Abstract:

Abstract:Objective To evaluate the influence of  black dots,isolated line above the best correct visual acuity and multiple lines containing the best correct visual acuity in the accuracy of Jackson cross cylinder examination.Methods Forty students were chosen (11 males,29 females,between 24 to 29 years old).Routine examination of phoropter was used to check under the maximum plus to maximum visual acuity (MPMVA) status.The sequence of three fixation targets was chosen randomly.Astigmatism chart was used to judge the best one when the different results were obtained.Results Among the 80 eyes of 40 students,12 eyes were spherical (the cylinder degree below 0.25 DC).The response of three fixation targets was the same in 19 eyes（27.9%）,23 eyes （33.8%）were sensitive to the black dots target,14 eyes （20.6%）were sensitive to the isolated line above the best correct visual acuity,12 eyes（17.6%） were sensitive to multiple lines containing the best correct visual acuity.Kruska Wallis Test was used to detect the difference among three groups.No significant difference was found (χ2 =4.026，P=0.134 ).Conclusion According to the efficiency of examination,communication and judgment,black dots target is recommended although no difference is detected among three fixation targets.

Key words: subjective refraction;cross cylinder;fog;visual acuity