The powers of an astigmatic eye are 6100D in the horizontal

The powers of an astigmatic eye are +61.00D in the horizontal and +63.50D in the vertical meridian. The eye has a normal length for the emmetropic reduced schematic eye. What is the refractive error in each orthogonal meridian? What is the prescription in positive cylinder format? What is the prescription in negative cylinder format?

Solution

Power of horizontal meridian = +61.00D

Power of vertical meridian = +63.50D

Refractive error= 06.50D

Cylinder refers to the amount of astigmatism. Cylinder can be expressed as either positive or negative number, most of surgeon use positive number known as plus cylinder format while non-surgeon use negative number known as minus cylinder format

Prescription for minus cylinder need to be convert into puls cylinder. To convert a prescription simply add the sphere and cylinder to obtain the converted sphere and change to a positive number if the axis = > 90, then subtract 90 for the new axis , otherwise add 90