Refractive Status of the Eye

Refractive Status of the Eye

• Refractive status signifies the relationship between the refracting system of the eye and its axial length, or the position of the principal focus compared to the retina, with no accommodation.

Static Refraction

• Measured with accommodation relaxed or at rest.
• Describes the relationship between the posterior principal focus of the eye's refractive mechanism and the retina.

Dynamic Refraction

• Accommodation is not at rest.
• Determines the refractive power of the eye.

Refractive Anomalies (Errors of Refraction)

• Variations from perfect coincidence of the principal focus of the eye with the retina.

Classification of Refractive Status

• Emmetropia: Refractive status with accommodation at rest, where incident parallel rays of light converge to form the circle of least confusion on the retina.
• Amertropia: Refractive status with accommodation at rest, where incident parallel rays of light converge to form the circle of least confusion:
  • In front of the retina: Myopia
  • Behind the retina: Hyperopia

Incidence and Distribution of Refractive Errors

• Premature Infants: High incidence of myopia, which disappears in early infancy.
• Infants born with different weights:
  • Over 1,700 gms: Exhibited myopia of 0 to 6.00 Diopters, which stabilized at 4 to 6 weeks of life and then altered towards emmetropia.
  • Under 1,250 gms: Exhibited a different refractive pattern.