Corneal Densitometry with Galilei Dual Scheimpflug Analyzer

Abstract

This study aims to apply the densitometry distribution analysis (DDA) method to study corneal densitometry depending on age and corneal region from Galilei Dual Scheimpflug Analyzer tomography. A total of 83 healthy participants aged 39.02 ± 18.34 years (range 9–81 years) were screened using a Ziemer Galilei G2. Images were analysed using the DDA, and two parameters, α (corneal transparency) and β (corneal homogeneity), were estimated. A two-way ANOVA analysis was performed to investigate whether α and β are influenced by age, corneal región (four concentric areas were considered), and their interaction. The parameters α and β statistically change with age and corneal region. A statistically significant interaction effect of 13% (α) and 11% (β) exists between age and corneal region. However, the corneal region plays a more significant role than aging in corneal densitometry; 31% (α) and 51% (β) of the variance can be attributed to the corneal region, while 28% (α) and 5% (β) can be attributed solely to aging. Corneal densitometry can be objectively assessed from Galilei G2 images using the DDA method. The corneal region plays a more significant role than aging in corneal densitometry. Consequently, general results on corneal densitometry and aging should be taken cautiously.

Relationship between corneal tissue and shape in short‐term soft contact lens wear

“…Corneal transparency and homogeneity were estimated (up to 12 mm) using the DDA method; a custom-made set of algorithms previously validated. 15,18,20,23,24 Scheimpflug images corresponding to 26 corneal meridians (a fixed size of 1004 × 1004 pixels) were exported in .bin format for further analysis (i.e., 1144 images in total = 22 subjects × 2 sessions × 26 images/measurement). The image analysis protocol applied to Galilei G2 images has been explained in detail in a previous work 18 but is presented in brief as follows.…”

“…This step consisted of modelling the intensity of the corneal pixels using the bi-parametric Weibull distribution function, as performed in previous works. 15,18,20,23,24 From this function, two parameters were extracted (α and β), which accounted for tissue transparency and homogeneity, respectively. These were α (scale parameter) and β (shape parameter).…”

“…18 The DDA offers two parameters: α, scale parameter and β, shape parameter, which account for tissue transparency and homogeneity, respectively. 20 A complete characterisation of the anterior ocular surface should include analysis of the macrostructure (i.e., morphometry, including corneal topography, corneoscleral topography and corneal thickness) and microstructure (i.e., variations in intrinsic tissue properties, including corneal transparency and homogeneity) simultaneously. However, the simultaneous investigation of morphometric and tissue parameters linked to CL wear has not been considered to date.…”

“…To describe microstructure variations in terms of tissue transparency (α) and homogeneity (β), the DDA method was applied to the Galilei G2 Dual Scheimpflug Analyzer images. 20…”