms. Only half of them had partial to significant improvement. Further, 8% to 9% of patients who returned for long-term follow-up developed retinal tears not evident 6 months after YAG vitreolysis,” he said.
In addition, the procedure is not FDA approved, and the legal risk is therefore high.
“For these reasons, I do not perform YAG vitreolysis,” Shah said, “but there are colleagues who do it with success, like my friend Paul Singh, who does it very ethically with excellent outcomes.”
Editor’s note: In part 2 of this series, another group of clinicians discusses differential diagnosis and the finer points of performing vitrectomies.
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- For more information:
- Michael Albrecht, MD, of Heidelberg University Hospital, Germany, can be reached at michael.albrecht@med.uni-heidelberg.de.
- Chirag P. Shah, MD, MPH, of Ophthalmic Consultants of Boston, can be reached at cpshah@eyeboston.com.
- I. Paul Singh, MD, of The Eye Centers of Racine & Kenosha, Wisconsin, can be reached at inderspeak@gmail.com.
- Paulo-Eduardo Stanga, MD, of The Retina Clinic London, United Kingdom, can be reached at p.stanga@theretinacliniclondon.com.
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