Astigmatism is state of refraction where in the
refractive power varies in the different meridian such that the rays of light entering the eye cannot converge to a point focus but form focal lines.
They are the most common modality for the measurement of the actual refractive error of the eye and
refractive power. Moreover, it also measures pupillary distance and pupil size.
Tell your patients to blink throughout the examination to refresh the tear film, as most of the
refractive power of the eye is at the air / tear film junction.
"If we carefully tailor these changes, we can adjust the corneal curvature and thus change the
refractive power of the eye," says Vukelic.
In 15 unilateral cases, long-term (4 to 15 years) changes in refraction, axial length, and
refractive power of the cornea were evaluated and compared with nonoperated eyes, and no significant differences in the axial length or
refractive power of the cornea between the operated and nonoperated eyes were detected, although there was significant myopic change in the operated eyes.
Objective exam to "measure the
refractive power of the eye by interpreting the light reflected from its retina when illuminated with the retinoscope" (15).
Holladay, "
Refractive power calculations for intraocular lenses in the phakic eye," American Journal of Ophthalmology, vol.
Age of commencement,
refractive power at the beginning, and
refractive power at the present were compared in between the two groups (Table 1).
Surgical intervention resulted in an increase in the mean
refractive power of cornea after one month of surgery, which indicates a steepening of the flattened cornea.
In both conditions, the
refractive power of the refractive media is the same in all meridians.