Question:

PRK, unlike LASIK, does not require artificial elevation of the intraocular pressure during the procedure. Rick Cohn, MD glaucoma specialist (eyegu…@aol.com)

Response:

In article <1998061221183400.RAA07…@ladder01.news.aol.com

,

  eyegu…@aol.com (EyeGuyRC) wrote: – Hide quoted text — Show quoted text -

During LASIK, the intraocular pressure (IOP) is elevated to greater than 80

mm.

of mercury by a suction ring placed around the edge of the cornea.  This is left in place for usually less than 30 seconds.  I therefore doubt if this could cause any significant optic atrophy in a patient with glaucoma.  Blood flow to the optic nerve and retina may be compromised during this time, so the suction ring should not be left on for longer than this.      Topical steroid medications used for up to 3 months after PRK or LASIK

can

be associated with a steroid-induced rise in IOP.  Such a case of steroid-induced glaucoma after PRK was just reported in the Journal of

Cataract

and Refractive Surgery (May, 1998).  The risk of this, however, is quite low.      Several articles have documented a reduction in measured IOP after refractive surgery.  Thinning or weakening of the cornea, a result of such surgery, makes it easier to flatten, giving a falsely lowered measurement.

The

measured reduction is usually on the order of 2-3 mm of mercury at most.  I would not let a history of glaucoma stop me from investigating refractive surgical options unless I had a history of moderately advanced glaucoma or steroid-induced pressure problems. Rick Cohn, MD glaucoma specialist (eyegu…@aol.com)

great answer thank you very much —–== Posted via Deja News, The Leader in Internet Discussion ==—– http://www.dejanews.com/   Now offering spam-free web-based newsreading

Response:

Dr. Robert Ritch responds: c…@journyx.com wrote: Is LASIK safe for patients who have glaucoma under control? We don’t know enough yet to say one way or another Also, I’ve heard PRK can cause pressures to be read incorrectly lower than they are in reality, leading to a false sense of security about glaucoma control.  Has anyone out there found real data on this? It’s under investigation but, basically, yes.

is there a guideline for indicating how many pressure points one should add in general after prk?  should you add 4  points?  10%?  is there any reliable way after PRK to calculate your true pressure? if a definitive answer can’t be given because it’s still under study, is there likely to be a way soon without additional new techniques or tools? __________________________________________________________________    Web-Based Time Tracking                      journyx WebTime    is FREE for 60 Days at                        (512)834-8888  http://journyx.com/wts.html                    c…@journyx.com —————————————————————— —–== Posted via Deja News, The Leader in Internet Discussion ==—– http://www.dejanews.com/   Now offering spam-free web-based newsreading

Response:

i’ve heard that during the lasik operation, IOP is artificially lowered for a brief time to around 80, and that in at least one case a patient’s visual field deteriorated dramatically immediatly after the operation Is LASIK safe for patients who have glaucoma under control? Also, I’ve heard PRK can cause pressures to be read incorrectly lower than they are in reality, leading to a false sense of security about glaucoma control.  Has anyone out there found real data on this? __________________________________________________________________    Web-Based Time Tracking                      journyx WebTime    is FREE for 60 Days at                        (512)834-8888  http://journyx.com/wts.html                    c…@journyx.com —————————————————————— —–== Posted via Deja News, The Leader in Internet Discussion ==—– http://www.dejanews.com/   Now offering spam-free web-based newsreading

Response:

Hi; Dr. Robert Ritch responds: c…@journyx.com wrote:

Is LASIK safe for patients who have glaucoma under control?

We don’t know enough yet to say one way or another

Also, I’ve heard PRK can cause pressures to be read incorrectly lower than they are in reality, leading to a false sense of security about glaucoma control.  Has anyone out there found real data on this?

It’s under investigation but, basically, yes.

