Prescribing for Astigmatism

Toric Soft Lens Pearls From Students

BY PAM SATJAWATCHARAPHONG, OD, & TIMOTHY B. EDRINGTON, OD, MS, FAAO

As educators, we annually have the pleasure of participating as mentors in a toric soft contact lens workshop. This workshop provides third-year optometry students with the opportunity to interact with volunteer patients who are candidates for toric soft contact lenses. In addition to working on patient management skills, the students are able to trial fit a number of different soft toric lenses that are currently on the market. At the conclusion of the workshop, the students reconvene to share clinical pearls that they learned from the activity.

Because it is never too late to take a trip back to school, we would like to share a few of those pearls.

Set Yourself up for Success

Imagine that a patient sits in your examination chair and tells you that he is ready to try contact lenses. During your slit lamp examination, you observe that the patient has significant meibomian gland dysfunction and a tear breakup time of five seconds. Upon further questioning, the patient reveals that he has symptoms of dry eye.

With this new information, it would be wise to pause before proceeding with the contact lens fitting and to remember to treat the patient as a whole. Managing secondary conditions such as dry eye syndrome and allergic conjunctivitis will improve patients’ chances for successful lens wear.

Settle Down

After placing a pair of your chosen toric lenses on your patient’s eyes, you find that the visual acuity is poorer than expected. Recall that rushing to assess the performance of the lenses may yield varied results. Whether working with a double-thin-zone or prism-ballasted design, allowing the toric lenses to settle into their proper orientation will help you avoid the confusion of fluctuating or decreased visual acuities.

Stay Centered

Now that your toric lenses have settled, you are ready to check the fit. Your eyes immediately begin searching for that sometimes elusive lens marking that indicates whether the lens is rotated or not. It can also help you determine rotational stability.

However, before you draw a conclusion about the rotation of a lens, first assess the centration. A decentered lens may appear rotated when it actually is not.

The End is in Sight

With an acceptable fit, you feel ready to move on. However, even if your patient is seeing 20/20 or 20/15, it behooves you to perform an over-refraction to ensure that you have not over-minused your patient. Consider the age of your patient when deciding on the final power to prescribe. A quarter diopter of extra minus for young myopes may not be problematic, and may perhaps even be helpful during night driving. However, a quarter to one-half diopter of additional minus for patients who are nearing presbyopia may make their near tasks more challenging. For patients not achieving the desired visual acuity, perform a spherocylindrical over-refraction to determine whether a change in cylinder power or axis is needed. CLS