This is seen with direct visualisation as a solid chunk of matter becoming a gas bubble and rising in the vitreous cavity. The size of the bubbles is akin to those seen in the anterior chamber with Selective Laser Trabeculoplasty (SLT) using a YAG laser.

Regrettably, not all vitreous opacities can be treated with YAG Vitreolysis and pars plana vitrectomy remains the definitive procedure to eradicate troublesome floaters.3

The best ones are those which are:

Easily visualised with a biomicroscopy lens (say a 90D or a 78D) at the slit lamp with the patient looking straight ahead (as opposed to ones further out in the periphery seen only in extremes of ocular gaze) Isolated, well circumscribed ones (as opposed to diffuse, ‘fluffy’ cloudy ones) Not too close to the posterior lens capsule (in a phakic eye) and not just in front of the macula.

More Complicated Cases

It is very difficult to dissolve the thick curtain-like ‘veils’ seen at the interface between a posterior vitreous detachment and the fluid behind it (i.e. opacification of the posterior hyaloid face). Yet these are very common with posterior vitreous detachments.

Pseudophakic eyes are easier to treat than phakic eyes but the latter is not a contraindication. This is because the optical clarity is better in a pseudophakic eye and there is no risk of induction of cataract if the lens is inadvertently hit with the laser beam. However, multifocal IOLs make focusing the laser beam more challenging.

Weiss rings are perfect for treatment with YAG laser vitreolysis.

On the other hand, there is no hope of significant improvement in cases of asteroid hyalosis. Fortunately, these patients are usually oblivious to the multitude of opacities in their vitreous cavities.

Despite the restrictions above, many eyes are suitable for YAG laser vitreolysis.

How the Procedure is Performed

YAG laser vitreolysis is done in an office setting, much like a YAG laser capsulotomy. The pupil needs to be maximally dilated. Topical anaesthesia is used to allow a contact lens to be placed on the eye but the procedure itself is painless. No sedation is necessary. It takes about 10 to 15 minutes… longer than a capsulotomy or an SLT.

Pressure on the cornea with the contact lens often causes the cornea to become a little cloudy and this restricts the amount of time the operator has to complete the process. Highly mobile floaters take longer as one has to wait for them to float back into view before firing the next shot. For numerous floaters, or ones that are large and poorly circumscribed, the procedure is performed over two or three sessions.

You can see the procedure being performed at vitreousfloatersolutions.com.

The Risks

There are no known long term risks with YAG laser vitreolysis. However, it is possible to damage the crystalline lens (causing an instant cataract), hit the retina (causing a retinal burn) or cause a rise in intraocular pressure.4,5

Additionally, it appears that pseudophakic eyes are most likely to have a rise in IOP following vitreolysis, particularly if they have previously had a posterior capsulotomy. The mechanism of the pressure rise is unknown, though migration of microdebris into the anterior chamber has been suggested as a possibility.5

Retinal detachment has been reported with YAG laser application to the vitreous, though not for the treatment of floaters.4

Because vitreous strands are lysed during the procedure, relieving any traction on the retina, it has been suggested that the procedure may reduce the risk of a retinal detachment in the long term after detachment of the vitreous.6

In experienced hands, the only likely risk is that there are some persistent floaters remaining, which can lead to suboptimal levels of patient satisfaction. Obviously, vitrectomy is the definitive treatment for these troublesome floaters as it is likely that every single one will be removed.

Post-treatment Requirements

To reduce the risk of an IOP rise, topical anti-glaucoma medications are instilled immediately after the procedure. No other medications are prescribed. I have not seen iritis warranting corticosteroid prophylaxis to date.

An IOP check and review of any persisting floaters is usually performed a week later and, if possible a month later, as rises in intraocular pressure can be delayed.5

Some You Can’t Help

Patients can be very irritated by floaters in their field of view and too often are told “there’s nothing that can be done”. However, they are often very motivated to seek relief. This is evidenced by the numerous floater forums which go into the subject matter in great detail.

Regrettably, obsessive patients are attracted to practices that offer YAG laser vitreolysis. A large floater in the visual axis can be vapourised yet the patient still manages to find a couple here and there, which they want treated.

Sometimes it seems that there is no end to their pre-occupation with the tiniest little opacities, and a floater that I can’t see, even one they feel is in the centre of their visual field, continues to bother them.

It’s possible to question whether they are seeing streaks in their tear film rather than real floaters. These patients will be disappointed with any treatment we can offer them.

Conclusion

Though not new, YAG laser vitreolysis has advanced to a degree that allows the successful relief of symptoms from troublesome floaters in many patients. Success is maximised with careful patient selection. Risks need to be explained to patients but the procedure avoids some of the risks of intraocular surgery. It should be considered as a possible alternative to pars plan vitrectomy for floaters though the latter remains the definitive treatment.

Dr. Con Moshegov completed his medical and specialist training in Australia and undertook further training in England before commencing practice in Sydney. He performed his first refractive laser procedure in London in 1994 and has had widespread experience in cataract and laser eye surgery. Dr. Moshegov is a consultant to major ophthalmic companies who seek his input into the incorporation of new technology into the clinical arena.

