How to identify Refractive Diagnosis of a Spectacle Prescription?

Identifying refractive diagnoses is very easy. Just you need to know the basic rules to identify a refractive diagnosis. There are a few simple steps given below to identify the refractive diagnosis.

At first, you need to look at signs of spherical power & cylindrical power along with spherical and cylindrical power values. If you want to do Spectacle prescription transposition to re-confirm - you should...

If spherical power is Zero or Plano & cylindrical power has a plus sign - This is called Simple hypermetropic astigmatism. 

Example:
1. Sph 0.00 / Cyl +0.75  Axis 180 or any axis.
2. Sph 0.00 / Cyl +2.75  Axis 90 or any axis.

If spherical power value is with plus sign & cylindrical power value is with a minus sign with same spherical and cylindrical power values - Again this is called as Simple hypermetropic astigmatism. 

Example:
1. Sph +1.75 / Cyl -1.75  Axis 180 or any axis.
2. Sph +0.25 / Cyl -0.25  Axis 90 or any axis.

If spherical power is Zero or Plano & cylindrical power has a minus sign - This is called Simple myopic astigmatism. 

Example:
1. Sph 0.00 / Cyl -1.00  Axis 180 or any axis.
2. Sph 0.00 / Cyl -3.25  Axis 70 or any axis.

If spherical power value is with minus sign & cylindrical power value is with plus sign with same spherical and cylindrical power values - Again this is called as Simple myopic astigmatism. 

Example:
1. Sph -1.25 / Cyl +1.25  Axis 170 or any axis.
2. Sph -2.25 / Cyl +2.25  Axis 100 or any axis.

Till here you have learned about simple hypermetropic or myopic astigmatism. 

If spherical power value is with plus sign & cylindrical power value is also with plus sign with any power values - This is called as Compound hypermetropic astigmatism. 

Example:
1. Sph +0.50 / Cyl +0.75  Axis 180 or any axis.
2. Sph +3.00 / Cyl +0.25  Axis 60 or any axis.

If spherical power value is with plus sign & cylindrical power value is with a minus sign but cylindrical power value should be lesser than spherical power values - Again this is  called as Compound hypermetropic astigmatism. 

Example:
1. Sph +3.50 / Cyl -1.75  Axis 160 or any axis.
2. Sph +3.00 / Cyl -0.25  Axis 80 or any axis.

If spherical power value is with minus sign & cylindrical power value is also with a minus sign with any power values - This is called as Compound myopic astigmatism. 

Example:
1. Sph -1.50 / Cyl -1.75  Axis 50 or any axis.
2. Sph -4.00 / Cyl -0.50  Axis 130 or any axis.

If spherical power value is with minus sign & cylindrical power value is with a plus sign but cylindrical power value should be lesser than spherical power values - Again this is  called as Compound myopic astigmatism. 

Example:
1. Sph -3.50 / Cyl +0.75  Axis 10 or any axis.
2. Sph -5.00 / Cyl +2.25  Axis 80 or any axis.

Till here you have learned about compound hypermetropic or myopic astigmatism. 

Now I am going to tell you about mixed astigmatism. So, you need to be very careful while looking at the spectacle prescription and writing a refractive diagnosis.

If spherical power value is with plus sign & cylindrical power value is with a minus sign but cylindrical power value should be more then spherical power values - This is  called as Mixed astigmatism. 

Example:
1. Sph +0.50 / Cyl -0.75  Axis 10 or any axis.
2. Sph +1.00 / Cyl -3.25  Axis 80 or any axis.

If spherical power value is with minus sign & cylindrical power value is with plus sign but cylindrical power value should be more then spherical power values - This is  called as Mixed astigmatism. 

Example:
1. Sph -1.50 / Cyl +2.75  Axis 100 or any axis.
2. Sph -0.25 / Cyl +1.25  Axis 140 or any axis.

Hope you have learned about refractive diagnosis very well.