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Influence of iris color on corneal densitometry
Ana R Arizcuren1, Alejandra Consejo1
1Aragon Institute for Engineering Research (I3A), University of Zaragoza, Zaragoza, Spain.
Journal of Optometry
|January 23, 2026
Summary
Iris color significantly impacts corneal densitometry (CD) measurements from Scheimpflug imaging, causing overestimations in lighter eyes. An objective IrisColor metric was developed to quantify iris pigmentation and aid in correcting this bias.
Area of Science:
- Ophthalmology
- Medical Imaging
- Image Analysis
Background:
- Corneal densitometry (CD) is crucial for assessing corneal health.
- Scheimpflug imaging is a common method for CD measurement.
- Potential biases in CD measurements require investigation for diagnostic accuracy.
Purpose of the Study:
- To investigate if iris pigmentation biases corneal densitometry (CD) values obtained via Scheimpflug imaging.
- To develop an objective metric for quantifying iris color.
Main Methods:
- Assessed CD as mean pixel intensity from Scheimpflug images in 91 eyes.
- Quantified iris brightness artefacts using automated image processing.
- Characterized iris color objectively using a novel IrisColor metric derived from CIELAB components.
- Evaluated associations using correlation and linear mixed-effects models.
Main Results:
- Corneal densitometry (CD) positively correlated with iris brightness artefacts (r=0.47).
- Iris brightness artefacts negatively correlated with the IrisColor metric (r=-0.83).
- Lighter irises (lower IrisColor values) showed a significant 6.6% relative overestimation in CD values.
Conclusions:
- Iris pigmentation introduces a measurable bias in Scheimpflug-based CD estimates.
- Increased brightness artefacts in lighter irises are the primary cause of bias.
- The IrisColor metric allows objective iris color classification and potential bias correction in diagnostics.
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