Objective Accommodative Amplitude and Dynamics with the 1CU Accommodative Intraocular Lens

Abstract

The objective accommodating effects of the 1CU lens appear to be limited, although patients are able to track a moving target. Subjective and objective accommodation was reduced at the 2-year follow-up. The greater subjective amplitude of accommodation is likely to result from the eye's depth of focus of and the aspheric nature of the IOL.

Accommodating intraocular lenses: a review of design concepts, usage and assessment methods

“…The accommodative ability of passive-shift AIOLs is limited, with reported anterior movements insufficient to provide functionally significant amplitudes of accommodation. 6,59,76,91,133 Even if the designs of such implants could be modified to enable the magnitude of forward movement to be increased, it is likely that the levels of anterior shift needed to provide accommodative amplitudes facilitating spectacle independence (for example, 2.0 mm) would interfere with anterior segment geometry, causing problems that include iris bulging and pigment dispersion. 5,47 Despite the limited accommodative effects, passive-shift implants are used clinically around the world.…”

“…60,78 Over time, the accommodative ability of the 1CU may decrease and the enhanced near visual function provided by the implant has been found to be reduced at 12 105 and 24 months. 59 Those studies which have analysed axial optic movement in response to pilocarpine stimulation have found significantly more forward shift with the 1CU than the non-accommodative implants, although the maximum mean anterior movements reported for the AIOL are -0.82 Ϯ 0.3 mm in a randomised control trial 61 and -0.83 Ϯ 0.25 mm in a non-randomised study. 77 …”

“…54,55 Although subjective testing is of use in investigating patient satisfaction, such methods do not differentiate between pseudoaccommodation and true accommodation and may also be affected by patient and practitioner motivation. Objective attempts to evaluate the dynamic performance of implanted AIOLs have included retinoscopy, 56,57 aberrometry 35,58,59 and autorefraction, 59 in addition to analysis of optic movement. 60,61 Objective measurement of dioptric power change While direct measurement of refractive change in response to an accommodative stimulus may appear to be the optimum method for determining AIOL success, there are controversies associated with the available methods.…”

“…69 Several authors have questioned the application of autorefractors in AIOL research 5,47 due to difficulties in data capture associated with miotic pupils 68,71 and the sub-prime optical quality of the eye caused by bright Purkinje images from the anterior optic surface, and the likely presence of some level of posterior capsular opacification. Wolffsohn and colleagues 59 were able to measure static objective refractive change and record the objective accommodative response through undilated pupils in a cohort of mainly elderly subjects, using a commercially-available open-view autorefractor (Shin-Nippon SRW-5000). They found the static objective accommodation averaged +0.72 Ϯ 0.38 D (range 0.17 to 1.16 D).…”

“…These studies also used a diverse range of metrics to determine that AIOLs are stable over time with no significant difference between measures such as vision, distance and near visual acuity, accommodation, defocus curve fitting and lens position. Meanwhile, the near performance of currently available AIOLs has been reported to decrease over time, 5,59,105 probably as a consequence of capsular fibrosis and shrinkage limiting optic movement. 6,91 To verify the benefit of AIOLs in providing true accommodation, there is a critical need for more randomised, patient and practitioner-masked, clinical trials that involve long-term follow-up.…”