prk Eye Surgery Pro­ce­dure: Pho­tore­frac­tive Ker­a­te­c­to­my

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.