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Correction of Presbyopia by Monocular Bi-Aspheric Ablation Profile
Published on: September 20, 2024
Relationship between anterior corneal asphericity and refractive variables
Amelia Nieto-Bona1, Amalia Lorente-Velázquez, Robert Mòntes-Micó
1Department of Optics II, University School of Optics, University Complutense of Madrid, Madrid, Spain. amnop@fis.ucm.es
Summary
Corneal asphericity (Q) varies with refractive properties and corneal diameter, particularly in astigmatism. Geometric eye properties, not just manifest refraction, influence this relationship.
Area of Science:
- Ophthalmology
- Optometry
- Biomedical Engineering
Background:
- The anterior cornea's shape is modeled by conic sections, defined by asphericity (Q) and apical radius.
- Corneal topography provides detailed corneal shape data.
- Understanding corneal asphericity is crucial for refractive error assessment.
Purpose of the Study:
- To compare anterior corneal asphericity (Q) values across different corneal diameters.
- To investigate the relationship between corneal asphericity and refractive state.
- To evaluate the influence of corneal power and astigmatism on asphericity.
Main Methods:
- Q-values were measured in 118 eyes using videokeratoscopy and specialized software.
- Q-values were analyzed for various corneal diameters (3.0-8.0 mm).
- Data were stratified by refractive error, corneal power, and corneal astigmatism.
Main Results:
- Mean corneal asphericity was -0.35 +/- 0.03.
- Asphericity did not significantly vary with refractive error or corneal power.
- Asphericity differed significantly among corneal astigmatism groups (p < 0.01).
- A trend towards more negative Q-values with increasing corneal diameter was observed, significant in astigmatism.
Conclusions:
- Corneal asphericity (Q) values are influenced by refractive properties and corneal diameter.
- Corneal astigmatism significantly impacts asphericity measurements.
- The relationship between refractive state and corneal asphericity is primarily driven by geometric eye properties (e.g., corneal power, axial length).
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