# Age-Related Trends in Corneal Refractive Parameters: A Fourier Analysis of Videokeratography in Healthy Eyes

## TL;DR

This study examines how corneal refractive parameters change with age in healthy eyes, identifying key trends and inflection points that could improve eye surgery and diagnosis.

## Contribution

The study introduces age-related trends in corneal refractive parameters using Fourier analysis in healthy eyes, revealing inflection points with clinical implications.

## Key findings

- Corneal refractive parameters like SphRMin and Asti.Central show distinct age-related trends with inflection points.
- Irregular astigmatism (Irregul) increases in early childhood, decreases in young adulthood, and rises again after age 30.
- All parameters are statistically correlated with age, with significant differences across age groups.

## Abstract

Purpose: To investigate the distribution and trend of corneal parameters in different age groups without corneal diseases. Methods: A retrospective cross-sectional study. We enrolled 2545 patients (5074 eyes) without corneal diseases (mean age 37.0 ± 26.8, range 4–95) between August 2018 and December 2022. This study aimed to analyze corneal refractive power parameters derived from Fourier transform (minimum spherical refractive power (SphRMin), central regular astigmatism (Asti.Central), peripheral regular astigmatism (Asti.Periph), and irregular astigmatism (Irregul)). The differences in these parameters across age groups were compared, and both linear and nonlinear equations were fitted to model the age-related changes. Results: In people without corneal diseases of all ages, the mean values of SphRMin, Asti.Central, Asti.Periph and Irregul were 7.71 ± 0.28, 0.10 ± 0.062, 0.11 ± 0.068, and 0.028 ± 0.019. There are differences in Asti.Central, Asti.Periph, and Irregul among the different age groups (all p < 0.001). SphRMin, Asti.Central, Asti.Periph and Irregul were correlated with age (all p < 0.001). SphRMin increased before 15 years and decreased after 15 years (p < 0.001). Asti.Central increased up to 19 years, decreased between 19 and 60 years, and then increased after 60 years (p < 0.001). Asti.Periph increased up to 18 years, decreased from 18 to 48 years, and then increased after 48 years (p < 0.001). Irregul increased up to 13 years, decreased from 13 to 30 years, and then increased after 30 years (p < 0.001). SphRMin, Asti.Central, Asti.Periph and Irregul were all correlated (all p < 0.05). Conclusions: We report the mean values of corneal refractive parameters obtained by the Fourier transform in patients without corneal diseases at different ages, its changing trend with age, and important inflection points. This has great clinical implications for the diagnosis of abnormal refractive state corneas and the design of ophthalmic surgery.