What do you need to know?
Automatic refraction measurement is performed with a precision ophthalmic device, called a refractometer, used to determine dioptric power in the treatment of: myopia, astigmatism, presbyopia, in the determination of pupil axis and distance, and in the prescription of visual corrections. With the retroillumination function, checks for the appearance of certain lens opacities can be performed. Based on its results, glasses or contact lenses are prescribed.
Autorefractometry is considered an objective method of examining the refraction of the eye, because the measurements are made without any patient action or subjective information from the patient.
During the procedure, a beam of infrared light emitted by the device, reflected from the retina, is fixed by electronic sensors at the entrance and exit of the eye. The computer program then analyses the measurement results and returns the required values in figures.
In the case of some eye defects, the transmission of the light beam to the retina and its reflection are interrupted. Consequently, auto refraction in such cases is not effective.
Refractometry is interpreted by reading the refractive indices, recorded in 3 columns:
- First column indicates Sf (sphere) – determines myopia or hyperopia
- The second column describes the CYL (cylinder) indicator – determines the presence or absence of astigmatism
- The third column, the AX (axis) indicator shows the angle of the lens fitting in astigmatism
- PD measures the distance between pupils and is required when making glasses
Keratometry – is a diagnostic procedure used in ophthalmology to determine the curvature of the anterior surface of the cornea and detect various irregularities in its shape. The determination of the curvature and degree of refraction of the cornea is a necessary study for the choice of contact lenses and the diagnosis of corneal disorders. The measurement results are automatically printed. These results are sufficient to allow the initial assessment of the patient’s vision and the choice of glasses or contact lenses.