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Medical Forum / General / Vision / July 2006New Contacts, Old Infections. Warning for extended wear contacts!
The newest extended-wear contact lenses have a similar risk of eye infections as older soft lenses worn for fewer nights. That news is reported in Ophthalmology. It comes from postmarketing studies funded by CIBA Vision, which makes the silicone hydrogel lenses, marketed as Night & Day. The researchers included Oliver Schein, MD, MPH, of Johns Hopkins University's medical school. Lenses' History The FDA approved the silicone hydrogel lenses in 2001 for continuous wear for up to 30 nights. Older generations of extended-wear contacts had been associated with rare cases of vision loss and eye infections. That prompted the FDA's 1989 decision to cut extended wear to seven days. Years later, silicone hydrogel lenses were developed. Compared with older lenses, they allow four times as much oxygen to reach the eye. Better oxygen flow was seen as a way to possibly lower infection risk in the eye's cornea. The FDA ordered postmarketing studies of silicone hydrogel lenses to check corneal infection rates. Year-Long Study The study included 6,245 people who had been given prescriptions for the silicone hydrogel lenses. Most (80%) wore their lenses nonstop for at least three weeks. During the year-long study, few participants had corneal infections. Two had corneal infections that led to vision loss. Eight others had corneal infections that didn't cause vision loss. Overall, the yearly rate of corneal infections was 18 per 10,000 people, the study shows. That's similar to rates previously reported for conventional, extended-wear soft lenses worn for fewer consecutive nights, according to the researchers. Researchers' Pecking Order Schein's team calls contact lenses "very safe" in general, though they note that contact lenses are associated with some extra risks, compared with eyeglasses. They rank the risk of vision loss from eye infection for different types of contact lenses: Lowest risk: Rigid, gas-permeable contact lenses for daily wear Next-to-lowest risk: Soft contact lenses for daily wear Highest risk: Silicone hydrogel contact lenses for extended wear of three-to-four weeks However, they're not calling silicone hydrogel lenses dangerous. The odds appear "reasonable," write the researchers, for people who understand the risks and want to wear their contacts around the clock. The study notes that one researcher is a CIBA Vision consultant and one is a CIBA Vision employee. SOURCES: Schein, O. Ophthalmology, Dec. 2005; vol 112: pp 2172-2179. News release, Johns Hopkins University. By Miranda Hitti Reviewed by Louise Chang, MD © 2005, WebMD Inc. All rights reserved. > Overall, the yearly rate of corneal infections was 18 per 10,000 > people, the study shows. > > That's similar to rates previously reported for conventional, > extended-wear soft lenses worn for fewer consecutive nights, according > to the researchers. No. This is not a correct conclusion. The incidence of microbial keratitis is much higher in prospective studies than it is in retrospective population studies. In retrospective population-based studies, the incidence of microbial keratitis in conventional hydrogel overnight lens wear is 1/500 per year. In a large, multicenter prospective study, the incidence is 1/210 per year, nearly twice as great. Therefore, one should be comparing apples to apples and not apples to oranges, and comparing an annual incidence of 1/600 for silicone-hydrogel, vs. 1/210 for conventional hydrogel. Also, different classification schemes for corneal infiltrates yields different results. Some corneal infiltrates are sterile. At the very least, silicone-hydrogel lenses are 3 times safer. Finally, do not make the erroneous conclusion that overnight RGP lens wear is the same as overnight OK lens wear just because the lens materials are the same. DrG > The newest extended-wear contact lenses have a similar risk of eye > infections as older soft lenses worn for fewer nights. reserved. Extended wear today is much safer than old extended wear for several reasons. See http://www.allaboutvision.com/contacts/extended.htm >The newest extended-wear contact lenses have a similar risk of eye >infections as older soft lenses worn for fewer nights. [snip] [So a study has shown silicone hydrogel contact lenses (SHCLs) worn for MORE nights have a similar risk of eye infections as HEMA CLs worn for FEWER nights? Duh.] I do not believe this to be true in general. And it certainly isn't the experience in my practice. SHCLs have basically "licked" the main problem I had with HEMA-based SCLs -- that is, poor oxygen transmissibility. I used to have to routinely deal with patients that had large amounts of limbal neovascularization, microcystic edema and subepithelial infiltrates due to EWCL abuse. It was especially problematic becuase many of these patients were asymptomatic; many wouldn't change their ways until they developed a corneal ulcer (some wouldn't even change after that). Most