Response:

During LASIK, the intraocular pressure (IOP) is elevated to greater than 80 mm. of mercury by a suction ring placed around the edge of the cornea.  This is left in place for usually less than 30 seconds.  I therefore doubt if this could cause any significant optic atrophy in a patient with glaucoma.  Blood flow to the optic nerve and retina may be compromised during this time, so the suction ring should not be left on for longer than this.        Topical steroid medications used for up to 3 months after PRK or LASIK can be associated with a steroid-induced rise in IOP.  Such a case of steroid-induced glaucoma after PRK was just reported in the Journal of Cataract and Refractive Surgery (May, 1998).  The risk of this, however, is quite low.      Several articles have documented a reduction in measured IOP after refractive surgery.  Thinning or weakening of the cornea, a result of such surgery, makes it easier to flatten, giving a falsely lowered measurement.  The measured reduction is usually on the order of 2-3 mm of mercury at most.  I would not let a history of glaucoma stop me from investigating refractive surgical options unless I had a history of moderately advanced glaucoma or steroid-induced pressure problems. Rick Cohn, MD glaucoma specialist (eyegu…@aol.com)

Response:

On Thu, 11 Jun 1998 12:45:00 GMT, c…@journyx.com wrote:

i’ve heard that during the lasik operation, IOP is artificially lowered for a brief time to around 80,

*Lowered* (?) to 80?  80 what?  Lowered *from what*?  80 mmHg (the usual units) is incredibly high. ……………

Ray

Response:

In article <35818933.1690…@news.sirius.com

,

  Raymond A. Chamberlin wrote:

On Thu, 11 Jun 1998 12:45:00 GMT, c…@journyx.com wrote: i’ve heard that during the lasik operation, IOP is artificially lowered for a brief time to around 80, *Lowered* (?) to 80?  80 what?  Lowered *from what*?  80 mmHg (the usual units) is incredibly high.

sorry, i meant ‘raised’ is it true that pressures are raised to 80 during LASIK as a part of the procedure?  is this not true for PRK? —–== Posted via Deja News, The Leader in Internet Discussion ==—– http://www.dejanews.com/   Now offering spam-free web-based newsreading

Response:

Question:

Sorry for a stupid question, but what do you mean by a tight fit of contact lenses? By tight fit I refer to the radius of the curvature of the lens. If I remember correctly I have a slightly smaller radius than my eye doc would normally prescribe.  I am not an expert on this so take all of this with a grain of salt.  My understanding is that they tend to prescribe a slightly larger radius that one that exactly matches the eye.  That leaves the edges loose and they can float easily. Can anyone either confirm or correct this?

I had a talk with my contact specialist yesterday and he was rather reluctant to give lenses with a smaller curvature radius. He said that they tried to match the curvature of the eye as much as possible, and that when the radius is too small the contact will be more loose in the center, also resulting in more loss. He also told that some people use lenses with a larger radius, so that they stick better under the eyelids, but that those can only be worn for a couple of hours and then your eye needs more oxygen… He gave me disposable contacts to try out, so I’ll be putting my head in a bucket of water this weekend and see how they work. At least with disposables I’ll have a lot of spare ones If they come out, I’ll ask for a second try with a tighter fit. Roos

Response:

Sorry for a stupid question, but what do you mean by a tight fit of contact lenses?

By tight fit I refer to the radius of the curvature of the lens. If I remember correctly I have a slightly smaller radius than my eye doc would normally prescribe.  I am not an expert on this so take all of this with a grain of salt.  My understanding is that they tend to prescribe a slightly larger radius that one that exactly matches the eye.  That leaves the edges loose and they can float easily. Can anyone either confirm or correct this? For me soft lenses unprotected by goggles is a no-no, a bit of splashing and they swim around blurring my vision. Maybe I use the wrong type, or the wrong "fit"?

I have never had this problem. Pete

Response:

Have worn soft lens contacts (accuvue) for 4 years with only occasional, annoying need to blink hard and fast after getting face-splashed.  As for surgery?  I could get and can afford it, but can’t wait for the headlines in a few years about peoples’ eyes falling out. PRK laser eye surgery has been around for over ten years with no ill effects. A new surgery which just started called Lasik is even better. No recovery time needed, healing totally in a few days.

First:  I’ve worn soft contacts on the river for several years.  I wear cheap swim goggles.  They tend to fog a bit for the first few minutes, but then stabilize.  Rain and waves in the face don’t bother me.  I roll with my eyes open.  I have to replace the goggles about every 30 runs or so.  They get scratched, etc.  The goggles saved my eye once when I found a rock with my face immediately after flipping.  I escaped with a black eye and a minor cut, rather than a major injury. Second:  I had my first visit to measure my eye topology for PRK surgery yesterday.  Yes, lasik heals a bit faster, but has a slightly higher risk and a slightly lower success rate.  Two success rate numbers are quoted:  the percentage who achieve at least 20-40, which is the threshold normally required to drive without correction; and the percentage who achieve 20-25.  The percentage achieving at least 20-40 is about 98% for both types of surgery. The percentage achieving at least 20-25 is something like 80-85% for lasik and 85-90% for PRK.  Lasik also requires temporary mechanical removal of the surface of the cornea, so that the laser works underneath.  The cornea heals from this very quickly (a flap is cut and laid to one side, then replaced), but the mechanical intrusion raises the risk of complications very slightly. Lasik offers correction for higher degrees of myopia and astigmatism than PRK. Lasik has a much shorter history and a much smaller statistical database than PRK.  The FDA (a United State governmental agency) has recently approved the use of PRK to correct diopters as great as -12. I think I will still wear goggles afterwards, but I could change my mind.            John Cooley

Response:

I also like the soft contacts (Acuvue daily) for paddling.  I’ve had my eyes open in pretty turbulent rolls and haven’t lost one yet.  Besides it is easy to carry spares.  I wear bi-focals normally but I see fairly well with single vision.  You don’t need to read War and Peace on the river, single correction should be enough for almost everyone while on the river.  As far as the comments about blurred vision when splashed, I haven’t found that contacts make this any worse.  I asked them to fit my lenses a little tight.  The eye doc though I was nuts.  He said they usually fit them as loose as they can so that you get maximum comfort.

Sorry for a stupid question, but what do you mean by a tight fit of contact lenses? For me soft lenses unprotected by goggles is a no-no, a bit of splashing and they swim around blurring my vision. Maybe I use the wrong type, or the wrong "fit"? JohanL

Response:

Have worn soft lens contacts (accuvue) for 4 years with only occasional, annoying need to blink hard and fast after getting face-splashed.  As for surgery?  I could get and can afford it, but can’t wait for the headlines in a few years about peoples’ eyes falling out.

PRK laser eye surgery has been around for over ten years with no ill effects. A new surgery which just started called Lasik is even better. No recovery time needed, healing totally in a few days. W

Response:

I have a bit of a problem seeing on the river what should I wear to correct it?  contacts or glasses or anything in between.  I’d like to hear of some peoiple who actually have the same problem I have.  Keep in mind I’m only sixteen and they won’t let me have corrective surgery yet. thanks a bunch Matt Young

Matt, You will probably have to experiment to see what works for you. The utility of contacts for you may depend on your eye structure, the type of water you paddle, the type of boat you paddle and your willingness to put up with water droplets on your glasses. For example, the size of your palpebral fissure may affect your use of contacts (this is how open your lids tend to be in a neutral resting position and is often interpreted as "big eyes" when the fissure is large). People vary from large (big deer eyes) to narrow slits (like a tundra dweller) and anywhere in between. If you have a large fissure (big deer eyes) like I do then contact lenses are more exposed and more easily dislodged or swim around when splashed (this eliminated contacts for me). If you paddle harder water then having a lens dislodged or swimming around may not be acceptable. For many years I frequently paddled class V such as the Lower Meadow. At levels around 1200 cfs you frequently can be engulfed by exploding waves where a crux move immediately follows. For me, closing my eyes or having a contact dislodged or swimming around at that moment was unacceptable. In easier water it may just be an annoyance. If you paddle kayak you will have more problems with water obscuring your vision than a C boater since you are closer to the water. One L. Meadow run with Dean T. pointed this out to me. It was something he had never considered. I use methods such as described by Bettina C. in a previous post. If you use the Dawn soap on the glasses method you need to make it convenient. The hardest part is finding a small dispenser bottle with a pop up spout. It needs to be small enough to not be in the way and immediately available so you will use it when you need it. I have a small bottle about 1.5 inches long that is tethered to my waist cord and rides in a crease of my PFD near my knife. You also need to get used to popping a drop on your finger when you eddy out, treat the inside of the lenses and then go. A convenient setup will make this feasible. In wetter runs you may have to do this every rapid. In dryer runs it lasts a lot longer. For nearly 20 years this has worked for me but each person must find their own solution. I would be skeptical about the jetski goggles since you will generally not be moving fast enough to force sufficient air through the vents. When you stop in a wind protected eddy and are hot from exertion I would predict they will fog immediately. Good luck. Jon

Response:

I’ve always worn prescription glasses/sunglasses. I am still in search of the Holy Grail, namely fog-free prescription glasses. As hypothesized in an earlier thread, the Holy Grail might be some device that provides significant air circulation AND distance between the prescription lenses and the face.  Or it might be a John Lennon style eyeglass (i.e., small surface area). I don’t know whether prescription Barz is the Holy Grail.  I hope someone who has tried it on the Nantahala or similarly cold water can say yay or nay. I saw some value in using Dawn (the dishwashing liquid) but have not been completely satisfied with that solution.  Various "fog-free" drops (Sea Drops, Rain-X, etc.) never worked for me. I found that prescription swimming goggles and diving masks fog up quickly, and obstruct peripheral vision.

