Several times over the past 20 years, Dr. Nathan Efron has predicted the total demise of rigid gas-permeable (RGP) and gas-permeable (GP) contact lenses. Well, we have yet to see that occur. I would, however, like to predict the demise of corneal GP lenses.
On the basis of my, as of now, only marginal experience with scleral lenses approximately—44 fits since January 2011—I ask: As contact lens fitters, why do we need corneal GP lenses when we have experienced the rebirth of the scleral lens, in highly gas-permeable materials, generated by algorithms on computer-driven lathes? This question is even more pertinent when you consider that these new lenses are more comfortable, stable and harder to lose or break; they are simply a more elegant device than corneal lenses.
—Bezalel Schendowich, OD
Optometrist and contact lens
Sha’are Zedek Medical Center, Jerusalem, Israel
Dr. Efron Responds:
I appreciate Dr. Schendowich’s keen interest in my writings on the future of rigid contact lenses. However, I must make one important correction to his opening statement: Many years ago, I predicted the virtual (not total) demise of rigid lenses. The essence of my prediction was that, by the year 2010, rigid lenses would cease to be a mainstream form of contact lens correction and would essentially only be prescribed for specialty fittings (i.e., keratoconus, post-trauma, etc.). Now, international rigid lens prescribing data has shown this prediction to be correct: New rigid lens fits represent less than 5% of all contact lenses prescribed in 40 nations surveyed over the past five years.1 In the light of this overwhelming evidence, I have even published an obituary for rigid lenses!2
Dr. Schendowich refers to the “rebirth” of scleral lenses and suggests that this may reinvigorate rigid lens fitting. The statistics tell another story. The prescribing data referred to above shows that these new scleral lenses represent 0.05% of all rigid lenses prescribed—hardly a ringing endorsement for this lens type.2
Dr. Schendowich mentioned comfort when describing the success of this new generation of scleral lenses. However, comfort is a relative sensation. It might be true that comfort with these lenses is greater than with conventional corneal GP lenses. This is because scleral lenses are large and stable on the eye, whereas GP lenses move with blinking and buffet against the lid margins—the main source of discomfort. But what is also important is that rigid lenses of any form, including scleral lenses, are far less comfortable than soft lenses; this largely accounts for the dominance of soft lenses in the marketplace. The other benefits of new-generation scleral lenses mentioned are unlikely to offset the discomfort factor when it boils down to patient choice.
Instead, perhaps there is a psychosocial reason for Dr. Schendowich’s recent success with scleral lens fitting. The median age of contact lens wearers in Israel, where Dr. Schendowich works, is 27 ±9 years, which means that most contact lens wearers are engaged in, or have recently completed, compulsory military service. Are these tough, young Israeli patients really going to complain to Dr. Schendowich about discomfort caused by a little piece of plastic in their eyes?
—Nathan Efron, PhD, DSc
Institute of Health and Biomedical Innovation and School of Optometry and Vision Science, Queensland University of Technology, Australia.
1. Efron N, Morgan PB, Woods CA, The International Contact Lens Prescribing Survey Consortium. International survey of rigid contact lens prescribing. Optom Vis Sci. 2012 Feb;89(2):122-9.
2. Efron N. Obituary—Rigid contact lenses. Contact Lens Ant Eye. 2010 Oct;33(5):245-52.