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170 Ophthalmic Lenses

Temple Length
Adjust length of temple to minimize sliding.

Fig. 11.53: Needs to lengthen side bend

Vertex Distance
Minimize Vertex distance by adjusting nose pads but avoid contacting the
eyelashes with the lens.
Once the above adjustment are done, take the following two
measurement:
1. Monocular PD for distance
2. The fitting height

Monocular PD for Distance
The monocular PD is the distance from the centre of the nose bridge to the
centre of the pupil, specified to the nearest 0.5mm. A number of devices
can be used to measure monocular PD:

1. Pupillometer

Fig. 11.54: Measuring PD with Pupillometer