Ensuring Positive (Scleral) Impressions

Scleral lens impingement is caused when the lens fits too tightly and the haptic or landing zone digs into the conjunctiva. Long-term impingement can cause conjunctival hypertrophy (impression ring) and lead to increased discomfort and lens awareness for the patient. Thus, it is important to address impingement during the fitting process. Here are some tips to relieve impingement that can be reported to our lens consultants:

• Inferior Impingement: Rule out if it is true impingement from the lens haptic being too tight vs. pseudo impingement from the lens haptic being too loose. When the latter happens, the pseudo impingement is due to the lens decentering and “falling” into the conjunctiva in the inferior quadrant. Perform a push-up test and evaluate the haptic alignment with the lens centered on the eye and re-assess the inferior haptic. If edge lift becomes apparent then the haptic needs to be tightened to better align the haptic and center the lens – this will get rid of the pseudo impingement. If during the push-up test the lens does not move because it’s too tight, then the haptic is too tight and needs to be loosened or flattened.
• If there is a circumferential impression ring, you can loosen/flatten the haptics in each meridian. However, if upon lens removal there is, in addition, significant rebound hyperemia, refit the patient by increasing the lens diameter by 1.0mm to move the landing of the lens outside of the impression ring. A larger lens provides a wider landing area to distribute the weight of the scleral lens more evenly and minimize compression.  

In some cases, even if the lens fit is optimized the patient may still report limited wear time due to a dull ache during wear, transient blurred vision on lens removal, or rebound redness after lens removal. Scleral lens suction should be ruled out. Increasing lens diameter, and adding two (2) SmartChannels_^® can be added on the horizontal meridian to reduce lens suction and improve your patient’s comfort and overall “impression” of scleral lenses.