Frequently
Asked Questions for Surgery
If
you have a question
that is not answered on this page, please Contact
Us.
Why
is the Astigmatome™ better than using freehand diamond cuts?
The
Astigmatome™ has a real advantage over hand held diamond knives.
With a diamond knife, you have to place it on the proper axis of cylinder, keep
it properly oriented and smoothly rotate the handle with precision. This is very
difficult to accomplish, particularly with any symmetry on paired incisions. The
Astigmatome incisions are centered on the astigmatism, they are symmetrical and
of uniform length. It’s a minimally invasive procedure and very difficult to
cause any harm.
When
do you use the Terry Astigmatome™ in conjunction with cataract
surgery?
Improved
spherical and astigmatic outcomes are well-recognized benefits of modern,
small-incision cataract surgery. The Astigmatome™ requires a firm globe, so
perform the LRI’s first. The single blade Astigmatome™ may be used to pair
an LRI opposite the cataract incision.
Will
correcting astigmatism influence IOL power calculations?
Yes,
but only slightly. Cliff Terry, M.D. has experienced a small hyperopic shift and
recommends the following adjustments:
K2 – K1 (Total cylinder)
Increase IOL by this amount
1-2 diopters
.25 diopters
2-3 diopters
.50 diopters
Do
you operate on the refraction or the K reading if the two are different?
If
the patient is phakic, use the refraction. Otherwise, use the K readings.
Does
patient’ age effect the nomogram or correction obtained?
Both
the patient’s age and geometry of the cornea affect the results. LRI’s are
less effective on younger patients. The correction obtained on an 80 year old
can be twice the amount obtained on a 40 year old.
Can
you use different LRI nomograms with the Terry Astigmatome™?
Yes,
several LRI nomograms are available. It is recommended that with experience the
nomogram be modified to adjust for your results.
Why
are there different treatment plans for With the Rule and Against the Rule
astigmatism?
Relaxing
incisions placed between 45° and 135° are less effective, therefore either
longer incisions are necessary or more centrally placed incisions are required.
When
do you use the 8mm Alignment Speculum?
The
8 mm Astigmatome was designed for use on corneas of small diameter and for the
correction of with the rule astigmatism. Limbal Relaxing Incision’s (LRI’s)
placed between the 45° and 135° axis obtain less effect. Therefore, to obtain
adequate correction the arcuate incisions are placed more corneal.
When
do you use the single blade Astigmatome?
For
cases of asymmetrical or non-orthogonal astigmatism. The single blade
Astigmatome™ is also useful when pairing a LRI with a cataract incision.
Is
pachymetry necessary?
Absolutely. Because the Astigmatome blades achieve an incision
depth of 100%, pachymetry is required. An Astigmatome blade setting of 50
microns less than pachymetry is recommended.
Does
a bias need to be applied to the Astigmatome blade?
No,
a bias is not necessary because the design of the Alignment Speculum and
Astigmatome™ maintains a firm globe. This results in easy and complete
penetration of the blades.
Is
pachymetry accurate on the periphery of the cornea?
It
depends on the pachymeter you use. If your not sure of your measurements,
measure a little inside the limbus.
Prior
to performing LRI’s do you discontinue contact lens wear?
The
procedure may be done immediately on patients that wear soft contacts. Hard
contact lens use should be discontinued 3-6 weeks prior to surgery.
Does
the procedure need to be done in a hospital?
No,
LRI’s can be performed in an office minor surgery room.
Can
you use the Astigmatome at the slit lamp?
Usage
of the Astigmatome at the slit lamp seems quite feasible, however it has only
been done a few times.
Are
you able to identify microperforations?
Yes,
if you see any fluid stop. It is recommended you dry the cornea before placing
the alignment speculum which makes it easier to see any fluid. Macroperforations
are possible, the blades are so sharp that the cuts are smooth and fast and you
can go the whole length and not know you perforated.
How
are enhancements performed for undercorrections?
I
use a guarded scalpel to extend the cut on both ends, usually 1 mm on both ends
is enough.
How
do you treat overcorrections?
For
overcorrections of greater than 1 diopter the ends of the incision are sutured.
Do
you irrigate the wounds?
Irrigation
is rarely required.
What
is the post-op recovery time?
The
patients see well the next day.
What
do you recommend for medication?
Older
patients are given antibiotic drops. Younger patients also receive a steroid.
Do
you patch the eye?
No.
Is
there any regression?
There is about a 1/2-diopter recovery of the cornea over 6 months.
Is
the Astigmatome reusable?
No,
the accuracy of the blade depth cannot be assured for multiple procedures. In
addition, the blades will lose their sharpness. The alignment speculum is
non-disposable and can be used for multiple, multiple cases.
Is
the procedure reimbursable by Medicare?
The
procedure is reimbursable by Medicare only when the patient has astigmatism as a
result of a previous surgical procedure and documented medical necessity is
required. If the astigmatism is pre-existing and is preformed to improve the
patient's vision, the patient should be billed. Additional payment information
is available from OASIS and the ASCRS web site at www.ascrs.org/
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©2000 Oasis Medical Corporation
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