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:
12.50mm
13.00mm
13.50mm
14.00mm
14.50mm & 15.00
0.30mm – 0.40mm
0.40mm – 0.60mm
0.60mm – 0.80mm
0.80mm – 1.00mm
1.00mm – 1.20mm
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 – Nasal position
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 – Nasal position
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 – Nasal position
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Cantor Barnard Ltd | Market Place | Brackley | Northants | NN13 7NN | UK
Below are types of lenses offered by Cantor Barnard and the clinical indications in which they can be used for: