UNIVERSITY OF MISSOURI-ST. LOUIS
SCHOOL OF OPTOMETRY
LABORATORY PROGRAM OPTOMETRY 553/563
CONTACT LENSES I
FITTING SOFT CONTACT LENSES
Introduction
Soft contact lenses may be manufactured by three methods or a combination of these methods. (Spincasting, cast-molded or lathe-cut) These will be discussed in more detail in the contact lens course. Today you will be fitting a partner with soft contact lenses. These lenses will be ordered and dispensed at a future lab time.
Fitting Procedure
Many labs suggest starting with a base curve radius 4-5D flatter than low "K". Another method to use is to fit the middle base curve available. Most of these type lenses are available in approximately 3 base curves, for example: 8.2mm, 8.6mm, 8.9mm. In this example, you would choose the 8.6mm. If you find it to be too flat, change to the 8.2mm and if too steep, change to the 8.9mm. Another method is to use the following as a guide for selection base curves:
Low K >345D Steeper BCR
Low K 41-45D Middle BCR
Low K<41D Flatter BCR
Diameter: A 13.8 or 14.0 diameter is fairly standard. HVID’s of about 10 or 11mm are fairly average. Eyes with a small HVID may need to go to a smaller diameter and eyes with a large HVID, a larger diameter.
Example: BCR Diameter Power Lab Type
8.6 13.8 -3.00 Ciba Cibasoft
Note: We are using Cibasoft lenses from Ciba Vision for this lab today. We use all types of lenses in clinic. We have changed the laboratory slightly from years past and I wanted to try ordering and dispensing lenses this year. Ciba was kind enough to supply the lenses.