Contact Lenses

[Lou]

Hmmm, I'm concerned now. I have monthly disposables (I have too much astigmatism by a mile for dailys) and I explained to my optician what I wanted them for and he said nothing of the above.

I wear my contacts maybe once ot twice a week, and always when out diving.  I never, ever sleep in them.  A prescription mask is no good really as when its off I can't see enough to be safe and I get seasick without my glasses on even more than normal.

However why is it more risky to wear them diving if you don't have a mask flood or open your eyes with no mask on underwater?  Surely they are as dry as normal and on the boat you are submitted to the same spray etc as sailors or even day trippers and less than folks who swim in them on holiday?

Can you elaborate more as to why there is a heightened risk, please?  Is it because of the trapped air volume in the mask, was that what you were referring to in the "warm, wet and slightly hypoxic atmosphere"?

Cheers

Lou

[Fee]

Hi lou,

Firstly, contact lens wear initially heightens rise of an eye infection simple because you have a foreign object in your eye and insertion/removal of the lens introduces these infective agents (unless you live in a sterile bubble and you use a steile, new lens each day).  The mechanical action of lens insertion causes breakages in the epithelium covering the cornea, which is unable to heal as quickly/efficiently as would be normal because the lens has created a hypoxic environment(all contact lenses retard oxygen diffusion to the front of the eye and induce corneal oedema).  These wounds are then open to attack from the normal commensal organisms of the eye(Staph. epidermidis, Staph. aureus, Strep. pneumoniae, Coliforms, Pseudomonas and Heamophilus all of which can be found in the conjuntival sac)  Ordinarily the conjuntiva and the cornea are protected from the agents by:

Blinking;washing away of debris and bacterial colonies in tear flow. This protective method is now defunct as a contact lens covering anything that could possible be washed away.

Entrapment of foreign particles in mucus.  This doesn't work now as the foreign particles are now trapped behind the lens.

Immunity; the tear has antibacterial properties.  This is your one saving grace, the tear is able to permeate all lenses as there is a state of dynamic equlibrium between the water content of the lens and the water of the tear, however because of the reduced efficacy of blinking the tear is not replenished as quickly as normal and thus this protective method is now reduced in efficacy.

Barrier; the epithelium of the cornea, only Neisseria gonorrhoea is able to penetrate an intact epithelium.  However now with the insertion of a lens this barrier is now broken so its party time on your eye ball.

The above are associated with contact lens wear in normal daily life.  When we bring water in to the equation the chances are multiplied.  You mentioned swimming, this is a huge no-no, again the risks can be reduced by throwing away you dailies immediately after your swim and wearing your spex for a few hours, or if you wear monthlies dropping them into peroxide solution for 6 - 8 hours and wearing your spex.

When diving our masks are never dry, to start with the vast majority of us spit in our mask and then wash it with sea water, and if you dont use spit but use a de-fogging agent it is still washed out with sea water.  Spit - I would treat a penetrating human bite wound more agressively with anti biotics than I would a dog bite.  The sea spray that you mentioned, normally this is combated by the aforementioned protective methods, however with your lenses the sea water is able to permeate the lens and any bacteria in it is considering himself a very lucky squatter.

I hope this answers any queries you have.  If there is anything else don't hesitate to post and I will reply as fast as possible.

Ian Daly

[Mdemon]

Fee, what are the signs and symptoms of having a munch-fest on your cornea - is it just conjunctivitis?  And if they do start, assuming one uses some suitable gunk, is the risk of permanent damage quite small?

Another thought - what about the monthlies you sleep in?  No mechanical damage since you sleep in them.  So we're left with just getting sea water near them.  Is this a safer form of lens diving-wise?

[Fee]

Hi Mdemon,

The signs and symptoms include:

Pain; usually severe unless the cornea is anaesthetic.
Purulent discharge.
Ciliary injection.
Visual Impairment; which can be servere especially if the visual axis is involved
Hypopyon.
White corneal opacities which can often be seen with the naked eye.

These symptoms are in common order.

IF YOU ENCOUNTER ANY OF THESE SYMPTOMS REMOVE YOUR LENSES AND SEE YOUR OPTOMETRIST ASAP.

If you can not get to your Optom go to your Gp as these are the only people that can refer you to an eye casualty.  If you go to an A&E department with a red eye you will be fairy low priority and it will be ages before you see an opthalmologist.

