First Author: M.Lewandowska POLAND
Co Author(s): A. J H. Zaj?c Pytrus M. Zaj?c
Purpose:
As a result of aging process the prolonged stay of artificial intraocular lens (IOL) inside the eyeball may cause the degradation of its surface and changes in its mechanical properties. Erosion of the IOL’s surface can affect the imaging quality, eg. by the appearance of scattered light. Other defects - volume and surface - may be generated in the production process.
The aim of this study was to investigate changes in the imaging characteristics of the IOL subjected to an aging process and to verify the influence of different types of production defects on the imaging quality.
Setting:
: The optical performance of IOLs depends to a large extent on the quality of the surface and possible internal defects. It is difficult to examine the impact of these factors in vivo. Laboratory tests and numerical simulations can give results that are difficult to achieve in any other way
Methods:
The study of aging IOL in vitro was carried out in a specially designed for this purpose container, which allows long-term holding of IOL’s in a special fluid containing salts, protein, glucose etc. (Basal Salt Solution, BSS), simulating the environment of the eye. The temperature was elevated to 50°C to accelerate the aging process.
Experimental measuremet of imaging characteristics of the investigated IOL’s was performed in the optomechanical model of an eye. The Modulation Transfer Function (MTF) characterising imaging properties of the IOL was evaluated on the basis of image of an edge.
Additionally numerical simulation of image given by the IOL with different types of imperfections was done with help of a computer programme ZEMAX EE for optical systems design.
Results:
Simulation of aging process proved a significant influence of the environment prevailing in the eye on the quality of the surface and thereby on the imaging properties of the lens. The slope of MTF after aging became steeper what means worse imaging properties. This effect can suggest a progressive deterioration of vision in patients with IOL’s implanted over time. The degree of the MTF worsening depends on the type of lesions on the lens.
Conclusions:
The developed technique enables to determine the imaging characteristics of IOL’s with different degrees of damage caused by prolonged exposure to the effects of aggressive environments. It may be useful to study the usefulness of various types of IOLs used in ophthalmic practice.
Determination of the effects of different IOL’s imperfections on the imaging quality can help in optimization of production processes and may be essential in evaluation of visual comfort of the patients
The work was done in the framework of the Research Project N N518 414138 funded by Polish Ministry of Science and Higher Education
Financial Disclosure:
None
