IN THE CLINIC
Call the specialist? Flashes, floaters and that sinking feeling
Mid-60s is the highest age peak for a retinal detachment
IN THE FIRST OF A NEW SERIES looking at the types of conditions seen in optometric practice that might warrant a referral to a specialist, one-time optometrist now consultant vitreo-retinal surgeon, Stephen Lash, looks at flashes and floaters... We have all been there, myself included all those years ago as a locum optometrist working weekends to pay for medical school. It’s a busy clinic, the pressure to ‘convert’ (profit is the requisite of business not the purpose) and you’re running behind. The next patient (squeezed in as being flagged with a potential problem) presents with textbook (or perhaps Google searched) symptoms of flashes and floaters, and has them down so well you are sure they have rehearsed. I am not being disrespectful to patients; history has to be teased out and refined – that is our job as professionals – using Occams Razor but ensuring Procrustes does not get hold of it (indugle me). This is a perfect storm and it means a late/no lunch, frustrated/delayed patients until closing, and the danger that this patient could lose their sight and you your career. Litigation in this area is second to none. So, how can I help? Firstly, let’s get a handle on the likelihood of a problem – before we reach for our Volk lens.
LOOK, ASK, EXAMINE Look at them. Posterior vitreous detachment (PVD) occurs in 25 per cent of 50-year-olds and 80-90 per cent of 80-90year olds. It is more common at an earlier age in myopes. You fear retinal detachment (RD) and although the background risk is around one in 10,000, there is a bimodal profile with the highest peak in the mid to late 60s: 6.00D of myopia = 6x the risk. Ask them. What are the flashes like? Thunderbolts or shimmers? It is a classic misdiagnosis. If it shimmers for around 20 minutes in both eyes, you can ‘relax’. If there are thunderbolts, you cannot. With
floaters, ask if there are lots of distinct ‘bits’. A patient once told me she had ‘black rain’, which is a perfect description of muscae volitantes – or ‘flying flies’ for the non-Latin speaker. Are the flashes and floaters related? If your patient presents with a very short history (24 hours) of flashes and a shower of floaters, they are much more likely to have a retinal tear. The risk of a tear is between five and 10 per cent. Tears in the acute situation have around a 50 per cent chance of progressing to a RD. Finally, ask if the floaters have coalesced into a fog such that the patient cannot see. A fundus obscuring vitreous haemorrhage (VH) has an extraordinarily high risk of a tear – up to 75 per cent – and they need to go to eye casualty. Of course, if they reveal that they are losing vision from an edge (I’ve never really understood the curtain thing – mine pull in from both sides) then get your receptionist to start looking up eye casualty’s number. Examine them. This is obvious but critical, especially if detachment follows. Is there a relative afferent pupillary defect? Check the pressure; low might be RD, high might mean Schwartz syndrome with photoreceptors clogging the trabecular meshwork (I have been caught out by that). Cells in the anterior chamber and flare in RD? I know you are itching to pick up that Volk, but leave it alone and look at the lens. Pseudophakic? One piece in the bag – uncomplicated surgery – but a higher risk of RD (1.7x). A three-piece lens in the sulcus suggests complicated cataract surgery, which has an even higher risk (44x). Leave that Volk alone, now look at the anterior gel and get the patient to look up and down
and stop. Look for pigment cells (apologies to Schaeffer and the tobacco industry this time). Pigment cells are a concern, lack of them is not reassuring. Is there blood? This is an even higher concern. Now pick up your Volk, look for Weiss ring and the retina. Be systematic, work round eight positions of gaze. Supero temporal is the most common quadrant for a horseshoe tear, and inferotemporal is most common for schisis and dialysis. After textbook history and examination, nothing. I am sure some of you have examined well, found nothing and both ended up in trouble. Document your negative findings and warn. If patients develop an increase in flashes or floaters or fading vision, they should telephone. Tears present from day one to day 30 with the average on day 11, so do not score an own goal at the last hurdle. Having tried to allay your fears over flashes and floaters, tears and detachments – all pressing and urgent issues – next time I will move on to a key question for all those who ‘look’: what do we do when we see something? I am not talking about the Volk lens and peripheral retina lesions, but central issues revealed by the rapid increase in access to OCT scans. Do you refer or not? We will go through some natural history and explore the variety of findings that cause heads to be scratched and referrals to be made or not. Stephen Lash BM, BSc (Hons), MCOptom, FRCOphth, MBA works part-time within the NHS and part-time as a private ophthalmic surgeon. www.stephenlasheyesurgery.com Vision Now MAY 2021
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