散光对使用C字视力表与E字视力表检测视力的影响
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摘要
目的:比较学生在不同散光欠矫下使用C字视力表和E字视力表所测的视力差别并分析其原因。方法:选取30名15～18岁的学生,在完全矫正屈光度MPMVA(maximum plus to maxim umvisual acuity)状态下,附加相应不同散光轴向的柱镜造成相应的散光度数后,比较使用两种不同的视力表测出的视力值。同时根据两种视力表不同的设计原理及记录方法,分析造成数值差异的可能原因。结果:与E字视力表组相比,C字视力表组附加各个轴向+0.25DC柱镜组测得视力值均值差异低度较小,附加+0.50DC差异较大,其中斜轴方向上的差异更大,差异有统计学意义(F=23.141,P<0.01)。在各个附加度组别中使用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,其中斜轴方向的附加组差值更大。C字视力表在各散光轴位测得视力值差异无统计学意义(F=1.446,P=0.231);E字视力表组在各散光轴位测得视力值相差为明显,在斜轴散光中数值与非斜轴散光数值差异有统计学意义。结论:散光患者使用C字视力表更加优异,不同轴向的散光测出来的视力值更加稳定。对于非斜轴散光患者来说,使用C字视力表比E字视力表更难,用小数记录法记录视力值可能相差3～4行,原因为散光眼在各个方向上的屈光度不一致及C字视力表和E字视力表的视标形状及排列不同导致。
Objective: To compare the differences of visual acuity measured by C-chart and E-chart under different astigmatism and analyze the reasons for the differences. Methods: Thirty students aged 15–18 years were selected.Under the condition of fully corrected refractive MPMVA(maximum plus to maximum visual acuity), the corresponding astigmatism was caused by adding corresponding columnar lenses with different astigmatism axes.The corresponding visual acuities measured by two different visual charts. According to the design principle and recording methods of two kinds of visual acuity charts, the possible reasons for the different values are analyzed.Results: Compared with the E-type visual acuity chart, the average difference of visual acuity measured by adding each axis +0.25 DC columnar lens group was smaller, and the difference between adding +0.50 DC group was larger, especially in the oblique axis direction(F=23.141, P<0.01). The average visual acuity measured by the C-type visual acuity chart in each additional degree group was smaller than that measured by the E-type visual acuity chart, and the difference of the additional group in the oblique axis direction was greater than that measured by the E-type visual acuity chart. There was no significant difference in the visual acuity measured by C-type chart at different astigmatism axes(F=1.446, P=0.231); there was a significant difference in the visual acuity values measured by E-type chart at different astigmatism axes, and there was a significant difference in the values of oblique astigmatism and non-oblique astigmatism. Conclusion: Astigmatism patients with C-type chart obtain more accuracy results, and the visual acuity values measured by different axes of astigmatism are more stable. For patients with non-oblique astigmatism, it is more difficult to use C-type chart than E-type chart. The difference of visual acuity recorded by decimal recording method may be 3–4 rows. The reasons are the inconsistency of diopter in different directions of astigmatism and the different shape and arrangement of visual icons between C-and E-type charts.
Objective: To compare the differences of visual acuity measured by C-chart and E-chart under different astigmatism and analyze the reasons for the differences. Methods: Thirty students aged 15–18 years were selected.Under the condition of fully corrected refractive MPMVA(maximum plus to maximum visual acuity), the corresponding astigmatism was caused by adding corresponding columnar lenses with different astigmatism axes.The corresponding visual acuities measured by two different visual charts. According to the design principle and recording methods of two kinds of visual acuity charts, the possible reasons for the different values are analyzed.Results: Compared with the E-type visual acuity chart, the average difference of visual acuity measured by adding each axis +0.25 DC columnar lens group was smaller, and the difference between adding +0.50 DC group was larger, especially in the oblique axis direction(F=23.141, P<0.01). The average visual acuity measured by the C-type visual acuity chart in each additional degree group was smaller than that measured by the E-type visual acuity chart, and the difference of the additional group in the oblique axis direction was greater than that measured by the E-type visual acuity chart. There was no significant difference in the visual acuity measured by C-type chart at different astigmatism axes(F=1.446, P=0.231); there was a significant difference in the visual acuity values measured by E-type chart at different astigmatism axes, and there was a significant difference in the values of oblique astigmatism and non-oblique astigmatism. Conclusion: Astigmatism patients with C-type chart obtain more accuracy results, and the visual acuity values measured by different axes of astigmatism are more stable. For patients with non-oblique astigmatism, it is more difficult to use C-type chart than E-type chart. The difference of visual acuity recorded by decimal recording method may be 3–4 rows. The reasons are the inconsistency of diopter in different directions of astigmatism and the different shape and arrangement of visual icons between C-and E-type charts.
引文
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9.顾海东,齐备.C字视力表与E字视力表对中心远视力定量分析的比较[J].中国眼镜科技杂志,2004(7):38-39.GU Haidong,QI Bei.Comparison of quantitative analysis of central distant vision between C-visual acuity chart and E-visual acuity chart[J].Chinese Journal of Ophthalmology Science and Technology,2004(7):38-39.
2.空勤人员和空中交通管制员体检鉴定医学标准[S].A C-67FS-001,2017年9月19日.Medical Standards for Medical Examination and Identification of Aircrew and Air Traf f ic Controller[S].AC-67FS-001,19September 2017.
3.郑曰忠,时冀川.规范视力的检测和统计方法[J].中华眼科杂志,2002,38(2):67-68.ZHENG Yuezhong,SHI Jichuan.Urgent need for standardization of visual acuity test and statistical method[J].Chinese Journal of Ophthalmology,2002,38(2):67-68.
4.刘文兰.调节对散光的影响研究[D].天津:天津医科大学,2012.LIU Wenlan.Study on the effect of regulation on astigmatism[D].Tianjin:Tianjin Medical University,2012.
5.王晨晓,瞿佳.视力表应用常见误解之分析[J].中华眼视光学与视觉科学杂志,2015,17(3):129-131.WANG Chenxiao,QU Jia.Analysis of common misunderstandings in the application of visual acuity chart[J].Chinese Journal of Ophthalmology and Visual Science,2015,17(3):129-131.
6.彭鹏,蒙昌亮,徐静,等.Landolt环视力表在民航工作中的再认识[J].航空航天医学杂志,2019,30(1):23-25.PENG Peng,MENG Changliang,XU Jing,et al.The Landolt C chart's knowledge in the work of Civil Aviation[J].Journal of Aerospace Medicine,2019,30(1):23-25.
7.Wright KW,Cem Mocan M,Najera Covarrubias M,et al.Comparison of visual acuity levels in pediatric patients with amblyopia using Wright figures(c),Allen optotypes,and Snellen letters[J].J AAPOS,2005,9(1):48-52.
8.姚进.散光眼的视觉分析与利用散光表视标检查散光[J].中国眼镜科技杂志,2007(11):44-45.YAO Jin.Visual analysis of astigmatism and examination of astigmatism with astigmatism indicator[J].Chinese Journal of Ophthalmology Science and Technology,2007(11):44-45.
9.顾海东,齐备.C字视力表与E字视力表对中心远视力定量分析的比较[J].中国眼镜科技杂志,2004(7):38-39.GU Haidong,QI Bei.Comparison of quantitative analysis of central distant vision between C-visual acuity chart and E-visual acuity chart[J].Chinese Journal of Ophthalmology Science and Technology,2004(7):38-39.