Abstract
Purpose: :
To investigate tension on the crystalline lens as a potential source of equatorial growth restriction in the development of juvenile myopia, and to determine if crystalline lens tension increases with age in school-age children.
Methods: :
Fifty-two children between the ages of eight and 14 were recruited. The amplitude of oscillations of the crystalline lens at the end of 20° saccadic eye movements were recorded and used as a measurement of tension on the crystalline lens. Spherical equivalent, cycloplegic autorefraction was the refractive error measurement used in analyses. Multilevel linear regression analyses were used to model the relationship between crystalline lens tension, refractive error, and age.
Results: :
The velocity of the saccadic eye movement was significantly associated with crystalline lens tension (β = 1.7, p < 0.001), with faster eye movements producing larger oscillations of the crystalline lens. Therefore saccadic velocity was included in subsequent models as a control variable. Refractive error was not associated with crystalline lens tension (β = –0.01, p = 0.45). Oscillations of the crystalline lens decreased with increasing age (β = –0.06, p < 0.001).
Conclusions: :
Crystalline lens tension was not related to refractive error in this sample, indicating that it is unlikely that the crystalline lens is the primary source of an equatorial growth restriction in children who become myopic. Nonetheless, tension on the crystalline lens did increase between the ages of eight and 14 years, which parallels the decreases in amplitude of accommodation that have been reported previously. These measures of tension using the amplitude of post-saccadic oscillations of the crystalline lens may be useful in studies of age-related changes in accommodation.
Keywords: myopia • refractive error development • accomodation