Visual, contrast sensitivity outcomes and aberration changes after transepithelial photorefractive keratectomy in high cylindric refraction: 9 month follow-up results
First Author: SoheilAdib Moghadam IRAN
Co Author(s): Fatemeh Adili-Aghdam Saeed Soleimanjahi
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Transepithelial Photorefractive Keratectomy (TransPRK) as one of new laser-assisted techniques was developed to decrease risk of mechanical damage after PRK and flap related complications and ectasia after LASIK. High cylindric refraction is one of the biggest challenges and controversies for refractive surgeons to select the safest and most effective technique with stable visual correction.The purpose of this study was to evaluate the visual acuity, refraction, contrast sensitivity (mesopic and photopic) and higher order aberration changes after aberration free mode TransPRK in high cylindric eyes, using the SCHWIND AMARIS 500Hz excimer laser.
: Bina Eye Hospital, Tehran, Iran
19 eyes with high cylindric refraction (≤ -1.5 diopters) undergoing TransPRK were included in this prospective study from July 2011 to June 2013. All TransPRK procedures were done by a single expert refractive surgeon (S.A.M.) using SCHWIND AMARIS 500 laser (SCHWIND eye-tech-solutions GmbH, Kleinostheim, Germany) and aberration free mode as an optimised treatment.The study was ethically approved by the local committee. Follow-up visits were completed up to 9 months post-operation. Visual acuity (uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA)), refraction, photopic and mesopic contrast sensitivity and aberration changes were measured before and after the surgery. The findings were analyzed with paired sample T test and differences with a value of <0.05 were defined statistically significant.
A total number of 19 eyes (10 OD/9 OS) were included in our study. Thirteen (68.4%) of our patients were females and six (31.6%) ones were males. Mean age of patients was 33±8.88 years. The frequency of different types of refraction were 13(68.4%), 3(15.8%), 2(10.5%) and 1(5.3%) eyes with compound myopic astigmatism, mix hyperopic astigmatism, simple myopia and simple astigmatism errors, respectively. The mean of UCVA improved significantly from 0.55 to 1.24 (P value=0.01); however, BCVA improvement from 1.03 to 1.09 was not statistically significant. No patient lost a Snellen line in both BCVA and UCVA during the follow-up period. The mean and standard deviation of post-operation subjective refraction for spherical and cylindrical components and axis were -0.1±0.28 diopter(D) , -0.38±0.42 D and 134.66± 61.17 degree ,respectively.Subjective refractive changes were -5.00±3.39 D, -2.15±0.83 D for sphere and cylinder and 9.50±18.58 degree for axis measurement (P value= 0.03, 0.001 and 0.26, respectively). The mean of photopic contrast sensitivity changed significantly from 3.29 to 1.15 (P value=0.000) and mesopic contrast sensitivity had notable improvement from 4.53 to 1.26(P value=0.000). Mean coma and Trefoil aberrations changed from -0.14 to -0.19 (P value=0.055) and -0.14 to -0.17(P value=0.34) respectively.
This study for the first time showed that aberration free mode transPRK with SCHWIND Amaris 500 laser could provide effective, safe and stable correction in eyes with high cylindric refraction until 9 months after the operation. This technique improves visual acuity, refraction and quality of vision while it has not great effect on aberrations. Further studies with longer follow ups could yield more definite stability results. FINANCIAL INTEREST: NONE