Hull C C, Crofts N C
Applied Vision Research Centre, City University, London, UK.
Ophthalmic Physiol Opt. 1996 Mar;16(2):150-7.
The Beer-Lambert law has been used to determine the total attenuation coefficient, mu t, of three hard and three soft contact lens materials. The three hard contact lens materials were PMMA, Polycon II and Boston IV whereas the 3 soft materials were chosen with differing water contents of 38, 55 and 70%, respectively. The total attenuation coefficients of all six materials were obtained from measurements of the axial transmission at 632.8 nm of a series of plano powered lenses varying in axial thickness from 0.5 to 3.5 mm. The value of the total attenuation coefficient depends on both scattering and absorption and hence PMMA and Boston IV, which both incorporated a handling tint, showed significantly higher values (P < 0.0001) of mu t (0.562 +/- 0.010 mm-1 and 0.820 +/- 0.008 mm-1, respectively) than Polycon II (mu t = 0.025 +/- 0.005 mm-1). A comparison between Polycon II and the three hydrated soft contact lens materials showed a significant increase (P < 0.02) in the total attenuation coefficients for the 38% and 55% water content materials, and a weakly significant increase for the 70% water content soft lens material (P < 0.1). On the assumption that the absorption coefficients of these four materials are approximately constant, then this change would be due to an increase in the scattering coefficient of the material and could contribute to an increase in intraocular scatter. No significant difference (P > 0.5) was found between any of the hydrated soft contact lens materials tested.
比尔-朗伯定律已被用于测定三种硬性和三种软性隐形眼镜材料的总衰减系数（μt）。三种硬性隐形眼镜材料分别是聚甲基丙烯酸甲酯（PMMA）、Polycon II和波士顿IV型，而三种软性材料的含水量不同，分别为38%、55%和70%。所有六种材料的总衰减系数是通过测量一系列轴向厚度从0.5毫米到3.5毫米变化的平光镜片在632.8纳米处的轴向透过率获得的。总衰减系数的值取决于散射和吸收，因此，都含有操作色标的PMMA和波士顿IV型材料的μt值（分别为0.562±0.010毫米-1和0.820±0.008毫米-1）明显高于Polycon II（μt = 0.025±0.005毫米-1）（P < 0.0001）。对Polycon II与三种水合软性隐形眼镜材料进行比较，结果显示，含水量为38%和55%的材料的总衰减系数有显著增加（P < 0.02），而含水量为70%的软性镜片材料的总衰减系数有微弱的显著增加（P < 0.1）。假设这四种材料的吸收系数大致恒定，那么这种变化将是由于材料散射系数的增加，并且可能导致眼内散射增加。在所测试的任何水合软性隐形眼镜材料之间均未发现显著差异（P > 0.5）。
