Question

# Locate the virtual F Prescribe a suitable bi-focal spectacles for a person who cannot see clearly the object nearer than 50 cm and 2 m/away or further. 75

Answer

+0.75 for distance and +2.25 for reading, with the virtual F for distance at 133 cm and virtual F for reading at 33 cm.

- Determine the prescription for the distance portion of the bi-focal. A: The prescription for distance would be +0.75
- Determine the prescription for the reading portion of the bi-focal. A: The prescription for reading would be +2.25
- Locate the virtual F. A: The virtual F for the distance prescription would be 133 cm and for the reading prescription would be 33 cm.
- Calculate the distance between the two virtual Fs. A: The distance between the two virtual Fs would be 100 cm.
- Prescribe the bifocal spectacles. A: The prescription for the bi-focal spectacles would be +0.75 for distance and +2.25 for reading, with the virtual F for distance at 133 cm and virtual F for reading at 33 cm.