Corneal Densitometry in Chinese Adults with Healthy Corneas: Associations with Sex, Age, Ocular Metrics, and Optical Characteristics

Abstract

Background This study aimed to determine the standard values of corneal densitometry (CD) using a Scheimpflug camera in healthy corneas. Additionally, this study aimed to investigate the correlations between sex, age, ocular parameters, and corneal density, as well as explore the impact of corneal density on the forward scattering and optical quality of the eye. Methods This retrospective observational study involved 990 healthy subjects from China, comprising 494 males and 496 females (mean age of 23.88 ± 6.90 years). The CD values at various depths and radial areas of 0–12 mm were measured using a Scheimpflug camera. Densitometric measurements were expressed in standardized grayscale units (GSU). In addition, the optical scatter index (OSI), modulation transfer function cutoff values (MTFcutoff ), and Strehl’s ratio (SR) were determined using an optical quality analysis system. Results The average CD within a 12 mm diameter area was 16.26 ± 1.35GSU. When considering different depths, the highest and lowest optical densities were observed in the anterior layer (21.41 ± 2.16GSU) and posterior layer (12.00 ± 1.01GSU), respectively (P < 0.001). Similarly, when considering different radial areas, the maximum and minimum optical densities were found in the 10–12 mm (14.09 ± 0.93GSU) and 2–6 mm (25.93 ± 4.77GSU) circles, respectively (P < 0.001). There was no statistically significant difference in the average CD within a 12 mm diameter area between males and females (P > 0.05). However, upon adjusting for variables such as age, central corneal thickness (CCT), corneal curvature, white-to-white (WTW) corneal diameter, and axial length, females exhibited a greater average CD within the 12 mm diameter and in the 6–10 mm and 10–12 mm circles compared to males. Age-related changes in CD were evident, except for the 2–6 mm circle. Notably, there was a correlation between CCT, corneal curvature, WTW corneal diameter, partial depth, and radial area CD. Additionally, CD in different areas correlated with the OSI, MTFcutoff, and SR (P < 0.05). Conclusions This study provides normative CD measurement data in Chinese adults with healthy corneas, emphasizing the significance of factors such as sex, age, CCT, corneal curvature, and WTW corneal diameter in CD evaluation. Importantly, elevated CD can lead to increased forward scatter within the eye, thereby affecting the optical quality.