Abstract
Purpose: :
The accommodation microfluctuations increase in magnitude under various stimulus conditions, which suggests that they provide negative feedback information to the accommodation controller. The microfluctuations are also larger in myopic compared to emmetropic individuals. The aim of this study was to investigate the relationship between eye size and the magnitude of the accommodation microfluctuations.
Methods: :
Fifteen subjects (mean ± SD age: 20.8 ± 2.3 years) with refractive errors (MSE) ranging from -7.00D to + 5.00D and axial lengths ranging from 22.5mm to 27.2mm participated with informed consent in the study. All subjects had normal ocular health, VA of 0.0 logMAR or better and normal accommodation for their age. Subjects monocularly viewed a high contrast (80%) Maltese cross target in a 12D Badal lens system at dioptric vergences of 0.0D and 4.5D. Two minutes of continuous accommodation responses were measured at a sampling rate of 52 Hz using a modified open view Shin-Nippon SRW-5000 autorefractor. Biometric measures of axial length were obtained using the Zeiss IOL master.
Results: :
The magnitude of the accommodative microfluctuations increased significantly (p<0.01) and axial length increased slightly (p=0.05) when the near target was viewed. There was a significant negative correlation between the increase in the magnitude of the microfluctuations for the 4.5D target and that found when viewing the 0.0D target (p<0.01). The magnitude of the accommodative microfluctuations was not significantly correlated with axial length.
Conclusions: :
The magnitude of the microfluctuations of accommodation does not appear to be related to eye size. This supports the suggestion that the microfluctuations are not a manifestation of mechanical noise but are a potential source of negative feedback for the accommodation controller.
Keywords: accomodation • myopia • refractive error development