Borkenstein Andreas F, Borkenstein Eva-Maria
Ophthalmology, Borkenstein and Borkenstein, Private Practice at Privatklinik Kreuzschwestern, Graz, AUT.
Cureus. 2024 Sep 28;16(9):e70383. doi: 10.7759/cureus.70383. eCollection 2024 Sep.
Introduction The material of modern intraocular lenses must meet the highest standards and fulfill various requirements. It is crucial that the material shows the best biocompatibility and should be flexible for an uncomplicated implantation process through small corneal incisions but also sufficiently rigid for good stability and centering in the capsular bag. In addition, the optic must remain clear for life and retain the best optical properties. Methods In this laboratory experiment, we performed scratch tests for the mechanical assessment of acrylic intraocular lenses. The aim was to determine differences in the behavior in regard to the manufacturing process and water content of hydrophilic and hydrophobic acrylic intraocular lenses. The scratch tests were performed using a Nano Scratch Tester. A conical indenter with a tip radius of 1 µm and a cone angle of 90° was selected to scratch the samples at three different constant loads of 5, 10, and 15 mN, respectively. The scratch length was set to 100 µm at a scratch speed of 200 µm/min. Hydrophilic and hydrophobic acrylic intraocular lenses (with different water content) were tested. Results The results showed that for sample A (hydrophilic acrylate), the penetration depth increases steadily with increasing force from 25-30 µm (5 mN) to 28-33 µm (10 mN) and 34-37 µm (15 mN). The penetration depths during the scratches seem to be load-dependent. In sample B (hydrophobic acrylate), the same forces lead to steadily increasing penetration depths: 25-30 µm (5 mN), 40-44 µm (10 mN), and 54-57 µm (15 mN). The evaluation of the residual depth showed much lower values for all samples. In the hydrophilic, softer samples (A), the residual depth was between 1 µm and 4 µm. In the hydrophobic, more solid, samples (B), the residual depth was more pronounced with values between 5 µm and 17 µm. The plastic influence and deformation zone seemed to be wider for the hydrophobic samples than for the hydrophilic samples. Conclusion The laboratory experiment confirms that modern, acrylic intraocular lenses are sensitive to scratches/touch, and penetration depths during scratching depend on the load. The remaining depths after the scratches are significantly lower and show a load dependence. The deforming zone was higher in the hydrophobic acrylates than in the hydrophilic acrylates. However, the results confirm that damage can occur with hydrophobic and hydrophilic acrylic materials, depending on the force applied. Therefore, careful handling during the preparation and implantation process is crucial to prevent permanent defects.
引言 现代人工晶状体的材料必须符合最高标准并满足各种要求。至关重要的是，该材料要展现出最佳的生物相容性，并且应具有柔韧性，以便能通过小的角膜切口进行简单的植入过程，但同时又要有足够的刚性以在囊袋中实现良好的稳定性和居中定位。此外，光学部件必须终身保持清晰并保留最佳的光学性能。
方法 在本实验室实验中，我们对丙烯酸人工晶状体进行了划痕测试以进行机械性能评估。目的是确定亲水性和疏水性丙烯酸人工晶状体在制造工艺和含水量方面的行为差异。划痕测试使用纳米划痕测试仪进行。选择尖端半径为1 µm、锥角为90°的锥形压头，分别在5、10和15 mN这三种不同的恒定载荷下对样品进行划痕。划痕长度设定为100 µm，划痕速度为200 µm/min。对亲水性和疏水性丙烯酸人工晶状体（具有不同含水量）进行了测试。
结果 结果表明，对于样品A（亲水性丙烯酸酯），随着力从25 - 30 µm（5 mN）增加到28 - 33 µm（10 mN）再到34 - 37 µm（15 mN），穿透深度稳步增加。划痕过程中的穿透深度似乎与载荷有关。在样品B（疏水性丙烯酸酯）中，相同的力导致穿透深度稳步增加：25 - 30 µm（5 mN）、40 - 44 µm（10 mN）和54 - 57 µm（15 mN）。对残余深度的评估显示所有样品的值都低得多。在亲水性、较软的样品（A）中，残余深度在1 µm至4 µm之间。在疏水性、更坚固的样品（B）中，残余深度更明显，值在5 µm至17 µm之间。疏水性样品的塑性影响和变形区似乎比亲水性样品更宽。
结论 实验室实验证实，现代丙烯酸人工晶状体对划痕/触摸敏感，划痕过程中的穿透深度取决于载荷。划痕后的剩余深度明显更低且显示出载荷依赖性。疏水性丙烯酸酯的变形区比亲水性丙烯酸酯更高。然而，结果证实，根据所施加的力，疏水性和亲水性丙烯酸材料都可能发生损坏。因此，在制备和植入过程中小心处理对于防止永久性缺陷至关重要。
