By Martin Conway FBDO, FIACLE, FBCLA – Guest Columnist
Scleral lenses have been utilized for many years by a small group of specialist fitters around the world working with their local laboratories. Because of the specialist nature of the work, labs and practitioners developed their own techniques for designing scleral lenses without the cross-pollination of ideas that has occurred following the explosion of interest in the subject over the past five years or so.
I recall one of those practitioners who was attending the Global Specialty Lens Symposium (GSLS) in 2013. He was, and still is, a very experienced scleral lens practitioner with thousands of successful patients under his belt. The hot topic at the GSLS was scleral lenses and, in particular, the phenomenon of fogging which appeared to plague around 30% of fits. He called home to his lab in Switzerland from the meeting in Las Vegas and asked “What’s this fogging they are all talking about?” It was something that neither he, nor his colleagues had experienced.
I was working with Pat Caroline at the time and we decided to investigate. Pat selected several patients who suffered from the fogging phenomenon and refitted them using the Swiss design.
RE Post 8 hours Swiss Design
RE Post 8 hours Current Design
There was clearly a difference. It was demonstrated in both eyes and also in other patients. If you look at the edges of the lenses, you can perhaps see where the two fitting philosophies differ significantly.
Current Design 8 hours
Swiss Design 8 hours
The philosophy in the U.S. was to avoid the limbus at all costs, whereas the European design was fit in close alignment with the limbus and some light touch was acceptable. This is a demonstration of how scleral fitting philosophies had developed differently over the years on a regional basis.
Many Northern European practitioners are not used to using diagnostic lenses, they prefer to design their own GP lenses, whether they are corneal, ortho-k or, as in this case, scleral. They may use a diagnostic lens, but will modify the fitting to their own requirements. In the U.K. and North America, practitioners tend to fit using designs specified by laboratories and will then modify the fit in collaboration with the laboratory consultants.
This approach to fitting highlights how different approaches evolved separately around the world. Current thinking in scleral fitting is evolving at a remarkable pace and that knowledge is being disseminated globally. Our understanding of scleral shape and the behavior of the lens on eye over time is improving. The scleral lens modality is being adopted in mainstream practices as well as specialist and hospital based practices.
Toric peripheries to provide better alignment are now routinely utilized to align with the true shape of the sclera. This information is being shared in meetings around the world and through electronic media each day.
This globalization of information means that scleral lens fitting techniques are changing rapidly, and ideas are evolving and being propagated at a rate that has never occurred with any other lens modality that I can recall. Interest in GP fitting, whose demise had been forecasted for many years, is seeing a resurgence. New material technologies, such as surface treatments, are also improving comfort levels for patients in the speciality lens sector.
Dr. Melissa Barnett is a Principal Optometrist at the UC Davis Eye Center in Sacramento, specializing in anterior segment disease and specialty contact lenses. Dr. Barnett is the Immediate Past President of The Scleral Lens Education Society. She lectures and publishes extensively on topics including dry eye, anterior segment disease, contact lenses and creating a healthy balance between work and home life for women in optometry.