Abstract
Purpose: :
Multifocal intraocular lenses (IOLs) provide good far and near vision, however usually with limited intermediate vision. Accommodating IOLs, designed as monofocal lenses, may provide good vision at all distances through active accommodation. Clinically, range of vision is measured with the defocus curve test i.e. measurement of visual acuity through trial lenses, where negative lenses simulate near vergence (eg: -3D for 33cm). In this study, defocus testing was performed on subjects implanted with dual-optic accommodating IOL, apodized diffractive multifocal IOL and standard monofocal IOL, including a cycloplegic condition (i.e. ciliary muscle paralysis) to evaluate accommodative ability.
Methods: :
Manifest refraction, near vision at 40 cm, and defocus testing (+1.5D to -3.0D lenses in 0.5D steps) with and without cycloplegia (1% Cyclopentolate) were performed in each eye of bilaterally implanted subjects (16 accommodating, 16 multifocal and 15 control subjects) at least 6-months after cataract surgery. A 4mm aperture was used to limit changes in depth of focus with pupil dilation. Defocus testing was also performed binocularly, without cycloplegia.
Results: :
Near vision with control IOL in uncorrected (mean ± SD: 0.49 ± 0.27 logMAR) and distance corrected (0.46 ± 0.15 logMAR) conditions were worse than accommodating (0.15 ± 0.15 and 0.15 ± 0.16 logMAR, respectively) and multifocal (0.15 ± 0.19 and 0.08 ± 0.15 logMAR, respectively) groups (p<0.05, one-way ANOVA). Defocus curve, without cycloplegia, was different between groups under binocular (F2, 396 = 20.85; p<0.05) and monocular (F2, 819 = 19.83; p<0.05) conditions. Visual acuity of control group declined at 1-line per 0.50D. Multifocal IOL group had good vision at -3D lens (20/32), poor vision with positive (20/65 at +1.5D) and intermediate negative lenses (20/40 at -1.5D). Accommodating IOL group maintained vision through negative lenses (20/32 at -3D), but not with positive lenses (20/44 at +1.5D). Cycloplegia did not affect control and multifocal defocus curves, but led to reduced negative lens performance in the accommodating IOL group (F1, 558 = 9.05; p<0.05); indicating loss of accommodation with ciliary muscle paralysis.
Conclusions: :
Dual-optic accommodating IOL provided continuous range of clear vision through active accommodation, as indicated by the decline in performance with cycloplegia, when compared to apodized multifocal IOL with good vision only at far and near distances.
Clinical Trial: :
http://www.clinicaltrials.gov NCT00425464
Keywords: presbyopia • accommodation • intraocular lens