At the recent invigorating American Academy of Optometry meeting, scleral lenses continue to be a hot topic. There were multiple scleral lens workshops, lectures and discussions. In a few sideline discussions, the same topic kept coming up—scleral lens suction. In an excellent article by Carrasquillo and Byrnes in Contact Lens Spectrum, the authors defined cling, or suction, as the necessary force to pull a lens from the eye and how this may influence corneal epithelial edema.1 Since scleral lenses are semi-sealed to the surface of the eye, when fitting scleral lenses, lens suction should be avoided. If tear exchange is present, it is a good indicator that the lens adherence is not present. Even with an ideally fit scleral lens, tear exchange cannot be observed without mechanical manipulation. If a patient reports difficulty with lens removal or hyperemia after the lens removal, both may be a result of a tight lens or improper removal technique.
To confirm that the lens is not suctioned, resistance is tested by a practitioner by removing the lens in office. If the practitioner can easily remove the lens but the patient is experiencing difficulty, then further application and removal instruction may be needed. Likewise, if reactive hyperemia of the eye is not present after practitioner lens removal, re-instruction may be needed. If resistance is indeed present with removal, the lens landing zone may require loosening/flattening.
Keep in mind that some patients who have an optimal fit with adequate tear exchange may experience exacerbations of inflammation, chemosis and hyperemia due to their underlying ocular or systemic condition.2 Once the ocular or systemic condition quiets down, the lens fit may once again improve. If a lens has a tight fit or there is significant crowding at the limbal area, Carrasquillo and Byrnes recommend increasing the lens diameter, ensuring adequate limbal clearance, and adding channels under the scleral lens haptic.1 Channels are distinct tunnels that can be milled into the back surface of the scleral lens. Evaluating and excluding scleral lens suction should be assessed for every scleral lens fit, especially when corneal or limbal edema is present.
A sealed-off and suctioned lens with the limbal chemosis and hyperemia.
Image courtesy of Lynette Johns and Optometry Times (July 2016).
Carrasquillo, K, Byrnes S. Corneal Edema and Scleral Lenses. Contact Lens Spectrum. November 1, 2018.
Barnett M, Johns LK. Contemporary Scleral Lenses: Theory and Application. Bentham Science 2017. Volume 4 ISBN: 978-1-68108-567-8, 48-67.
Dr. Barnett is a principal optometrist at the University of California Davis Eye Center in Sacramento, specializing in anterior segment disease and specialty contact lenses. She is the past president of the Scleral Lens Education Society. She is an advisor to and/or has received honoraria or travel expenses from AccuLens, Alcon, Alden Optical, Allergan, Bausch + Lomb, Contamac, CooperVision, EveryDay Contacts, Johnson & Johnson Vision, Ocusoft, Paragon Bioteck, RaayonNova, ScienceBased Health, Shire, SynergEyes, and Visioneering Technologies.