Abstract
Purpose: :
To investigate the relationship between the induced accommodation and anterior segment biometry using an ultra-long scan depth spectral domain optical coherence tomography (UL-OCT).
Methods: :
Ten young healthy subjects (7 women and 3 men, mean ± SD age: 24.1 ± 2.47 years) were recruited. Each subject was required to fix an external target with the left eye. The target was moved towards the subject to induce various accommodative stimuli from 0 to 5.50D gradually by a 0.50D increment. A custom UL-OCT (7.8 mm scan depth and 6µm axial resolution) was used to image the entire anterior segment with both mirror images. The right eye during non-accommodative and various accommodative conditions was imaged. Custom algorithms were developed to use both mirror images to obtain a full range of the entire anterior segment (15.6mm scan depth equivalent). After image correction, the software yielded biometric dimensions, including anterior chamber depth (ACD), pupil diameter (PD), lens thickness (LT), anterior (ASC) and posterior (PSC) surfaces curvatures of the lens.
Results: :
Within 1.00D accommodation stimuli, the changes of ACD, ASC, PSC and LT were similar (Re-ANOVA and post hoc test, P > 0.05). With increased accommodative stimuli more than 1.00D, ACD, and the radii of ASC and PSC were found significantly decreased compared to the non-accommodative condition (P < 0.01). The LT was found significantly increased (P < 0.05). Negative correlations of the induced accommodative stimuli were found with ACD, and the radii of ASC and PSC (r range: 0.87 - 0.99, P < 0.01). The induced accommodative stimulus was positively correlated with LT (r = 0.98, P < 0.01).
Conclusions: :
It appeared that the increased accommodation (more that 1.00D) is a function of the anterior segment biometric dimensions, which may provide useful information on modeling the accommodation system. The UL-OCT holds the promise for studying accommodation on human eye.
Keywords: accommodation • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • anterior segment