Empirical OrthoK systems

Empirical lens fitting is controlled entirely by the lab which makes it analogous to the ‘auto’ or ‘P’ button that has become common on digital cameras. In other words, a good outcome will be achieved most of the time, but like the auto camera setting, it will do a bad job if you fall outside of its normal range of use. E.g, a smartphone will still take a photo at night without using flash but will result in a dark image lacking any detail.

Empirical OrthoK fitting requires you to send the patient's spectacle refraction and corneal topography to the lab, and they in return will send you the final fit lens to issue to the patient. To troubleshoot at follow up visits you again send refraction measurement and topography maps to the lab, and they will advise the steps to take while supplying new lenses if required.

This makes an empirical design a great way to start out in OrthoK because you don’t need to fork out for a trial or inventory set and you gain access to the lab's extensive experience in fitting the lens that they have gained through helping other customers. You can also gradually take over more control as you gain experience. However, although it is tempting to think you can stop here and let the lab do everything, you still need to sound credible to your patients, and besides, you are a professional not just a remote technician to a lab! If you are going to be using an empirical based system still take the time to learn how the lenses are working as you still need to interact with your patient to explain the process even if you are not doing the bulk of the technical work.

Advantages
  • Reduced start-up cost as no fitting lenses like those needed for trial or inventory systems are required
  • No prior experience of rigid lens fitting required
  • Good refractive outcome if lens fits well
Disadvantages
  • Delay in getting first lens on eye
  • Delay in receiving next lens if change needed
  • Reduced practitioner control – all aspects of lens fitting are handled by the lab
Examples
  • Emerald (Euclid, USA)
  • Forge (Innovative Contact Lenses, Australia)
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About Paul

Dr Paul Gifford is a co-founder of Eyefit, an information resource to assist contact lens practitioners in all modes of practice. Learn more about him here.

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