Abstract
Abstract: :
Purpose: To use a high–speed corneal and anterior segment optical coherence tomography (CAS–OCT) system to image changes in crystalline lens and anterior chamber (AC) during accommodation. Methods: A high–speed (2000 a–scan/sec) 1.3–micron wavelength CAS–OCT system was used. The AC and lens was imaged in both eyes of a 39 years old subject. The fixation target was viewed through incrementally varied add power (+1 to –6 D) to control accommodation. OCT was repeated after instillation of phenylephrine 2.5% and then tropicamide 1%. Lens thickness and AC depth were measured along the line normal to corneal apex. Results: The AC depth decreased with accommodation in the dry state (OD 0.032mm/D, OS 0.030mm/D) and after phenylephrine (OD 0.032mm/D, OS = 0.015mm/D). The lens thickness increased with accommodation line were all negative and statistically significant in OD and OS both without drops (OD –0.057mm/D, OS –0.044mm/D) and after phenylephrine (OD–0.031mm/D, OS –0.049mm/D). All slopes of regression lines presented above were significantly different from zero with p < 0.01–0.001. The mean axial position of the lens was not significantly different from zero. Tropicamide abolished the accommodative response. Conclusions: OCT provided objective measurements of anatomic changes during accommodation which are consistent with the Helmholtz Theory. This simple and noncontact imaging method may be useful for the development and validation of presbyopia therapies.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical • ciliary muscle