Final answer:
Ensuring proper centration is the most important thing to do when fitting soft multifocal lenses.
Step-by-step explanation:
When fitting soft multifocal lenses, the most important thing to do is to ensure proper centration. This means that the lenses should be positioned correctly on the cornea to ensure optimal vision and comfort. Proper centration helps to minimize visual disturbances and achieve the best visual outcomes for the wearer.
Other factors, such as verifying the prescription with manifest refraction, focusing on tear film stability, and assessing corneal curvature for a suitable fit, are also important in the fitting process. However, centration is particularly crucial as it directly affects the lens's alignment with the visual axis.