[Quantitative evaluation of corneal irregular astigmatism using computed corneal topography]

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Optometry

Context:

• Corneal topography is crucial for understanding refractive errors.
• Quantifying irregular astigmatism presents a challenge in clinical practice.
• Pterygium can significantly alter corneal shape and refractive properties.

Purpose:

• To develop and validate a novel method for quantifying corneal irregular astigmatism.
• To establish a reproducible parameter for irregular astigmatism using computed corneal topography.
• To assess the impact of pterygium on corneal irregular astigmatism.

Summary:

• A new method quantifies corneal irregular astigmatism by analyzing discrepancies between actual and approximated sine curve refractive powers from corneal topography.
• Validation with artificial models and normal human corneas demonstrated reproducibility and low baseline irregular astigmatism (0.10-0.25D).
• Eyes with pterygium showed significantly higher irregular astigmatism, which persisted post-surgery in large pterygium cases.

Impact:

• Provides a quantitative, reproducible measure of corneal irregular astigmatism.
• Offers a new tool for diagnosing and monitoring conditions affecting corneal shape, such as pterygium.
• Distinguishes between regular and irregular astigmatism, aiding in surgical planning and outcome assessment.