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[Relationships between refractive parameters: sphere, cylinder and axis]
O Touzeau1, T Gaujoux, J Bullet
1Service 5, centre hospitalier national d'ophtalmologie des Quinze-Vingts, 28, rue de Charenton, 75012 Paris, France; Inserm, institut de la vision, 17, rue Moreau, 75012 Paris, France. touzeau@quinze-vingts.fr
Journal Francais D'Ophtalmologie
|June 8, 2012
Summary
Refractive astigmatism is largely independent of spherical refractive error, except in high ametropia. Fellow eyes show strong correlations in refractive parameters, unlike relationships between different refractive components.
Area of Science:
- Ophthalmology
- Optometry
- Vision Science
Background:
- Understanding refractive error relationships is crucial for diagnosing and managing visual impairments.
- Fellow eye symmetry and refractive parameter correlations provide insights into ocular development and stability.
Purpose of the Study:
- To investigate the interrelationships among refractive parameters (sphere, cylinder, axis) in a normal population.
- To analyze the degree of symmetry and correlation between the fellow eyes' refractive parameters.
Main Methods:
- Prospective data collection of subjective refraction and auto-refractometry from 500 patients.
- Analysis of refraction data in a 3D dioptric coordinate system.
- Quantification of WTR/ATR ratio and enantiomorphism using specific mathematical functions.
Main Results:
- Spherical component showed minimal influence on refractive astigmatism, except in high ametropia. Higher cylinder was observed in eyes with spherical equivalents >4D.
- Cylinder and age significantly influenced the WTR/ATR ratio and enantiomorphism, with younger individuals and higher cylinder correlating with WTR and enantiomorphic axes.
- Strong correlations were found between fellow eyes for both cylinder (r=0.66) and spherical equivalent (r=0.96). Oblique axes were less enantiomorphic and associated with lower cylinder.
- Gender had no significant impact on refraction, except for a slight relative hyperopia in females.
Conclusions:
- Refractive astigmatism is largely independent of the spherical component, barring high spherical ametropia.
- Cylinder moderately affects axis orientation (WTR/ATR ratio) and enantiomorphism.
- Fellow eye refractive parameters exhibit significantly stronger relationships than inter-parameter relationships within a single eye.
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