Abstract
Purpose :
To investigate changes in ciliary body ring diameter, lens dimensions and lens refractive index distributions with accommodation in young adults.
Methods :
A 3T clinical magnetic resonance imaging scanner imaged right eyes of 38 18-29 year old participants using a multiple spin echo (MSE) sequence to determine accommodation induced changes in ciliary body ring diameter, lens dimensions and refractive index distribution profiles along the lens axial and equatorial directions. Accommodation stimuli were approximately 1 D and 5 D.
Results :
With accommodation, ciliary body ring diameter and equatorial lens diameter decreased (–0.43±0.31 mm and –0.30±0.23 mm, respectively), and total axial lens thickness increased (+0.34±0.16 mm). Change in the lens shape causes redistribution of the internal structure of the lens leading to a change in the refractive index distribution profiles. With accommodation, in the axial direction refractive index profiles became flatter in the center and steeper near the periphery of the lens, while in the equatorial direction they became steeper in the center and flatter in the periphery.
Conclusions :
Both axial and equatorial lens refractive index profiles showed alteration with accommodation. The results suggest that the anatomical accuracy of optical models of the crystalline lens can be improved by accounting for changes in the refractive index profile during accommodation.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.