As with all infective disease the quicker you 'em the better the outcome.  Treatment may be as simple as Chloramphenicol if the corneal epithelium is damaged but with no other signs of infection.  If this is the case lens wear should cease until a slit lamp evaluation shown a complete healing of the wound.  But unfortunately if the signs are ignored and there is a bit of a "shin-dig" happening on the ol' peepers then a corneal scrape may be required from the ulcer for gram staining then the patient would be treated with intensise topical anitbiotics.  The drops are given hourly, daily and nightly for the first day or so and then reduced in frequency as clinical improvement occurs.  In severe or unresponsive cases the cornea may perforate in which case a coneal graft is required, this is also used to combat a persistant scar which is disrupting vision.

Mdemon, I see you train of thought with extended wear lenses.  Now this is going to be a little biased as I strongly oppose extended wear lenses unless used as a bandage lense.  Now for my rant;- There are only two monthly lenses on the market that can be perscribed for extended wear, Ciba Night and Days and Baush and Lomb PureVision, any other lenses that are use for extended wear are being perscribed outside product guidlines. Rant over.

As I said in a previous post "all contact lenses retard the diffusion of oxygen to the cornea", although the low water content polymers that are used in Extended wear lenses do allow good diffusion there is still a drop in oxygen and at night with eye closed this is further exacerbated so if an ulcer does form the patient doesn't normally know untill it is very large and painful and they are taken out of lens wear for good.  Furthermore, people very rarely where the lenses solidly for a month and then swap to another pair which they wear solidly for a month, in general a wearer will remove the lens for a day or two and then pop 'em back in.  This has the added problems of increased handling of the lenses, thus greater chance of infection, epithelium damage from insertion and removal, and also what do people store them in when they are out of the eye, I would bet a £ to a penny, its only saline solution with no disinfective properties what so ever.  

You are quite correct really with only having to contend with getting them wet as the possiblity mechanical damage is reduced, but if you do you have to contend with the aforementioned problems and the decrease in the effectiveness of the other protective methods;

Blinking; washing away of debris and bacterial colonies in tear flow. This protective method is now defunct as a contact lens covering anything that could possible be washed away.  This especially true in extended wear lenses as mucus plugs are able to build up and block the pores in the lens that allow oxygen flow.

Entrapment of foreign particles in mucus.  This doesn't work now as the foreign particles are now trapped in the mucus but behind the lens and can't be readily washed away and then sit there and decrease oxygen flow.

Immunity; the tear has antibacterial properties.  This is your one saving grace, the tear is able to permeate all lenses as there is a state of dynamic equlibrium between the water content of the lens and the water of the tear, but because the extended wear material is of low water content (approx 24%, most daily wear lenses over 50% and up into the 60's) not much tear gets into the lens. Then because of the reduced efficacy of blinking the tear is not replenished as quickly as normal between the front surface of the eye and the back surface of the lens and thus this protective method is now reduced in efficacy.

And also realise that the eye gets no relief as the lens is not going to be removed.

So no - I don't think extended wear lenses are a good alternative to dailies for diving.

HTH

Ian Daly - not Fee

[Mdemon]

Thanks Ian - scarey stuff.  I didn't get all the S&S though - English is my first language!  

So, how long does the mechanical damage associated with removal/insertion take to clear up?  Does it always happen regardless?

By the way, if you don't rate extended wear, what about the old laser treatments - any thoughts?

[Rob Evans]

Well thanks for that Ian - I'll be having nightmares for months after this thread.
I'd heard anecdotal stuff about why you don't want to dive with contact lenses re:infection etc but never had any hard facts so didn't pay it a whole lot of attention.  The 'bloke inna pub said' sort of stuff really.
Having had the facts laid out so clearly and succinctly has been a real boon.  I dive daily disposables anyway, but had always kept them in for the rest of the day after the day's diving (well you don't want to waste the money really do you, I'm talking a whole quid here for a pair of lenses).
Well that practice has just gone right out of the window, thanks to you - much appreciated.
Just of of interest, are there differing standards of quality as regards daily disposables?  Mine are from Specsavers - whenever I mention to a good dispensing optician mate of mine that's where I go she goes all purple, chokes on her beer and then rants for a minimum of 1/2 hour about what a nobber I am.  Mind you, that might not actually have anything to do with the lenses - she has known me for a while

[Fee]

Sorry 'bout that if you have any Q's about the the signs and symptoms mail me off-line if you wish I am only too happy to help.

