PRK Nomograms

by Guy M. Kezirian, MD, MBA, FACS

June 2014


Many surgeons have expressed concern about Alcon’s requirement to remove PRK nomograms from SurgiVision® DataLink Alcon Edition. We agree, it has been a great inconvenience to many surgeons and makes surgical planning for PRK more difficult.   To my knowledge, there are no valid nomogram sources for PRK (or any other) nomograms that can be shared among surgeons. All lasers and all surgeons require nomograms specific to the laser and the surgeon (hence the so-called “Surgeon-Specific Nomograms” provided in SurgiVision® DataLink Alcon Edition).  Paper nomograms, shared nomograms, nomograms based on linear regression models, etc. do not provide the same predictability as Surgeon-Specific nomograms, and may only provide an artificial sense of comfort.   I’ve received many inquiries about what to do about surgical planning for PRK. Here are my thoughts:


  • PRK with Alcon WaveLight lasers is not FDA approved.
  • In my research, I have analyzed the data looking for consistent relationships between LASIK and PRK nomograms. I have been unable to find any.
  • There is no generalizable PRK nomogram for WaveLight lasers. Anywhere. Period.


Oddly enough, I have had several people say “well I’ll just use another program for PRK.” Of course, surgeons can and will do anything they please. Surgeons can choose to operate without a nomogram, with bad nomograms, or using valid ones (DataLink). Surgeons can choose to perform off-label procedures or stay on label. It is up to you. I only ask one thing: Do not be duped into using invalid nomograms for PRK!   This observation causes me to wonder: Is it really worth the liability risk to do PRK?   In the meantime, we recommend that all surgeons disclose that PRK is not FDA approved with the Alcon WaveLight laser during informed consent. While it is unlikely to be sued for a refractive miss, many lawsuits are filed in the context of enhancement complications. If the case goes badly, you will expose yourself to criticism for off-label procedures and, if the lawyer is good (and many are), you may be drilled on your nomogram selection and disclosure of the FDA approval status of the PRK. Transparent informed consent is essential.   Which begs the question, why perform PRK off-label? PRK accounts for less than 20% of the laser vision correction procedures performed in the United States. Is it worth it?   I welcome your comments.