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Identifier 000437524
Title Οι μονοχρωματικές εκτροπές υψηλής τάξης του οφθαλμού κατά την παιδική ηλικία
Alternative Title Ocular monochromatic higher -order aberrations during childhood
Author Παπαμαστοράκης, Γεώργιος
Thesis advisor Παλλήκαρης, Ιωάννης
Reviewer Τσιλιμπάρης, Μιλτιάδης
Σιγανός, Χαράλαμπος
Abstract Purpose: To explore the statistics of ocular higher-order aberrations in a population of primary and secondary school children. More specifically, spherical aberration and its correlation to refractive error was explored in children of 10-15 year old. Methods: A sample of 557 children aged 10---15 years was selected from two primary and two secondary schools in Heraklion, Greece. Children were classified by age in three subgroups: group I (10.7 ± 0.5 years), group II (12.4 ± 0.5 years) and group III (14.5 ± 0.5 years). Ocular aberrations were measured using a wavefront aberrometer (COAS, AMO Wavefront Sciences, USA) at mesopic light levels (illuminance at cornea was 4 lux). Wavefront analysis was achieved for a 5 mm pupil. Statistical analysis was carried out for the right eye only. Results: Myopia rates were higher the older the children while myopia was more prevalent in female adolescents with the effect being statistically significant (55% vs 40% of males, p = 0.015). Spherical aberration was found to be positive and showed the highest correlation between the two eyes compared to any other aberration. Spherical aberration in the oldest group (group 3; 0.030 μm) was found three times higher than the other two groups (group 1; 0.007 μm, group 2; 0.011 μm). This observation was not true when the absolute values of the spherical aberration were analysed. Conclusions: The low values of monochromatic aberrations and the almost zero mean population values of most aberrations may be indicative of a process similar to emmetropization, that reduces the higher order aberrations similar to the gradual decrease of myopia and astigmatism early in life. The increase of the spherical aberration with the age in childhood may be related with the typical changes of eye growth in its refractive power (cornea curvature, axial length, lens thickness and lens power). The change of spherical aberration after the age of 10 may be due to the increase of the axial length and/or to the changes of the lens refractive index that happens at late childhood. Low values of spherical aberration in the youngest age group may reflect changes in inner spherical aberration of the lens. The positive increase of the Zernike coefficient of the spherical aberration with the age is consistent with the increase of spherical aberration in older people due to the constant growth of the lens.  
Language Greek
Subject Astigmatism
Spherical aberration
Σφαιρική εκτροπή
Issue date 2021-03-29
Collection   School/Department
  Type of Work--Doctoral theses
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