Purpose : To investigate the activity of the ciliary muscle during accommodation as a function of age by quantification of the crystalline lens wobbling in two groups of young and presbyopic subjects.
Methods : An instrument was developed combining a high speed video recording of Purkinje images at 376 fps with a binocular open-view Hartmann-Shack sensor. Measurements of lens wobbling after forced saccadic movements were performed by analysing Purkinje images from the cornea and the lens. Accommodation dynamics was measured in a subsequent experiment by a 90 degree rotation of a hot mirror in the combined instrument, using exactly the same stimulus (two Maltese crosses subtending 1 degree), placed at infinity and at 4 D distance from the eye. Both measurements were taken under binocular unrestricted conditions. Ten young subjects (mean age 18 years old; SD 3 years) and 17 presbyopic subjects (mean age 49 years old; SD 6 years) participated in the study.
Results : The contraction of the ciliary muscle when accommodation was induced generated higher oscillations of the crystalline lens (wobbling) after forced saccades (9 degree amplitude). The increase in the amplitude of wobbling from far to near viewing conditions was found to be very similar in both young and presbyopic groups (78 ± 45 mm and 77 ± 83 mm respectively). On the other hand, the amplitude of accommodation decreased with age as expected (from 2.6 ± 0.4 D in the younger group to 1.0 ± 1.0 D for presbyopic subjects). There was individual variability, being larger in the older group. Both magnitudes, the change in the amplitude of wobbling with accommodation and the accommodative amplitude were uncorrelated. This suggests that the ability of the muscle to contract was not affected by age.
Conclusions : Crystalline lens wobbling with accommodation was similar for young and presbyopic subjects. These results support a purely lenticular-based theory of presbyopia and it might stimulate the search for new solutions to presbyopia by making use of a remaining contraction force still presented in the aging eye.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.