方法：选择门诊及住院长眼轴(眼轴长度>24.5mm)老年性白内障患者81例81眼，使用IOL Master 500进行术前眼生物测量。将研究对象按照术前眼轴长度分为两组：轻度长眼轴组(24.5mm<眼轴长度≤27mm)； 中重度长眼轴组(眼轴长度>27mm)。由同一术者完成超声乳化白内障吸除联合后房型人工晶状体植入术，手术顺利，人工晶状体植入囊袋内，无手术并发症。手术后3mo由同一检查者进行裂隙灯及综合验光仪联合显然验光，确定术后实际屈光度。将其分别与应用Haigis公式、SRK/T公式、Hoffer Q公式、Holladay 1公式和SRK Ⅱ公式计算出的预期屈光度进行比较分析，观察上述公式在不同眼轴长度组中的准确性。

结果：轻度长眼轴组：SRK Ⅱ公式与其他四个公式间差异有统计学意义，Hoffer Q公式和SRK/T公式间差别有统计学意义(P<0.05)，其他各公式间差异无统计学意义(P>0.05)。中重度长眼轴组：SRK Ⅱ公式与其他四个公式间差异有统计学意义，Hoffer Q公式和SRK/T公式、Hoffer Q公式和Haigis公式间差异有统计学意义(P<0.05)，其他各公式间差异无统计学意义(P>0.05)。5个公式在两眼轴长度组中的准确性差异均有统计学意义(P<0.05)。

结论：对于眼轴长度>24.5～27mm的轻度长眼轴白内障患者，应用Haigis公式、SRK/T公式、Hoffer Q公式、Holladay 1公式进行预测均可获得较准确结果； 对于眼轴长度超过27mm的中重度长眼轴白内障患者，Haigis公式、SRK/T公式和Holladay 1公式准确性占优。以上5个公式的预测准确性均随眼轴增长而降低。

METHODS: Fifty-one eyes of 51 cases of age-related cataract and with mild long axial(24.5mm27mm)were collected who's optical biometry were performed by the Zeiss IOL Master500 before operation. They underwent regular phacoemulsification and posterior chamber IOL implantation. The actual postoperative refraction was measured with the methods of phoropter and subjective optometry 3mo after surgery. Then we compared the differences of the predicted and actual postoperative refraction of the five formulas in each group.

RESULTS: In the mild axial lengths cases, the differences between SRK Ⅱ formula and the other four formulas were statistically significant(P<0.05), and the difference between Hoffer Q and SRK-T formula was statistically significant(P<0.05); there was no difference among the other formulas(P>0.05). In the moderate and severe long axial lengths cases, the differences between SRK Ⅱ formula and the other four formulas were statistically significant(P<0.05), and the difference between Hoffer Q and SRK-T formula, Hoffer Q and Haigis formula were statistically significant(P<0.05); there was no difference among the other formulas(P>0.05). The differences of all the five formulas between the two groups were statistically significant(P<0.05).

CONCLUSION: In the mild axial lengths cases, Haigis, SRK-T, Hoffer Q, Holladay-1 performed well. In the moderate and severe long axial lengths cases, Haigis, SRK-T and Holladay-1 performed better than other formulas. The accuracy of all the five formulas decreases as the axial length getting longer.