Abstract
Purpose: :
To identify relationships among ocular components which contribute to ocular refraction in esotropic amblyopic eyes and compare these relationships with those of the sound fellow eye and of normal control eyes.
Methods: :
Forty amblyopic patients and 40 normal control patients, age range from 5 to 8 years, were enrolled prospectively and underwent a comprehensive ophthalmic examination, including cycloplegic refraction, keratometry and A-scan ultrasonography. Anterior chamber depth, crystalline lens thickness, vitreous chamber length and total axial length were recorded. The crystalline lens power was calculated using Bennett’s formulas.The statistical analysis was performed using Pearson’s correlation coefficient.
Results: :
Statistical analysis revealed a strong relationship between axial length and refraction (p< 0.001) in amblyopic eyes (r=-0.72), sound fellow eyes (r=-0.72) and normal control eyes (r=-0.76). A significant correlation was also found between axial length and corneal refractive power in amblyopic eyes (r=-0.39, p=0.011), sound fellow eyes (r=-0.41, p=0.006) and normal control eyes (r=-0.50, p=0.001). Anterior segment length was significantly correlated with refraction in normal control eyes (r=-0.40, p=0.009), but not in amblyopic(r=-0.25, p=0.107) and sound fellow eyes (r=-0.28, p=0.076). Crystalline lens thickness decreased significantly with increasing vitreous chamber length in amblyopic (r=-0.40, p=0.01) and sound fellow eyes (r=-0.33, p=0.03), but not in normal control eyes (r=0.05, p=0.75). Crystalline lens power was significantly correlated with refraction in amblyopic (r=0.48, p=0.001) and sound fellow eyes (r=0.44, p=0.004), but not in normal control eyes (r=0.091, p=0.57).
Conclusions: :
The data suggest that the crystalline lens may play a role in the development of esotropic amblyopia, contributing to a greater amount of refracting power to the eye’s optics. The different correlations observed in the amblyopic subjects compared with those of normal control patients may be the cause or a consequence of amblyopia. The data also suggest that unilateral amblyopia may be associated with a developmental insult that affects both eyes and may reflect bilateral dysregulation of globes that have failed to achieve proportional harmony.
Keywords: amblyopia • refractive error development • refraction