Abstract
Purpose: :
To evaluate induced changes in accommodative micro-fluctuation for different accommodative stimuli with two different multifocal contact lenses (CL).
Methods: :
Eleven subjects (age 20-32) participated in this study. The refractive error of accommodative response was measured by an auto refract-keratometer (Speedy-i, Righton, Japan) under the conditions of wearing three types of soft CLs, of which one was a single distance-vision CL (RohtoiQ14Aspheric, Rohto, Japan) as a control, and two were multifocal CLs (RohtoiQ14Bifocal Type D/N +2.00 D Add, Rohto, Japan) of different additional power designs. The latter two multifocal CLs were one of simultaneous focus center distance with peripheral near zone (MFCL Type D) and one of center near with peripheral distance zone (MFCL Type N). The accommodative response was measured for eight accommodative stimuli from + 0.50 D to -3.00 D of badal optical system of Speedy-i and the spectral power of the high frequency component (HFC) of accommodative micro-fluctuation was calculated by an accommodative micro-fluctuation analysis program (Speedy-i ver. MF-1, Righton, Japan).
Results: :
No significant difference was found among the mean accommodative response of the three CLs studied. The HFC of single vision CL (SVCL) for accommodative stimulus of +0.50 D was 53.90 ± 5.42, that of MFCL Type D was 59.23 ± 3.02 and that of MFCL Type N was 58.17 ± 5.61. For accommodative stimulus of 0.00 D, the HFC of SVCL was 55.68 ± 5.47, that of MFCL Type D was 62.04 ± 4.70 and that of MFCL Type N was 59.97 ± 5.37. Significant differences were found in HFC for accommodative stimuli of +0.50 D and 0.00 D between SVCL and MFCL Type D (Bonferroni, p< 0.05). There was no other significant difference in HFC for other accommodative stimuli.
Conclusions: :
Data obtained in this study shows that in young participants, one of MFCLs studied induces changes in accommodative micro-fluctuation in particular situations compared with SVCL. It is suggested that the design of MFCL may have some influence on ciliary body muscle strain.
Keywords: contact lens • accommodation • ciliary body