Changes in eye axis length and corneal curvature in central China from the perspective of birth year.

Objectives: To explore the changes in eye structures over time in the Chinese population from the perspective of birth year.

Methods: We collected measurement data of intraocular lens Master from patients who underwent intraocular lens Master biometry for a routine cataract or refractive examination (ametropia and presbyopia) between April 2012 and October 2023, then screened them. Selected patients were divided into ten groups of 10 years each according to their year of birth (called birth decades). Birth-year-dependent changes in axial length and corneal curvature were compared between the groups.

Results: The average axial length increased from 23.52 mm to 25.95 mm, and the corneal curvature dropped from 44.20 D to 43.33 D in patients born in before-1930 and 1990s. The proportion of short average axial length and steep corneal curvature decreased, whereas the proportion of long average axial length increased with the birth decade. The proportion of patients with corneal curvature < 40 D was 4.18% in 1970s, 5.73% in 1980s, and 3.38% in 1990s, which were significantly higher than those of other age groups. The average axial length of the eyes among primary school students was 23.96 mm, and among college students, it was 25.86 mm.

Conclusions: Overall, with the birth decade, average axial length increased and corneal curvature decreased. There were generational differences in ocular biological parameters, changes in the eye might affect the incidence of eye diseases such as glaucoma and fundus diseases, which in turn might lead to changes in the spectrum of eye diseases.