Abstract
Purpose: :
Selection of an IOL material that can be implanted for an extended period of time in children was studied using light transmittance, IOL cross section, and weight change rate data obtained in a severe accelerated deterioration test.
Methods: :
1) Acrylsoft, PMMA, and silicone IOLs subjected to severe accelerated deterioration for 173 days (predicted to be 30 years) were divided into Group A with reduction of ≥50%, Group B with reduction of <10%, and Group C with no reduction in terms of light transmittance [partially presented at American Academy of Ophthalmology (AAO) meeting in the United States in 2008] at 400-800 nm, and sections of each IOL were compared.2) Weight change rates of IOLs in the three groups were compared.Group A: Acrylsoft: MA60BM, SA60AT, SN60AT; PMMA: MZ60BDGroup B: Acrylsoft: AR40e, VA-60BB, YA-60BB, N4-18B, N4-11YB; PMMA: ENV-23; Silicone: ClariflexGroup C: Acrylsoft: HP60M; PMMA: LS-106S, NR-81C, NR81-G; Silicone: AQ-310AiThree of each type of IOL were used for investigation of weight change rate.Severe accelerated deterioration experiment: IOLs were put in a screw tube bottle containing ultrapure water and kept in an oven (100ºC) for 173 days. For accelerated deterioration, 173 elapsed days were considered 30 years, based on the Arrhenius equation.
Results: :
1) Sections: SN60AT and MZ60BD in Group A were uniformly clouded. MA60BM and SA60AT showed more brownish-red linear opacity on the inside than on the surface. IOLs in Group B and Group C had maintained their transparency for the most part.2) Weight change rate: In Group A, the IOL weight change rate was -2.4%, -1.9%, and -1.5% for MA60BM, SA60AT, and SN60AT, respectively. The weight change rate of acrylic IOLs in Group B was less than ±1%. The weight of PMMA IOLs increased in Groups A, B, and C by +1.8 to +3.7%. The weight change rate of AQ-310Ai in Group C was -1.7%.
Conclusions: :
The weight change rate of Acrylsoft IOLs was bigger in Group A than in Group B. As for the weight loss in the case of the Acrylsoft IOLs, what likely occurred was a decrease in mass due to decomposition of side-chain ester bonds to acrylic acid (methacrylic acid) and alcohol as a result of hydrolysis and leaking of alcohol into the water. Since deterioration was pronounced in the case of the Acrylsoft IOLs in Group A, which showed pronounced hydrolysis, we suspect that reinsertion will be necessary if they are inserted in children.
Keywords: cataract • intraocular lens • pathology: experimental