If the prescription for a lens is +6.00 - 4.00 x 050, what number would you read on the power wheel of a manual lensometer when the sphere target lines are in focus?

When determining what you would read on the power wheel of a manual lensometer when the sphere target lines are in focus, it is essential to understand the components of the prescription. The prescription given is +6.00 - 4.00 x 050. This notation indicates a lens that has a spherical component of +6.00 diopters and a cylindrical component of -4.00 diopters oriented at 50 degrees.

In a lensometer, the reading is primarily based on the spherical value when focusing the spherical target. Since the sphere component is +6.00, when you align the lens in the lensometer so that the sphere target lines are in focus, the power wheel will reflect the spherical power of the lens. Therefore, the correct reading on the power wheel is +6.00 diopters.

The numbers on the power wheel of a lensometer typically represent the spherical power of the lens, which in this case reveals that the lens has a positive power. The other components of the prescription (the cylindrical power and the axis) do not affect the reading when the sphere lines are in focus, as cylinder adjustments are made separately after establishing the sphere.

Thus, when the sphere lines are sharp and clear in the lensometer,