A Spectacle Discovery?

[Ken G]

Hello all!

Please forgive the somewhat interrogatory tone of this, my first post. It's just that I am very keen to get people's opinions.

I am 43 years young, and was first diagnosed at 19. At that time my KC was moderate to severe in my right eye, and mild in my left. The advice I received at that time was to persist with spectacles, it being the opinion of both my optician and the Professor to whom I was referred that contact lens wear might actually accelerate the progression of the condition. After a couple of years attendance at the eye hospital I decided to opt out of the eye care system altogether. I guess I was scared and didn't want KC to dictate my life choices. So I foolishly 'got by'.

Now, twenty two years later I have decided to re-engage, and made an appointment with a KC specialist in my area. This was largely fuelled by a frustration at not seeing well, but also because it was my understanding that by the time someone hits forty the condition is likely to have stabilised. Therefore, if I were to wear lenses this would not cause the KC to progress. I thought that my KC had progressed to the point where correction witgh glasses would no longer be possible.

In making the appointment I had anticipated this meaning getting fitted for lenses. The consultant quickly detected my utter terror at this prospect and expressed a view that at my age it would be highly unlikely that the KC had not stabilised (this based on his many years working with KC patients), and that, if at all possible, I should try and get another prescription for glasses. Interestingly, it was also his view that contact lens wear might make trhe KC worse. This I was able to do, albeit that the correction does not give me anything like perfect vision, but certainly good enough for driving.

All of which leads me to the following. Whilst for many sufferers the rapid transition from glasses to lenses is both unavoidable and necessary, is there an argument that for those with more mild/moderate conditions to sacrifice 20/20 aspirations, and to 'get by' without lenses? This in the hope of seeing out their teens/twenties at which point there is greater likelihood of stability?

My second question is more personal and bizarre! My new prescription glasses are giving me improved acuity and I'm pretty happy with them. Then, just the other day I happened to accidentally tilt my spectacles on my face (a la Eric Morecambe for those of you old enough to remember!) and was astonished at the result. Basically by looking through my glasses at an angle (probably about 20 degrees off centre) I can see though my good eye with a sharpness and clarity the likes of which I have not experienced since my teenage years. I get the same result from my spare pair.

Obviously I have made an appointment to go back to the optician, but strange as it may seem, I am petrified that this correction cannot be achieved in a conventional prescription. Can anyone shed any light on this? Might this be an aberration, or a quirk of KC, or what?

Thank you for reading.

[jayuk]

Ken

You raise some very good points! and I find it amazing that you actually just dropped out of the system and got by for all those years!

I think the transition from Specs to Lens is based on the Individual. When a person gets KC its hard enough acknowledging the fact that you have it, but its worse when the vision deteriorates. An element of mind games kicks in, and "we" want to get our initial vision back.....thats why I would suspect people continue with the management path. In hindsight, I can see your point on whether its necessary and whether the individual should make do with 6/12 rather the 6/6 with lenses........

Your Specs comment I have also experienced in the past 2-3 months. If I take my glasses off and look through the off centre whilst holding them close to my eyes, I can achieve variable vision, some times good sometimes a little worse (post graft eye).

To say that Lenses could make KC worse is a whole topic in itself, in my opinion. There is a valid concern on whether Contact Lenses actually warp the already distorted Cornea, and in the process increase scar tissue.....however I really cant see research being conducted into this, as if this was found to be true, than would would be the implication to "normal" eyes?.......

J

[GarethB]

Your comment re-specs is quite common among people with astigmatism. When I wore specs I could make people look fatter or thinner depending which way I roatated the specs!!!!

Regarding sacrificing 6/6 is also a good point, perhaps we set our expectations too high, modern computer screens mean we can still see a good proportion of the screen information with a large enough screen and still sit a norma distance away so reduce eye strain. As for driving, the legal requirment is not 6/6 in each eye, just so long as you can read a normal number plate in normal conditions at 20.5m then you are considerd to beet the legal requirments.

It is something perhaps we should all think about, especially those with mild/moderate KC. For me however, I could not reach the minimum requirment to drive for my right eye with glasses, but I can easily with the left and as you can legaly drive with on eye, perhaps I would have been better with this option?

Now departing to think about it!

[Ken G]

Thanks for the responses guys!!

An interesting study might be to identify the 'threshold' at which most people opt for lenses, and then compare this group's KC progreaaion against those who continue with specs. If it were found that the former population had comparatively greater progression, then this would have potentially profound consequences for the early management of the condition.

