[Experimental study of spherical aberrations of intraocular lenses with different materials and designs].

Objective: To study the characteristics of spherical aberrations (SA) of the traditional intraocular lenses (IOLs) produced by different materials and designs.

Methods: A special optical metrical system was established in the laboratory to measure the SA of IOLs by using the Hartmann-Shack aberrometer. Eight different types of IOLs were divided into two Groups. Group 1 consisted of 4 types of IOLs made by different materials, Group 2 consisted of 4 types of IOLs made by different designs. SA of these IOLs was measured at 3, 4, 5, 6 and 7 mm apertures separately. All data was analyzed statistically.

Results: With the size of aperture increased, SA in these two groups was both increased. There were positive correlations between the size of aperture and the SA (r = 0.6465, 0.7872; P < 0.01). The numbers of IOLs fitted with Rayleigh criterion at apertures of 3, 4, 5, 6, and 7 mm were 8, 5, 3, 2 and 2, respectively. In Group 1, the acrylic IOL (SA60AT) with high refractive index showed the greatest SA, and the acrylic IOL (AR40e) with low refractive index showed the smallest SA. The difference of SA between these two IOLs was statistically significant (P < 0.01). SA of the silicon IOL (SI40NB) and PMMA IOL (PC330UV) lied between these two extremities. In Group 2, the convexo-convex IOL with the posterior surface more curved than the anterior surface had the greatest SA. The convex-plano IOL had the smallest spherical aberration. The difference of SA between these two IOLs was statistically significant (P < 0.01). SA of convexo-convex IOL with the anterior surface more curved and the epuiconvex IOL was lied between these two extremities.

Conclusions: IOLs made by different materials and designs under different apertures show significant difference of SA, which is useful for the improvement of optic quality of IOLs. Further studies on the exact mechanism of these differences are required.