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Identifier

000350686

Title

Ασφαιρικότητα κερατοειδούς μετά από τις διαθλαστικές επεμβάσεις

Author

Σαχινίδου, Σοφία

Thesis advisor

Παναγοπούλου, Σοφία

Reviewer

Γκίνης, Χαρίλαος
Παλλήκαρης, Ιωάννης

Abstract

Introduction: Nowadays, there is a great number of patients who are subjected to refractive surgery in order to correct their spherocylindrical error. Continuous effort constitutes the optimization of algorithm ablation in order to ensure the best and the safest visual result. Purpose: The purpose of this project was to study whether there is a difference in the refractive result and particularly in asphericity among customized operations based on the preoperative asphericity and the conventional operations. Methodology: Our study was included 44 patients who were subjected to laser refractive surgery aiming at the correction of their vision. All patients were myopic. Both eyes of each patient (n = 88) were operated in series. The conventional correction (control group) was applied on one eye while on the other was applied the correction with individualized asphericity (study group). 31 of the patients were subjected to PRK and 13 to LASIK. The patients were examined preoperatively as well as 1, 3 and 6 months after the surgery. These examinations involved the measurement of the refraction and the non corrected visual acuity (UCVA) as well as the best corrected visual acuity (BCVA). The topography of the cornea was measured by using the Allegretto Wave Topolyzer. The wavefront aberrations were measured while pupils were dilated, by using Allegretto Wave Analyzer. RMS (Root Mean Square) was used as metric for the wavefront. Results: The correction of the refractive error and the stability of the result were successful for both groups. Post-operatively, the asphericity presented a strong trend towards the positive values and therefore, the prolate cornea became oblate in both groups. In all post-operative controls, the asphericity (Q) presented a stronger trend towards positive values in the study group than in the group control. Furthermore, a trend towards a greater alteration in asphericity and more oblateness were observed on the eyes, where the highest myopic corrections were applied in both groups. The spherical aberration increased with a linear format considering the myopic correction quantity in both groups. In addition, the Q more positive values were more associated with the spherical aberration higher levels in the study group. Post-operatively, the error RMS of the high order aberrations increased in both groups according to the degree of myopic correction. Conclusions: Both the conventional and the individualized excision algorithm for the correction of the myopic astigmatism alter the corneal asphericity and the ocular high order aberrations. As a result, a trend towards the positive values of asphericity (in other words, towards oblateness) and a greater increase of aberrations were observed especially when greater myopic correction was attempted. As far as the safety, the stability and the correction effectiveness of refractive error are concerned, no significant differences were observed between the two groups.

Language

Greek

Subject

Refractive Surgery

Issue date

2007-07-26

Collection

School/Department--School of Medicine--Department of Medicine--Post-graduate theses

Type of Work--Post-graduate theses

Notes

Διατμηματικό μεταπτυχιακό πρόγραμμα σπουδών:"Οπτική και Όραση"

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