Monday, 30 April 2018

Low vision

Back with another random insight into patient's lives.

Visual impairment is a very subjective thing, I've seen people with best corrected VA of 6/12 (the legal driving standard) say their vision is fine, mostly non-drivers thankfully, and I've also seen people request referral for cataract, and be listed for surgery, with VA of 6/6+ in the affected eye because they feel they are getting glare and having problems whilst driving at night. I suppose it's all to do with how much of a problem their vision is causing them, which is why the cataract referral guidelines now make no link to VA and it's based on how the patient is being affected. I still try to put off patients with 6/6 VA, particularly if it's unaided, as they may well end up with worse vision after operation if the IOL isn't exactly the right prescription.

Low vision is also difficult to fully classify as some people don't want to admit that their sight is failing and using magnifiers is the last step to losing their independence. However just because you have low vision it doesn't mean you have to be downhearted, although there is an increased incidence of depression in patients with low vision.

A little while ago (read a few months as I haven't got round to writing this up) I had a patient in who had accepted his low vision and was thriving. Mr L, a gentleman in his mid 70s, came into the store and as he was being booked in the optical assistant asked how he felt his vision was with his glasses, to which the patient replied it was terrible. At this point the optical assistant was bracing herself for a rant about how we needed to do much better but the patient just commented that it wasn't any different from normal. The patient was then pretested and brought upstairs ready for the sight test. I quickly popped out of my room and grabbed the board to have a quick scan to see what the patient was like before calling them in, saw VA of 6/45 for both eyes from last sight test, and my heart sank. I was initially hoping it was a mistype for 6/4.5 but that would probably be a bit too much to expect for the average 70 year old (I have managed it at times). So I called Mr L in and started the test, it turned out that he had extensive dry AMD in one eye and had had wet AMD in the other eye but the treatment hadn't helped, just resulting with extensive macular scarring. This had happened about 10 years ago so patient had adapted to the poor vision, and whilst they couldn't drive or see much for close work they were confident getting around, albeit steadily. The test was more to just check there weren't any changes to the back of the eye, there weren't, rather than expecting any massive improvement in his vision. The actual refraction part of the sight test was relatively quick; retinoscopy will give a much better idea of prescription compared to subjective in this situation (especially when don't have a specialist low vision chart) then a quick subjective which surprisingly enough didn't reveal much of a change and certainly wasn't improving his vision in any substantial way so we left his spectacles as they are. Chatting with him after the test had finished I discovered he was registered severely sight impaired and had regular checks with the Welsh low vision service so had a range of magnifiers at home. He knew his vision was poor and that it wasn't going to get any better but was making the most of what he had and not letting it get him down.

So the moral of the story is just to make the most of what you've got, if you can improve it then take the opportunity.

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