What's the difference between daily and monthly contacts?

[optostudent]

I'm an optometry student, and I'm trying to figure out the difference between daily and monthly contacts. A few dailies seem to have the same materials, water contents and oxygen permeabilities as biweekly/monthly lenses of the same brand. Sometimes these dailies are thicker, thinner, or the same thickness as their biweekly/monthly counterparts. So is it just the packaging and care procedures that are different, or is there some other attribute that distinguishes them?

The lenses I'm looking at are:
SofLens Daily Disposables / SofLens 59
ProClear 1-Day / ProClear
1-Day Acuvue / Acuvue Colors

[Judy Canty]

I'm sure that one of your professors could enlighten you.

[PKCRM114]

it really depends on the manufacturer. as B&L found out years ago, you are not allowed to market the exact same lens under different modalities, but depending on the manuefaacturer there are greater or lesser differences. methafilcon, polymacon as well as some other materials haved been use for 2 week, monthly, and full year modalities. but most lenses that have come out more recently have distinct materials for different packaging.

[Judy Canty]

I do not believe this is an Optometry student. More likely, a consumer trying to choose for an online order.

[edKENdance]

Interesting question though.

[fjpod]

can't wait to hear what Chip tells him.

[PhillyEyes]

I do not believe this is an Optometry student. More likely, a consumer trying to choose for an online order.

+1 seems that way

[optostudent]

The headline was intentionally simple to attract attention, but I think it's a legitimate question. I did of course consult a professor some time ago, but he only provided a vague non-answer that wasn't very satisfying, and my curiosity has lingered since. I don't think there's any reason for mystery around the subject. I figured that practicing ECPs who were actually fitting patients might have a better knowledge of specific products and their distinguishing characteristics. I had speculated that perhaps biweekly/monthly modalities would benefit from a protein- or lipid-resistant coating that dailies wouldn't need, similar to how certain silicone hydrogels are treated with a hydrophilic plasma coating. I'm sure there are other bits of manufacturing esoterica that aren't listed in EyeDock or other contact lens databases. Why, for example, did B&L find they couldn't use the same lens for different modalities?

[fjpod]

Optostudent...can you tell me if daily soft lenses are spin cast or lathe cut?

[optostudent]

I don't know, I thought most manufacturers had moved to injection molding.

Update: Yeah, they're molded in various ways, though Ciba advertises something called Lightstream Technology, whatever that is.

[Wes]

I don't know, I thought most manufacturers had moved to injection molding.

I thought so too, aside from gas perms. Maybe it was a trick question.

[drk]

I'm sure that one of your professors could enlighten you.

LOL. So funny. So true.

[drk]

Having said that, either this consumer is an engineer or something or this kid is the real deal. Pretty intelligent line of discussion.

[fjpod]

OK, you gave the right answer. Spin casting and lathe cutting are not commonly used anymore. It was a trick question.

Consumable health care products such as drugs and contact lenses should be used as intended by the maker and approved by the FDA. Otherwise the safety and efficacy of the product is compromised, and the patient and you the prescriber, are put at risk.

[chip anderson]

In some cases it's just marketing. Several large manufacturer's got suied a while back for marketing the same lens under several different regimens. Probably since then they have made sure there are some discernable differences between DW and FW and EW. Over the years the difference has supposedly been water content, thickness, materials and whatever the FDA would give approval for the differing applications. Sometimes it is as little as the quality controls used during manufacture.

Sorry I can't give a better explaination. However I can say that there is a much higher risk of serious and minor complications with EW than with DW (not the lenses, just the application). The other side of the coin is that those practices that do not advocate EW (like mine) will see a serious decline in CL patient load.

Chip

[optostudent]

I'm not specifically interested in off-label use, but your (fjpod's) mention of the FDA reminded me that soft contacts are considered class II devices that don't require clinical trials or premarket approval (except for extended wear). Instead, it must be demonstrated that the contacts are substantially equivalent to devices already on the market. So I checked, and Proclear 1-Day lists Proclear as its substantially equivalent device. (The SofLens and Acuvue dailies are too old to have PDFs of their applications online.) The Proclear 1-Day application simply says, "The technical characteristics, formulation, manufacturing, and sterilization processes of this lens are equivalent to omafilcon A soft contact lenses currently marketed by CooperVision, therefore no clinical data is required." The FDA determined substantial equivalence had been demonstrated.

[optostudent]

Chip: Do you remember who was sued, by whom, and/or roughly when? I'd like to look those cases up.

Update: Also, when I'm talking about dailies and monthlies, I mean daily disposables for daily wear and monthly disposables for daily wear. I'm not talking about extended-wear contacts at all. So I was confused when I was comparing dailies and monthlies, and you were comparing daily wear and extended wear.

[lind2020]

it was B&L regarding their vial lines -vs- the Optima I believe - they were simply packaging the vial lens in a blister and selling it as freq. replacement

I would guesstimate it was in the mid 1990's

[optostudent]

Oh, interesting. I had seen that the SofLens brand had replaced Optima, but I believe SofLens and Optima are both blister packs, and I thought the modalities were the same, so I'll have to look up which vial lenses were involved. I do see some sites advertise the same contacts as biweekly and monthly, and the SofLens 38 package insert actually says it's for frequent/planned replacement or traditional wear. I believe originally soft contacts were all traditional wear, then the concept of planned replacement was introduced later.

[GAgal]

Hey! In regards to the contacts that you requested

Soflens Dailies and Soflens 59- They are the exact same contact, however Soflens 59 cannot be sold in the US because of the same contact lens different modalities parameters set up by the FDA. Both are hilafilicon B, Dk 22X10 water content 59% and ct of .05-.75

Proclear 1day and Proclear- Proclear 1 day has a lower water content of 60% and a slightly lower DK of 21X10 vs a water content of 62% and dk 27X10

1day Acuvue and Acuvue 2 colors- I don't think there is any difference in these lenses except color which is all it needs to differentiate itself. I have heard that vistakon is planning to discontinue this lens. Not sure if this is true or not or if this may be one of the reasons.

[optostudent]

Thanks GAgal, I looked at the package inserts for Proclear and they back you up. It's strange that contact lens databases show different data, though.

[optostudent]

I found some fascinating reading about the lawsuits against B&L and J&J regarding identical contacts for different modalities:

Roberts v. Bausch & Lomb, Inc.

Kropinski et al. v. Johnson & Johnson

[sharpstick777]

Welcome to Optiboard Optostudent!
Sorry for the less than friendly welcome. We occaisionly get consumers here that pose as professionals.

In theory, daily lenses don't require surviving a daily disinfecting and cleaning regime, nor do they have to survive repeated removal and insertion. They don't have to have the same thickness or surface treatments that 2-4 week lens have that are designed to shed protien and bacteria, and survive cleaning and removal without tearing. 2-4 week lenses always return a small degree of solution to the eye (even if its self neutralized), daily lenses don't have to cleaned so they only carry their original solution. That is theory, in reality manfactures will interpret those options differently in their lenses.

The real difference to me is that even 2-4 week lenses that are cleaned properly degrade due to wear, air, chemicals, UV exposure, bending, build up and cleaning solution that degrades the surface in contact with the cornea over time. A daily lens will have less surface degradation. Combine a pristine surface with a thinner lens and you will simply have in general more potential comfort.

I do find dailies more comfortable myself, just like new socks.

I'm an optometry student, and I'm trying to figure out the difference between daily and monthly contacts. A few dailies seem to have the same materials, water contents and oxygen permeabilities as biweekly/monthly lenses of the same brand. Sometimes these dailies are thicker, thinner, or the same thickness as their biweekly/monthly counterparts. So is it just the packaging and care procedures that are different, or is there some other attribute that distinguishes them?

The lenses I'm looking at are:
SofLens Daily Disposables / SofLens 59
ProClear 1-Day / ProClear
1-Day Acuvue / Acuvue Colors

[eyechick1969]

ditto optostudent
I never saw whatever got all the uptightness on you or your question to begin with.
you just wanted some old pros real opinions. Who better to ask!
I think you know the truth.
If the percentage of all the materials is equal, lens thickness.....etc is all the same then, you are probably busting some of the big manufacturers for their 100% similarities. And if that's the case, rock on brother. You'll be great for the industry if you're ready to fight corporate. Someone has too.

[optostudent]

Thanks for the welcomes. And thanks, sharpstick, for the theories on daily lens differences. I’m going to bullet-point and address them:

- Theory: Monthlies are more durable to stand up to solutions, bending, and insertion/removal. / I’m not sure what would make monthlies more durable other than thickness. But 2-4 week lenses don’t seem particularly thicker than dailies. 1-Day Acuvue, 1-Day Acuvue Moist and 1-Day Acuvue TruEye are all thicker than regular Acuvue, Acuvue Advance and Acuvue Oasys. In fact, the thinnest contact I’ve found is the plain old polymacon SofLens 38 that’s been around since the ‘70s. They’re less than half the thickness of most dailies. I tried searching for patents on contact lens technology that would make contacts more durable, but I didn’t find anything. That may be because I don’t know how best to search for patents, though.

- Theory: Monthlies are designed to shed protein and bacteria. / The only particularly protein-resistant contact lens material I could find is phosphorylcholine, which is used in the ProClear product line. But it’s used in both the daily and monthly modalities.

- Theory: Monthlies return solution to the eye. / This article is a good summary of internal humectants, which appear to be what enable contacts to return solution to the eye. It looks like this technology was first used in dailies, but several 2-4 week lenses now use this system, too. The biweeklies/monthlies absorb the solution they’re soaked in overnight and release it over the course of the day. The dailies also absorb the packaging solution they’re soaked in and release it over the course of the day. The systems seem pretty similar. Acuvue, the apparent leader in this technology, uses the same humectant, PVP, in both its dailies and biweeklies, whether it’s called Lacreon or Hydraclear.

So in summary, it still looks like there is, on the whole, no major difference between daily and monthly lenses. There are different lens technologies, but they seem to be applied to all modalities.