The study of surface properties of intraocular lens by nanometric analysis

Abstract

 

Purpose

 

To analyze the essential factors of the surface properties of various intraocular lenses, such as the optic surface roughness, electrostatic charge and contact angle by means of corresponding physical measurements.

 

Methods

 

Ten commercially available lenses from different manufacturers were studied, three types of materials including poly methyl methacrylate (PMMA), silicone, hydrophobic acrylic IOLs were involved. The surface roughness was evaluated with atomic force microscopy (AFM) using the tapping mode at ambient temperature.The roughness paraments were quantitatively analyzed using Nonoscope8.0 software. Meanwhile, the electrostatic charge on IOLs was measured using Electric Force Microscopy (EFM). The contact angle measurement was performed according to the Sessile Drop Method. Images of contact angle could be obtained by contact angle imaging system ( DSA100, Germany ). Computer-assisted and researcher-controlled image analysis identified IOL contour and water drop tangent lines.

 

Results

 

AFM demonstrated statistically significant differences in the surface roughness values between IOL optics of various materials (P<0.05). The topographic images of PMMA lens surface showed numerous grooves and scratch with different orientations. All the acrylic lenses had distinct pores that varied in depth and dimensions. Silicone IOL had relatively flat surface, some protruding microgranular features, and ridge-like structures. The electrostatic charges on IOLs were significantly different between each other. There is no absolute relationship between the surface electrostatic charge and material. Contact angle measurement of the IOLs revealed different values within different materials. The contact angles of PMMA were found to have values between 49 and 62. Lenses made of Acrylic had values between 68.54 and 89.45. The angle of Silicon IOL was relatively big, 106°.

 

Conclusions

 

The surface topography of IOLs may vary with different manufacturing process. Acrylate and silicone have smoother and hydrophobic surfaces relative to the PMMA material, which makes them ideal choices for IOLs.

 

 

The topographic images of PMMA lens surface showed numerous grooves and scratch with different orientations. All the acrylic lenses were smoother and had distinct pores that varied in depth and dimensions.

 

 

The contact angle of PMMA were found to have small values between 49 and 62. The angle of Silicon IOL was relatively big, 106°.

 

Keywords: 567 intraocular lens • 445 cataract • 733 topography