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Identifier

000353459

Title

Μέτρηση και σύγκριση των εκτροπών υψηλής τάξης σε εμμέτρωπες νεαρής και πρεσβυωπικής ηλικίας

Author

Ζερβός, Χρήστος

Thesis advisor

Παναγοπούλου, Σοφία

Reviewer

Τσιλιμπάρης, Μιλτιάδης
Παλλήκαρης, Ιωάννης

Abstract

Τhe objective was to investigate the distribution and the correlation of the overall, the corneal and the internal higher-order aberrations between two emmetropic groups of young and presbyopic subjects as well as to compare their contrast sensitivity scores. At first, we tested the visual acuity of 48 subjects aged between 18 and 31 years and 35 subjects aged between 47 and 58 years. The binocular UVA in both groups was >10/10 and >9/10 for each eye. The total higher-order aberrations were determined using a COAS Hartmann-Shack analyzer and the corneal aberrations were measured by the topographic system Topolyzer (Wavelight, Germany) for a 6mm pupil while all eyes were cyclopleged. The relative contribution of the internal optics (posterior surface of the cornea and lens) to overall aberrations were measured indirectly. We found increased values of total HO RMS in the group of presbyopes with more prominent increase the spherical aberration and the 4th order RMS. We did not find significant differences between the two groups in 3rd order RMS and coma. From the analysis of corneal higer aberrations we found significant increase of the total and 4th order RMS, but not for 3rd order RMS. We also, did not find significant difference among the two groups in the total internal HO RMS, as well as in the 3rd and 4th internal RMS with the exception of spherical aberration, tetrafoil (both axes) and trefoil (x axis) which seem to be larger in the presbyopes. The measurement of the contrast sensitivity function οf 29 young and presbyopic subjects, was performed using Functional Vision analyzer, under photopic and mesopic conditions and showed that older subjects had reduced contrast sensitivity when compared with their younger counterparts. For all the subjects, the area under the log contrast sensitivity function (AULCSF) was not associated significantly with the total HO RMS and the 3rd order RMS, but there was a significant negative correlation with 4th order RMS and spherical aberration. The present study revealed that the optical system of the human eye behave as an auto-compensating mechanism because there is a balance between corneal and internal aberrations that results in smaller ocular aberrations. Further studies on the probable paths leading to that compensation and ontogenetic changes in aberration structure should provide further insights.

Physical description

76 σ. : πιν. ; 30 εκ.

Language

Greek

Subject

Ophthalmology

Οφθαλμολογία

Issue date

2008-12-15

Collection

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

Type of Work--Post-graduate theses