Contact lens

Fitting guide

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

12.50mm
13.00mm
13.50mm
14.00mm
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

Good fit primary position
Good fit – Primary position
Good fit nasal position

Good fit – Nasal position

Flat fit

  • May give poor centration

  • May give unstable vision

  • Can cause discomfort

  • Try steeper base curve (If available)

  • Over-refraction

Flat fit primary position

Flat fit – Primary position

Flat fit nasal position

Flat fit – Nasal position

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

Steep fit primary position

Steep fit – Primary position

Steep fit nasal position

Steep fit – Nasal position

Eye conditions

Suitable lenses

Below are types of lenses offered by Cantor Barnard and the clinical indications in which they can be used for:

Sterile soft contact lenses

  • Myopia
  • Hyperopia
  • Astigmatism
  • Presbyopia
  • Symptoms that can co-occur with Academic Skills Disorders
  • Symptoms that can co-occur with Colour Deficiency
  • Masking of Cosmetic Defects of the Eye

Rigid gas permeable lenses

  • Myopia
  • Hyperopia
  • Astigmatism
  • Presbyopia
  • Keratoconus