Laser Vitreolysis

Key Points at a Glance

Key Points of This Disease

• Laser vitreolysis is an outpatient procedure that uses an Nd:YAG laser to vaporize and break up vitreous opacities (floaters).
• Floaters are perceived by approximately 76% of the general population and can severely affect quality of life in some patients.
• Indications are floaters that impair visual function, with cases that have persisted for at least 2 months without spontaneous improvement.
• A safe treatment condition is that the opacity is at least 2 mm away from the lens and retina.
• In RCTs, 54% of the YAG laser group showed symptom improvement, significantly higher than 9% in the sham treatment group.
• Complications such as cataracts, retinal damage, and increased intraocular pressure have been reported.
• Vitrectomy has higher patient satisfaction than laser treatment but is a more invasive procedure.

1. What is Laser Vitreolysis?

Laser vitreolysis is a procedure that uses nanosecond-pulsed Nd:YAG laser (wavelength 1064 nm) to vaporize and fragment vitreous opacities. It is intended for the treatment of floaters.

Epidemiology and Impact of Floaters

Floaters are one of the most common ocular symptoms. In a survey by Webb et al., 76% of 603 participants reported experiencing floaters, and 199 of them reported significant visual impairment. Patients with myopia and hyperopia had a 3.5-fold and 4.4-fold increased risk of moderate to severe floaters, respectively.

The utility value of floaters is comparable to that of age-related macular degeneration and close to that of glaucoma, mild angina, and stroke. It has also been reported that contrast sensitivity decreases by 52.5% after posterior vitreous detachment (PVD).

The most common cause of floaters is vitreous liquefaction due to aging or myopia. Collagen fibers in the vitreous gel break and collapse, forming small clumps or thread-like opacities that float in the vitreous cavity. With posterior vitreous detachment, the glial ring (Weiss ring) in front of the optic disc becomes free, causing floaters.

History of Treatment

Early reports of YAG laser vitreolysis for floaters described treatment of patients with vitreous opacities in front of or near the center of the optic disc, with cases showing immediate resolution of floaters after surgery. No vision loss or recurrence was observed during 12 months of follow-up.

Early studies showed limited efficacy and safety concerns, but those studies used laser technology not optimized for floater treatment. Currently, advances in illumination and optics allow simultaneous visualization of the retina and floaters.

Q How common are floaters?

A

Approximately 76% of the general population is estimated to experience floaters. Floaters associated with posterior vitreous detachment are strongly perceived immediately after onset, but symptoms gradually diminish as vitreous liquefaction progresses and the Weiss ring moves away from the retina.

2. Main Symptoms and Clinical Findings

Subjective Symptoms

The main subjective symptoms of floaters are as follows.

• Floaters: Against a bright background, objects resembling mosquitoes, soot, or rings appear to move with eye movements.
• Decreased visual quality: Difficulty during reading, driving, or computer use. Contrast sensitivity may be reduced.
• Photopsia: Flashes of light may be perceived due to posterior vitreous detachment, caused by vitreous traction on the retina.

Floaters associated with posterior vitreous detachment are most noticeable immediately after onset. As vitreous liquefaction progresses and complete posterior vitreous detachment occurs, the Weiss ring moves away from the retina and symptoms diminish.

Clinical Findings

Clinical evaluation findings for floaters are as follows.

• Slit-lamp microscopy: Identifies fibrous opacities in the vitreous or a Weiss ring. Observe dynamically with a narrow slit beam and maximum illumination.
• B-scan ultrasonography: Evaluates the location, size, and distance from the retina of vitreous opacities.
• Optical coherence tomography (OCT): Objectively evaluates shadows (artifacts) caused by vitreous opacities. Also useful for assessing the presence and progression of posterior vitreous detachment.
• Scanning laser ophthalmoscopy (SLO): Evaluates the position, size, and mobility of opacities relative to the visual axis.

Vitreous opacities are classified into the following five types based on cause.

Classification	Main Cause
Congenital opacity	Persistent hyaloid artery
Degenerative opacities	Aging, myopia, posterior vitreous detachment
Inflammatory opacities	Uveitis
Hemorrhagic opacities	Diabetic retinopathy
Neoplastic opacities	Malignant lymphoma

Q Should I see a doctor immediately if I have floaters?