doctors I have spoken to, myself included, can't contain the smile when we see how much healthier this type of persons' corneas look after switching them to SHCLs. I wish I had an anterior segment camera and could show these patients the difference. It's a "Night and Day" improvement so to speak, pun intended. When SHCLs came out, I knew they would be a tremendous improvement over HEMA lenses, but I still approached EW with caution. I discovered I was right because there is still CLARE and bacterial keratitis associated with EW of SHCLs. However, it IS in my practice a lower incidence than that associated with HEMA lenses. As I have wrote here is several Usenet articles, I believe (and the literature supports this belief) the reason is poor tear circulation in the post-lens tear area. This *should be* a relatively easy problem to fix in the vast majority of patients -- fit the flattest base curve that you can to allow the maximum lens movement that comfort will allow. I also think that continuing to look at modifying the lens design somehow would help. Anything to help allow the tears to not become stagnant that are between the anterior surface of the cornea and the posterior surface of the contact lens. We have learned, in the past, with CIBA's (was Wessley-Jessen) Freshlook contact lenses -- be careful what you ask for. That lens was designed to move a tremendous amount due to the fact that this is what eye doctors were wanting. I love how this lens moves on most patients eye -- a large 1.0-1.5 MOB. However, many patients (mostly former SCLs wearers) were unable or unwilling to tolerate this lens because they were very aware of its movement -- even worse with a cosmetic colored lens for it to move excessively. I bet in hindsight, they wish they would have designed it differently. And besides licking the oxygen transmissibilty problem, they have been great for most patients with dry-eyes. They are certainly my soft contact lens material of choice in 7/2006. The only reason I prescribe anything BUT these lenses for my CL patients who are candidates for them is patient cost issues. Do they have their problems? Yes. They deposit easier and are more lipophilic, but this is a problem in only a small number of patients. And in this small number of patients, this is a relatively easy problem to fix -- either increase the cleaning regimen or increase the frequency of replacement. Of course, no EW is best. But for patients who insist on EW of SCLs, choosing SHCLs over HEMA lenses is a no-brainer -- just make sure there is adequate circulation of the post-lens tear film. [Aside: I have found that Ciba O2Optix, Acuvue Advance 8.7 BC and 8.6 Ciba Focus Night & Day (CFND), and B&L Purevision tend to move the most while Acuvue Oasys, 8.4 CFND and 8.3 Acuvue Advance tend to move the least. In fact, I don't even fit 8.4 CFND anymore unless the patient complains of the movement of the 8.6 BC flavor or the patient has Ks of say, 48.00.] Do that, and I think you will find the incidence rate of bacterial keratitis/CLARE will drop a huge amount over HEMA lenses, not just the 3X rate reduction the literature states with SHCLs over HEMA CLs. Overnight extend wear lens countinues to spur debate and controversity. The biggest reason is because its as quick and easy to pop out your contacts before going to bed as its to tie your shoes. I have several friends who wear contacts, most dont sleep in them unless they come home too drunk to remove the lens that night. They also see no point when it takes half a minute to pop them out and near a minute to insert them in. Cleaning them is quick and easy thanks to no-rub solvents. It is irrevelent how much safer silicone hydrogels are, they are not 100% safe for sleeping in. There is NO point sleeping in contacts(except orthoK) and whats even worse than sleeping in contacts is leaving them on your eyes for 2, 3 even 4 weeks strait. All the dirt and bacteria can accumulate when you dont clean your contacts for so long! My own optometrist knows this and he also warns patients against extend wear contacts reguardless of brand. Some people are stubborn and dumb and dont listen to their *doctor* then they pay the price with ruined eyes. Before SHCL's many people were ruining their eyes with improper wear of hydrogel contacts. They developed infections and uclers and I read the story of one woman who was going to need a cornea transplant in one eye and her doctor told her she might go legally blind in that eye. All because she didnt have the sense or patient to take HALF A MINUTE to remove her contacts before bed! >Overnight extend wear lens countinues to spur debate and >controversity. The biggest reason is because its as quick and easy to >pop out your contacts before going to bed as its to tie your shoes. I agree, but a portion of the population is lazy and apathetic. EWSCL abusers have the same mindset IMHO as people who continue to smoke, not floss their teeth, abuse alcohol, and make other poor healthcare decisions. To not address that issue as a doctor and not attempt to come up with a solution