Products / Onefit

The versatile and dynamic solution for both healthy and mild to moderately irregular corneas.

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Attributes

Blanchard 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.

All Onefit designs offer superior comfort, stability of fit, consistent vision, reduced glare and starbursts, and relief from dry eye symptoms. Onefit is ideal for active individuals and dissatisfied soft toric lens wearers. They are designed for corneas with a normal prolate profile, with or without astigmatism, post graft and irregular corneas including nipple, oval, or fruste keratoconus cases.

Onefit (14.9mm standard), and Onefit SC (14.7mm standard) – previously known as the Onefit A lens – simplify fitting for a wide range of applications. They are designed to vault a given topography with an optimal sag height, and are specified by the value of the base curve in millimeters of radius curvature; streamlining the fitting process and making it more user-friendly.

Onefit SC was developed for smaller corneas that have less flattening towards the periphery. These lenses are easier to handle for smaller palpebral fissures. With a smaller standard diameter and different paracentral edge geometry, a dedicated Onefit SC fitting set is required to reflect those distinctions with precision.

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)
  • Any offending scleral elevation – utilizing Controlled Peripheral Recess (CPR)*

*Controlled Peripheral Recess, or “CPR” technology, is a manufacturing process that creates a precise, controlled and reproducible peripheral recess to accommodate any scleral elevations that may contribute to lens discomfort and/or poor lens centration. CPR technology is available for Spherical, Oblate, Multifocal, Sym-Toric, Toric Haptic, and Quadrant Specific specifications.

The user-friendly CPR Tool gives you total control of CPR placement and size, simplifies the design and ordering process, and provides a visual representation of the lens design. Connect directly to the CPR Tool, along with other innovative fitting tools, at http://prod.blcalculator.com/tools/.  Learn more by watching this informational video on CPR: https://vimeo.com/293963567

Onefit lenses are available in an oblate design with five Central Clearance Reduction (CCR) options to satisfy the needs of your post-refractive surgery patients.

Multifocal optics, delivering superior visual performance for today’s presbyopes, are available in both the prolate and oblate design.

 

 

 

 

 

 

 

 

Toric Haptics are available and are the preferred stabilization method for Onefit and Onefit SC. However, with smaller lenses sometimes toric haptics are not always sufficient. To that end, we developed Sym-Toric – an advanced front toric design option that requires no additional diagnostic fitting sets.  Sym-Toric enhances patient comfort, consistency of vision performance, and greatly simplifies the practitioner fitting experience for scleral astigmatic patients. This design option relies on corneal shape rather than scleral asymmetry to stabilize itself on the ocular surface.

Extra Limbal Clearance (XLC) is also available for Onefit lenses, but is not available with Onefit SC, as the design already incorporates XLC.

Fitting Philosophy

Onefit is supported by the conjunctiva and the fluid layer under the lens, rather than by the cornea and 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. Harvitt-Bonanno and Holden-Mertz published criteria for scleral lens fitting indicates that fluid layer thickness is extremely important 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.

That is why all Onefit lenses were designed with the Harvitt-Bonanno and Holden-Mertz criteria in mind – to maximize oxygen transmission when combining the lens and tear layer thickness. With the Onefit family of scleral lenses, the tear lens is thinner over the limbus compared to other designs and the lenses are manufactured only in materials offering a minimum permeability of 100 DK. Onefit’s unique geometry reduces the thickness of the tear layer from the center out to the limbal area.  Optimal 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.

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.