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Trial Set Questions

Trial set-related fitting questions from fitters and replies by Paul Rose

last updated 2021.1.8


Q: Is it necessary to purchase a trial set for the nipple cones, or can you also order it from the Rose K2 KC?

A: Because the nipple cone set has a smaller back optic zone and considerably more peripheral flattening it is best to use a nipple cone trial set. Judging the correct fit from a normal Rose K2 KC set would be very difficult in estimating the correct BC and edge lift.

Q: How often would you recommend replacing the fitting set - would you expect lens warpage of these lenses after a few years affecting trial fitting?

A: Trial sets are normally very stable as they are made of lower Dk materials. However to have your lab check the set after 5 years would be advisable.

Q: Does one trial lens kit come with all the designs in one or do we have to have the various design trial lenses?

A: Each design requires a different trial set.

Q: How do you select total diameter when choosing the first Rose K2 lens?

A: In the Rose K2 (KC) trial set, the diameter changes with the Base Curve, increasing as the BC flattens. On the eye you then have to make a judgement whether this diameter is the appropriate one. Location, aperture size, lid tension are all factors which will influence this decision. The diameter of the trial set lenses was based on analysing over 30,000 fits and using the average diameter for each BC. However you will frequently need to make changes to the diameter to get the optimum fitting.