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Identifier

000359125

Title

Πολυπαραγοντική ανάλυση αποτελεσμάτων διαθλαστικής χειρουργικής

Alternative Title

Multiple linear regression analysis of refractive surgery outcomes

Author

Στράτος, Αιμιλιανός Α.

Thesis advisor

Κυμιωνής, Γεώργιος

Reviewer

Μοσχανδρέα, Ιωάννα
Κουνής, Γεώργιος

Abstract

Photorefractive keratectomy (PRK) was introduced in the beginning of 1980 and since then it is considered to be one of the main refractive surgery techniques. Some of the disadvantages of PRK are postoperative pain and slow visual rehabilitation. The main complication is postoperative haze formation due to irregular collagen formation from the keratocytes. Lately, haze formation is being precluded by the use of Mitomycin-C intraoperatively. Mitomycin-C is an antibiotic that can be used as a chemotherapeutic agent. In the cornea it inhibits keratocyte activity, resulting in decreased haze formation and faster visual rehabilitation after PRK. Patients who underwent PRK with the use of Mitomycin-C in our institute presented an apparent overcorrection. Purpose: The purpose of this study is the development of a regression model that would predict the residual refractive error based on certain preoperative factors, including the time of application of Mitomycin-C, intraoperatively in PRK procedures. Methods: In this retrospective study, 186 patients (340 eyes) who underwent PRK with Mitomycin-C for the correction of myopia and astigmatism were included. Patients were examined at three months postoperatively. For the data analysis, the term “Defocus Εquivalent Refraction” was used in order to include in our sample all cases that indeed, presented residual refractive error. A multiple linear regression was fitted to asses possible predictors of post-op residual refractive error. The explanatory variables in the model were age, central corneal thickness (CCT), attempted correction of myopia and astigmatism and Mitomycin-C time of application. Results: From the data analysis an overcorrection in patients who underwent PRK-MMC for the correction of myopia and astigmatism was evident. Based on the results of the multiple linear regression, the residual refractive error depends on attempted correction and time of application of Mitomycin-C but not on age and CCT. The equation for the regression model is: RemDEF = 0,379 - 0,048 * ΑttemSph - 0,080*ΑttemCyl + 0,005*MMCt. Conclusion: An overcorrection in patient who underwent PRK-MMC is evident. Based on the results of the multiple linear regression analysis, the residual refractive error after PRK-MMC is related to the attempted correction (amount of myopia and astigmatism corrected) and the time of application of MMC. The equation of multiple linear regression analysis can be used as a nomogram in order to ensure the accuracy of the results outcome.

Language

Greek

Subject

Myopia

Mytomicin

Ophthalmology

Refractive Surgical Procedures

Regression model

Μιτομυκίνη

Μυωπία

Υπερδιορθώσεις

Issue date