Enhancement Procedure for Small Abalation Zone

I had bilateral Lasik done for myopia (-6D both eyes) 7 weeks ago. I am
slightly under-corrected (-0.5D in R eye, -0.75D in L eye); this is not a
problem to me. My vision is good in bright light.

My problem is poor low-light vision: the usual haloes etc, and blurring in
even relatively low light, not just at.night. At a follow-up visit, my
ablation/optical zone was found to be significantly smaller than my pupil
size in low light (I forget the actual figures). The optical zone is well
centred. My residual corneal bed thicknesses are 285 micron right eye, and
302 micron left eye. I am 43 years old.

Does anyone have experience of enhancement prodecures to enlarge the optical
zone? Is it possible with the above information? Would it help my low-light
problems?

I would greatly appreciate any info, from eye-care professionals, and
especially from patients.

Thanks

Mike

(Please remove 123 from e-mail address when replying).

 

Hi Mike,

I'm sorry to hear about your problems.

At seven weeks postop you can expect some improvement with healing and
adaptation, however it appears that your problems are significant and
may not be resolved with healing. I suggest that you not do anything
surgically to correct this problem until at least three months postop.
Delaying treatment should not be problematic. Contacts, glasses, and
eye drops should be fine, but you want things to settle down before
any additional surgery.

For more information how pupil size affects refractive surgery
outcomes, visit http://www.complicatedeyes.org/pupil_size.htm

You should look into getting fitted with rigid gas-permeable (RGP)
contact lenses. Often this type of contact will reduce or eliminate
the problem, but this is obviously only a management response, not a
resolution.

You could ask your doctor to prescribe Alphagan C drops. These drops
will cause your iris to constrict, making the pupil smaller. This may
also help managed the problem until a permanent resolution is found.

Most doctors are looking toward Complex Wavefront Retreatment (CWR)
for situations like yours. Although it is easiest to think of
"expanding the treatment zone" as the answer, CWR would look at your
cornea from a perspective of what is happening to the light passing
through your eye, rather than what has been done to the surface of
your cornea. This perspective will provide a detailed analysis of the
Higher Order Aberrations (HOA) that are causing or contributing to
your low light vision problems. Laser treatment that is guided by
this wavefront analysis will attempt to correct the HOA that are
caused by the irregularities in your cornea, including the ablation
size issue.

There are not many surgeons in the US or abroad that are performing
CWR, and fewer who have much experience in this area. If you would
like a referral to a doctor for contacts, drops, or evaluation for
CWR, contact me directly.

Your undercorrection is both advantageous and problematic. At age 43,
you would start to suffer the effects of presbyopia (needing reading
glasses). Being slightly undercorrected in your non-dominant eye may
help defer the need for reading glasses. You should consider
monovision correction if you have an enhancement or wear contacts.
For more on monovision, visit
http://www.usaeyes.org/faq/subjects/monovision.htm.

Being undercorrected provides a margin of error for any retreatment
without overcorrecting you into hyperopia (farsightedness). You
really don't want to be hyperopic and presbyopic. This combination
provides poor vision at almost all distances.

Although monovision may defer or reduce your need for reading glasses,
your current undercorrection may be contributing to your low light
vision problems. If the halo and other night vision problems
dissipate with glasses (not contacts) that fully correct your vision,
then the undercorrection is contributing to the problem.


Glenn Hagele
Executive Director
Council for Refractive Surgery Quality Assurance
http://www.USAeyes.org
http://www.ComplicatedEyes.org
glenn dot hagele at usaeyes dot org

I am not a doctor.

 

Results differ, but here's one story.
http://www.drsalz.com/chris.htm

Why aren people getting treatment zones too small in the first place?
Every new treatment reduces the cornea thickness and increases the
risks.

 

Your situation might be improved by a system called TOSCA, for Topography
Supported Customized Ablation. Using a small beam laser, such as a Mel 70
or Mel 80, the system generates a customized ablation profile from
topography and ablates the difference between the smaller optical zone and
the larger optical zone. One can see an excellent presentation on this
subject at the following website: www.mitchelleyecentre.com .

Otherwise, consider contact lenses.

DrG