ASTIGMATISM
Astigmatism is a type of refractive error, caused by irregular shape of the front part of our eye called the cornea.
If we take a X axis & Y axis, all rays should focus at a single point to give a clear image on the retina as seen in the diagram .
In astigmatism, the rays coming along the X & Y axes do no coincide
Hence one axis will be blurred & the other clear
Child will have confusion between the alphabets & numbers, commits lots of spelling mistakes
If your eyeglass or contact lens prescription contains three parts rather than one, your doctor has found some astigmatism in one or both of your eyes. A prescription with three parts looks like this: -2.75 -1.25 x 90.
- The first part indicates your main spherical correction (short /long sight), meaning the amount of power (in diopters) required in a lens to sharpen your visual acuity to an acceptable level. In this example, the person has myopia and requires a negative (concave) lens to correct it.
- Part two shows the amount of the astigmatism in diopters. Again, the minus sign means a concave lens is needed.
- Part three is the axis (in degrees) of the cylinder required to bend certain light rays to compensate for the cornea's irregular shape
Child need glasses for constant wear
Contact lenses can e given in older children
Soft lenses do no correct this defect.
We will need a Soft- Toric lens or a semi-soft lens to correct this.
Extreme forms of astigmatism results in a condition called keratoconus
Prognosis for astigmatism is generally good