Lens Transposition and Spherical Equivalents

Converting a lens prescription from one format to another, typically from a 'plus cylinder' format to a 'minus cylinder' format or vice versa.

The transposed lens prescription is +3.00 -2.00 x 180. The sphere power increases by the cylinder power, the cylinder power becomes negative, and the axis rotates by 90 degrees.

The transposed lens prescription is +2.25 -3.00 x 090. The sphere power becomes +2.25 ( -0.75 + 3.00), the cylinder power is now -3.00, and the axis is rotated to 90 degrees.

The transposed lens prescription is +5.75 -1.50 x 045. The sphere power becomes +5.75 (+4.25 + 1.50), the cylinder power changes to -1.50, and the axis is rotated 90 degrees to 45 degrees.

The transposed lens prescription is -1.00 -3.00 x 135. The sphere power decreases to -1.00 (-4.00 + 3.00), the cylinder power becomes negative, and the axis increases to 135 degrees.

A single value that represents the average refractive power of a lens, calculated by adding half of the cylinder power to the sphere power.

The spherical equivalent is Plano, meaning the lens has no overall refractive power. Calculated as -1.00 + ( 2.00 / 2) = 0.

The spherical equivalent is +3.25. Calculated as +2.00 + (2.50 / 2) = +3.25.

The spherical equivalent is -1.25. Calculated as -2.50 + ( 2.50 / 2) = -1.25.

The transposed lens prescription is -1.00 -2.00 x 120. The sphere power is -3.00 + 2.00 = -1.00, the cylinder power becomes -2.00, and the axis is rotated by 90 degrees to 120 degrees.

The transposed lens prescription is +5.00 -2.00 x 120. The sphere power becomes +5.00 (+3.00 + 2.00), the cylinder power becomes -2.00, and the axis is rotated by 90 degrees.

Converting the distance visual acuity from feet to meters, maintaining the same ratio. For example, 20/20 feet is equivalent to 6/6 meters.

20/30 feet is equivalent to 6/9 meters. We divide both numerator and denominator by 3.33 to get this conversion.

20/40 feet is equivalent to 6/12 meters. We divide both numerator and denominator by 3.33 to get this conversion.

20/50 feet is equivalent to 6/15 meters. This is derived by dividing both the numerator and denominator by 3.33.

20/60 feet is equivalent to 6/18 meters. This conversion is achieved by dividing both numbers by 3.33.

20/70 feet is equivalent to 6/21 meters. This conversion is achieved by dividing both the numerator and denominator by 3.33.

20/80 feet is equivalent to 6/24 meters. This is achieved by dividing both numerator and denominator by 3.33.

20/100 feet is equivalent to 6/30 meters. This is achieved by dividing both numerator and denominator by 3.33.