Age-related changes in Scheimpflug corneal densitometry and their correlations with corneal topographic measurements in a healthy Chinese population.

Background: Objective measurement of corneal densitometry (CD) values can be used to assess corneal transparency and health status, to investigate corneal diseases, and to review anterior segment surgeries. However, literature regarding the association between CD and corneal parameters in healthy adolescent and older individuals is limited. This study investigated age-related changes in Scheimpflug CD values and their correlations with age, sex, and corneal topographic parameters.

Methods: This retrospective cross-sectional observational study included 347 eyes from 181 consecutive healthy Chinese participants aged between 5 and 90 years. They were divided into 9 age groups: 5-9, 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, and 80-90 years. CD and corneal topographic measurements were measured using the Oculus Pentacam. To evaluate CD, the cornea was divided into 3 layers according to depth (anterior 120 µm, central, and posterior 60 µm), and into 4 annular regions according to diameter (0-2, 2-6, 6-10, and 10-12 mm).

Results: CD across different depths and regions was positively correlated with age (all P values <0.001). Of the 3 layers of corneal thickness, CD was highest in the anterior 120 µm and lowest in the posterior 60 µm (all P values <0.05). Among the 4 annular regions spanning the corneal diameter, the lowest CD values were 6-10, 2-6, and 0-2 mm at 5-29, 30-69, and 70-89 years, respectively. The highest CD values were 10-12 mm at 5-79 years, and 6-10 mm at 80-90 years (all P values <0.05). CD values of 10-12 mm in the anterior 120 µm corneal layer were significantly lower in men than in women (Z=-2.353; P=0.019). CD of 0-10 mm in each layer was not significantly different between sexes (all P values >0.05). Corneal topographic measurements, including flat-axis keratometry (K1), steep-axis keratometry (K2), and spherical aberration, were slightly positively correlated with age and CD (all P values <0.05). However, central corneal thickness (CCT) and thinnest corneal thickness (TCT), and age or CD showed no correlation (all P values >0.05).

Conclusions: With age, CD, keratometry, and spherical aberration gradually increased, while the corneal thickness did not change significantly.