Influence of lens thickness on the accommodative range in healthy eyes

Background: The maximum accommodative range is a useful indication of visual function. It decreases with age, but the exact cause of this decrease is not fully understood. It is associated with the increasing rigidity of the lens and changes to the lens shape, as well as the geometry of the zonular attachments. This work aims to determine the relationship between the accommodative range and lens shape in a group of healthy young adults.

Methods: This study includes 40 emmetropic participants between 20 and 30 years of age. They filled in a questionnaire and underwent accommodation measurements using the RAF Convergence Rule and the Negative Lens Test. After a drop of Tropicamide 0.5 % and Cyclopentolate 1 %, participants underwent measurements with autorefractor, Scheimpflug tomography (Pentacam HR, Oculus), anterior segment Optical Coherence Tomography and optical biometry.

Results: The accommodative range did not correlate significantly (p>0.05) with any of the lenticular or ocular parameters considered, such as lens thickness, lens radii of curvature, axial length, or corneal power.

Conclusion: The crystalline lens shape does not affect the accommodative range of the eye. This may be due to the smaller deformation required to bring a thicker lens to the same level of accommodation as a thinner lens. The amount of force on the zonular fibres may therefore be similar, in all lenses, regardless of the lens shape.