Weighing Up the Options Dr. Devinder Chauhan In the past, vitrectomy has been commonly considered the gold standard for the treatment of debilitating floater symptoms, but the risk of complications means that it may not be suitable for all patients. Under such circumstances, laser vitreolysis may provide a viable option to eliminate the visual disturbances caused by floaters. Pars plana vitrectomy provides an effective way to eliminate floater-related symptoms, leading to substantial improvements in stray light and contrast sensitivity measurements, as well as improved quality of life for patients.1,2 Vitrectomy is extremely effective in removing floater symptoms, since the vitreous is removed entirely. In one study, it fully resolved symptoms in 93.3 per cent of patients.3 Another study noted that symptoms were completely resolved in 84 per cent of patients and an additional 9.3 per cent of patients had a reduction in symptoms.4 However, like other invasive surgical procedures, vitrectomy carries various risks that need to be considered on an individual patient basis before the procedure is performed for the treatment of floater symptoms. One of the most frequently discussed risks associated with vitrectomy is the development of cataracts.5 One recent study noted that 96 per cent of patients undergoing 20-gauge pars plana vitrectomy (PPV) developed at least mild lens changes. Indeed, vitrectomy can be considered a catalyst for the development of cataracts in phakic eyes, speeding up the process of lens opacification even in younger patients. Other potential complications of vitrectomy include retinal tears and detachments, as well as endophthalmitis, vitreoretinal haemorrhages, glaucoma and macular oedema.6 However, for many patients, resolving the severe symptomatic effects of floaters substantially outweighs the adverse effects of potential intra- and post-operative complications. Additionally, recent technological developments have led to a reduction in the rate of complications. In my experience, vitrectomies are ideal for patients with multiple floaters that are dense. Where there are alternative non-invasive options for floaters that are smaller and lighter, such as laser vitreolysis, it would be advisable to pursue these, since they entail less risk of complication. Dr. Devinder Chauhan MBBS, MD, FRANZCO FRCOpht is a retinal and macular specialist. His senior ophthalmology training was at Moorfields Eye Hospital and he went on to undertake three further years of retinal training, with a year each at the Royal Victorian Eye and Ear, Bristol Eye and Moorfields Eye Hospitals, before working as a consultant in vitreoretinal surgery at the Birmingham and Midland Eye Centre in Birmingham, UK. Dr. Chauhan is a member of the Oceania Retinal Association and European Society of Retina Specialists. He is currently involved in teaching vitreoretinal surgery to local eye surgeons in Myanmar, as part of a world’s first such program. He practises in Melbourne at Vision Eye Institute. References

1. J Sebag, MD, FACS, FRCOphth, FARVO, Reassessing the Surgical Treatment of Floaters, Retina Today, March 2014, 66, http://retinatoday.com/2014/03/reassessing-the-surgical-treatment-of-floaters/.

2. Foos RY, Wheeler NC. Vitreoretinal juncture. Synchysis senilis and posterior vitreous detachment. Ophthalmology. 1982;89(12):1502-1512.

3. YM Delaney, A Oyinloye and L Benjamin. Nd:YAG vitreolysis and pars plana vitrectomy: surgical treatment for vitreous floaters . Eye (2002) 16, 21–26. doi: 10.1038/sj.eye.6700026.

4. de Nie KF, Crama N, Tilanus MA, Klevering BJ, Boon CJ. Pars plana vitrectomy for disturbing primary vitreous floaters: clinical outcome and patient satisfaction. Graefes Arch Clin Exp Ophthalmol. 2013 May;251(5):1373-82. doi: 10.1007/s00417-012-2205-3. Epub 2012 Dec 19.

5. Charles P. Wilkinson, Safety of Vitrectomy for Floaters–How Safe Is Safe?, American Journal of Ophthalmology 151, no. 6 (June 2011): 919–20.e1, doi:10.1016/j.ajo.2011.01.037.

6. Hao Feng and Ron A Adelman. Cataract formation following vitreoretinal procedures. Clin Ophthalmol. 2014; 8: 1957–1965. Published online 2014 Sep 23. doi: 10.2147/OPTH.S68661.

References

1. Aron-Rosa D and Greenspan D.A. Neodymium:YAG laser vitreolysis. Int Ophthal Clinics. 1985; 25: 125-34.

2. Tsai WF, Chen YC and Su CY. Treatment of vitreous floaters with neodymium YAG laser. Br J Ophthalmol. 1993; 77: 485-8.

3. Delaney YM, Oyinloye A, and Benjamin L. Nd:YAG vitreolysis and pars plana vitrectomy: surgical treatment for vitreous floaters. Eye. 2002; 16: 21–6.

4. Tassignon MJ, Kreissig I, Stempels N and Brihaye M. Indications for Q-switched and mode-locked Nd:YAG lasers in vitreoretinal pathology. Eur J Ophthalmol. 1991; 1:123–30.

5. Cowan LA, Khine KT, Chopra V et al. Refractory Open-Angle Glaucoma After Neodymium–Yttrium-Aluminum-Garnet Laser Lysis of Vitreous Floaters. Am J. Ophth. 2015; 159 (1): 138-43.

6. Laser Treatment of Eye Floaters. John R. Karickhoff. Washington Medical Publishing. 2013.