Bellucci R
Department of Ophthalmology, University of Verona, Italy.
Ann Ophthalmol. 1992 Oct;24(10):374-7.
A retrospective biometric study was done on 132 patients with diffractive multifocal intraocular lenses. The two principal focal points induced by the intraocular lens were refracted for distance in each patient. The difference in diopters between the refractions was obtained, and the A constant (SRK formula series) and anterior chamber depth (ACD, Binkhorst formula) were calculated. Our results showed the A constant was 116.46. This value was consistent and not affected by the axial length of the eye in the 22mm to 24.5mm range. In patients who had emmetropia with the intraocular lens power implanted alone, the constant was equal to 116.3. The ACD was 3.94mm. This value was lower in shorter eyes and higher than 3.94mm in longer eyes. On the basis of the data obtained, when the SRK-II formula is used, an A constant of 116.4 should be used in preoperative biometric calculations.
对132例植入衍射型多焦点人工晶状体的患者进行了一项回顾性生物测量研究。对每位患者人工晶状体诱导的两个主要焦点进行远距离屈光测定。得出屈光度数之间的屈光度差值，并计算A常数（SRK公式系列）和前房深度（ACD，Binkhorst公式）。我们的结果显示A常数为116.46。在22mm至24.5mm范围内，该值是一致的，且不受眼轴长度的影响。在仅植入人工晶状体度数时为正视眼的患者中，该常数等于116.3。前房深度为3.94mm。该值在眼轴较短的眼中较低，在眼轴较长的眼中高于3.94mm。根据所获得的数据，当使用SRK-II公式时，术前生物测量计算中应使用116.4的A常数。