A

Floaters associated with posterior vitreous detachment may be accompanied by photopsia. In such cases, strong traction on the retina is suspected, and prompt fundus examination is necessary to rule out retinal tears or retinal detachment.

3. Causes and Risk Factors

The most common causes of floaters are as follows:

• Age-related vitreous liquefaction: Collagen fibers of the vitreous gel break and collapse, causing opacities to float in the liquefied cavity. By age 80–90, more than 50% of the total vitreous volume is liquefied.
• Posterior vitreous detachment (PVD): The vitreous cortex detaches from the internal limiting membrane of the retina. Release of the Weiss ring is a major cause of floaters. Approximately 10% of patients with posterior vitreous detachment have retinal tears.
• Myopia: Vitreous liquefaction progresses faster in myopic eyes compared to emmetropic or hyperopic eyes. Posterior vitreous detachment is also thought to occur about 10 years earlier.

Other causes of floaters include inflammatory opacities (uveitis), hemorrhagic opacities (diabetic retinopathy, age-related macular degeneration), and neoplastic opacities (malignant lymphoma).

Prevention and Daily Care

• In many cases, floaters are a physiological change associated with aging. There is no need to worry excessively.
• However, if floaters suddenly increase or are accompanied by photopsia, there may be a retinal tear or retinal detachment. Please see an ophthalmologist promptly.
• Symptoms of floaters become more noticeable in bright places or when looking at a white wall. Using sunglasses may reduce subjective symptoms.

4. Diagnosis and Examination Methods

Before performing laser vitreolysis, a comprehensive preoperative evaluation is necessary.

Subjective Assessment

The severity of symptoms is assessed using the Vitreous Floaters Functional Questionnaire (VFFQ) or the National Eye Institute Visual Function Questionnaire (VFQ). Having the patient draw the location and shape of the troubling opacities helps distinguish symptomatic opacities from asymptomatic ones.

Imaging Diagnosis

• B-mode ultrasonography: A primary method to evaluate the location of vitreous opacities and their distance from the retina and lens. It is also used as a quantitative indicator of floater severity.
• Optical coherence tomography (OCT): Objectively evaluates the shadow cast by vitreous opacities. It is also useful for assessing the progression of posterior vitreous detachment.
• Scanning laser ophthalmoscopy (SLO): Quantifies the umbra and penumbra projected by opacities, serving as an index of size and density.

Slit-Lamp Microscopy

Examines the anterior, central, and posterior vitreous structures. Using a special contact lens improves visualization of the intermediate vitreous cavity.

Dilated Fundus Examination

Exclude retinal tears, retinal detachment, and other retinal pathologies. If vitreous hemorrhage is present due to posterior vitreous detachment, evaluate the peripheral retina using indirect ophthalmoscopy and scleral depression.

5. Standard Treatment

There are three management options for symptomatic floaters.

Observation (Patient Education)

This is the most common approach. Symptoms of floaters due to posterior vitreous detachment usually diminish within a few months. Educate patients about symptoms of retinal tears or detachment and provide warnings ¹⁾.

Laser Vitreolysis

Indications

Cases meeting all three of the following criteria are eligible.

• Significant floaters interfering with driving, reading, or computer use
• Symptoms persisting for more than 2 months without spontaneous improvement
• Opacity located at least 2 mm from the lens and retina

Chronic Weiss ring or isolated central opacity is the best indication.

Contraindications

• Too many floaters
• Floaters caused by recurrent inflammation
• Fresh vitreous hemorrhage or preretinal hemorrhage
• Floaters associated with untreated retinal tear or retinal detachment
• Floaters outside the visual axis that cannot be treated
• Uncompensated glaucoma or high intraocular pressure
• Cases where corneal opacity or excessive lenticular astigmatism prevents visualization of the aiming beam

Procedure

1. Obtain informed consent
2. Instill mydriatic drops
3. Administer topical anesthesia
4. Place a vitreolysis contact lens
5. Apply laser (power 3–10 mJ, typically fewer than 100 shots)
6. Postoperative eye drops are usually unnecessary
7. Additional treatment can be performed the next day, but up to one month may be required to assess the effect

The number of required sessions has been reported to be 1 to 6.

Effectiveness

Shah et al. conducted the first randomized controlled trial using a YAG laser designed for floaters. 54% of the YAG laser group showed symptom improvement, significantly higher than 9% in the sham group. The laser group also had better visual disturbance scores ²⁾.

