How Does Night Time Wear Compare to Day Time?

Jesterhester · #1 (**permalink**) 02-11-2008, 02:26 PM

If you wear a pair of contact lenses for 24 hours straight, assuming this these are contacts that are designed to be worn overnight, would that be considered one day of wear, or two?

Zana · #2 (**permalink**) 03-11-2008, 01:53 PM

Quote:

Originally Posted by Jesterhester

If you wear a pair of contact lenses for 24 hours straight, assuming this these are contacts that are designed to be worn overnight, would that be considered one day of wear, or two?

If the lenses are designed for overnight use, then one day equals one day. Simple.

If they're not designed for overnight wear, I've heard that one night equals 1.5 days. So if you wear your contact lenses for 24 hours straight without taking them out and disinfecting them, that would be equivalent to 2.5 days of wearing them only during the day.

Jesterhester · #3 (**permalink**) 04-28-2009, 12:12 PM

Quote:

Originally Posted by Zana

If the lenses are designed for overnight use, then one day equals one day. Simple.

If they're not designed for overnight wear, I've heard that one night equals 1.5 days. So if you wear your contact lenses for 24 hours straight without taking them out and disinfecting them, that would be equivalent to 2.5 days of wearing them only during the day.

Let me see if I got this straight. Let's say you put your contacts in at 7 am, go to bed at 10 pm and wake up again the next morning at 7:00. From 7 am to 10pm is one day. 10 pm to 7 am is one and a half days for a total of two and a half days?

Zana · #4 (**permalink**) 04-29-2009, 09:40 AM

Quote:

Originally Posted by Jesterhester

Let me see if I got this straight. Let's say you put your contacts in at 7 am, go to bed at 10 pm and wake up again the next morning at 7:00. From 7 am to 10pm is one day. 10 pm to 7 am is one and a half days for a total of two and a half days?

That's what I've heard, yes. Can anyone else tell us more about this?

bammer · #5 (**permalink**) 05-06-2009, 07:31 PM

The main difference that I have noticed is that at night there is less problem with glare unless I am driving and the headlights. AT night I wear very light sunglasses to reduce the sudden glare of headlights. I have photo sensitive sunglasses that are barely yellow at night and get slightly browner in the bright sun during the day.

sunshine4 · #6 (**permalink**) 05-07-2009, 09:26 AM

I would think that if you wear your contacts for a 24 hour period, that is considered one day.

Jesterhester · #7 (**permalink**) 05-28-2009, 03:16 PM

Quote:

Originally Posted by bammer

At night I wear very light sunglasses to reduce the sudden glare of headlights. I have photo sensitive sunglasses that are barely yellow at night and get slightly browner in the bright sun during the day.

What kind of sunglasses are those? Are they intended for night driving?

shirley · #8 (**permalink**) 09-19-2009, 11:31 PM

Quote:

Originally Posted by Zana

If the lenses are designed for overnight use, then one day equals one day. Simple.

If they're not designed for overnight wear, I've heard that one night equals 1.5 days. So if you wear your contact lenses for 24 hours straight without taking them out and disinfecting them, that would be equivalent to 2.5 days of wearing them only during the day.

well in my analysis one day is equivalent to 24 hours..just curious though..is there such contact lenses for overnight use?

Frodo · #9 (**permalink**) 09-22-2009, 11:32 AM

Quote:

Originally Posted by shirley

Just curious though..is there such contact lenses for overnight use?

Oh yes indeed. There are a whole bunch of contacts you can wear all night. How long would you like to wear a pair of contact lenses? A week or a month?

Jesterhester · #10 (**permalink**) 10-05-2009, 11:54 AM

Quote:

Originally Posted by shirley

well in my analysis one day is equivalent to 24 hours..just curious though..is there such contact lenses for overnight use?

Like Frodo said, there are contact lenses you can wear day and night for a week or even as long as a month. You can go to lens.com and look at the different brands and prices. Then if you see two or three kinds you like, you can ask you doctor about these brands. If you think you might like to try them, you can get a prescription from your doctor and order them from lens.com for probably less than the doctor will charge.

Zana · #11 (**permalink**) 12-03-2009, 03:13 PM

Quote:

Originally Posted by Jesterhester

Like Frodo said, there are contact lenses you can wear day and night for a week or even as long as a month. You can go to lens.com and look at the different brands and prices. Then if you see two or three kinds you like, you can ask you doctor about these brands. If you think you might like to try them, you can get a prescription from your doctor and order them from lens.com for probably less than the doctor will charge.

I wonder if Shirley has read this and tried some extended wear contact lenses. Are you out there Shirley?

Knotlob · #12 (**permalink**) 12-03-2009, 04:17 PM

Hi

I think Zana's figure of 1,5 days equivalent for a night's sleeping in contact lens originates from the way the cornea derives it's oxygen.

In daytime, eye open, oxygen flows to the cornea (which has no capillary blood supply normally) via the tear film and the air around the lens. The contact lens is a physical barrier and will reduce this oxygen flow, but the newer silicone gel lenses have much higher oxygen permeability and are better for the eye's oxygen supply.

At night when the eyes are closed, the oxygen supply to the cornea is via the capillaries in the eye lid, but the oxygen supply is less that would occur in daylight when the eyes are open. This causes the eyes to swell by around 4%, (but some lower figures around 2.5% are also being quoted).

If you wear contact lenses (which are for day time use only) at night, the oxygen supply to the eye will be further critically restricted - hence the equivalent of 1.5 days for one night's sleep with contact lenses.

As has been posted here already, the newer silicone hydrogel lenses are claimed to be able to exceed the eye's oxygen requirements, even wearing the lenses 24/7 for a month.

My previous optician always recommended that when I awoke in the morning, I should try and wait 45 mins before I put my (yearly soft) lenses in - this was in order that my corneas could obtain as much oxygen after sleeping, before I restricted the oxygen flow by wearing contact lenses.

I discussed the capillary problem earlier here:
Post #30
http://www.lens101.com/general-eye-health/21755-if-you-dont-stop-youll-go-blind.html

knotlob

Jurassicmark · #13 (**permalink**) 12-04-2009, 12:09 PM

Quote:

Originally Posted by Knotlob

Hi

I think Zana's figure of 1,5 days equivalent for a night's sleeping in contact lens originates from the way the cornea derives it's oxygen.

In daytime, eye open, oxygen flows to the cornea (which has no capillary blood supply normally) via the tear film and the air around the lens. The contact lens is a physical barrier and will reduce this oxygen flow, but the newer silicone gel lenses have much higher oxygen permeability and are better for the eye's oxygen supply.

At night when the eyes are closed, the oxygen supply to the cornea is via the capillaries in the eye lid, but the oxygen supply is less that would occur in daylight when the eyes are open. This causes the eyes to swell by around 4%, (but some lower figures around 2.5% are also being quoted).

If you wear contact lenses (which are for day time use only) at night, the oxygen supply to the eye will be further critically restricted - hence the equivalent of 1.5 days for one night's sleep with contact lenses.

As has been posted here already, the newer silicone hydrogel lenses are claimed to be able to exceed the eye's oxygen requirements, even wearing the lenses 24/7 for a month.

My previous optician always recommended that when I awoke in the morning, I should try and wait 45 mins before I put my (yearly soft) lenses in - this was in order that my corneas could obtain as much oxygen after sleeping, before I restricted the oxygen flow by wearing contact lenses.

I discussed the capillary problem earlier here:
Post #30
http://www.lens101.com/general-eye-health/21755-if-you-dont-stop-youll-go-blind.html

knotlob

That's a great post, Knotlob. Thank you very much for this valuable information. I've never heard it explained so simply and logically before.

Zana · #14 (**permalink**) 12-21-2009, 04:49 PM

Quote:

Originally Posted by Knotlob

Hi

I think Zana's figure of 1,5 days equivalent for a night's sleeping in contact lens originates from the way the cornea derives it's oxygen.

In daytime, eye open, oxygen flows to the cornea (which has no capillary blood supply normally) via the tear film and the air around the lens. The contact lens is a physical barrier and will reduce this oxygen flow, but the newer silicone gel lenses have much higher oxygen permeability and are better for the eye's oxygen supply.

At night when the eyes are closed, the oxygen supply to the cornea is via the capillaries in the eye lid, but the oxygen supply is less that would occur in daylight when the eyes are open. This causes the eyes to swell by around 4%, (but some lower figures around 2.5% are also being quoted).

If you wear contact lenses (which are for day time use only) at night, the oxygen supply to the eye will be further critically restricted - hence the equivalent of 1.5 days for one night's sleep with contact lenses.

As has been posted here already, the newer silicone hydrogel lenses are claimed to be able to exceed the eye's oxygen requirements, even wearing the lenses 24/7 for a month.

My previous optician always recommended that when I awoke in the morning, I should try and wait 45 mins before I put my (yearly soft) lenses in - this was in order that my corneas could obtain as much oxygen after sleeping, before I restricted the oxygen flow by wearing contact lenses.

I discussed the capillary problem earlier here:
Post #30
http://www.lens101.com/general-eye-health/21755-if-you-dont-stop-youll-go-blind.html

knotlob

Yes, knotlob. Like Jurassic Mark said, this posting made a lot of sense. Thank you for taking the time to write it all out.