Onefit MED

From - £93.64

An intuitive scleral lens that provides you with control to customise the ideal lens for highly irregular and medically indicated cornea or even normal corneas when a larger diameter is needed.

Specs

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When to use

For patients who suffer with:

  • Irregular Corneas
  • Ectactic Corneas (moderate to severe)
  • Nipple & Oval Cones
  • Post-RK, Post-LASIK
  • Pellucid Marginal Degeneration
  • Ocular Surface Disease
  • Astigmatism
  • Presbyopia
  • Normal Prolate Corneas
  • Pingueculas or other growths, shunts or scleral elevation – utilising Controlled Peripheral Recess
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Parameters

Diameter – Sag Height:

15.6 mm standard – 3800 to 6200 in 50 micron steps
16.0 mm – 3800 to 6600 in 50 micron steps
16.4 mm – 4000 to 6600 in 50 micron steps

Mid-Peripheral Value (M)+200 to -200 in 25 micron steps
Limbal Value (L)+200 to -200 in 25 micron steps
Edge (E)+250 to -250 in 25 micron steps

 

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Fitting Guide

Fitting philosophy
  • Onefit MED is supported by the conjunctiva and the fluid under the lens. It is designed to vault the entire corneal surface including the limbal area
  • The clearance over the cornea varies from centre to periphery to optimise oxygen transmission to the tissues, especially over the limbus where the stem cells are located
Initial fitting lens selection

Select initial diagnostic lens based on corneal profile:

  • Flatter (normal or refractive surgery) – 4000 sag
  • Average (moderate cones or irregularities) – 4600-4800 sag
  • Steep (highly irregular, steep cone, tilted or proud graft/host junction) – 5000 sag
Ideal clearance after four plus hours of wear
  • Central, or point of highest elevation: 150 to 175 microns
  • Mid-Peripheral: 100 to 125 microns
  • Limbal: 50 to 75 microns
  • Edge: aligned to the conjunctiva
Diameter
  • The standard 15.6 mm diameter will fit the vast majority of corneas
  • Rarely will the larger diameters (16.0 mm and 16.4 mm) be used, unless you encounter a severely protruded graft, severe keratoconus or an unusually large cornea
Central (Sag Value)
  • Use a slit lamp (no more than a 40° angle) or anterior segment OCT to evaluate the corneal/lens relationship
  • After the lens has settled for 30 minutes, look for clearance of 200 to 225 microns at the point of highest corneal elevation
  • After 4 plus hours of wear, clearance should be 150 to 175 microns at highest elevation
Mid-peripheral (m) and limbal (l) clearance
  • Mid-peripheral and Limbal zones are etched on Dx lenses with solid lines
  • The M and L values can be adjusted independently of each other
  • Sag height will be adjusted automatically if M, L or E (edge) values are changed
Edge (E) valueModifications of the edge lift is specified in microns of change. The range is from -250 microns (decreased clearance) to +250 microns (increased clearance) in 25 micron steps

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