Concern about regression after Lasik

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Concern about regression after Lasik

Postby aaa » Thu Nov 15, 2007 7:09 am

I have been reading this forum for sometime, and was doing some searching to see if anyone is in my situation, but cant find any similar questions.

I am booking for Lasik surgery in two weeks time, but I still have a reservation. So I am seeking some opinions.

I am 29, male, short-sighted,. -4.75 and 0.5 astigmatism in both eyes. I have been to two clinics for assessment (I am in Australia), and both said my eyes are healthy and ideal for Lasik surgery after a full assessment. Cornea thickness is about 550-560 (they did a few measurements).

My concern is that my eyes are not very stable. I have been wearing glasses for about 12 years. I had one checkup about 3 years ago, and wore glasses on -3.75 prescription. Then I had another one about 4 months ago, and my eyes changed ( I knew that was the case), it was about -4.25. But when I went to consultations about a week ago, it was about -4.75. I am not sure that the current glasses cause me any issue, as I dont feel very comfortable with them, or my eyes are changing. The two ladies, who did the measurements in both clinics, told me that my eyes should be stable by now because if my age.

On the 2nd clinic - which a very reputable one, I also met a surgeon who will be performing the surgery, he did a checking on my cornea as well. He said that variation in prescription is acceptable and I can have the surgery. He also said that to eliminate another possibility (not sure what it is, I should have asked), they put two drops into my eyes - so that I could not focus and enlarged my pupils (I dont know the name of the drops). After that, they check my vision again, and it does not really change. So they think it's good. I did feel the drops for about 2 days - could not focus very well in the first few hours, and bad glaring on sunlight for more than 1 days. The clinic said it is possible, and no link the effect from the surgery.

I am still afraid that my eyes will regress back to current (or -2 or something like that). Even though it costs money, it's not my main concern. I am more concerned with other risks that I have to go through and my eyes might go back to where they were. I do trust the surgeon but at the end of the day, he only checks up and measure it for that day only.

So should I still go for it? I feel I am at the right age to do it, not too young, and not too old so I dont have to wear reading glasses for awhile yet.
Thanks.
aaa
 
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Re: Concern about regression after Lasik

Postby LasikExpert » Thu Nov 15, 2007 9:04 am

About 0.25 diopter is considered within normal human fluctuation.

A technical point: “Regression” in Lasik means that after surgery your eye moves back toward your original refractive error. Lasik regression is common when correcting myopia (nearsighted, shortsighted) over about 6.00 diopters and virtually all hyperopia (farsighted, longsighted) correction. What you are describing is the natural progression of your myopia. Actually, the appearance of a natural progression of myopia. Read further why I emphasize appearance.

A quick and important point that if your eye prescription is for contact lenses it will likely be lower than if it is for glasses. If you look at one prescription for contacts and compare it to another for glasses, you could easily be 1.00 diopter off.

aaa wrote:I He also said that to eliminate another possibility (not sure what it is, I should have asked), they put two drops into my eyes - so that I could not focus and enlarged my pupils (I dont know the name of the drops). After that, they check my vision again, and it does not really change. So they think it's good.


This is excellent.

The natural crystalline lens within the eye is able to change shape and thereby change focus. This process of changing focus is called accommodation. In a natural and relaxed state, a normal eye is focused for distance vision (beyond about 20 feet/6 meters). To see objects close, a normal eye must accommodate.

The most common form of myopia is when the eye is longer than normal. In a relaxed state, the light entering the eye focuses in front of the retina, the light sensitive membrane on the back of the eye.

A manifest refraction is when the doctor uses different lenses (which is better, one or two?) to determine your best corrected visual acuity (BCVA). A limitation of the manifest refraction is that you are able to accommodate. That means that you may actually “focus around” some of your myopia through accommodation. This can provide an eye presctiption that is actually lower than your true myopia.

Up until about age 8-10 we have a tremendous amount of accommodation. This is a contributing factor why many myopes don’t need glasses until around this age. Our young eyes are able to “focus around” the myopia. After around age 8-10 the natural crystalline lens is less able to change shape and we start to have less accommodation. The reduction of accommodation is called presbyopia. Presbyopia continues throughout our lives, but is not really noticed until around age 40 we are much less able to accommodate enough to see close objects and need reading glasses or bifocals.

A cycloplegic refraction is the same as a manifest refraction except eye drops paralyze the crystalline lens so you cannot accommodate...you cannot focus around your myopia. A cycloplegic refraction will measure your actual refractive error.

