Take five: Contact lenses

September 21, 2021
New contact lens developments regarding keratoconus from a distinguished practitioner.
Contact lens developments regarding keratoconus

Excerpted from page 56 of the September/October 2021 edition of AOA Focus.

Clark Chang, O.D., cornea specialty contact lens director at the Wills Eye Hospital in Philadelphia, Pennsylvania, recently received the AOA Contact Lens & Cornea Section’s (CLCS’s) Luminary Award for Distinguished Practice. Dr. Chang focuses on specialty contact lenses for optical rehabilitation in patients with conditions ranging from keratoconus and ectasia to post-ocular trauma.

1. How does working in the cornea service at Wills Eye Hospital differ from working in another practice setting?

Patients are often referred to our cornea service as their last line of hope for new or viable treatment recommendations. This compels us to continue clinical research and/or become early adaptors of approved surgical or contact lens innovations. Often, we need to combine both surgical and contact lens treatments to best help our cornea patients. Because patients will return to the referral optometrist for specialty lenses and ongoing monitoring, I am also fortunate to help my optometric colleagues in guiding the co-management expectations prior to patient referrals.

2. Being nominated for “Top Keratoconus Doctor” in 2020, can you describe anything new in this field?

Corneal cross-linking (CXL) has revolutionized keratoconus management, and I am proud to have been involved in the clinical trials that led to epithelium-off CXL approval by the Food and Drug Administration (FDA) in 2016. The removal of epithelium can maximize CXL efficacy by reducing epithelial impedance of riboflavin, UVA and oxygen. The next step in the U.S. is to improve epi-on CXL efficacy, and current research by Glakuos indicates that supplemental oxygen may be key. Having another FDA-approved CXL treatment will be very exciting.

3. What are you most looking forward to in the contact lens field, either development-wise or research-wise?

The recent ability to customize keratoconus lens design via ocular surface moldings or scleral profilometry has largely improved patient fitting success. I also am currently testing an aberrometer that measures residual higher-order aberrations through scleral lenses on eyes to guide lens manufacturing in further reducing residual astigmatism and other aberrations. It holds great promise, and I hope to help streamline its clinical algorithm in the future.

4. How can we better explain the benefits of contact lens wear to our patients?

I believe the clinical benefits of contact lenses can be maximized when patients understand that these are Class II or Class III medical devices, as recognized by the FDA. As such, there are risks and benefits associated with usage, and patient compliance to instructions given by eye care professionals will help to best support desired clinical benefits.

5. If a doctor/practice is looking at expanding to include specialty contact lenses, where should they begin?

Different patient populations will need different specialty lens designs. Prior to adding a specialty lens service, it’s important to know the targeted patient population you wish to attract, i.e., myopia control, keratoconus, etc. Because each lens design may require different fitting approaches, I’d recommend focusing on serving one patient subgroup at a time. Once your patient population is known, it will be much easier to learn the clinical tools that you need to acquire in clinic.


The AOA CLCS provides timely clinical education, representation with state and national government agencies, and serves as a recognized and trusted voice to the public. Become a member to access a monthly newsletter for the latest information on contact lens and refractive surgery technologies, as well as clinical and practice management strategies for you and your patients.

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