Download LASIK/SMILE/PRK Surgery Guidelines* Prescription

LASIK/SMILE/PRK Surgery Guidelines*
Prescription
Our lasers are approved to treat up to -12.00D Myopia, -6.00D Astigmatism, and +6.00D
Hyperopia. Patients slightly above these limits may still be considered for off-label surgery on a
case by case basis. The minimum amount of required prescription for treatment is +/-0.75D S.E.
Pachymetry
Formula to calculate if patients have enough tissue for LASIK: Pach-Flap-Ablation=Residual Bed
Pachymetry: Recommend using your thinnest pach reading. Any cornea <480µ initially may
require PRK, regardless of the Residual Bed.
Flap: Our standard femtolaser LASIK flap is 110µ.
Ablation: Initial 24µ ablation for all treatments to create the wavefront optimized profile, and
then an additional 3µ per each 0.25D sphere and cyl for a 6.0mm optical zone.*
(example: -1.00-0.50x180 would be…24µ initial + 12µ for sphere + 6µ for cyl= 42µ).
Residual Bed: The FDA requires a minimum of 250µ, but Dr. Dishler prefers to leave at least 270µ
for a primary sx and 300µ to allow room for an enhancement.
(*These calculations are an estimate and should only be used as a general guideline to see if your
patient may qualify for LASIK and help to counsel them appropriately. Pachymetry readings may
measure slightly different on our diagnostic units and we may alter the flap depth or ablation
based on prescription, pupil size, aberrations and surgical nomograms.)
Topography
Inferior steepening on topography is often a sign of a weaker
cornea. When we see this pattern on topography we evaluate
whether there is correlated posterior steepening or thinning
to determine if PRK may be the best option. If you see
topography patterns similar to these at pre-op, the patient should
be counseled before surgery day on how this may affect their surgical candidacy.
Corneal
Findings
Patients with dense corneal scars from trauma or past infections may only be candidates for PRK.
We also recommend PRK for patients with significant neo/pannus that will extend into the flap
diameter, any basement membrane dystrophy, or history of multiple corneal abrasions. Any
patient with greater than trace SPK should be treated before surgery with dry eye therapy as
necessary (AT’s, steroids, punctal plugs, lid hygiene, Restasis/Xiidra); corneas that are severely
dehydrated during surgery are more prone for under/over corrections and flap complications.
Systemic
Conditions
Patients with underlying autoimmune disorders that require chronic steroid or anti-inflammatory
medications are more prone for corneal inflammation and dry eye. If a patient is well controlled
with a low dose med and has no signs/symptoms of ocular dryness they will be considered for
surgery as long as they are educated on the possible side effects. Diabetic patients need to have
documentation of stable MR, good ocular health and stable blood sugar by a normal HA1C taken
within 6 months of sx. LASIK/SMILE candidates need to be under the bed weight limit of 300lbs.
Monovision
Monovision targets can range from -0.50D to -2.00D. Patients should be shown a MV trial in the
office or with CL before surgery, as the results cannot always be surgically reversed. We do not
recommend MV for patients with high prescriptions because their surgical results can be more
unpredictable and they are likely to require distance or near glasses after surgery.
Enhancements
Please evaluate the flap edges closely on any LASIK patient that may require an enhancement
after surgery. If there is edge separation or epi ingrowth we may not recommend lifting the flap,
as it is much more prone to develop significant epi ingrowth afterwards. For these patients PRK
may be a safer option. Any LASIK flap that is more than 4 years old, primary PRK and SMILE
surgeries will also require PRK as a retreatment.
*These guidelines are not a substitute for professional care or evaluation by a surgery center for candidacy.