Abstract
Purpose: :
To investigate the subjective accommodative capacity due to ciliary body constriction and movement during accommodative stimuli of the Crystalens HD accommodating intraocular lens (IOL) using ultrasound biomicroscopy (UBM).
Methods: :
Twenty eyes from 10 patients with cataract were implanted with a Crystalens HD (Bausch&Lomb, Rochester, USA) accommodating IOL after phacoemulsification. The accommodative amplitude was determined 2 weeks after surgery with the negative-lens test, in which a negative lens of increasing power (0.25 dioptres steps) was added to the uncorrected near visual acuity (which was obtained at 40 cm using a Jaeger chart). Ultrasound biomicroscopy (UBM) was performed with a 35 MHz transducer (Reflex Ultrasound Bio-Microscope, Reichert inc, NY, USA) and a 50 MHz transducer (Zeiss-Humphrey Inc., San Leandro, CA, USA). Each eye underwent one axial scan (with the probe lined up on the center of the optic through the major axis of the haptics) and one radial section through the ciliary process on the temporal area. All the scans and measurements were performed with and without accomodative stimuli at least 3 weeks after surgery by the same experienced examiner. Anterior chamber depth (ACD) and scleral ciliary process angle (SCPA) were measured with both 35 and 50 MHz probes, while IOL optic thickness (T), IOL optic diameter (D), the anterior angles between the haptics and the optic (α1, α2) and the posterior angles between the haptics and the optic (β1, β2) were obtained with the 35 MHz probe.
Results: :
After a mean follow-up period of 55 ± 25.4 days, the mean accomodative amplitude was 1.48 ± 0.66 dioptres. During accommodative stimuli both UBM transducers found a significant reduction of SCPA (p<0.005) and an increase of ACD which was found to be significant only with the 50 MHz probe (p=0.004). The 35 MHz UBM examination failed to show any statistically significant differences after accommodative stimuli (p>0.05) for all the parameters which were analysed (T, D, α1, α2, β1, β2).
Conclusions: :
Crystalens HD provided excellent distance and near visual outcomes, with 85% of the eyes achieving Jaeger 2 or better without spectacle. UBM failed to confirm the supposed hypothesis of the accommodative mechanism due to an anterior displacement of the IOL proportional to the accommodative amplitude during near vision .
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • intraocular lens • anterior segment