In the clinic

I am sure you have come across many people with floaters. Can we do anything about it, or perhaps more importantly, should we do anything about it? In this article, I want to explore the options – focusing on primary floaters as oppose to ‘pathological floaters’ like vitreous haemorrhage or sudden onset.

The vitreous gel collapses throughout life; fluid pockets appear and the collagen clumps. Seeing bits float around inside your eye is not uncommon – 76 per cent in one study1 – but some people are willing to risk blindness and even death to get rid of them2 . When we examine the eyes, we usually see very little and this puts us in a difficult position; offering ‘dangerous’ surgery to remove something we cannot see. It then becomes easier to tell the patient to ignore them and send them on their way.

But floaters are common and people are willing to take a risk to get rid of them. So, is vitrectomy dangerous? No. In fact, rapidly progressing technology within this sub-specialty is leaving more general ophthalmology behind. US ophthalmologist/vitreoretinal specialist, Ferenc Kuhn, says to his patients that the most dangerous thing that can happen during surgery is him dying. There is a one to two per cent risk of retinal detachment, but it’s the same as any other indication for vitrectomy – so why not for floaters?

SCATTERING LIGHT EFFECTS Examining floaters involves looking into a dark globe; the light is scattered back off the vitreous floaters. Looking out of an eye with floaters involves looking through them and suffering the forward scatter. A former floaterectomy patient, who also happens to be a professor and math genius, was so impressed with his result that he started to model these effects – and the initial results are astounding. This scatter effect could be up to one million times worse for the patient. Those of us who treat floaters have always suspected as much. Interestingly, a 2015 study found that surgeons with floaters themselves were more likely to offer their patients surgery3 .

The best objective measure of the effect of floaters is contrast sensitivity function (CSF). Posterior vitreous detachment (PVD) can result in a 52 per cent reduction in CSF4. In a small series, we have seen similar effects on lower contrast lower frequency aspects of CSF. Further objective evidence can sometimes be gained using the shadowgram function on OCT. Anything we can do to demonstrate an objective effect is to be welcomed. DIFFERENTIATING THE DISEASE What do I really like to hear and see in floater patients? I like to hear a global reduction in vision intermittently, like a windscreen wiper across the vision. When I hear this, I often see a PVD with the gel bunched up behind the lens; especially in psuedophakes and even more so when it is a multifocal. The refractive and diffractive gymnastics these lenses have to perform seem to further interfere with the effect of floaters.

With a pseudophakic eye, the nodal point sits just behind the intraocular lens, just where the bunched-up gel sits. I often visualise this effect to patients by holding my hand close to the floor, demonstrating the sharp shadow formed and then moving my hand upwards so the shadow blurs, fades and spreads. The floaters close to the retina form the sharp bits but it is my contention that the larger, more diffuse shadows from gel at the front of the eye are the real issue and impossible to get used to.

Like any disease, floaters can have a psychological overlay and I am wary of perfectionists who are very young (no PVD) and seem overly bothered by floaters and other entoptic phenomenon. Surgery does come with a risk, but up to 94 per cent of patients are happy after surgery5. I always quote Mr S, who came for floaterectomy surgery. I was unable to induce a PVD – and he was very happy. Two years later, he developed a giant retinal tear, had oil in the eye and we were unsure of his outcome. I asked if he was pleased he had had the surgery, and without hesitation he said: “Yes!”

REFERENCES

1. Webb BF et al. Prevalence of vitreous floaters in a community sample of smartphone users. Int. J. Ophthalmol. 2013;6:402-405. 2. Wagle AM et al. Utility values associated with vitreous floaters. Am. J. Ophthalmol. 2011;152:60-65. 3. Cohen MN et al. Management of symptomatic floaters: current attitudes, beliefs and practices among vitreoretinal surgeons. Ophthalmic. Surg. Laser

Imaging Retina. 2015;46:859-865. 4. Garcia GA et al. Degradation of contrast sensitivity function following posterior vitreous detachment. Am. J. Ophthalmol. 2016; 172: 7-12 5. Mason 3rd JO et al. Safety, efficacy, and quality of life following sutureless vitrectomy for symptomatic vitreous floaters. Retina 2014;34:1043-1045.

Stephen Lash BM, BSc (Hons), MCOptom, FRCOphth, MBA works part-time within the NHS and part-time as a private ophthalmic surgeon.