Objective: To explore the influences on modulation transfer function (MTF) as a function of age and pupil in adult emmetropic eyes.
Methods: It was a prospective clinical study. All the 102 emmetropic eyes were divided into three groups according age: group A, 40 eyes (age 20 - 30 years); group B, 30 eyes (age 31 - 40 years); group C, 30 eyes (age 41 - 50 years). The total MTF and subtracted lower order aberration MTF curve were measured in all emmetropic eyes in 3.0 mm, 4.0 mm and 5.0 mm pupil sizes with a iTrace Visual Function Analyzer at six spatial frequencies (5, 10, 15, 20, 25, 30 cpd). The association between age and the two MTFs was analyzed, the two MTFs were compared among different age groups and different pupils using univariate analysis.
Results: In 3.0 mm, 4.0 mm and 5.0 mm pupil sizes and at all six spatial frequencies, there was a negative correlation between age and the two MTFs, there were significant differences among the three groups (F = 18.773, P < 0.05). At all six spatial frequencies, the two MTFs decreased with the increasing pupil.
Conclusions: The total MTF and subtracted lower order aberration MTF in adult emmetropic eyes decreased with aging and increasing pupil, so when using the two MTFs to evaluate the visual quality of human eyes, we must use different criteria according to the different age and pupil size.