I have two research passions: scleral lenses and myopia management. Is it possible to combine the two? Let’s see...
The idea of using scleral lenses for myopia management is not new (Fadel, 2017). Indeed, it has been proposed to use scleral or corneoscleral technology to generate an orthokeratology (ortho-k) effect (Cotie and Herzberg, 2012). Theoretically, however, it is difficult to conceive how this could work without molding the cornea with the lens itself (mechanical effect). Modern ortho-k lenses change the corneal profile by using the hydraulic pressure of tears (Mountford et al, 2004). It may be difficult to conceive of achieving the same end with a much larger reservoir—while vaulting the cornea—with a scleral lens. A corneo-scleral lens may work better if already fit with a corneal touch. However, the use of the mechanical effect would likely increase the risk of corneal erosion and significant adverse effects (Cho and Mountford, 2007).
Scleral Lens Advantages
While a scleral ortho-k lens may not be feasible from a practical standpoint, scleral lenses have several advantages over ortho-k lenses. The first is that they are very stable, which is essential in the management of myopia (Frogozo, 2021). The second advantage is their comfort versus smaller GP lenses.
Third, it is possible to generate optics in a scleral lens that are similar to those with ortho-k (Peguda et al, 2020) while maintaining the fitting standards of a scleral lens and protecting the cornea. Modern manufacturing techniques make it possible to generate optical profiles on the surface of a scleral lens that would be compatible with effective myopia management with ortho-k and that could be similar to those of soft lenses, either with multifocal optics or extended depth of focus.
Another advantage of scleral lenses lies in the ability of the fluid reservoir to compensate for high corneal astigmatism while maintaining a spherical lens design.
Scleral Lens Disadvantages
While a scleral ortho-k lens may have some tempting advantages, what disadvantages would be related to its use? The first element to consider is the time required for scleral lens adaptation in a pediatric population. This process is already complex in adults and would need to be further refined for children.
It is known that Asian eyes have a different corneal profile and diameter compared to Caucasian eyes (Matsuda et al, 1992). Very few manufacturers currently offer a scleral design that is specific to the Asian population.
Smaller-diameter lenses may be needed to facilitate their handling. This is likely the most important point to consider. It is already difficult to teach young patients how to handle GP or soft lenses; the use of scleral/corneoscleral lenses would likely generate a wave of burnout among staff in our clinics.
A final consideration is the cost. Scleral lenses are expensive, and with the refractive changes that can occur at any time in children, even under effective management of their myopia, the lenses would probably need to be replaced for children more often than for adults. For myopia management to become a standard of practice, it must be affordable and accessible to all patients, not just to the wealthy.
For all of these reasons, I believe that the scleral/corneoscleral ortho-k lens is a false good idea. I will have to resign myself to pursuing my two passions separately. CLS
For references, please visit www.clspectrum.com/references and click on document #314.