Theoretical derivation and clinical validation of the resolution limit of human eye to spherical lens change:A Self-controlled Study

AbstractBackground/AimsTo deduce theoretically and verify the resolution limit of human eye to spherical lens change for more reasonable design of the trial lenses.MethodsFirst, the resolution limit of discernible change in spherical power was derived based on the optical model. Then, the volunteers were observed to see if they could perceive the changes in spherical power as per the resolution limit and compare the difference in the best corrected visual acuity obtained with the resolution limit and interval of 0.25D.ResultsAssuming that the cone cell diameter is 3 μm and the pupil diameter of 4 mm, the theoretically resolution limit was 0.05D. When the diopter of spherical power was increased, the ratios of ability to perceive 0.05D spherical lens change were 98.3% and 96.7% in right and left eyes. When the diopter of spherical power was decreased, the ratios of ability to perceive 0.05D spherical lens change were 78.9% and 83.2% in right and left eyes. The best corrected visual acuity obtained with the 0.05 D interval trial lens was significantly better than in the 0.25 D interval on both eyes (Right eye -0.04±0.07 vs -0.02±0.06, t=6.729, P<0.001; Left eye -0.07±0.06 vs -0.04±0.06, t=8.825, P<0.001).ConclusionThe resolution limit of human eye to spherical lens change was about 0.05D and the better corrected visual acuity can be obtained by adjusting the spherical power at an interval of 0.05D.What is already known on this topicAt present, the spherical power is generally adjusted at 0.25D for optometry. In clinical practice, we find that a more than 80% of myopia patients with clear red prototypes will directly see clear green in case of a decrease by 0.25D, unable to achieve the red-green balance.What this study addsMore than 80% of myopia patients can perceive the changes in spherical power as per 0.05D.How this study might affect research, practice or policyAdjusting the spherical power per 0.05 D can help us to achieve a higher full correction rate (>80%) and realize better visual acuity.[Synopsis/Precis]The resolution limit of human eye to spherical lens change is about 0.05D and better corrected visual acuity can be obtained by adjusting the spherical power at an interval of 0.05D than 0.25D.