FREQUENTLY ASKED QUESTIONS REGARDING THE TREATMENT OF VITREOUS EYE FLOATERS WITH A YAG LASER
IS THIS A LEGITIMATE TREATMENT OPTION?
Yes. Ophthalmic YAG Lasers have been used for more than 20 years. The American Medical Association has established a Common Procedural Terminology Code CPT code associated with Laser Vitreolysis (67031) and our laser is labeled by the FDA for use in the vitreous cavity for vitreous membranes. Commercial insurance plans have reimbursed patients for the procedure with the appropriate documentation.
IS THIS PROCEDURE FDA APPROVED?
FDA approval refers to the LABELING of the device and approval that it is a safe device for the indications within the package labeling. The Lasers used to treat floaters are FDA approved for use in the eye and the laser that Doctor Johnson uses is approved for its use in treating posterior (chamber of the eye) membranes. Additionally, in 2002 Dr. John Karickhoff submitted a document to the FDA outlining the current understanding of the laser physics, the past published studies as well as a summary of his years of experience with the procedure of treating floaters with the laser. The FDA had ruled that his proposed study of laser treatment of vitreous opacities was a non-significant risk device study. They further ruled that a special device exemption from the FDA to use a YAG laser in the study was not required. In addition, our laser IS FDA approved for treating vitreous strands. As such, the use of the YAG laser to treat vitreous floaters can be considered an ON LABEL use of the laser. Ultimately it may not be as important a concept as you may think. The FDA does not regulate what procedures can/can not or should/should not be used with each device they approve. It is up to the individual physician to make that determination. Devices and medications are used “off label” all the time. As an example, it is estimated that 75% of all pediatric medications prescribed are done off label. Much of the progress and innovation in medicine occurs when physicians adapt and expand from existing indications.
WHY AREN'T MORE DOCTORS DOING THIS TREATMENT? or similarly, "IF THIS REALLY WORKED, DON'T YOU THINK MORE DOCTORS WOULD BE DOING IT?"
The explanation as to why this procedure is not more popular is manifold and multifaceted. Here are a few contributing factors:
- Very few eye doctors are aware of the procedure, or have seen it performed, or have seen the results of the procedure.
- Floaters are thought to be benign by the professional community. They are not usually a cause of decreased function and the floaters themselves are not part of a progressive degenerative eye condition.
- It is technically a very difficult procedure to perform well. There is a slow learning curve. In our experience, it may take 100,000 laser shots or so to really begin to acquire the experience and skill to do it well.
- There are no official or unofficial teaching or training courses where doctors can learn the basic skills and science behind the procedure of the procedure.
- There have only been a couple of published articles on the topic. The results with the particular technique and energy levels that were used were not impressive, although it was at least deemed a safe procedure.
- The pharmaceutical and device manufacturers have not yet realized that there is money to be made treating eye floaters.
- The common practice of eye care professionals in evaluating eye floaters has been to rule out retinal pathology, reassure, and send the patient on their way.
- We are aware of some doctors attempting the procedure at sub-therapeutic energy levels and then giving up on the procedure never to try it again.
WHAT HAPPENS TO THE FLOATER? AREN'T YOU JUST BREAKING IT INTO SMALLER PIECES?
The technical details: The YAG laser emits the beam in a cone-shaped pattern. At the apex (or tip) of the cone there is a concentration of the energy. Using focusing lenses, this apex is directed onto the front surface of the floater material. The laser “shot” lasts only 20-30 nanoseconds (0.000000030 seconds), and at that moment the concentrated laser light creates a small plasma-state “bubble”. As you all will remember from your physics courses, plasma is the fourth state of matter, (the first three being solids, liquids, and gas). Matter that has been converted to plasma has the electrons pulled away from their usual location and creates a high energy state of the matter. This process actually converts the floater material to a small gas bubble. It is important to understand that the laser does not just break the floater into small pieces, but actually changes it to a gas. The gas is reabsorbed into the bloodstream over the course of a few hours.
WHAT ARE A PATIENT'S ODDS OF SEEING SIGNIFICANT IMPROVEMENT? NO IMPROVEMENT?
Every eye is different and there are too many variables to list here, but it is reasonable to expect 60-90% improvement and decrease in the mass or amount of the floaters. Most patients will need a second (and sometimes a third or more) treatment to clear up most of the rest. There have been a few patients (about 15% of consultations) that have such thin, transparent floaters (or too close to the retina) that we haven’t even able to see them or treat them. These patients are almost always younger than 30-35 years of age.
WHAT DETERMINES HOW MANY FLOATERS CAN BE REMOVED DURING THE PROCEDURE?
Time, location, and total energy. In addition, floaters that are too close to the retina or lens may not be safely treated. During the treatment, we monitor the energy of each shot, as well as the total energy used during the treatment and keep it within an empirically determined range.
HOW DO YOU KEEP THE EYE FROM MOVING AROUND? I DON'T THINK I CAN HOLD STILL.
There is a head strap on the laser that firmly holds the head in place. In addition, the hand-held contact lens stabilizes the eye quite well. The combination allows us to focus on objects that are very small (fibrous strands < 1/20 of a millimeter) with great accuracy. Although we have mild sedatives available, we have only used them once, and afterwards the patient suggested he probably didn’t need it after all. Even very nervous patients will agree afterwards that it is a very tolerable, painless, procedure.
HOW DO FLOATERS OR FLOATER TREATMENT AFFECT VISUAL ACUITY? DOES PRESCRIPTION CHANGE AFTER TREATMENT?
