Kerasoft lenses and haloing/glare

[Ian Miller]

I have just started wearing Kerasoft lenses after 10+ years in RGPs (although for the last few months, i've only been wearing RGPs for a couple of hours a day due to tolerance issues). I'm almost a week into my first wearable set of Kerasofts, and have an appointment to go back for further adjustments in a week.

My vision in daylight is ok - not as good as with RGP lenses (especially in my peripheral vision) - but ok. However my night vision is awful. Every light has a massive halo/glare around it; streetlights, car lights etc all merge into one making night driving totally unsafe.

I appreciate it takes some time for the eye to de-mould from RGP use. However please can anyone advise whether Kerasoft, or any other soft lens for KC, can solve the problem of haloing/glare from lights at night, or whether soft lenses always have this problem? It is not an issue I had with RGPs. My KC is relatively advanced in both eyes, so the cone is pretty steep.

Many thanks in advance.

Ian

[munster]

I don't think any soft lens can fix that problem.

I think its inherit of the soft lens. A soft lens tends to mold itself to the shape of the cornea, due to its flexible structure.

An RGP on the other hand vaults over the cornea to recreate a regular surface.

I use Kerasoft 2 lenses and dark/night vision give me light streak circles around all light sources.

I'm currently getting fitted with Kerasoft IC's which I'm not confident about much improvement. I may consider trying RGPs, just to test my vision.

My crude drawing of vision with KS 2:

[Ian Miller]

Thanks for the info munster...although not really what I was hoping to hear...!

I would say the vision I am getting at night is worse than your drawing shows - the halos are probably 2-3 times the size at least

[munster]

TBH, it is only a crude drawing to show people what my vision at night looks like thru my eyes.

My light streak circles are bigger than I have drew. If only I was a good artist, then I'd be better at it

My consultant has said that, only a corneal graft will eliminate the visual errors caused by the damaged cornea.

[GarethB]

I have just started wearing Kerasoft lenses after 10+ years in RGPs (although for the last few months,

This actually has nothing to do with soft lenses, many people get this with RGP lenses too and it is all down to the lens fit. No lens can fix the problem completly, but a good lens fit will reduce it significantly to the point it has no negative effect on your night vision. The issues I feel you are most likely experiencing are the same as I went through and that is the cornea demoulding. Even a well fitting RGP lens due to its rigidity will shape the cornea to a greater or lesser degree. My right RGP drew the cornea out and is now flatter since wearing a soft lens whereas my left RGP flattened the cornea which is now steeper, but in both eyes the vision is far better with the soft lenses.

Prior to fitting soft lenses, I took a week off work with no RGP's which was one of the hardest things I've done, and when I first got the lenses, the vision was off for the first week or two, but came to what it should. It then slowly went off again as my cornea demoulded from the RGP lens but was still within driving limits, so we would get my vision as best we could and only change the lens once the vision approached the driving limit to keep lens chenges to a minimum. I had only been in RGP lenses for 4 years before becoming intolerent of them and it took my corneas 6 - 9 months for a majority of the demoulding to take place.

An RGP on the other hand vaults over the cornea to recreate a regular surface.

This is true, but because the RGP vaults the cornea, the space is filled with a pool of tears and the size of this pooling that determines the size of the halos.

For me with RGP lenses halos were always present and if they got worse I knew the lenses needed adjusting, since being on Kerasoft lenses for the past 5 years I have experienced nothing like this and my day and night vison in soft lenses is far better than it ever was in RGP lenses.

My consultant has said that, only a corneal graft will eliminate the visual errors caused by the damaged cornea.

This is utter rubbish, post graft you are extremely likely to still have these visual errors to a greater or lesser degree, this is why at least 50% of KC people post graft still need to wear contact lenses, most of the others wear glasses. The purpose of any corneal surgery for us it to provide a 'more regular' corneal surface whereby vision correction is easier. Your consultant must be doing something very special if the grafts he does eleminiates all visual errors because it means his post graft patients all have 6/6 vision without correction.

I appreciate you probably didn't want to hear that, but I find honesty is the best policy.

