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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.