Most of the time after treatment, there is not an improvement or overall change in Snellen Chart visual acuity. This is the testing that most are familiar with: small, high-contrast letters 20 or so feet away. This vision is usually noted as 20/20 or 20/something in the US. This only tests the central (albeit most important) visual acuity. There are other aspects of vision such as contrast sensitivity, color, peripheral, and a vague and harder to quantify “quality of vision”. For instance, you could have 20/15 vision by the chart. Excellent vision, right? But what if you have advanced glaucoma with tunnel vision? Or in the case of floaters, what if you have swirling soup moving about with every eye movement. It may be 20/15, but who cares if you have that junk moving around in your eye.
Occasionally there is a dense, stable floater stuck right in the middle of the visual axis. With treatment we have seen improvements of up to four lines of vision after a series of treatments. That situation is rare, though, and I never give a patient that expectation. More often the floater will drift through the central axis temporarily blurring the vision in that eye. The optics of the eye don’t change with treatment. The corrective spectacle prescription is a function of the corneal curvature, the strength of the crystalline lens and the length of the eye which are not affected by laser treatment for floaters. Unlike LASIK laser vision correction, we are not attempting to improve visual acuity, but we are improving the overall quality of vision which is admittedly hard to define and even harder to quantitatively measure.
CAN LASER FOR FLOATERS BE DONE AFTER LASIK? PRK? RK? CATARACT SURGERY?
Yes, but with some technical difficulty. The difficulty with post-laser refractive surgery eyes is that there is a central area of the cornea (approx 8-9mm) that has been reshaped, and then a surrounding “transition zone” of about 1mm, and then the peripheral, untouched cornea. When you shine the ophthalmoscope into the eye and see the “cat’s eye” light reflex, there appears to be a lens within a lens or a “button” of different optical quality. Even if the pupil is a larger 10-11 mm, the effective working diameter is only that 8mm. When treating with the laser, every millimeter of pupil dilation matters. LASIK essentially restricts the coherent, organized focus of the laser. The bottom line is that the efficiency of the laser can drop way down. Sometimes as little as 1 in 5 shots may be actually affecting the floater.
Other times in LASIK patients, the laser is fully efficient and you’d never know the difference. We can’t always tell beforehand. The difficulty is likely related to the amount of correction, and the distance to the floater treated. In spite of some of the anticipated optical challenges after LASIK or RK, there should NOT be any additional risk to the patient. More about that HERE
1. HOW DO YOU DETERMINE THE DISTANCES FROM THE LENS TO A FLOATER AND FROM THE FLOATER TO THE RETINA? and 2. HOW DO YOU FOCUS THE LASER TO A PARTICULAR DISTANCE?
The short answer is experience. There are a few clues the surgeon uses at the YAG laser to get a good accurate assessment of the distances involved: 1) there is a very narrow depth of field optical plane using the biomicroscope. When we are focusing on an object, nearly everything is blurry anterior and posterior to that focal plane. If the background is a diffuse blurry orange then we know the focus is plenty far from the retina. As the laser is focused further back and the retinal detail becomes more distinguishable, then we know we are approaching the retina. The doctor can then rely more on binocular depth perception and the shadows cast onto the retina by the floater aid in distance estimation. In addition there are two red laser focusing beams that are 16 degrees apart. Those have to be coincidental (converged) on the surface of the floater. These beams diverge again on the far side of the focal point. The further and blurrier these beams are from each other, then the farther the focus is from the retina. Another factor is experience. My laser shot count is over is in the millions – fired only at floaters so there is a conscious and subconscious awareness of where the focus is located in three-dimensional space. These are just a few factors that come with experience. If you are considering treatment, it is imperative the doctor has the experience of hundreds of thousands (or in Dr. Johnson’s case, millions) of individually aimed, assessed, and fired laser shots. There is no substitute for experience in treating eye floaters.
I HAVE FOUND JUST A FEW STUDIES ON THE TREATMENT OF FLOATERS. ALTHOUGH THEY HAD POSITIVE RESULTS, WHY ARE THERE SO FEW STUDIES?
The studies you referenced are also available as full PDF downloads from our web site.
If you scratch beneath the surface and know what to look for there are some important considerations that help explain why they had a relatively low success rate (about 30%, but didn’t define what success was). They can be categorized into 1). Energy levels, and 2). Strategy/technique.
1. ENERGY: The lasers are FDA approved for delivering energy to intraocular structures, specifically the posterior lens capsule. The lens capsule will often opacify making a successful cataract surgery seem to backslide. The laser is fired through a thin, clear implant lens directly at the capsule. The nominal energy level listed on the laser is often in the 2-4 mJoule range. This is the energy range that the doctors are used to using. When aiming further back into the vitreous space, the laser is fired through a thick treatment contact lens, a thicker biological crystalline lens, and deeper into the vitreous. The laser can be partially blocked by the iris, and the focus and concentration of the laser energy is diminished when firing even slightly off the central visual axis. The result is that the laser energy must be set higher to compensate for these factors. These referenced studies used low energy levels which were inadequate to achieve the quantum bump in energy to get the vaporization of tissue.
2. TECHNIQUE: British study describe their technique and approach to try to disrupt the posterior hyaloid face and attempt to sever the suspensory strands that hold the floater in place. They were primarily trying to move the floater out of the way instead of actually vaporize the floater material. I have very rarely seen the opportunity where either of these techniques worked very well.
With these considerations, I’m actually surprised they got even a 30% success / satisfaction rate.