Eyeworld

EW INTERNATIONAL 66 April 2018 by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer Attempted versus achieved refraction, shown by the spherical equivalent, revealed an efficacy index in the alcohol-assisted group of 0.97 and 0.93 in the transPRK group. There was a slight overcor- rection in both treatment groups. Emmetropia was achieved in 42% of the alcohol-assisted and 55% of the transPRK patients. The spherical equivalent refraction accuracy in the alcohol-assisted group showed 90% of eyes within –0.50 D to +0.50 D of the intended target. Also, in the transPRK group, 90% of the eyes achieved within –0.50 D to +0.50 D of the intended target. "The retrospective comparison seems to indicate that both proce- dures are equally safe and effective," Dr. Villada said. "Alcohol-assisted blunt PRK had a greater number of patients losing one line of BCDVA. The patients in the transPRK group experienced slightly higher pain on the treatment day and the first day of the postoperative period; however, during days 2–5 the pain decreased quicker in the transPRK group. When both techniques are possible, I prefer transPRK. There are situations where transPRK is not advisable, such as in simple myopic eyes with less than –1.25 D error and in compound myopic astigmatism when the least myopic meridian is less than –1.25 D, when the total treated zone is more than 9 millime- ters, as in big scotopic pupils or high astigmatism. In all of these situa- tions, I perform a blunt alcohol-as- sisted PRK. There are also patients who should not have surface abla- tion at all. I don't perform surface ablation in hyperopic patients, com- pound hyperopic, mixed astigma- tism, or when a second treatment is going to be likely. For all these cases I prefer a LASIK treatment." EW Reference 1. Bilbao-Calabuig R, et al. Combined etha- nol-assisted and blunt mechanical corneal epithelial peeling technique. J Emmetropia. 2014;5:145–149. Editors' note: Dr. Villada has no finan- cial interests related to his comments. Contact information Villada: jvillada@vision-ooglaseren.nl two-step procedure or complication- ridden mechanical debridement. Comparing the two approaches Dr. Villada's retrospective study in- cluded 31 eyes (17 patients) treated by alcohol-assisted PRK and 29 eyes (16 patients) treated by transPRK that all had undergone the respec- tive procedure in his clinic since October 2016 and had at least 3 months of follow up. Both groups had a mean age of 34 years. The alcohol-assisted group consisted of eight female and seven male pa- tients, while the transPRK group had 10 female and six male patients. The preoperative spherical equivalent (SE) in the alcohol-assisted group was –3 ± 1.46 D, and in the transPRK group it was –3.55 ± 1.41 D. Dr. Villada analyzed patient records for the refractive outcomes and discom- fort, if any, experienced after the treatment. The comparison revealed no sig- nificant differences in visual acuity or safety indices. The safety index for the alcohol-assisted group was 1, and it was 0.97 in the transPRK group, which was not statistically significant. In the alcohol-assisted group, the mean preoperative best corrected distance visual acuity (CDVA) was logMAR 0.016 ± 0.04. After the pro- cedure, the CDVA was logMAR 0.02 ± 0.03, and the uncorrected distance visual acuity (UCDVA) was logMAR 0.05 ± 0.1. In the transPRK group, the preoperative CDVA was logMAR 0.023 ± 0.04. Postoperatively it was logMAR 0.02 ± 0.05, and the UCDVA was logMAR 0.076 ± 0.11. In the alcohol-assisted group, roughly 37% of the study patients lost one line of UDVA, 58% neither lost nor gained lines, and about 5% gained one line of visual acuity. In the transPRK group, 42% of the eyes lost one or more lines of uncor- rected visual acuity, 50% remained unchanged, and about 8% gained one line. Change in lines of CDVA in the alcohol-assisted group was 74% unchanged, 16% lost one line, and 10% gained one or more lines. In the transPRK group, 69% was unchanged, 11% lost one line, and 21% gained one or more lines of CDVA. ly faster recovery, and the most important feature, it is less likely to have an infectious keratitis. I am also happy with blunt alcohol-as- sisted PRK, introduced by Dr. Rafael Bilbao about 3 years ago, because it is a reproducible and 'clean' tech- nique with no use of instruments on the eye." PRK: Two approaches Blunt alcohol-assisted PRK involves the application of 20% ethanol to the cornea for 50 seconds by means of a BVA sponge. The epithelium is then peeled off in a capsulorhexis- like fashion. An unrelated study that performed alcohol-assisted PRK in 838 cases demonstrated the uniform removal of the corneal epithelium in all cases with minimal patient dis- comfort. 1 The alcohol had the effect of loosening the adhesions between the epithelium and the corneal stro- ma, allowing the surgeon to easily lift off the epithelium. In transPRK, refractive error is corrected by excimer laser in a well-controlled, no-touch procedure that removes the corneal epithelium and stroma in a single step, includ- ing the removal of 55 µm of epithe- lial tissue from the central cornea and 60 µm from the periphery, as opposed to the more cumbersome Two safe and effective procedures show parallel outcomes, according to results of new comparative study A retrospective review that included all eyes that un- derwent either blunt alco- hol-assisted photorefrac- tive keratectomy (PRK) or transPRK since October 2016 in the Department of Cornea and Refrac- tive Surgery, Vision Ooglaseren, Am- sterdam, the Netherlands, revealed that the major difference between the two methods does not concern the refractive outcome as much as the degree of discomfort during the postoperative period in both tech- niques and the delay this may cause for patients to return to routine ac- tivities. According to the lead author of the paper that was presented at the XXXV Congress of the ESCRS, Jose R. Villada, MD, medical direc- tor, Clínica Baviera, Albacete, Spain, and Vision Ooglaseren, it still may be preferable to perform transPRK over alcohol-assisted PRK. "I currently prefer to perform transPRK," Dr. Villada said. "It is quicker to perform, popular among patients and doctors, has a slight- TransPRK versus blunt alcohol-assisted PRK Presentation spotlight In blunt alcohol-assisted PRK, adhesions of the corneal epithelium are loosened by applying pressure in a circular motion over the central cornea with a sponge. Source: Jose Villada, MD

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