is a disservice. >I have several friends who wear contacts, most dont sleep in them >unless they come home too drunk to remove the lens that night. Great. They abuse alcohol but are saints when it comes to contact lens care. Nice. >They also see no point when it takes half a minute to pop them out and >near a minute to insert them in. I have a subset of my population of my patients who think that small amount of time, or waking up and not seeing immediately clear is a big issue. >Cleaning them is quick and easy thanks to no-rub solvents. No rub solution have minimal cleaning power. They merely kill sufficient bugs without the rubbing action to get the FDA "OK" to be "no rub". No real difference than putting a dirty T-Shirt in a bucket of bleach water. It will kill the bugs, but not get the shirt clean. The rubbing is akin to putting that shirt in a washing machine. It is the agitation action that gets the contact lenses "clean". >It is irrevelent how much safer silicone hydrogels are, they are not >100% safe for sleeping in. No contact lens wear is 100% safe; it's all relative. I think the risk-to-reward ratio is very acceptable with SHCLs when they are worn primarily on a DW basis. I have no real problem with most patients who EW them say 1X/week. It's when the frequency continues to increase when the risk goes up. In fact, I think if most EW SHCL patients would take their lenses out once a day for 15 seconds, rinse it with multipurpose solution, put a couple drops of artificial tears in and then reinsert the lenses (would take maybe a minute) then EW with SHCLs is relatively safe. >There is NO point sleeping in contacts(except orthoK) and whats even >worse than sleeping in contacts is leaving them on your eyes for 2, 3 >even 4 weeks strait. There's a point, but I agree this is laziness plain and simple. And people "tickling the dragon" by going longer and longer between CL removal is A big contributor to CL related problems. [snip] . > >There is NO point sleeping in contacts(except orthoK) and whats even > >worse than sleeping in contacts is leaving them on your eyes for 2, 3 [quoted text clipped - 3 lines] > people "tickling the dragon" by going longer and longer between CL > removal is A big contributor to CL related problems. Is there really any point in debating the issue of overnight wear? People who sleep in lenses aren't "lazy," any more than people who get LASIK are irresponsible. We know what the risks are, and they are reasonably low. In more than 20 years of practice, I have documented one patient who suffered a loss of one line of acuity from sleeping in a contact lens, and it was an RGP lens at that. Silicone hydrogels are only the beginning. DrG >> >There is NO point sleeping in contacts(except orthoK) and whats even >> >worse than sleeping in contacts is leaving them on your eyes for 2, 3 >> >even 4 weeks strait. > >Is there really any point in debating the issue of overnight wear? >People who sleep in lenses aren't "lazy'" I guess we will just agree to disagree. I think people who sleep in their lenses for 30 days straight are lazy. > I agree, but a portion of the population is lazy and apathetic. EWSCL > abusers have the same mindset IMHO as people who continue to smoke, > not floss their teeth, abuse alcohol, and make other poor healthcare > decisions. To not address that issue as a doctor and not attempt to > come up with a solution is a disservice. I am guilty of some bad habits, almost everyone is. I can see why there is a market for EW lenses, its probably to serve those who have been sleeping in the older hydrogel lenses which are much worse. However one thing I dont like is the way they market those EW lenses as "safe" then people who would never think about sleeping in contacts may be under the false impression that its perfectly safe with the new EW lenses. I understand the issue needs to be addressed, but what should be done is perhaps provide a disclaimer for EW lenses so the patient is informed or verbally warn about the risks. I am glad my optometrist did or I could be sleeping in contacts and wearing them for several weeks strait without even knowing how risky that is. > Great. They abuse alcohol but are saints when it comes to contact > lens care. Nice. The less bad habits, the better. Maybe they get lots of enjoyment from alcohol but it makes no difference to them if they save a few seconds it takes to pop out their lenses if they arent too tired or intoxicated to do so. > I have a subset of my population of my patients who think that small > amount of time, or waking up and not seeing immediately clear is a big > issue. There is always glasses they can reach for. If they have a low(er) prescription, its not such an emergency. I am in the -4 range and even I can do perfectly fine without correction after waking to brush my teeth and eat. What can be done is warn them of the risks of sleeping in contacts and if they insist on sleeping in them, then the least they can do is take them out for cleaning everyday. > No rub solution have minimal cleaning power. They merely kill > sufficient bugs without the rubbing action to get the FDA "OK" to be > "no rub". should people be rubbing their contacts? Should they be using a different solvent? > No contact lens wear is 100% safe; it's all relative. I think the > risk-to-reward ratio is very acceptable with SHCLs when they are worn > primarily on a DW basis. That much ill agree. However wearing contacts for a month strait without taking them out increases the risk 20x fold then its not so safe at all, in fact there is controversity which is riskier, EW contacts or lasik, especially when we look into the long term damage each does to one's eyes. There is no excuse to get either, just take proper care of your contacts and eyes. Many people who get lasik in fact have worn and abused contacts for many years and damaged their eyes and/or their eyes have rejected contacts. They could not get used to glasses having worn only contacts for many years and also it may be a vanity thing. It appears that 75% of those getting lasik are contact wearers, nearly all of them with problems with contacts. > I have no real problem with most patients > who EW them say 1X/week. It's when the frequency continues to [quoted text clipped - 3 lines] > in and then reinsert the lenses (would take maybe a minute) then EW > with SHCLs is relatively safe. The less nights they sleep in them, the more often they remove and clean them, the safer. > There's a point, but I agree this is laziness plain and simple. And > people "tickling the dragon" by going longer and longer between CL > removal is A big contributor to CL related problems. The difference with orthoK is you can remove it when you wake up, giving your eyes the chance to breath and you get to see clearly for many hours too. OrthoK is great for athlates, pilots, cops, swimmers where regular contacts would not be very approperate. Much less risky than lasik and less risky than EW contacts in fact. OrthoK can be worn 8 hours at night every other day. Thats 8 hour orthoK wear out of 48 hours vs. nonstop wear with EW contacts for a week or more. If someone wants good vision, there is natural vision improvement and orthoK, both which are far better. Lasik is a last resort choice when none of the other options work AND when you have very good reasons why you refuse to stick with glasses. I dont really have much reason not to stick with glasses. I admit itll be nice to reduce dependancy on glasses, but nothing riskier than orthoK is worth taking. Most people regret lasik if it backfires on them, others just go into denial. >Overnight extend wear lens countinues to spur debate and controversity. >The biggest reason is because its as quick and easy to pop out your [quoted text clipped - 17 lines] >because she didnt have the sense or patient to take HALF A MINUTE to >remove her contacts before bed! I have been wearing Ciba Vision Night & Day since they first came out and there is no way I would go back to taking lenses out every day. If you are long sighted like I am it takes ages trying to get them back in even using a strong magnifying mirror.I have very dry eyes and these are the only contact lenses I am happy with. The only time I take them out is when they have to be changed after a month.I personally think the little you have to handle your lenses the better. Mary -- > I have been wearing Ciba Vision Night & Day since they first came out > and there is no way I would go back to taking lenses out every day. [quoted text clipped - 7 lines] > > -- You are going to ruin your eyes soon. There are tricks to taking them out. What you could do is take one contact out, clean it then insert it then take out the other one to clean then insert it. You really shouldnt be going a month strait without cleaning them! You will have problems in a matter of time and may have to go back to glasses. > I have been wearing Ciba Vision Night & Day since they first came out > and there is no way I would go back to taking lenses out every day. [quoted text clipped - 3 lines] > them out is when they have to be changed after a month.I personally > think the little you have to handle your lenses the better. Actually, there are a couple of studies recently published that underscore this experience. One studied the adherence of bacteria to the surfaces of lotrafilcon A and balafilcon A lenses at 2 and 4 weeks of wear. The researchers found that the lotrafilcon A surface was initially rougher and less wettable than the balafilcon A surface, but that these differences became insignificant after 4 weeks. But, lotrafilcon showed decreased adherence of all bacterial strains at 4 weeks compared to 2. The balafilcon A showed declining adherence of pseudomonas a., but an increasing adherence of staph. aureus 835. The second bit of evidence is found within the study quoted by our resident amateur scientist, "Ace." The rate of presumed microbial keratitis was lower for users reporting typical wear of 3 or more weeks than for those wearing the lens for less than a 3-week continuous period (P = 0.02). DrG |
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