Keratoconus

It is often perceived that you have to be a contact lens expert to fit keratoconus patients. Nothing could be further from the truth. Keratoconus fitting requires trial-and-error fitting, common sense and patience. The result can often be a very appreciative patient. The different fitting relationships are described below:

Fitting Philosophy - Description

Keratoconus Fitting Pearls

• Use a diagnostic fitting set. Contact your CLMA member laboratory about fitting set information. There are numerous designs, including Soper, McGuire, Rose K, ComfortKone and others.
   
• The most popular philosophy is to obtain three-point touch. Select a base curve radius equal to the steep "K" reading. Evaluate the fluorescein pattern via a cobalt blue in combination with a Wratten filter with the biomicroscope. (A Burton Lamp is also very beneficial in viewing keratoconic fluorescein patterns.) If apical clearance is present, flatten the base curve progressively until minimal apical touch is present. This resulting bulls-eye pattern should show apical bearing, paracentral clearance, mid-peripheral bearing and peripheral clearance.
   
• Good centration is imperative with these designs.
   
• The optical zone diameter should decrease as the condition progresses. One commonly used philosophy is to select an OZD equal to the base curve radius in millimeters. For example: BCR = 7.00mm; OZD = 7.00mm
   
• Multiple peripheral curves are usually necessary to correspond with the rapidly flattening mid-peripheral and peripheral cornea. The peripheral curve should be flatter and wider than conventional designs to minimize peripheral seal-off.
   
• Bitoric lenses are rarely indicated due to the irregular astigmatism of the cornea.
   
• One suggested fitting philosophy is presented below:

 
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