Response:

   I also have had good results with soft lenses on the river.  (Until I needed bifocals anyway).  The disposable ones are inexpensive enough to carry a spare pair and you  can loose one in a swim with a clear conscience.

I also like the soft contacts (Acuvue daily) for paddling.  I’ve had my eyes open in pretty turbulent rolls and haven’t lost one yet.  Besides it is easy to carry spares.  I wear bi-focals normally but I see fairly well with single vision.  You don’t need to read War and Peace on the river, single correction should be enough for almost everyone while on the river.  As far as the comments about blurred vision when splashed, I haven’t found that contacts make this any worse.  I asked them to fit my lenses a little tight.  The eye doc though I was nuts.  He said they usually fit them as loose as they can so that you get maximum comfort. I went for one step tighter than he would usually recommend.  He said this was still in the acceptable range.  I have been very satisfied with the results.  Someone on this NG had suggested the tighter fit after having switched to a tighter fit themself because of losing too many lenses. BTW: I only wear contacts for paddling.  I wear glasses the rest of the time. Pete

Response:

I have a bit of a problem seeing on the river what should I wear to correct it?  contacts or glasses or anything in between.  I’d like to hear of some peoiple who actually have the same problem I have.  Keep in mind I’m only sixteen and they won’t let me have corrective surgery yet.

Hi Matt, I personally prefer soft contacts as well: I’ve been using them ever since I started WW-Kayaking and although I had to blink once or twice while being on the river, I didn’t loose one (yet). Mine only cost 20US$ for half a year (excluding the rinsing-fluids), so I always take along a spare pair on vacations. You should be within the Dioptrical (sp?) limits that the cheap ones come in. I can only get them to maximum -8 over here… so if your eyes are worse than mine, you might have to search for better ones. I don’t like spectacles on the water: I’ve seen some disappear beneath the surface when the rubber strap broke, and they can: fog over, get splashed, break, etc.. All things that just happen when Murphy’s Law is applied. Good luck finding something that suits you! — Sociology Student  at the Tilburg University,  The Netherlands Whitewater Kayaker                         AD&D Dungeon Master Secretary  of  the  Eindhoven  Canoe Club  "De Genneper Molen"   No man is wise enough, nor good enough                                      to be trusted with unlimited power.                                       Charles Colton

Response:

I have a bit of a problem seeing on the river what should I wear to correct it? contacts or glasses or anything in between.  I’d like to hear of some peoiple who actually have the same problem I have.  Keep in mind I’m only sixteen and they won’t let me have corrective surgery yet.

I’ve been wearing soft disposable contacts on the river for nine years and hardly ever have a problem with them.  I guess I lose about one or two a year on average, just carry a spare pair with you.  I have never had anything but problems with eyeglasses on the river.  Go with contacts. Joel D.

Response:

I have a bit of a problem seeing on the river what should I wear to correct it?  contacts or glasses or anything in between.  I’d like to hear of some peoiple who actually have the same problem I have.  Keep in mind I’m only sixteen and they won’t let me have corrective surgery yet.   thanks a bunch Matt Young

Response:

Have worn soft lens contacts (accuvue) for 4 years with only occasional, annoying need to blink hard and fast after getting face-splashed.  As for surgery?  I could get and can afford it, but can’t wait for the headlines in a few years about peoples’ eyes falling out.

Response:

    I also have had good results with soft lenses on the river.  (Until I needed bifocals anyway).  The disposable ones are inexpensive enough to carry a spare pair and you  can loose one in a swim with a clear conscience. Nelson Highley

– Hide quoted text — Show quoted text -I have a bit of a problem seeing on the river what should I wear to correct it? contacts or glasses or anything in between.  I’d like to hear of some peoiple who actually have the same problem I have.  Keep in mind I’m only sixteen and they won’t let me have corrective surgery yet. thanks a bunch Matt Young

Response: