Photorefractive Keratectomy (PRK)

PRK laser eye surgery, or Pho­tore­frac­tive Ker­a­te­c­to­my is part of a fam­i­ly of pro­ce­dures called “sur­face abla­tions” because the laser is applied direct­ly on the sur­face of the cornea rather than under a flap, as with LASIK.

The PRK surgery is done under top­i­cal anes­the­sia and takes about 5 min­utes per eye.

Sur­geons world­wide have per­formed PRK for over 20 years now.  It’s con­tin­ued pop­u­lar­i­ty is a tes­ti­mony to the long term sta­bil­i­ty and effi­ca­cy of the pro­ce­dure observed over this time peri­od.    While a Major in the US Air Force, Dr Stet­son (for­mer­ly Chief of the US Air Force Acad­e­my laser eye clin­ic) stud­ied sur­face heal­ing on PRK patients using many dif­fer­ent meth­ods to remove the epithe­li­um such as alco­hol and laser-assist­ed, before it became clear that using a rota­tion­al brush offered the most effi­cient and con­sis­tent sur­face prepa­ra­tion of the corneal sur­face in his hands.  As a result, Dia­mond Vision uses a rotat­ing brush (Amoils Brush) to gen­tly and safe­ly remove the sur­face cells in the treat­ment zone in just about 10 sec­onds! Though more expen­sive for us, this is far faster then alco­hol-assist­ed removal, and allows us to main­tain bet­ter con­trol over the dura­tion of the surgery while min­i­miz­ing anx­i­ety for our patients by reduc­ing their time under the laser.

We also use mit­o­mycin C (MMC) for our PRK laser eye surgery treat­ments which require the removal of more than 30mi­crons of tis­sue.  MMC has been shown to reduce the risk of corneal haze/scarring in many peer- reviewed stud­ies while hav­ing a good track record of min­i­mal adverse effects.  For more on why we use the Amoil brush for our pri­ma­ry PRK treat­ments, and MMC in our larg­er PRK surgery treat­ments, and to review ref­er­ences to relat­ed stud­ies, click below.

The Amoils brush also allows us bet­ter con­trol of what epithe­lial tis­sue we remove and what we leave behind. For a large astig­mat­ic cor­rec­tion, the laser pro­duces and ellipse, so it makes sense that the sur­face removal should occur in the same ellipse. This is not pos­si­ble when using the laser to remove the sur­face cells nor is it pos­si­ble using a cir­cu­lar well with alco­hol . There­fore we can save a great deal of sur­face cells that would oth­er­wise be removed.

In con­trast of the 7–10 sec­onds it takes to remove the sur­face cells with the Amoils brush, one large cohort study of over 1200 eyes found that using alco­hol-assist­ed sur­face removal took an aver­age of 96 sec­onds, and such a long elapsed time can allow for the cornea to become dehy­drat­ed, which may lead to less pre­dictable out­comes, some­thing we are not will­ing to risk. It’s inter­est­ing to note that even in this study where a much less pre­cise mechan­i­cal removal of the corneal epithe­li­um with a blade took place, 93.3% of the­se 593 patients enjoyed uncor­rect­ed visu­al acu­ity of 20/20 or bet­ter com­pared to 90.9% in the alco­hol group was shown to be In addi­tion, in the same study the heal­ing time for mechan­i­cal debride­ment (removal of sur­face cells direct­ly with an instru­ment, just as we do with the brush) was an aver­age of 3.8 days ver­sus an aver­age of 4.2 days in the alco­hol-assist­ed group. Though the above study did not find a sta­tis­ti­cal­ly sig­nif­i­cant dif­fer­ence here, we have also seen heal­ing times gen­er­al­ly improved by at least 1/2 a day to 1 full day with our alco­hol-free Amoil brush method. It has been pos­tu­lat­ed that using the Amoils brush may allow more rapid heal­ing because it avoids alcohol’s tox­i­c­i­ty to neigh­bor­ing epithe­lial cells and corneal stro­ma. Sev­er­al stud­ies have also shown that post oper­a­tive pain and inflam­ma­tion may be reduced by avoid­ing the use of alco­hol or the addi­tion­al ener­gy of using the laser to remove the epithelium.2
In a rab­bit mod­el, it was shown move all of the epithe­li­um by mechan­i­cal meth­ods cre­at­ed the least amount of inflam­ma­tion where­as the use of the laser result­ed in the most (p=0.0001) Fur­ther, The great­est loss of ker­a­to­cytes (corneal cells) was observed using alco­hol to remove the epithe­li­um where­as mechan­i­cal removal result­ed in the least dam­age (P=0.009) 3

Final­ly, a study out of the Army in 2014 ana­lyzed visu­al acu­ity and haze (scar­ring) results in mod­er­ate to high myopes fol­low­ing PRK, ver­sus, PRK with MMC, ver­sus LASIK. The results showed that less haze (in fact no sig­nif­i­cant haze) was found in the MMC group where­as the oth­er 2 groups had a small num­ber of patients who devel­oped clin­i­cal­ly sig­nif­i­cant haze. Visu­al acu­ity salts or sim­i­lar across the board and no com­pli­ca­tions arose from the use of mit­o­mycin. This study’s results reflects the major­i­ty of the lit­er­a­ture avail­able over the last 10 years on the subject.4

1. Ghor­eishi, M. et al. j Oph­thalmic Vis Res, 2010;
2.Comparison of post­op­er­a­tive pain in patients fol­low­ing PRK ver­sus advanced sur­face abla­tion. Blake CR et al. J Cat Ref Surg 2005; 31:1314–1319;
3.Campos, M. et al. Oph­thal­mol­o­gy, 1994;
4.The US Army Sur­face Abla­tion Study: com­par­ison of PRK, MMC-PRK and LASIK. Sia, RK et al. J Refrac­tive Surg, 2014.

How does PRK compare to LASIK?

Advantages of PRK:

  • You keep more corneal tis­sue than with LASIK, ensur­ing the long-term sta­bil­i­ty and integri­ty of your eyes.
  • You are also bet­ter able to have a “touch up” pro­ce­dure if nec­es­sary
  • There is no risk of flap-relat­ed com­pli­ca­tions.
  • You are at less risk for dry eyes, because there is no dis­rup­tion in the nerves that tell your eyes to pro­duce tears.
  • PRK is more com­fort­able dur­ing the pro­ce­dure.

Disadvantages of PRK:

  • Recov­ery takes longer after PRK. Most peo­ple do not work for at least 2 days after surgery to allow their eyes to rest. In a Dia­mond Vision sur­vey of patients who have had sur­face abla­tions, sev­en­ty-five per­cent were back to work after 3 days.
  • Com­pared to LASIK, PRK is not as com­fort­able for a few days after­wards. How­ev­er, advances in fol­low-up care have con­sid­er­ably improved the com­fort of PRK. When patients in our Dia­mond Vision study were asked to rate their dis­com­fort from zero to four, the major­i­ty (56%) said their dis­com­fort was zero or one.

What should I expect after PRK?

Once the eye is cor­rect­ed, the sur­geon will place a soft con­tact lens to pro­tect your eye while the heal­ing takes place. Dur­ing the heal­ing time – 5 to 7 days – it is nor­mal to expe­ri­ence blur­ry or fluc­tu­at­ing vision, light sen­si­tiv­i­ty, dry­ness and/or a for­eign body sen­sa­tion. It is com­mon for one eye to heal faster than the oth­er, so do not be alarmed if your vision is bet­ter in one eye com­pared to the oth­er. You will be given oral pain med­ica­tion if nec­es­sary, along with top­i­cal eye drops. You may find that you do not feel con­fi­dent dri­ving while the pro­tec­tive lens­es are in.

At your one-week vis­it the con­tact lens­es are removed and your vision will slow­ly improve. Drops will be given to use for sev­er­al weeks, which will aid in heal­ing and pre­vent inflam­ma­tion.

Although it can take a few weeks to a few months for patients to ful­ly reach their opti­mal vision, your visu­al out­come will be the same as if you had LASIK. How­ev­er, the long-term safe­ty and sta­bil­i­ty of your eyes will be high­er than if you had LASIK. A few days or weeks of patience will be reward­ed by a life­time of bet­ter vision.

What is better for me, LASIK or PRK?

In most cas­es, PRK is rec­om­mend­ed for patients who have thin­ner corneas, slight­ly irreg­u­lar corneas, or are at risk for dry eyes or oth­er con­di­tions. Your Dia­mond Vision doc­tor will be able to make a rec­om­men­da­tion for you based on exten­sive test­ing.

In oth­er cas­es, patients who are can­di­dates for LASIK chose to have PRK instead, because they prefer a flap­less or blade­less pro­ce­dure.

Why is PRK more expensive than LASIK?

PRK is a spe­cial­ty pro­ce­dure, meant to address the needs of peo­ple with unusu­al eye mea­sure­ments. Com­pared to LASIK or the old PRK, the new PRK offered at Dia­mond Vision uses more sophis­ti­cat­ed and expen­sive intra-oper­a­tive eye drops such as Mit­o­mycin-C, and improved sur­gi­cal instru­ments such as the Amoils rotary epithe­li­um brush. The new Lotemax gel drops are also used at Dia­mond Vision for post-oper­a­tive care after PRK.

Why is PRK becoming more and more popular?

Many stud­ies show that LASIK and PRK pro­duce the same visu­al results after a few weeks or mon­th. Now that the dis­ad­van­tages of the “old PRK” have been con­quered, doc­tors like the extra long-term safe­ty afford­ed by PRK in many patients.

How do I learn more about PRK?

If you would like to dis­cuss the pro­ce­dure with patients who have had PRK (or a very sim­i­lar pro­ce­dure, LASIK), please ask our staff for a list of patient phone num­bers. As always, we encour­age you to speak to our knowl­edge­able doc­tors for any ques­tions regard­ing this pro­ce­dure

Click Here To Sched­ule a Free Con­sul­ta­tion

Or call 888–678-4341