目的：比较不同受检者在相同近视屈光欠矫下使用C字视力表和E字视力表所测得的视力差别及探讨导致这种差别的原因。方法：选取不同年龄段250名受检者，在完全矫正屈光度[最正之最佳视力(maximum plus to maximum visual acuity，MPMVA)]情况下附加相应的球镜造成相应的近视度数后比较使用2种不同的视力表测出的视力值变化情况。同时根据2种视力表的设计原理及视力表的不同记录法探讨造成数值不同的可能原因。结果：同一附加度情况下分别用C字视力表组和E字视力表组行方差分析，不同年龄组间差异无统计学意义(P>0.05)。相同附加度情况下同一受检者使用C字视力表组和E字视力表组行t检验，两者差异具有统计学意义(t=?15.798，P<0.05)，C字视力表测得视力平均值小于E字视力表测得视力平均值。结论：受检者使用C字视力表比E字视力表检测视力结果更加优异；C字视力表和E字视力表的视标形状及开口方向不同是2种视力表检测结果差异的主要原因。

Objective: To compare the difference of visual acuity measured by C-chart and E-chart in the same myopic refractive undercorrection and to explore the causes of the difference. Methods: Two hundred and fifty subjects of different ages were selected to compare the changes of visual acuity measured by two different visual meters after adding corresponding spherical lenses to the maximum plus to maximum visual acuity (MPMVA) corrected diopter. At the same time, according to the design principle of the two kinds of visual acuity meters and the different recording methods of visual acuity tables, the possible reasons for the different values were discussed.Results: There was no significant difference between different age groups (P>0.05). Under the same degree of additionality, the visual acuity of the same subjects was tested by t-test with C visual acuity chart and E visual acuity chart. The difference was statistically significant (t=?15.798, P<0.05). The average visual acuity of C visual acuity table was smaller than that of E visual acuity table. Conclusion: The visual acuity of myopic patients tested by C visual acuity chart is better than by E visual acuity chart. The main reason for the difference between C visual chart and E visual chart was the different shape and opening direction of visual icons.