A look back at ophthalmic history
The video above demonstrates how scleral lens was fabricated for use some 70 years ago. As a standard this was the only way how scleral lenses could be appropriately designed
and fitted satisfactorily in practice at the time.
Before modern imaging and digital workflows, ocular impressions were taken with casts created in dental stone and with lenses being designed by hand from the haptic outward.
While the tools have evolved, the objective remains the same: ocular surface protection and visual rehabilitation.
A timely reminder of both the ingenuity of earlier clinicians and how far our field has progressed.
Dental stone plays a critical role in the physical casting and fabrication of impression-based custom scleral lenses. While modern optometry heavily utilises digital 3D corneal topographers, specialised impression-based techniques still rely on this material to create an exact structural match for highly irregular eyes. [1, 2, 3, 4, 5]
The Fabrication Process
When standard diagnostic trial lenses cannot properly fit a severely deformed or traumatised eye, a direct physical mould is required.
- Ocular Impression: The practitioner applies an ophthalmic-grade polymer material (such as polyvinyl siloxane) to the anesthetised eye using a specialised plastic tray to capture a negative mould.
- Positive Cast: Once removed, this soft negative mould is filled with a mixture of dental stone and water.
- Hardening: The dental stone cures into a highly dense, precise, and rigid physical replica (a positive biomodel) of the patient's anterior ocular surface.
- Lens Molding: Lab technicians use this hard dental stone model to compute, reverse-engineer, or heat-mold the final rigid gas-permeable scleral lens, ensuring an exact bespoke fit over the sclera.
Historical vs. Modern Context
Historically: Nearly all early scleral lenses from 70+ years ago relied entirely on taking physical eye impressions and casting them in dental plaster or stone.
Today: This physical technique is primarily reserved for specialised, ultra-custom prosthetic lens systems, such as the EyePrint PRO, which captures the exact micro-contours of the eye. Most general scleral lens fittings now use standard diagnostic trial sets combined with high-tech computerised optical scans.