The correlation between the degree of binocular suppression and the fusion

• Main Authors: ChIh-Yi Chen, 陳志毅
• Other Authors: Shyan-Tarng Chen
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/9pcsp4

碩士 === 中山醫學大學 === 視光學系碩士班 === 106 === Purpose: It is the purpose of this study to explore the process of developing the binocular vision in healthy adults. There are two important factors, the fusion image and binocular suppression. The good binocular fusion is based on the suppression phenomena in order to create better binocular vision. What kind of relations are there between the angle of the binocular disparity and the fusion or with the suppression? Methods: There are 41 participants in this study. However, one of the male subjects who has retinoschisis was excluded. The average age of the 40 participants is 20~30 years old. 24 of the participants are male and 16 are female. The average age of the male group is 22.53±2.17 and for the female group the average age is 22.19±1.94. There are two measurements in the project, which are both followed by analysis. Firstly, to measure suppression phenomena by having the test subjects look at the line of the stimulate card in the Telebinocular, setting the distance at 20 cm. When there are two different stimulation signals between the right and the left eyes, the binocular rivalry appears, which will induce the suppression phenomena. When seeing a horizontal single line, the test subjects need to say “appear”; when the line disappears, they need to say “disappear”. At the same time, we use the timer to record the suppression’s accumulation time and frequencies. Secondly, to measure the Fusion Vergence (FV) by measuring the amount of the distance base in (BI) and base out (BO) vergences at blur point (if no blur point, use break point). Finally, to carry out the analysis on the results of the FV and suppression. Results: With the smallest vertical double-line spacing, the suppression’s accumulation time or frequencies are slightly lower (the suppression time of the 7'' angle was 14.33 seconds; the frequency was 0.27 times/second). With the appropriate spacing, the suppression’s accumulation time or frequencies are the highest (the suppression time of 14'' angle was 14.68 seconds and the frequency of the 29'' angle was 0.308 times/second). With the largest spacing, the suppression’s accumulation time and frequencies are the lowest (the suppression time of the 3 ̊52'' angle was 3.45 seconds and the minimum frequency of 0.079 times/second). The relationship between the single-line suppression’s accumulation time and the FV has statistically significant differences at 7''-t, 14''-t and 29''-t. (r = 0.366, p = 0.02; r = 0.516, p = 0.001; r = 0.400, p = 0.011). However, there is no significant difference between the suppression’s accumulation time and the FV at 58''-t, 1°57''-t and 3°52''-t, with large spacing (r=0.091, p=0.578; r=0.120, p= 0.462; r=0.031, p=0.851). In addition, there is no significant difference between the horizontal single-line suppression frequencies and the FV in every spacing configuration. Conclusion: The findings of this study are with the appropriate binocular disparity to achieve single binocular vision is through relying on the binocular rivalry phenomena and with the smaller and larger binocular disparities, it relies on the fusion phenomena. The fusion and rivalry perceptions appear in the fovea of retina’s nasal and temporal sides. The uncrossed disparity is when the subject is outside the Apparent Fronto-Parallel Plane (AFPP). As a result, the image disparity falls on the nasal side, which could induce the fusion perception. The crossed disparity is when the subject is inside the AFPP. Consequently, the image disparity falls on the temple side, which could induce the rivalry perception. For the test subjects with weak fusion perception, they have difficulty identifying the stereo vision, which affects the fusion with the larger and smaller spacing configurations. However, with the appropriate spacing, the rivalry perception is not affected.