Soft Torics Versus Spherical GPs for Correcting Astigmatism
Reader and Industry Forum
A New Way To Classify Scleral Contact Lenses
By Gregory W. DeNaeyer, OD, FAAO
Scleral lenses have become an important component of modern specialty contact lens practice, and the majority of labs now manufacture their own scleral lens designs. Traditionally, scleral-type GP lenses have been strictly classified by their diameter (Sindt, 2008; DeNaeyer, 2010). However, rather than attempting to differentiate between various lens designs on the basis of size alone, description by fitting characteristics provides more useful distinctions between various lens designs. With that said, there needs to be a consensus of terminology going forward when practitioners and researchers discuss, write about, lecture on, or study scleral lens fitting and design.
A New Classification System
The Scleral Lens Education Society (SLS) has developed a revised classification system that defines scleral lens types based on both size and fitting characteristics. This classification system (Table 1) was recently published in A Guide to Scleral Lens Fitting (van der Worp, 2010) and is detailed as follows.
Corneal Lenses (8.0mm to 12.5mm) rest entirely within the limbus and are supported completely by the cornea. Corneal contact lenses do not hold a tear reservoir.
Corneal-Scleral Lenses (12.5mm to 15.0mm) extend beyond the limbus and are supported by both corneal and scleral tissue. Corneal-scleral lenses hold a limited tear reservoir.
Scleral Lenses (15.0mm to 25.0mm) place all lens bearing on the sclera. Scleral lenses are further subdivided as follows:
• Mini-Scleral Lenses (15.0mm to 18.0mm) have a somewhat limited tear reservoir capacity.
• Full Scleral Lenses (18.0mm to 25.0mm) have an almost unlimited tear reservoir capacity.
A universally accepted terminology system is critical to accurately educate and research scleral lens fitting and design. CLS
To obtain references for this article, please visit http://www.clspectrum.com/references.asp and click on document #191.
Dr. DeNaeyer is the clinical director for Arena Eye Surgeons in Columbus, Ohio. His primary interests include specialty contact lenses. He is also a consultant to Visionary Optics. Contact him at email@example.com.
Contact Lens Spectrum, Issue: October 2011