How far above the lower segment line will the lower edge of the top segment of a double seg lens be?

In the context of double-segment lenses, which are often prescribed for patients who require bifocal vision correction, the placement of the segments is crucial for effective visual performance. The distance between the lower segment line and the lower edge of the top segment typically depends on the design of the lens and the wearer's needs.

The correct measurement of 13-14 mm aligns with standard practices in ophthalmic dispensing, ensuring that there is ample space for visual fields. This distance helps to provide a seamless transition between the two segments, facilitating comfortable vision for both far and near tasks. A proper placement of the segments enhances the overall effectiveness of the lens by reducing the likelihood of visual discomfort or adjustment issues.

The specified range also takes into consideration the average frame size and the typical positioning of the segments on various face shapes, ensuring that the wearer can utilize both segments effectively without obstruction. This attention to detail in segment placement is vital for achieving the intended vision correction and optimizing the patient's visual experience.