Laser vitreolysis uses a Neodymium: Yttrium-Aluminum Garnet (Nd: YAG) laser to achieve “optical breakdown” and to vaporize floaters within the eye.
The YAG laser is commonly used in other eye procedures including posterior capsule opacification and peripheral iridotomy. For those common treatments the laser is used to disrupt tissue, however if these settings are used for vitreolysis the floater will be fragmented into small pieces. Therefore in vitreolysis the laser is set slightly higher. The surgeons offering this type of treatment may have various types of YAG laser e.g. Zeiss, Litetechnia, Microrupter II laser from Lasag.
After dilating their pupil, a numbing eye drop is given to the patient and a special contact lens for treating eye floaters is placed on their eye. Then the laser, which is focused to a 6 micron spot, is carefully aimed and either the floater itself or its attachments are vaporized so that the floater is repositioned to a different part of the eye. This disruption also helps the eye to absorb any remaining particles. After vaporizing the big floater or floaters the doctor may have to leave tiny particles that are just too small to aim at.
The disruption is carried out with a beam of invisible light through the pupil. There is no incision or discomfort. Depending on the type and number of floaters, the procedure may take as little as 5 minutes or up to half an hour. Postoperatively there are no restrictions on activities.
In general it is not possible to eliminate all floaters in one sitting. The two main reasons for this are:
- A hazy cornea caused by the rubbing of the contact lens. This prevents adequate focusing of the laser.
- Most experienced doctors will limit the numer of shots to about 500 per session. This is often not enough to treat all floaters present. It has been observed that sessions of more than 1000 shots can cause a raised intraoculair pressure.
Laser vitreolysis is generally considered to be safer than a classic, surgical vitrectomy since it is less invasive. Despite a variety of studies describing this procedure as a treatment for vitreous floaters there is no published proof about its safety and efficacy and it is not widely practiced. This may be for a couple of reasons: many ophthalmologists regard eye floaters as harmless and believe that people will learn to live with them. Additionally, it is a difficult technique to master there is no formal teaching available which can lead to bad results such as central hits to the crystalline lens.
The success of laser treatment very much depends on the type of floaters and their position. Dr Scott Geller writes that some patients, predominantly those under the age of 35, cannot be treated (for floaters) as the floaters may be too close to the retina in an area referred to as the ‘pre-macula bursa’ (the consequence of which is that the floater is more dominant in the patients view, its size exaggerated as a result of the distance to the retina). To qualify this Dr Geller recommends ensuring that your ophthalmologist uses a Goldmann examination lens.
There are five subtypes of floaters that can be treated with lasers, in general:
- Weiss rings with approximately 95% success rate.
- One or two small to moderate sized floaters can be treated with approximately 85% success rate.
- Numerous clumps, or clumps that are large and free-floating in the vitreous, whilst difficult to treat, can still be treated. They will often need several sessions which can be spread out over consecutive days or over months.
- A small peripheral floater this crosses the central line of sight with eye movements. These are very challenging because in the center they are too close to the fovea to be safely treated and have to be treated in their peripheral location. This can sometimes be done with the Karickhoff 30mm off axis lens.
- If a large degenerative cloud is suspended within the line of sight with one or two strands, the doctor can cut the strands which in effect relocates the floater clump to another part of the vitreous. Success rates are higher as the results are more dramatic for these floater types (usually approximately 90% or higher)
But any measure of success is very subjective in definition and therefore hard to quantify. It depends on the detail of examination and one’s own definition of success. Some forums report that the results can be variable and in particular some users reporting no change or indeed a worsening of floaters. As such we recommend you consult with your surgeon beforehand to ensure the right expectation is being set.
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Reviewed by Feike Gerbrandy MD, Aug 2012.