Abstract: Objective Discuss whether reducing the interval of spherical trail lens can increase the Duochrome test realization rate and help myopia patients obtain better visual quality. Design Prospective clinical controlled studies. Participants 98 myopia patients who were recruited to undergo a vision test and refraction in Beijing Tongren Eye Center. Methods Use spherical trail lenses with 0.25 D intervals and 0.05 D intervals to perform Optometry using the same steps. If red and green balance can be achieved, the prescription of spherical power is equal to the count point; if the red and green balance cannot be achieved, record the maximum redness spherical power. Compare the rate of red-green balance on the Duochrome test, prescription spherical lens power, best corrected visual acuity (BCVA, LogMAR), and contrast sensitivity obtained by the same patient using different interval trail lens. Record the minimum spherical lens power change that can cause changes in the definition of the red and green background as the red-green difference perception threshold, and analyze the difference in the red-green difference perception threshold between different people. Main Outcome Measures The realization rate of red-green balance, prescription spherical lens power, BCVA. Results The realization rate of red-green balance on the Duochrome test for the 0.05 D interval group was significantly higher than for the 0.25 D interval group in both eyes (Right eye 82.6 % vs 11.2 %, χ2=100.38, P<0.01; Left eye 81.6 % vs 7.1%, χ2=110.14, P<0.01). The prescribed spherical power of the 0.05 D interval group was significantly higher than the 0.25 D interval group in both eyes (Right eye -3.79±1.52 D vs -3.70±1.52 D, t=11.86, P=0.000; Left eye -3.49±1.63 D vs -3.40±1.63 D, t=13.24, P=0.002). The BCVA (LogMAR) in the 0.05 D interval group was significantly better than in the 0.25 D interval group on both eyes (Right eye -0.039±0.076 vs -0.009±0.069, t=6.485, P=0.000; left eye -0.028±0.068 vs -0.003±0.070 t=6.209, P=0.000). 83.7% of people can distinguish the changes in the definition of the red and green visual indicators caused by the ≤0.05 D spherical trail lens. Conclusion Reducing the interval between spherical refraction lenses can significantly increase the realization rate of the red-green balance test. Myopias who use the red-green balance prescription obtained with 0.1 D interval spherical refraction lenses can obtain better visual quality. (Ophthalmol CHN, 2021, 30: 184-188)

Key words: trail lens, spherical lens, manufacturing precision, Duochrome test, visual quality