both under-correction and over correction after PRK(ASA)

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both under-correction and over correction after PRK(ASA)

Postby sarvarsandhu » Sun Jul 20, 2008 6:34 am

I was diagnosed with signs of keratoconus which was non-progressive
in one of my eye(left eye).Lasik was considered too risky , So PRK followed by Cross linking procedure was advised to me .


Treatment for right eye ( 5 months to operation to date )

PRK followed by Cross linking ( C3-R) Procedure was done in right eye .
After 2 weeks my vision in right eye was +0.5 spherical ,+0.5 cylindrical which has
remained the same even after 5 months .
Doctor told that over-correction might have been because of Cross-linking C3-R procedure.
There was some mild haze in the eye ( no mitomycin was used ) , epithelial was removed manually .

Treatment for left eye ( 3 weeks to operation to date)
PTK to remove epithelial layer , Surface ablation with Allegretto wave
laser .followed by Collagen Cross linking procedure with riboflavin eye
drops .As the other eye (right eye) had healed differently to be
over-corrected ,This eye was under-corrected on purpose . But again
this healed differently from right eye to be under-corrected . After 3
weeks my vision in this eye is -0.75 spherical ,-0.75 cylindrical.




Age : 29 years Old

Pre-op
Right eye : -3 , - 1 cylindrical ( no signs of keratoconus)
left eye : -3.25 , -1.75 cylindrical (some signs of keratoconus)

Post-op
left Eye : -0.75 spherical , -0.75@77 cylindrical ( 3 weeks post operation )
right Eye : +0.5 spherical ,+0.5 cylindrical ( 5 months post operation ) .


So finally I am left with one eye over corrected and one under-corrected :( .
It gives me problem with both distance vision and near vision
and I am usually left with headaches and nausea by end of day .


I would like the opinions of other members . Should I seek enhancement
for over-correction ( +0.5 spherical ,+0.5 cylindrical ) ? Would it be worth
the risk considering I do have mild haze from the previous operation ?
How much cornea tissue will be removed for this correction ?


Thanks in advance .
sarvarsandhu
 
Posts: 10
Joined: Sat Jul 19, 2008 3:09 pm
Location: india

Postby LasikExpert » Sun Jul 20, 2008 5:16 pm

With or without corneal collagen crosslinking (CxL) you are at a very increased risk of problems due to your diagnosed keratoconus. Keratoconus is a corneal disease that causes weakening of the corneal tissue, usually presenting first as extreme astigmatism. If Keratoconus is present in one eye it is very highly likely that the other eye will also be affected.

PRK changes the refractive error by removing corneal tissue. While this may initially provide the desired change in refractive error it also weakens the cornea. Weakening a cornea that is affected by a corneal weakening disease is less than wise.

Your low refractive error indicates that you would likely have been a candidate for Intacs, which both reduce myopia (nearsighted, shortsighted) vision and has been shown to stabilize the progressive disease keratoconus.

While CxL is designed to stabilize a cornea affected by keratoconus, there is very little evidence that it neutralizes the problem enough that laser assisted corneal refractive surgery is appropriate. There is no long-term evidence that CxL and PRK is appropriate.

Having additional laser assisted corneal refractive surgery after CxL is much less predictable than without. All laser assisted corneal refractive surgery calculations and virtually all science behind the technology is based on the reactions of a normal healthy cornea. The amount that CxL has changed the cornea (stiffening it similar to advance age) would be difficult to predict. The amount of laser energy required to make the relatively small changes would be even more difficult to predict.

Since you are relatively young and your ability to accommodate (change focus for near objects) should be rather good, you need to have a cycloplegic refraction (which is better, one or two?), which paralyzes the natural lens within the eye and provides a true refractive error, not refractive error that is diminished by you attempting to "focus around" it.

I suspect that your real hyperopia (farsighted, longsighted) refractive error is much more than the 0.50 diopters from a manifest refraction (which is better, one or two without the paralyzed lens) and your nausea is caused by your over-stressed accommodation to try to balance your vision.

I very, very highly recommend you not have any additional elective laser assisted refractive surgery until you are at least one year postop from your CxL. Two years would probably be better. And I also highly recommend you seek a second opinion from a corneal specialist within a university affiliated teaching hospital before making a decision.
Glenn Hagele
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Postby sarvarsandhu » Mon Jul 21, 2008 7:48 am

Glenn, Thank you very much for your detailed and insightful answer .
I had spoken to my doctor about constant headaches , he said 0.5D of
over correction can not cause this . Now I know that it may be only manifest refraction .


Intacs were an option , but my doctor told me that they are not as accurate , might require some
visits for fitting and providing more that 2.5 D of correction may be tough .


I am sorry to bother you with couple of more questions .

Can CLAPIKS work for me ? I wanted to add that although I was diagonsed with keratoconus symptoms there was no change in
topography over a period of 2 years .
And the right eye ( the one I am looking for CLAPIKS solution )
does not show any symptoms of keratoconus at all . My refraction has
been stable for last 12-15 years .


I do have mild haze from previous treatment( 5 months to date ) , do you
think it will resolve with time ?
Last edited by sarvarsandhu on Sun Jul 27, 2008 1:22 pm, edited 1 time in total.
sarvarsandhu
 
Posts: 10
Joined: Sat Jul 19, 2008 3:09 pm
Location: india

Postby LasikExpert » Mon Jul 21, 2008 5:51 pm

sarvarsandhu wrote:Can CLAPIKS work for me ?


It is impossible to predict how CLAPIKS would affect a kerataconus cornea after CxL. If your cycloplegic refraction is only about 0.50 diopters, then CLAPIKS would likely be helpful for a normal healthy cornea.

sarvarsandhu wrote:I wanted to add that although I was diagonsed with keratoconus symptoms there was no change in
topography over a period of 2 years .


This is all very important and very good news, however keratoconus can be progressive and has a high probability of affecting both eyes. There are refractive surgeons who will not provide laser assisted vision correction surgery for anyone with a family history of keratoconus, regardless of the patient's specific symptoms or lack thereof.

sarvarsandhu wrote:And the right eye ( the one I am looking for CLAPIKS solution ) does not show any symptoms of keratoconus at all .


Let's hope it never does.

sarvarsandhu wrote:My refraction has been stable for last 12-15 years .


This too is a very important factor in deciding to have laser assisted vision correction surgery in the presence of keratoconus, but keep in mind that the use of rigid gas permeable (RGP) contact lenses can mask keratoconus' effects. You may have stabilized keratoconus, but others reading this my have different circumstances.

sarvarsandhu wrote:I do have mild haze from previous treatment( 5 months to date ) , do you think it will resolve with time ?


The cornea is very good about healing and clearing corneal haze, although it can take a very long time (even years). I cannot predict how the CxL may have affected the issue of haze.
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

Postby sarvarsandhu » Mon Jul 21, 2008 7:17 pm

Thank you Glenn for all the answers !
sarvarsandhu
 
Posts: 10
Joined: Sat Jul 19, 2008 3:09 pm
Location: india


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