Summary of the July 1999 Session "Keratoconus," with Loretta Szczotka, OD, FAAO

Please note that the ideas presented during the chat are those of the participating eyecare professionals. They do not necessarily represent the views of the moderator or guest expert, and are not endorsed by the GP Lens Institute.

• Dr. Szczotka presented a case from her practice: a monocular keratoconic who came in for a second opinion. Was the fellow eye becoming keratoconic? His ophthalmologist thought so. Her conclusion was that the eye was not keratoconic, the diagnosis was a result of having a topographer available. Why? No slit lamp signs, no change in acuity, and age 43. The original ophthalmologist made the diagnosis based on topography showing an inferiorly decentered corneal apex. Her opinion was that the apex has been inferior all along, but the advent of the topographer led to this diagnosis.
   
• Lens recommendation was GPs. The previous intolerance could have been due to the flat fitting relationship preferred for keratoconus in the 1970s.
   
• Keratoconus can develop in the late 20s and even early 30s, it is not just a disease of teens.
   
• A "feather" touch is preferred now for keratoconus fits to achieve maximum visual acuity, but any more than a light touch may lead to intolerance and scarring.
   
• Dr. Szczotka uses topography to determine base curve, then designs a tricurve lens for keratoconics. It is similar to the design used in the CLEK study. The overall diameter is 8.5 with an OZ of 6.5 mm.
   
• If the base curve is steeper than 7 mm you need to specify a heavy blend.
   
• Dr. Maller prefers smaller diameters for nipple kones.
   
• Sagging cones are the most frustrating to fit you need a large optical zone to vault it.
   
• Debris under the GP may be a problem with piggyback fits, one trick that helps is to specify a steeper peripheral curve (to dovetail into the grove of the SCL).