Effects of Scleral Landing Zone on Tear Exchange

Introduction: Scleral lenses are a form of contact the rests on the sclera of the eye completely vaulting the cornea. This form of correction is ideal for patients with severe ocular surface disease or irregular corneas because once inserted into the eye it becomes the new functional surface of the eye negating or significantly mitigating any anomalies behind that impact vision. This is achieved by the formation of a tear reservoir between the back surface of the contact lens and the front surface of the cornea. While the fitting of scleral lenses is a fantastic option to improve vision for patients with irregular corneas and ocular surface disease many will experience a phenomenon called tear exchange. Tear exchange is a process by which tears from outside the reservoir move under the lens bringing in debris which can reduce quality of vision by producing a “fog” over the patient’s vision. Methods: In this study we compared the Valley Custom Stable Elite scleral lens to an experimental Valley design called the Limbal Lite. The Limbal Lite features and enlarged scleral landing zone making a larger footprint in contact with the patient’s sclera. It is this larger footprint we hypothesize that will reduce the amount of tear exchange under the lens improving quality of vision. To test this both lens designs were fitted to participants using anterior segment OCT and slit lamp observation. The lenses were then allowed to settle for one hour. After settling time the lenses were again observed behind a slit land and anterior segment OCT to evaluate tear exchange. Conclusion: No conclusive data can be from this studying due to the limited sample size. The Limbal Lite lens did appear to be more effective at controlling for tear exchange when compared to the Custom Stable Elite but subjectively the patients felt the Custom Stable Elite was more comfortable.