目的：探讨运用Barrett Universal Ⅱ公式(BUⅡ公式)计算人工晶状体(intraocular lens,IOL)屈光力时，可选参数角膜横径，又称白到白(white-to-white,W T W)与晶状体厚度(lens thickness,LT)的实际应用价值。方法：采用单中心、前瞻性临床研究，连续纳入同一术者顺利进行白内障超声乳化吸除术联合MX60(IOL植入术患眼279眼，术前使用OA-2000非接触式光学生物测量仪测量眼部数据并计算IOL植入度数，代入B UⅡ公式保留或去掉可选参数WTW、LT计算预测结果，进一步根据患者眼轴长度(axial length,AL)分亚组分析。主要结局指标：随访患者至术后1个月以上，比较使用和未使用WTW和LT两个参数、BUⅡ公式预测误差(prediction error,PE)、绝对预测误差(absolute error,AE)、AE小于0.5 D所占比例。结果：总体1上，忽略W T W + LT，PE为-0.05 D(-0.26, 0.18)(P=0.011)，其他参数组合的PE与0比较差异无统计学意义(P>0.05)。各参数组合的AE比较差异无统计学意义(0.22~0.23 D，P= 0.404)。同时忽略WTW + LT时AE出现最大值(+1.5 D)。应用WTW + LT、忽略WTW + LT、忽略WTW和忽略LT时纳入患者AE ≤ 0.50 D的比例分别为80.65%、79.57%、80.65%和81.36%。在各眼轴亚组中，忽略LT时，AE ≤ 0.50 D的百分比在短眼轴亚组(80.00% vs.66.67%~73.33%)与长眼轴亚组(77.78% vs. 73.33%~75.56%)中较高。在中等眼轴亚组中，AE ≤ 0.50 D百分比代入全部参数时略高(83.11% vs. 80.82%~82.19%)，忽略WTW + LT计算时稍低(80.82%)。结论：使用BU Ⅱ计算IOL屈光力时，可选参数WTW和LT无论是否代入公式中，皆可得到相近的平均预测水平；但是，同时忽略WTW和LT可能出现较大预测误差。对于22 mm ≤ AL<26 mm眼，推荐代入全部参数计算；当AL≤ 22 mm或AL ≥ 26 mm，仅输入WTW的计算方法累积精确度更高，可优先采用。

Objective: To investigate the practical application value of the optional parameters of corneal horizontal diameter or white to white (WTW) and lens thickness (LT) a using Barrett Universal II formula. Methods: Single-center, prospective clinical study. Eligible 279 eyes who underwent uneventful phacoemulsification and enVista MX60 implantation by the same surgeon were consecutively enrolled. OA-2000 (Tomey, Japan) non-contact optical biometry was used to measure the ocular data and calculate the IOL implantation power preoperatively. The BU II network formula was used to retain or remove optional parameters WTW and LT, and the predicted results were calculated. Further subgroup analysis was conducted based on the patient's axial length. Main outcome measures: Follow up patients for more than 1 month after surgery, compare the proportion of using and not using WTW and LT parameters, BU II formula prediction error (PE), absolute prediction error (AE), and AE less than 0.5 D. Results: Overall, ignoring WTW + LT, the median PE was -0.05 D (-0.26, 0.18) (P = 0.011) , and there is no statistically significant difference in PE compared 0 for the other parameter combinations (P > 0.05). There was no significant difference in the median AE of each parameter combination (0.22~0.23 D, P = 0.404). While ignoring both WTW and LT, the maximum AE value (+1.5 D) was found. The proportion of patients with AE ≤ 0.50 D included in the application of WTW+LT, neglect of WTW+LT, neglect of WTW, and neglect of LT were 80.65%, 79.57%, 80.65%, and 81.36%, respectively in each axial subgroup, when LT was ignored, the percentage of AE ≤ 0.50 D was higher in the short axial subgroup (80% vs. 66.67%~73.33%) and the long axial subgroup (77.78% vs. 73.33%~75.56%). In the subgroup of moderate eye axis, the percentage of AE ≤ 0.50 D was slightly higher when all parameters were substituted (83.11% vs. 80.82%~82.19%), and slightly lower when WTW+LT calculation was ignored (80.82%). Conclusions: When applying Barrett Universal II to calculate the refractive power of artificial lenses, the optional parameters WTW and LT can obtain similar average prediction levels regardless of whether they are substituted into the formula; However, ignoring both WTW and LT may result in significant prediction errors. For eyes with a diameter of 22 mm ≤ AL<26 mm, it is recommended to use all parameters for calculation; When AL ≤ 22 mm or AL ≥ 26 mm, the calculation method that only inputs WTW has higher cumulative accuracy, and it is suggested to be prioritized.