Abstract
Purpose:
In this study, used the Acrysof® SN60WF, which were manufactured recently to devise a way for eliminating sub-surface nano glistenings (SSNGs), to predict the changes in deterioration after 20 years. We observed the appearance, measured the weight, optic diameter and light transmittance of the lenses, and analyzed the preservative solution of the IOLs with gas chromatography-mass spectrometry (GC-MS)
Methods:
Forty five Acrysof® SN60WF IOLs were used. Each IOL was immersed in ultrapure water placed in a 9-mL screw-top vial at 100˚C for 115 days on the assumption that storage in an oven at 100˚C for 23 days is equivalent to 4 years at 37˚C. After 115 days which is corresponding to a period of 20 years, the appearance of the lens was observed with a stereoscopic microscope, and then the change in weight, optic diameter and light transmittance were measured. The preservative solution was analyzed with GC-MS.
Results:
Appearance: Glistening was observed in all of the 45 lenses. Assumed changes to indicate deterioration such as cracks on the lens and discoloration of the optic were observed in 11 lenses (24%).<br /> Rate of change in lens weight: The weight of the lens decreased significantly. After drying, the average rate of change in lens weight was -2.45%.<br /> Rate of change in optic diameter: The optic diameter decreased significantly. After drying, the average rate of change in optic diameter was -0.84%.<br /> Rate of change in light transmittance: Deterioration was observed in 11 lenses. At 500 nm, the light transmittance in the 10 lenses decreased about 1% to 7%, and in one lens decreased about 36%.<br /> Preservative solution: The peaks of phenylethyl alcohol, or a hydrolysate[A1] , were observed in 9 of 11 lenses.
Conclusions:
In a 20-year severe accelerated deterioration test, although opacification was observed in appearance of all the SA60AT and SN60AT lenses (20 of 20 lenses, 100%) after drying, the speed of deterioration may have been slowed because SN60WF lenses showed fewer changes of deterioration (11 of 45 lenses, 24%) compared to SA60AT and SN60AT, and the deterioration had little impact on the light transmittance of the lenses. However, the weight and optic diameter of the lenses decreased significantly. The phenylethyl alcohol leaked into the preservative solution. These results indicate that the lenses had deteriorated. It is assumed that the deterioration was due to the cast molding method for manufacturing the lenses.