The regenerative capactive of the epithelium layer is amazing and only takes 6 - 8 hours to be fully recovered.  And yes it does always happen regardless as it is only a few cells thick.

Laser treatment, well I am not gonna even start; this topic was mention previously and after two or three posts by Fee we decided to not bother replying.  All I will say is that both Fee and myself know an awful lot of doctors, surgeons and because of my job optometrists and between us niether of us know anyone in those professions that have had it done.  Read into that what you want.  Again offline I am happy to answer yours and anyone elses questions concerning these matters or any other aspect of occular health as is Fee with with any aspect of ENT, but you better get in quick as she is changing speciality come August.

Going to add this now as I posted the first bit another post was sneaked in there.  Contact lenses are a type 2 medical aid and as such have comply with a minimum stanard of production but they have all the downfalls associated to them "I don't like that one I only use that type" so on and so forth that you get with all medical aids.  A good number of my friends are Optometrists that work for Specsavers in Cardiff, and thats where I take my children, I should imagine your DO friend goes purple from the business aspect rather than the care point of view.  Now Fee occaisionally uses specsavers dailies and having just looked at them they appear to be repackaged lenses made by CibaVision, a very reputable company.  Althought the lens of choice amongst my collegues is Acuvue.  You would need to speak to an Optometrist or Contact Lens Optician about the actual difference but I beleive it has something to do with material that the lens is coated with and then you could always ask for a free trial.

I don't mean to scare anyone I just I beleive that the decision should be yours to take and that can only be done once you are in possession of all the facts.  I know on the face of that its sounds like you eye ball will fall out just for looking at a boat but these are the facts, and like I have stated previously some one will always know a person who is overweight, smokes 70 a day, dives to 80m on air and has been wearing the same contacts for 2 and 1/2 years and he's ok.  Knowledge give you the power to make these decisions.  Safe diving and just remember, there are old divers and there are bold divers but there are very few old and bold divers.

HTH

Ian Daly

[Lou]

Thanks very much for that in depth help, Ian.

I am going to get some peroxide based cleaner now!

I never wear my lenses for "extended" periods of time and I do always make an effort to keep my eyes protected on the boat when I have my lenses in (so if you see me wearing sunglasses when the sun is absent it isn't coz I'm a poseur!  I understand that there is a risk (which is more than I did before...thanks Mr Optician who prescribed) but at least understanding it I can mitigate those risks.

Now, what shall I do about spitting in my mask.....?

Cheers


Lou

[Mr T.]

Like a Muppet, and whilst I was living in the Maldives (more on that later), I kept my soft lenses (the remove at the end of each day and soak in cleaning solution etc. type) in for over a year - I can just hear the heckles (justified) now!  

The reason I kept them in was that the staff accommodation was not as squared away as the guest accom in that the desalination plant on the island would break down frequently(invariably when you were in the shower or just when you were about to get in the shower), and in such events, the guests got the 'sweet' water reserves whereas us staffers got the 'ground' water - a vile smelling amonia stench liquid with added 'bits' floating in it! Needless to say, there was no way on God's green earth that I was putting that witch's-brew any where near my eyes and/or contact lenses, so I kept them in.

This was 11 years ago and I've had my eyes checked regularly ever since with very little residual ill effect.

That said, I never wear lenses anymore and now stick to glasses, prescription sunglasses and a presciption mask - so all eventualities covered.

The above said, my wife dives in soft lenses (the 'bin-at-the-end-of-the-day' type) and has no problems - never has had where diving's concerned.

HTH.

[daz]

Originally Posted by [b

Quote[/b] (Bren Tierney @ June 30 2003,17:51)]The above said, my wife dives in soft lenses (the 'bin-at-the-end-of-the-day' type) and has no problems - never has had where diving's concerned.

HTH.

<font color='#000080'>Yep that helped Bren, &nbsp;

I've met you in the flesh so know what you look like, &nbsp;I would suggest the wife gets her prescription checked &nbsp;

Daz

See ya Friday &nbsp;