Spherical GP Fitting and Problem-Solving
The fitting of GP lenses is actually quite straightforward. This process begins with presenting the benefits of GPs and then presenting GPs in a realistic, but non-threatening manner. Avoid terms such as “discomfort,” “pain,” and “hurt.” GPs can be presented in the following way: “You will experience some initial lens awareness due to the lid sensing the lens movement on the eye. This will go away over time.” The use of a topical anesthetic during the fit will help the patient ease into the adaptation process.
- Present GPs in a non-threatening manner
- Use topical anesthetic
- Use diagnostic lenses (contact CLMA member laboratory for assistance if necessary)
- Apply fluorescein to evaluate the fitting relationship
- Use yellow filter over observation system of slit lamp to enhance fluorescein pattern
Fluorescein Pattern Evaluation
|Strive for an alignment (“even”) fluorescein pattern. This is not necessarily equal to an “On K” base curve selection due to the asphericity of the cornea. Photo shows an Alignment Pattern.
|An apical clearance fluorescein pattern reflects a steep fitting relationship. Photo shows a Steep Pattern. This can cause peripheral sealoff, resulting in poor tear exchange and possibly adherence. Select a flatter base curve radius to improve the fitting relationship.
|In addition, excessive clearance in any region can result in trapped bubbles between the lens and the cornea or “dimple veiling.” Photo shows Dimple Veil.
|An apical bearing fluorescein pattern reflects a flat fitting relationship. Photo shows a Flat Pattern. This relationship can ultimately result in corneal distortion in the region of bearing. This can be easily managed via selecting a steeper base curve radius.
Fitting Tip Checklist
Any design changes made to affect the GP fitting relationship should be significant in nature, such as listed on the checklist.
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