Development of keratoconus after contact lens wear.

[al]

As I am new here, it might be that you have discussed this a long time ago.
Although I have (very?) mild keratoconus on only one eye, the topic has engaged me. I see that you are many that have quite big problems, and that there are others like me with little-no problems. Since I just got the diagnosis at the age of 31 (seems to be late), and I am working as a researcher (qurious by nature) I have of course many questions regarding the causes and development of the disease.
I did a quick search on http://www.scholar.google.com (where you find more research stuff), and found an article of interest: Development of keratoconus after contact lens wear. Patient characteristics. Macsai MS, Varley GA, Krachmer JH.Arch Ophthalmol. 1990 Apr;108(4):534-8. I see that it is quite old, but the abstract is interesting:
"A retrospective review of 398 eyes of 199 patients with keratoconus revealed 106 eyes of 53 patients with an association between contact lens wear and the development of keratoconus. The absence of keratoconus at the time of contact lens fitting was confirmed by slit-lamp examination, keratometry readings, and manifest refraction. Keratoconus was diagnosed after a mean of 12.2 years of contact lens wear. This group was compared with patients with sporadic keratoconus with either no history of contact lens wear or a history of contact lens wear after the diagnosis. They were older at the time of diagnosis, had central vs decentered cones, and had a tendency toward flatter corneal curvatures. We believe that these patients suggest that long-term contact lens wear is a factor that can lead to keratoconus."

Hence 53 out of 199 patients (27 % !!!!) developed keratoconus!!!!!!! Perhaps this is an old article??? Does anybody know of other news regarding this topic? I am then ofcourse wondering if I sould continue wearing contacts (I wear them about 14 hours per day, alomost every day. I know that when I had non gas permable lenses, my cornea suffered in the sence of cells that got distroyed, but my optometrist said it repaired itself within a couple of days if I used glasses. With gas permable lenses I feel and see a difference (my eyes are not read and do not feel dry). But still...perhaps it is not good to wear them at all?????

It would be interesting to find out how many that actually have discovered keratoconus in their late age, afer using contac lenses.

Questions: what is the normal thickness of cornea? what is really thin cornea?

al

[jayuk]

Al

All i can give you here is personal experience..I wore Glasses for a year and a half when first diagnosed with KC...it then developed quite agressivly to which point I HAD to wear lenses........the research you quoted unfortunatly cannot be proved as we dont have the underlying cause of KC yet...

A normal thickness for a Cornea i beleive is 0.5 mm...and thin cornea is around half that........thats it memory serves me correct......but maybe someone else can correct me here...

[Sajeev]

Hi Al,

For me any study needs to be duplicated showing the same results with a follow study...and remember its up to the people doing these studies to do this, and to do what is need, not us!.

Any advice about this would be told to you by your medical team and listern to the people you in-trust who look after your KC....namely the professional advice given to you by your own KC specialists, that you take advice from FACE to FACE! (this is why there are regular check ups to see if there are problems..!)...up until their advice changes you must continue with the advice being given to you now!

[Lynn White]

AL

This IS an old study... and if you are interested in research.. then it is fascinating how the wrong conclusions can be drawn from data...

Research over the years pointed to two "facts" of K being a cause... eye-rubbing and contact lens wear.

Eye-rubbbing... well most people with KC rub their eyes... but most people with KC have allergies and dry eyes..which tend to make you rub your eye.. so which came first?

Contact lenses... right! The main flaw with the research paper you quote is the "fact" of no diagnosis of KC. What this paper pre-supposes is that the current diagnostic specification is accurate for KC. At the moment, you have to have a steep corneal measurement to count as a KC diagnosis...

But the advent of KC precipitated by refractiove surgery means we have NOT been getting the diagnosis right.It is appearing more and more that you can have KC with a flatter cornea. In fact many so-called cases of "just" irregular astigmatism may in fact be sub-clinical KC - which may have a whole different way of progressing.

Now.. since patients with KC see better with contact lenses.. it may well follow that these patients actually stay with their contacts much more than non KC'ers... as they would progressively get worse vision in spectacles as time went by. So the fact that they are in contacts may becasue they are developing KC... not that KC was caused by the contacts.

I hope you can see that research papers can be very misleading. I certainly would NOT advise you give up your contacts based on the evidence of this paper.

My experience in Trinidad where people were simply not diagnosed and not given contacts showed they still had VERY advanced KC ... but they DID have less scarring than those with RGP lenses... those lenses were fitted to an assumption that you fitted flat to "push down the cone". So this would suggest that KC is not caused by contacts but that some contact lens fitting techniques may contribute to scarring.

But then again... my experiences may be explained by genetics or geographical location...

My advice is to be VERY careful making judgements based on a research paper... these papers are directed towards fellow professionals who understand the undercurrents and background experimental work done elsewhere. You may find a poaper that seems to say a certain thing.. there could be a dozen papers refuting it out there.,.. but as you are not in the "profession".. you may not find them!

Lynn