تغييرات آسفريسيتي و ابيراهي‌هاي رده بالا چشم در عمل كراتكتومي فوتورفركتيو (PRK)

Effects of optimized photorefractive keratectomy (PRK) operation on the asphericity and high-order aberration changes

سابقه و هدف: Optimized روش رايجي است كه در آن ابيراهي­ هاي رده بالا توسط دستگاه در بيمار القا مي­ شود. هدف از انجام اين مطالعه بررسي ميزان ابيراهي ­هاي رده بالا القا شده خارج از كنترل جراح و تاثير آن بر نتايج بينايي بعد از عمل كراتكتومي فوتورفركتيو (PRK) بود. روش بررسي: در كارآزمايي باليني Before and after treatment، تعداد 24 بيمار شامل 48 چشم وارد مطالعه شدند. براي كليه بيماران قبل و 6 ماه بعد از عمل اورب اسكن، اندازه گيري ابيراهي­ هاي چشمي، قرنيه و اسفريسيتي با توپولايزر ارزيابي شد. يافته ­ها: بيماران شامل 8 مرد و 16 زن با ميانگين سني 5±29 سال بودند. ابيراهي­ هاي كلي رده بالاي چشمي پس از عمل افزايش پيدا كرد و بين ابيراهي ­هاي قرنيه ­اي و چشمي رده سوم و چهارم زرنيكه قبل و پس از عمل تفاوت معني داري مشاهده نشد. ابيراهي كروي قرنيه ­اي و چشمي افزايش يافت. ميانگين آسفريسيتي قبل و بعد از عمل مشابه بود. همچنين رابطه معني­داري بين مقدار اكي والان اسفر و ابيراهي­ هاي رده بالاي كل و ابيراهي كروي يافت شد. نتيجه­ گيري: بر اساس نتايج مطالعه حاضر، پس از عمل اختلالات انكساري چشم بيمار بهبود مي­ يابد، ولي با القاي ابيراهي هاي رده بالا به حالت ايده ال و بدون اختلال نمي­رسد، هرچند سبب بهبود رفركشن مي ­شود كه بر كيفيت بينايي بيماران اثرگذار است. با توجه به يافته ­هاي موجود به نظر مي­رسد روش optimized علي رغم برتري بر روش مرسوم كماكان موجب القاي ابيراهي­ هاي رده بالا و تغيير آسفريسيتي از حالت prolate به oblate مي­ شود.

Background: Optimized is a common and important method in which aberrations are created by the device and the surgeon, but high-grade aberrations are out of the surgeon's control and are induced by the device in the patient. The aim of this study was the evaluation of out-of-control high-order aberration changes before and after PRK surgery and these impact on vision outcome. Materials and methods: In this before and after clinical trial study, we recurred 24 patients consist of 48 eyes. For the patients with myopic astigmatism, before the operation, a complete visual examination (visual acuity, refraction, etc.) and imaging including orbscan, zywave, and topolyzer were performed and tests were repeated six months after surgery. The results were compared before and after surgery. Results: 24 patients included 8 males (33.3%) and 16 females (66.7%) with a mean age of 29±5 years recurred in the study. The total higher-order aberration increased after operation. There was no significant difference between the third and fourth-order corneal aberrations before and after the operation. The ocular and corneal high-order aberration was increased. Mean asphericity was similar before and after the operation. Also, significant correlations among spherical equivalent, total high order abbration, and occular abbaration were found. Conclusion: Regarding our study, eye sporadic defect improved after the operation but it would never achieve the optimal goal. According to the findings, it seems that the optimized method with the Allegretto EX500 device, despite its superiority over the conventional method, still induces high-grade aberrations and changes the asphericity from prolate to oblate mode. However, it improves refraction, which affects the quality of patients' vision.