[Ian Miller]

Gareth & munster, thank you very much for your replies, and for the information. I will keep my fingers crossed that further lens adjustments will improve things.

munster - I think your drawing is a very good impression of night vision and the problem of haloing...I hope you don't mind if I take a copy of it to my next eye appointment to try to help explain the issue I am having!?!!

Thanks again

Ian

[munster]

munster - I think your drawing is a very good impression of night vision and the problem of haloing...I hope you don't mind if I take a copy of it to my next eye appointment to try to help explain the issue I am having!?!!

Sure you can take a copy, if it helps to explain your vision. Thats why I drew it. I have a larger image of that, you can get it here http://image.strangerdanger.eu/nite.jpg

This is utter rubbish, post graft you are extremely likely to still have these visual errors to a greater or lesser degree, this is why at least 50% of KC people post graft still need to wear contact lenses, most of the others wear glasses. The purpose of any corneal surgery for us it to provide a 'more regular' corneal surface whereby vision correction is easier. Your consultant must be doing something very special if the grafts he does eleminiates all visual errors because it means his post graft patients all have 6/6 vision without correction.

You seem to misunderstand me. I said "visual errors caused by the damaged cornea". He never said that I would be 20/20 vision. Just some specific visual problems would be eliminated.

Also, to note. I have never wore RGPs, and have only used Kerasoft 2 lenses. So my cornea is untouched from molding, just the naked damage on show.

[GarethB]

Also, to note. I have never wore RGPs, and have only used Kerasoft 2 lenses. So my cornea is untouched from molding, just the naked damage on show.

My response regarding demoulding was for Ian, hence the quote above my response.

Kerasoft 2 is another matter that I tried these once and I was very vocal on this forum regarding my views on how poorly these lenses performed. At the time, the moderators asked me to edit my post whereas the manufacturers of the lenses invited me to discuss the issues I was having further which I duly did and spent time with the R&D Director who had designed the lens. Once they saw how the lens fitted to my eye, they went and redesigned the lens that later evolved into the Kerasoft 3. Since this time I have been fortuante to be invited back several times so that they can try their new lens designs and materials on my eyes along with many other Kerasoft users.

I think the issue with Kerasoft 2 is partly down to the lens thickness because of the type of material used and if I recall correctly the optics are on the back surface, so the fit is never the same as you get from the fitting kit.

The Kerasoft 3 and IC is a very different material in that it is silicon hydrogel that can be lathe cut and although thicker than a normal silicon hydrogel it is much thinner than a Kerasoft 2 and has a similar oxygen permeability to an RGP lens. The Kerasoft 2 is less permeable to oxygen so some aborations can be creted due to oxygen starvation of the cornea. I have gone back and looked at the diary I kept when I tried Kerasoft 2, I would get halos start as a a ring the colour of the light I was looking at but if I was looking at a white light, it would later developed in to a circular rainbow. This was diagnosed as oedema which is water logging of the cornea as it tries to get the required level of oxygen from another source.

I beleive on the Kerasoft 3 and Kerasoft IC that the optics are on the front surface so the fit on the cornea remains unchanged from the fitting kit plus with oxygen permeability comparable with an RGP lens the vision and comfort is far superior. Unfortuantly many optoms still think a thick soft lens is needed to correct KC, my right eye is -7 or -8 (always need to look at the bottle), but the central thicknes of the optical zone is 0.15mm or 0.2mm.

[Whiteshepherd]

I would ask them if the lens if fitting correctly. I have ectasia and the left eye is worse than the right eye. The left lens whether it is a mini scleral or hybrid lens gives some distortions at night. Then I do have a 14mm lens that I can actually get no glare or halos etc but the vision is not as good. I would guess from my experience that the fit is not perfect yet. I tried the Clearkone by Synergeyes for a while and the daytime vision was good but at night the streaks from lights were not tolerable and the lens was horrible to take out.

I would ask your doctor to check the fit and see if a little more power will help. In my eyes sometimes a little more power to the lens helps but it could be too tight too.

Brad