Purpose:
To establish the relationship between the optical and visual performance of populations implanted with monofocal and multifocal IOLs for different pupil diameters.
Methods:
In a previous study, we reported the correlation between optical and visual performance of a population implanted with multifocal IOLs for one specific pupil size (ARVO 2007). Here, we extend this analysis in two ways: we include monofocal IOLs (also in the presence of defocus), and we evaluate the data at 3 different pupil sizes for both IOL groups.Spherical monofocal and aspherical diffractive multifocal IOLs were ‘implanted’ in 46 physiological eye models. The eye models were defocused by putting a spectacle lens in front of the eye. For each defocus value, a simulated visual acuity (sVA) was determined as the intersection of the radial MTF curve and a neural threshold curve. The values were compared to clinically established data. Clinical data comprised of the measured defocus curves (visual acuity), in steps of -0.5 diopters within the range 0.0 to -5.0 diopters. Pupil sizes were ≤2.5 mm, >2.5 and <4.0 mm, and ≥4.0 mm. Each pupil group consisted of at least 11 patients.
Results:
The simulated Visual Acuity ranged between -0.2 and +0.6 logMAR, and the VA found clinically ranged between -0.15 and +0.8 logMAR, demonstrating that sVA was better than the clinical visual acuity. Simulated Visual Acuity correlated very well with clinically measured defocus curves for all pupil sizes (R2=0.96; figure). The correlation was independent of lens type, being a refractive monofocal IOL, or a diffractive multifocal IOL.
Conclusions:
The sVA of the eye models with the multifocal and monofocal IOLs correlated very well with clinically measured VA for all defocus values and pupil sizes. This indicates that sVA is a good predictor for the population average of VA for patients receiving IOLs, as well as for the depth of focus of these patients.
Keywords: visual acuity • computational modeling • intraocular lens