How to Design a Custom Soft Toric Contact Lenses from SpecialEyes
SpecialEyes custom soft toric contact lenses can be designed in a wide range of parameters; even the thickness and size of the optical zone can be specified. Visit our products page to learn more about our parameter offerings. Designing custom toric contact lenses from SpecialEyes is simple. A practitioner can utilize our Prescribing Nomogram or computerized Arc Length Calculator to determine the base curve and diameter of the contact lens. The Prescribing Nomogram uses the flat keratometry reading as a starting point to determine initial base curve and diameter. This nomogram is designed for average sized corneas with a horizontal visible iris diameter (HVID) of 11.6mm to 12.0mm. Click here to view tips on how to measure HVID.
My favorite method to designing custom toric contact lenses, which I believe is the easiest, is to utilize the SpecialEyes Arc Length Calculator. This tool incorporates not only the patient’s corneal curvature through the use of keratometry readings but also takes into consideration the patient’s corneal diameter or HVID in order to arrive at an appropriate base curve and diameter for your patient’s cornea. Incorporating the patient’s HVID into the custom soft toric contact lens design increases the probability of a successful fit on the first attempt. The calculator features a simple plug-and-play design. All you have to do is enter the patient’s HVID (or use 11.8mm as an average if the HVID value is not available), K readings, manifest refraction, and then click calculate. The software program will determine the exact base curve and diameter needed and the manifest refraction will be vertexed for you. If you desire a certain diameter for your patient, the SpecialEyes calculator provides an option to manually override and select a specific diameter. Upon specifying a certain diameter, the software will adjust the base curve to compensate for the diameter change. The preference to specify a certain diameter is a great option when fitting younger patients in a custom soft toric contact lens or fitting patients that have a need for a smaller lens based on physical features, such as a small fissure. And, as always, you can contact our consultants at 866-822-2020 and they will be more than happy to design a lens for you.
Joanna Chmiel, ABOC, NCLEC
Joanna Chmiel is an ABO and NCLE certified consultant at SpecialEyes. She brings with her 8 years of experience in the optical and contact lens industry.