Abstract
Purpose: :
The purpose of this study is to compare and to assess the optical image quality of multifocal intraocular lenses.
Methods: :
Modulation Transfer Function (MTF) measurement in a physical eye model is a well known and useful tool to assess the optical image quality of intraocular lenses (IOL). The cornea of the standard ISO eye model for measuring IOLs was adapted to include the average corneal spherical aberration and the average chromatic aberration. This enabled measurement of white and green light MTFs for a 3mm and a 5mm pupil. In addition, an US Air Force target 1951 was used to visualize the simulated retinal image. In total 10 different multifocal lens models were measured. The lens models could be subdivided into type of material: refractive index and Abbe number; and secondly in type of multifocal
Results: :
For a 3mm pupil the white light results ranged from 0.20 to 0.45 MTF units for distance focus. For near focus the range was from 0.15 to 0.40 MTF units. In general the results decreased for larger pupils, and some models started behaving more like monofocal lenses. For a 5mm pupil at distance focus, the results ranged from 0.10 MTF units to 0.35 MTF units and for the near focus from 0.05 to 0.40 MTF units. The subjective observed sharpness and contrast in the US Air Force images seem to correspond with the measured MTF levels.
Conclusions: :
There is a huge spread in MTF results among the different lens models. Most of the MTF measurement results could be directly explained by IOL design. For most models the 5mm pupil optical performance was less than the corresponding 3mm performance, which in most cases can be explained by the pupil-dependent IOL design and/or the spherical aberration compensation provided by the IOL design. The MTFs of some models were relatively pupil size independent for both the near and the distance focus. The quality of the optical retinal images obtained with the projected US Air Force targets illustrate the trends seen in MTF results.
Keywords: intraocular lens • imaging/image analysis: non-clinical