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Optical Quality of Explanted Intraocular Lenses after more than 20 Years in the Eye


Purpose : After implantation in the eye, the material of the intraocular lenses starts interacting with the environment of the anterior segment and the long-term results of such interaction are ignored. The aim of this study is to determine the change in optical quality of IOLs of different materials implanted for more than 20 years in human eyes.

Methods : A custom-made instrument based on the optical integration method was used to assess the amounts of straylight in eight extracted IOLs with negative and positive power. The mean and standard deviation of the time that the IOLs under study remained implanted are 21.5 and 4.1 years, respectively. The IOLs were measured immersed in a wet cell with physiological saline (0.9% NaCl). The radially averaged wide-angle (up to 5.1 degrees) point spread function (PSF) of the IOLs was determined for each lens. The straylight parameter (s) was calculated as the product of the PSF value and the angle squared. A new (unused) monofocal IOL was also measured as reference. By slightly modifying the developed instrument, images of a target test through the IOLs were also recorded. This produced an indication of the spatial resolution of the lenses that complemented the straylight measurements.

Results : The explanted lenses presented increased values of straylight as compared to the new reference lens. However, this increase was only moderate. All the studied implanted lenses presented an amount of straylight superior to that occurring in the reference old observer (CIE). The amount of straylight produced by the IOLs at 3.5 degrees increases as the time since its implantation (t) increases. We found that such increase can be described by the exponential relationship s=A.exp(B.t), where the A and B constants are equal to 0.376 sr-1deg2 and 0.127. No-correlation was found between the loss of spatial resolution in the test images and the straylight value for each IOL.

Conclusions : A series of explanted IOLs were measured in an optical bench. They showed a moderate increase in straylight as compared with a new lens. The increase of scatter is correlated with the time the lens was implanted in the eyes. Despite the increment, the optical quality of the explanted IOL were still of a reasonable good quality.

This is a 2020 ARVO Annual Meeting abstract.

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