Vitrectomy (PPV)

This is considered for cases that do not respond to medication or laser therapy. It is an option when floaters persist for several months ¹⁾. Improvement in postoperative contrast sensitivity has been reported.

In a review comparing PPV and Nd:YAG laser vitreolysis, PPV resulted in higher patient satisfaction than laser therapy, while laser therapy provided only moderate symptom improvement ¹⁾.

However, PPV is an invasive procedure with potential risks such as retinal tears, retinal detachment, proliferative vitreoretinopathy, choroidal hemorrhage, and cataract progression.

Complications and Precautions

The following complications have been reported for laser vitreolysis:

• Cataract: Caused by laser energy damaging the posterior lens capsule. Maintaining a safe distance from the lens is important.
• Retinal damage: Transient posterior pole retinal hemorrhage and scotomas have been reported.
• Retinal detachment: Rarely reported. Should be avoided immediately after Nd:YAG posterior capsulotomy.
• Increased intraocular pressure: Transient or persistent elevation may occur. Rarely, secondary glaucoma requiring trabeculectomy has been reported. Avoid excessive laser applications exceeding 300 shots per eye in total.

Q Is laser vitreolysis covered by insurance?

A

The US FDA classifies this procedure as “not a significant risk” and has approved YAG lasers. In Japan, insurance coverage requires individual confirmation and varies by facility.

6. Pathophysiology and Detailed Mechanism

Age-related changes in the vitreous and mechanism of floaters

The vitreous is composed of 99% water and 0.1% macromolecules such as collagen and hyaluronic acid. Collagen fibers form a scaffold, and hyaluronic acid retains large amounts of water to maintain the gel structure.

With aging, collagen fibers break down and collapse, leading to vitreous liquefaction. About 20% of the total vitreous is liquefied by age 14–18, and over 50% by age 80–90. Within the liquefied cavities, fragmented collagen fibers float as small clumps or thread-like opacities, causing floaters.

Progression of vitreous liquefaction and decreased adhesion between the retina and vitreous lead to posterior vitreous detachment. With posterior vitreous detachment, the glial ring (Weiss ring) around the optic disc floats in the vitreous and is perceived as a ring-shaped floater.

Mechanism of laser action

The mechanism of laser vitreolysis is called “plasma formation” and “optical breakdown.”

Optical breakdown occurs due to a high-frequency electric field concentrated in a microscopic area. The central temperature reaches several thousand degrees. The laser converts solid floaters into gas through a combination of photochemical, thermal, thermoacoustic, and electromagnetic optical field effects.

The formed gas bubbles gradually dissolve after floating, and the dissolved gas passes through cell membranes and is eliminated by blood vessels. Since the pulse duration is as short as 4 ns, heat dissipates before the next pulse. Below the optical breakdown level (typically about 2.2 mJ), floaters are only fragmented, and the success rate is low.

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7. Latest research and future perspectives (research-stage reports)

For patients: Please read this

The following content is currently at the research stage or under clinical trial and is not standard treatment available at general hospitals. It is reference information for professionals regarding future medical developments.

Challenges toward establishing long-term safety

Appropriate prospective studies are needed to characterize the long-term safety and efficacy of laser vitreolysis. The spectrum of complications reported to the ASRS ReST Committee is consistent with previous reports, indicating that complications remain a relevant aspect of the procedure.

Optimization of indications

A single central floater, especially a chronic Weiss ring or isolated opacity, is considered the best candidate, but further clinical trials are needed to establish strict eligibility criteria. Given that vitreous floaters are not a vision-threatening disease, further improvement of the complication profile is desired.

Potential for Pharmacological Treatment

As a treatment for floaters other than laser or surgery, research on pharmacotherapy has also been proposed. However, at present, there is insufficient evidence for pharmacotherapy for floaters¹⁾.

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8. References

1. Posterior Vitreous Detachment, Retinal Breaks, and Lattice Degeneration PPP. American Academy of Ophthalmology. 2024.
2. Shah CP, Heier JS. YAG laser vitreolysis vs sham YAG vitreolysis for symptomatic vitreous floaters: A randomized clinical trial. JAMA Ophthalmol. 2017;135:918-23.