Well-fit scleral lenses are innately comfortable. However, comfort is quite subjective. With scleral lens wear, no pain or frank discomfort is typically experienced. With an optimally fit scleral lens, lens sensitivity or discomfort is occasionally experienced. There are a variety of lens parameters to improve comfort during scleral lens wear. When fitting scleral lenses, pay attention to subjective complaints that will guide parameter changes to achieve comfortable scleral lens wear. Symptoms of lens discomfort immediately after lens application vary significantly from those after hours of scleral lens wear.
Upon application, lens awareness may occur. An application bubble, even a small one, can lead to heightened lens awareness during the fitting process. With time, symptoms increase, and irritation is experienced. The remedy is to review handling and correct application techniques. It is critical to immediately remove and reapply the lens without a bubble. A tip to avoid application bubbles is to overfill the lens until the fluid is convex when applying a lens. Bubbles may also occur if aerated solution is used to fill the scleral lens bowl. The remedy is to use non-aerated preservative free solution for lens application.
The most common reason for discomfort with scleral lenses is excessive edge lift or standoff during the initial fitting process. The area of discomfort is easily located with excessive edge lift. If in doubt, edge lift can be confirmed with the addition of fluorescein or anterior segment OCT. Reducing the edge lift with a steeper peripheral curve will improve the area of discomfort.
Alternatively, if the edge profile is too tight, scleral compression or impingement may occur. This will lead to discomfort with scleral lenses after hours of wear. Symptoms, typically after hours of wear, include eye ache, discomfort, tightness, tiredness, soreness or the sensation of a bruise. To alleviate scleral compression or impingement, increase the edge lift, flatten peripheries, or increase the overall diameter to create a larger landing zone to distribute the weight of the lens more evenly.
If limbal or corneal contact is present, irritation may occur after hours of wear, especially after lens removal due to epithelial erosions from lens adherence. In extreme cases, the patient may report a foreign body sensation and excessive tearing after lens removal. During lens fitting, verify adequate central and limbal clearance with sodium fluorescein or anterior segment OCT to ensure that there is no touch or bearing. Adjust the scleral lens fit accordingly. For central bearing, increase the overall sagittal depth or steepen the base curve to increase apical clearance. Based on lens design, to eliminate limbal bearing, increase the limbal zone depth, increase the overall sagittal depth of the lens, increase the optical zone and/or increase the overall lens diameter.
Another source of bubbles in the post lens fluid reservoir causing discomfort is misalignment of the scleral landing zone. For example, edge lift in one or more quadrants or a lens with excessive movement may allow bubbles to enter. Mobile peripheral bubbles in a fenestrated scleral lens are acceptable. Alternatively, in a fluid-ventilated (semi-sealed) scleral lens, bubbles may lead to discomfort, desiccation and potential dellen formation. Application bubbles differ from those due to scleral lens fit. If a bubble appears with time, the scleral landing zone alignment should be evaluated. The path of the bubble can be established by excessive fluorescein exchange. Add toric peripheral curves to improve scleral lens alignment.
Keep in mind that scleral lenses are innately comfortable. Listen to your patients to achieve optimal scleral lens comfort.
Dr. Melissa Barnett is a Principal Optometrist at the UC Davis Eye Center in Sacramento, specializing in anterior segment disease and specialty contact lenses. Dr. Barnett is the Past President of The Scleral Lens Education Society. She lectures and publishes extensively on topics including dry eye, anterior segment disease, contact lenses and creating a healthy balance between work and home life for women in optometry. Dr. Barnett along with Dr. Lynette Johns co-edited the book Contemporary Scleral Lenses: Theory and Application with the unique perspectives and contributions of international experts.