Products / Onefit

Optimum Benefits from a Minimalist Approach

 

Attributes

Blanchard Contact Lenses has pioneered the minimalist approach to scleral lens design and fitting with the Onefit™ Scleral Lens Platform – delivering optimal oxygenation for long-term corneal health with minimal lens mass and tear lens thickness.

Hydrating comfort, crisp, clear visual acuity and superior lens stability make Onefit™ ideal for active individuals and dissatisfied soft toric lens wearers.  The Onefit Scleral Lens is unique and specifically designed for corneas with a normal prolate profile, with or without astigmatism, post graft corneas, as well as irregular corneas including nipple, oval, or fruste keratoconus cases. In addition, we have the Asian design of Onefit, Onefit A, which precisely addresses the physiological nuances of the Asian eye and Onefit Sym-Toric, which is an advanced front toric design for astigmatic patients.

The Onefit Scleral Lens Platform, with a standard diameter of just 14.9mm, and the Onefit A lens with a standard diameter of 14.7mm, simplify the fitting process for a wide range of applications, and minimize both lens thickness and tear layer required to support the lens, while maximizing oxygen transmission to the cornea and stems cells. Onefit lenses are designed to vault a given topography with an optimal sag height, and is specified by the value of the base curve in millimeters of radius curvature; streamlining the fitting process and making it more user-friendly.

With a trial set composed of only 14 lenses, practitioners can fit:

  • Normal prolate corneas
  • Astigmatism (Onefit Sym-Toric)
  • Irregular corneas
  • Multifocal
  • Oblate corneas (including oblate multifocal and toric optics)

All Onefit lenses are also available in an oblate design with three Central Clearance Reduction options to satisfy the needs of your post-refractive surgery patients.  Multifocal optics that deliver superior visual performance for today’s presbyopes are available in both the prolate and oblate design.  An Extra Limbal Clearance design option is also available for the Onefit Scleral Lens Platform (not available with Onefit A, as the design already incorporates the Extra Limbal Clearance option.)

The Onefit A design, for the Asian eye – embraces our same minimalist approach to fitting scleral lenses, while addressing the physiological specificities of Asian eyes.  Onefit A lenses need to be ordered from the Onefit A fitting set. With a smaller standard diameter and different paracentral edge geometry, a different fitting set is required to reflect with precision those distinctions.

Onefit Sym-Toric is an advanced front toric design option within the Onefit platform.  It was designed to enhance patient comfort, consistency of vision performance, and to greatly simplify the practitioner fitting experience for scleral Astigmatic patients.  Sym-Toric utilizes the existing Onefit Scleral Lens Platform diagnostic lens set.  (No additional diagnostic fitting set is required).

Onefit Sym-Toric does not rely on the prism ballast or toricity in the haptic, as is typically used to stabilize itself on the ocular surface.  While keeping the same edge elevation 360 degrees, the Onefit Sym-Toric posterior surface matches the different radii values of the cornea (similar to a corneal posterior toric lens). The lens is stable and comfortable and does not deprive the cornea of any oxygen due to excessive thickness.

Benefits provided by ALL Onefit lenses include superior comfort, stability of fit, vision that remains consistent throughout the wearing time, reduced glare and starbursts and reduced dryness.  These attributes make it an ideal lens for athletes and active wearers, unhappy soft and soft toric lens wearers and intolerant corneal GP wearers.  Onefit offers the crisp vision of a GP while providing the comfort of a soft lens.

Fitting Philosophy

Onefit is supported by the conjunctiva and the fluid layer under the lens, rather than by the cornea. It is designed to vault the entire corneal surface including the limbal area. The clearance over the cornea varies from the center to the periphery to optimize oxygen transmission to the tissue, especially over the limbus where the stem cells are located. Current published work indicates that fluid layer thickness is an important concern with scleral lenses. With an estimated DK value of 80, an excessively thick fluid layer under the lens can deprive the cornea and stem cells of sufficient oxygenation.

Keeping the Harvitt-Bonanno and Holden-Mertz criteria in mind, Onefit has been designed to maximize oxygen transmission when combining the lens and tear layer thickness. For this reason the tear lens is thinner over the limbus compared to other designs. Its unique geometry reduces the thickness of the tear layer from the center out to the limbal area.  Optimum results in fit and corneal health are achieved by minimizing lens thickness (between 200-250 microns) combined  with clearance of 150 to 175 microns at the apex of the cornea, or in the area where the cornea is steepest ( e.g. host-graft corneal junction ) with optimal limbal clearance at 40 microns. The lens peripheral edge should align with the conjunctiva. Onefit is manufactured in materials offering a minimum permeability of 100 DK.

Each 0.10 mm change in the base curve value results in an average change in the central clearance of 50 microns. For example, if the base curve is steepened by 0.10 mm the apical clearance will increase by 50 microns. On the other hand, if the base curve is flattened by 0.10 mm the apical clearance will be reduced by 50 microns.  This is accurate for the majority of patients but note that the results can vary slightly due to an individual’s scleral shape.