Abstract
Purpose: :
One would expect the reading distance to be identical for different diffractive multifocal intraocular (MIOL) lenses with the same labeled add power. The purpose of this study is to describe the prediction of reading distance as function of MIOL design and material, as well as the refractive state of the eye.
Methods: :
In order to be able to predict reading distances for myopic, hyperopic and emmetropic populations, simulations were performed using a realistic eye model. This eye model exhibits the average corneal spherical and chromatic aberration found in a population of cataract patients. From a published clinical report, the average measured axial eye length and chosen base MIOL power of the three groups were used. The position of the MIOL was based on the refractive state of the eye. This is determined from data collected in a 70 subject monofocal IOL study. Two MIOL designs were simulated and compared to published clinical data. Design 1 has the diffractive profile on the anterior side of the IOL. Design 2 has the diffractive profile on the posterior side of the IOL and is made from a different acrylic material.
Results: :
Clinical study data from 70 monofocal IOL patients showed a relationship between vitreous length and refraction. This confirms the results of earlier studies and was used in this study to determine the location of the MIOL in eye models. A difference of 2cm in reading distance was found between the two designs, both simulated and clinically. For both IOL designs, the reading distances are within 1cm of published clinical outcomes of the three groups.
Conclusions: :
The location of the MIOL in the eye can be predicted based on a linear relationship between vitreous length and refraction. The reading distance of a multifocal IOL depends on refractive state of the eye, MIOL design and MIOL material.
Keywords: intraocular lens • refraction • reading