Gas Permeable Keratoconus Lens From NOVA
|Step One: Start the trial fitting 0.2 steeper than the average of the K readings. |
Step Two: If this is a new rigid lens wearer, it may be advisable to use an anesthetic. this quickens the fitting process and allows a more accurate assessment of the fluorescein pattern because of reduced tearing.
Step Three: Too much fluorescein will give false patterns - so be careful when instilling it.
|Step Four: Trial fit for the base curve - but don't worry about the periphery at first. A light feathery touch at the apex of the cone is best. The rest of the pattern should look as close to alignment fir as possible. |
Step Five: Next consider the peripheral fit. the trial lenses have a standard edge lift, but an increased or decreased edge lift on the same base curve can be ordered. If the central base curvelooks good but you have inadequate peripheral adge lift ( see inadeguate lift fig. ) then order increased edge lift. Conversely, order decreased lift if their is excessive peripheral lift ( see excessive lift figure )
Step Six: The standard diameter is 8.70mm but any diametert is available. Smaller diameters of 8.10 - 8.30 work well on steep corneas and on highly astigmatic corneas. A larger diameter will tend to make the lens ride higher.
Note: Cone lenses often have an inferior ride over the apex of the cone.
Step Seven: Do a careful over - refraction using 1.00D steps initially and then refine.
|Further Detailed discussion of the Rose K lens by Mr Paul Rose - the designer |
For More details contact:
NOVA CONTACT LENSES
Unit 11 Avebury Court, Mark Road
Hemel Hempstead, Herts HP2 7TA
Tel:- 44 (0)1442-253456
Fax:- 44 (0)1442-253301
Author: John Dreyer Optometrist Bsc(Hons), MCOPTOM, DipCLP
Created: 28 Apr 2015, Last modified: 18 Apr 2019