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Steps to take before fitting

  • Full refraction and eye examination

  • Keratometry

  • Select diameter required 2-3mm larger than HVID

  • Select Base Curve according to corneal curvature, but with a flattening differential relative to the diameter of the lens shown below:

Lens Diameter





14.50mm & 15.00

Order Base Curve Flatter Than Flattest K By:

0.30mm - 0.40mm

0.40mm - 0.60mm

0.60mm - 0.80mm

0.80mm - 1.00mm

1.00mm - 1.20mm

Good Fit

  • Comfortable

  • Good centration with full coverage of limbus, even in upward gaze

  • Adequate smooth movement in all directions of gaze

  • Good recovery on push-up test

  • Carry out over-refraction and order exchange lens if required

Flat Fit

  • May give poor centration

  • May give unstable vision

  • Can cause discomfort

  • Try steeper base curve (If available)

  • Over-refraction

Steep Fit

  • Displays inadequate or no movement

  • Resists push up test with lower lid

  • Can cause blanching

  • Try flatter base curve (If available)

  • Over-refraction


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