The fact that your manifest refraction and cycloplegic refraction are the same is a very, very good sign. The fact that this particular doctor did a manifest and cycloplegic refraction is a sign of a much more comprehensive examination.

It is quite possible that during previous manifest refractions you were focusing to reduce your myopia, giving an eye prescription that misrepresented your actually refractive error.

Believe it or not, I oversimplified this explanation, but for now what is important is that your manifest and cycloplegic are the same.

aaa wrote:I did feel the drops for about 2 days - could not focus very well in the first few hours, and bad glaring on sunlight for more than 1 days. The clinic said it is possible, and no link the effect from the surgery.


Correct. Your pupils took a while to return to their normal and more constricted size and your crystalline lens took a while to regain accommodation. This is common.

Now, back to your “Should I Do It” question. I cannot give you that answer, but you already indicate that you understand the downside – enhancement surgery. If your eyes continue to change at the rate they appear to be changing, enhancement surgery in a few years seems probable. Keep in mind, the changes you note may only be the appearance of change. If your surgeon successfully corrects you, you won’t be trying to focus around your myopia.

There may be other issues that are causing an actual change in refractive error. I suspect your surgeon did a comprehensive examination for signs of ocular health problems. If anyone in your family has had eye problems, especially corneal transplant or must wear Rigid Gas Permeable (RGP) contact lenses to be able to see, you need to inform your doctor of the details.

I am obviously making assumptions without the benefit of detailed information from your examination, and I am not a doctor. Your doctor will be the best person to ask for a better explanation. I suggest you ask for an appointment or schedule a phone call to discuss your concerns, alternatives, and what in the opinion of your surgeon is best for you.
Glenn Hagele
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Thanks

Postby aaa » Thu Nov 15, 2007 11:17 pm

Glenn, thank you very much for the explanation. It makes a lot more sense to me now, as the doctor did not explain as well and as detailed as you did. But from your post, I think the doctor has done all the checks that he could.

We have no known cornea issues in the family, and both clinics did detail examinations, they both said my eyes are good for surgery. I think I am too cautious. But these decisions cannot be taken lightly. But I feel a lot better to make a decision after I understand it more from your help.

Again, many thanks.
aaa
 
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Re: Thanks

Postby LasikExpert » Fri Nov 16, 2007 1:48 am

I'm glad my explanation helped. Doctors do seem a bit rushed sometimes.

aaa wrote:I think I am too cautious.


I don't think that is possible when you are considering elective surgery, but remember that the probability of something happening is more imporant than the possibility. There are a gazillion things that can harm you every day, but the probability of being harmed is relatively small.
Glenn Hagele
Volunteer Executive Director
USAEyes

Lasik Info &
Lasik Doctor Certification

I am not a doctor.
LasikExpert
Site Admin
 
Posts: 3309
Joined: Fri May 12, 2006 6:43 am
Location: California

Re: Concern about regression after Lasik

Postby SteveR » Sat Nov 17, 2007 2:15 pm

LasikExpert wrote:The natural crystalline lens within the eye is able to change shape and thereby change focus. This process of changing focus is called accommodation. In a natural and relaxed state, a normal eye is focused for distance vision (beyond about 20 feet/6 meters). To see objects close, a normal eye must accommodate...

That means that you may actually “focus around” some of your myopia through accommodation. This can provide an eye presctiption that is actually lower than your true myopia...

A cycloplegic refraction is the same as a manifest refraction except eye drops paralyze the crystalline lens so you cannot accommodate...you cannot focus around your myopia...

It is quite possible that during previous manifest refractions you were focusing to reduce your myopia, giving an eye prescription that misrepresented your actually refractive error.



Hi Glenn,

That's interesting with regard to your comments about accommodation and myopia, since in my reading I've only seen accommodation referred to with relation to increasing the optical power of the eye, i.e. to ‘focus around’ long-sightedness or to accommodate for near tasks. I was not aware that the eye could focus around myopia too.

As far as I understood it, the myopic eye is optically too powerful/positive and requires negative lenses to correct, and the eye's accommodative ability is able only to increase the optical power of the eye. A paralysed crystalline lens would be in a relaxed state, but isn’t that the condition the myopic eye is in looking to infinity anyway? What would change for the myopic looking at distance with a paralysed lens? Can accommodation decrease the optical power of the eye, or failing that what accommodative mechanism is involved in ‘focussing around myopia’?

Regards
SteveR
 
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