So what is the deal with this 'angled' spec business. I am sitting in front of my tv and pc with my glasses perched at a weird angle and my three year old is taking the p***!! I guess I'm trying to control my expectations in case the optician cannot replicate it, but having now tasted what it feels like to see almost perfectly, I'm scared I won't be able to let this one go! Any thoughts or advice would be extremely welcome

Cheers!

[John Smith]

Hello Ken, and welcome to the forum!

I too have experienced the spectacle problem. In my case it was slightly simpler: "if I only look through the bottom edge of the lens, things are clearer". This turned out to be correctable as the dispensing optician had mis-measured me slightly.

I don't know if it's just me or if it's common to KCers in general, but I can detect the slightest improvement in acuity which would mean little to most people.

Certainly, as you tilt the specs lenses so that they are at an angle to the face rather than approximately parallel to it, you are looking through a slightly thicker portion of glass than you would be doing normally. More glass is likely to be a stronger prescription.

I know many opticians will not prescribe the best possible correction, but slightly under, citing reasons such as making your eyes work a little, and needing to keep a balance between left and right eyes to ensure that you don't get headaches or double-vision.

Well anyway, that's my 2p; maybe we can coax a response from any of the optometrists out there...?

[Lynn White]

Ahem...

Well I was tempted John... so I am here to answer!

Now.. the tilting of specs thing is actually quite common amongst all spectacle wearers... in fact, I have had one or two patients (NOT KC) who claim they see better through their specs if they are looked through back to front and upside down!

What is happening here is that looking through lenses that are tilted induces aberrations in the optical "system". Its like misaligning a lens in a telescope. Normally this would make vision more blurred but in some people, this actually makes the vision better.

This is because eyes are complex and have their own set of aberrations and tilting the lenses can sometimes induce other aberrations that offset the ones in the eye. This is actually a well known factor in fitting spectacles with progressive (varifocal) lenses. The angle of tilt (and it has a name: the pantoscopic angle) is very critical in these lenses, making the difference between comfortable reading and uncomfortable blur.

Now... KC'ers do have more aberrated eyes by definition and usually have high astigmatism and high powers.. all of which tend to mean that tilting lenses has more effect. I find that this happens for me also - and I am not a KC'er but I DO have a quite a high prescription.

Now, if you go back to your optician Ken, he may be able to adjust the frame so that they tilt more and so clear things up a bit. But your fear is also valid, we cannot really incorporate the tilt factor into the actual lens - not a standard lens anyway.


There are new spectacle lenses becoming available that can correct individual aberrations - but you need to have your eyes looked at by a special (expensive) machine to calculate your exact whole eye aberrations and even then it does not work for all angles of gaze when translated into spectacles.

John... its not that looking through the edge gives you a stronger part of the lens - its that tilting gives you line of sight through a more aberrated part of the lens!

Now then... to your question about contacts making KC worse..

This to some extent is a difficult one to answer in the UK because most agressively progressing KC'ers are detected when young and fitted with contacts. Only those that are not THAT progressive escape that net due to our health system.

Many of those who wear RGP's end up getting grafts because of corneal scarring and it is thought by some professionals that this is more a consequence of RGP wear than KC itself. However, the fact that people can actually SEE with RGP's is thought to mitigate the fact of scarring.

Now... as some know here... I worked for nearly three years in Trinidad, where KC is rife, as it is through a large area of the Caribbean. Now there I saw a good many patients who had progressed massively without ever coming near a contact lens. They had marked corneal scarring as well.

I also saw a great many "sub clinical" KC'ers as well who only advanced a very little before stabilising and they were perfectly happy with spectacles.

Just seeing so many KC'ers in one place confirmed for me the received wisdom that KC can stabilise at any time and if you can, at the point of stabilisation, see comfortably in spectacles then go for it. If you can't, then at the moment contact lenses are a good option.. Soft ones are especially good for mild to moderate KC.

Jay.... you say that there is an implication for mormal eyes if CL's cause scar tissue on KC eyes. No.... there isn't really. KC corneas are different to "normal" ones as they are thinner, so that they ARE more vulnerable to scarring because of the nature of the condition and people have been wearing CL's for years and this has not been a problem..

I am trying to put together a screening program for KC in Trinidad with the University of Tenessee Space Institute in order to try and detect various levels of KC and hopefully follow them up over years. This is a valuable exercise just because there are so many KC people there in one place. This study may well answer some of your questions, Ken

[Ken G]

Lynn

Thank you very much for taking the time to offer such a comprehensive and considered reply. I am most grateful.

I went back to my optometrist last week and she offered pretty much the same explanation for the vision improvements when the glasses are tilted. The metaphor she used was the hall of mirrors at the fairground.

Nevertheless. I was given another eye examination to determine whether any improvements could be eked out. I need to be careful not to misrepresent what she said, but it was something along thre lines that the eyes get used to working in a different way after a new prescription, and that sometimes this can result in some variance in eye test performance. Anyway, she was able to get me to one line before the 20/20 standard, a great result for me, but one that I was sure I had achieved at the first appointment. I'll ask her about this when I pick upmy new prescription. I was however, able to judge the new prescription against the old, and there has undoubtedly been an improvement. As I'm using my spare set at the moment, I'll compare what I get from the new prescription with the 'tilt' result.

[Lynn White]

Ken...

Getting spectacle prescriptions "right" for KC'ers is very difficult and I will try and explain a bit more here because there can be a good deal of frustration between patients and their optoms.

First let me explain about testing the sight of "normals". The major part of the refracting power of the eye is carried out by the cornea. In most people this is reasonably regular and consequently any astigmatism is regular.

What does this mean? Well in basic terms, astigmatism is when the corneal surface is curved more in one direction than in the other. The most usual analogy is one of a section cut from a rugby ball, in that a rugby ball has one meridian that has a flattish curvature and the meridian at 90 to that is more steeply curved.

When applied to the cornea, this gives different powers in meridians that are 90 degrees to each other. This is regular astigmatism.

Spectacle lenses that are made to correct astigmatism (toric lenses) are also made so that their main power meridians are at 90 degrees to each other. So far so good.

BUT - when you get keratoconus, all this nice neat regularity flies out of the window. Even in mild to moderate KC, astigmatism is generally irregular. This means the power meridans may be at 80 degrees to each other and you just cannot make standard spectacle lenses to match this, so any vision through these lenses is never "right".

Added to this problem is that just even finding the right prescription can be a nightmare. Our usual tools for measuring the power of the eye - retinoscope and auto- refracting machines are often made less effective by the distorted images presented by a KC eye. Often, once we have got a ball park figure, we then have to rely on subjective methods.. ie asking you what is best.

Then we are back to the problem that we are trying to correct your vision with lenses that are designed for normal eyes with regular astigmatism. So you may find your optom asking "Is your vision better in position one or two?" and you reply in frustration well.... number one is sharper but has a lot of ghosting and two has less ghosting but is blurry!

Once you have got a reasonably clear prescription and your brain has adapted to it - you then get more idea of what kind of option you prefer to see with and we can refine it better - which is I think what your optom was saying to you. Yes you probably read the same line last time... but not with the same level of confidence and reliability, I would say.

The whole issue here is that the KC eye is bedevilled with large amounts of aberrations and distortion which simply cannot be dealt with by standard optical correction. This is why there is generally a quick exodus to contact lenses which neutralise all these distortions fairly effectively.

One final word here.... in the end analysis you see with your brain, not your eyes... the eyes are only the messenger. This is why some people cope better than others and why a positive attitude can help enormously!!!

Lynn

[rosemary johnson]

Ken suggested that a study on the relationship between rapid KC progression and early move to contact lenses (cf. remaining in specs) would have implications for KC management.

I'm sure there is a *huge* correlation there!
But not that there's an implication for management.
Put simply - the faster one's KC is progressing, and the faster one's vision is deteriorating as a result, the faster you'll get into lenses so as to be able to see anything, and to be able to get on with life, study, etc.
If you can still see to cope in specs, fine; if you can't, you'll want lenses sooner.
I'd got to the stage where all I could see in glasses was the dust on the lenses even before I got the first set of lenses (PMMA sclerals, in 4st form of grammar school) and couldn't read the blackboard from the front row of the classroom, all in under 18 months of bing able to see the board fine from the back row with my specs on.

I think this is what the statisticians would describe as correlating non-independent variables.

Rosemary

[Ken G]

Hi Rosemary

Clearly when the KC progression is rapid, then it is necessary and unavoidable to move quickly to cl's.

The circumstances I'm talking about are when decent (depends on how you define this I guess) vision can still be achieved with specs. At this stage, is there a case for persisting with glasses rather than moving to lenses, RGP in particular. One might not be able to achieve the same acuity, but it could be argued that this is a sacrifice worth making if there are bona fide concerns about RGP's
accelerating the progression/scarring.

Lynn

Thanks again! Fascinating stuff. Your description of the eye examination is spot on, and your post has helped me get a few things clear in my mind. This new and expensive eye examination machine sounds interesting too.

I will enjoy asking my opthal about whether my improved prescription provides acuity approximate to that viewed through the pantoscopic angle!!!!