A 40-year-old female presented wearing scleral lenses. She has been “successfully” wearing her lenses for about two years. She has keratoconus OD and OS, with mild corneal scarring on the left cornea. Prior to being fit with scleral lenses, she was wearing soft toric lenses. All other ocular findings were unremarkable.
She loves the vision with her scleral lenses but reports that she has to take her lenses out of her eyes and rinse the lens bowls at least once a day because the vision gets cloudy. Sometimes she needs to take her lenses out twice a day to rinse and refill them with appropriate solution. She wishes that she could do something to prevent the clouding but says that it is a small inconvenience for the vision that the lenses provide.
Causes of Post-Lens Clouding
Several factors influence post-lens tear clouding. Here we will review some key considerations when patients experience this problem.
Appropriate Compliance Inappropriate solution use can cause post-lens tear clouding. Ask scleral lens wearers to bring in all of the solutions, drops, and anything else that they use in caring for their lenses. Oftentimes, what patients report using isn’t necessarily what they are using. A visual confirmation will ensure that they are using what you recommended during every step of the wear and care process.
Maintain Surface Coatings We apply a polyethylene glycol (PEG)-based coating to all scleral lenses to help mitigate surface drying that may also cause symptoms of visual fogging. This coating improves hydrophilic properties of the lens surface and helps resist lens deposits.
When lenses have this coating, patients should use only the solutions that the manufacturer says are compatible for use with coated lenses. Instruct patients to not use abrasive cleaners with these lenses.
Filling the Bowl Avoid preservatives in the bowl of a scleral lens when filling it prior to application. Preservatives in the bowl of the lens can cause corneal toxicity and post-lens tear clouding.
Many practitioners currently recommend nonpreserved, unit-dose vials of sterile saline to fill the lens bowl prior to application. There are also two filling solutions that are approved for this purpose. A new scleral filling solution is expected to be available later this year that will be ionically balanced with the natural tear ionicity.
Landing Zone If the landing zone of a scleral lens is elevated or not sitting appropriately at the lens periphery, there is a chance for tear debris to enter under the landing zone and accumulate behind the lens, causing fogging. Critically assess and appropriately alter the landing zone to compensate for this.
Back to Our Patient
Our patient was sometimes filling the bowl of her lens with multipurpose solution as opposed to the recommended filling solution. Assessing the landing zone revealed that while the lens was resting appropriately on the conjunctiva in the horizontal meridian, the inferior and superior regions were demonstrating edge lift.
We educated the patient about appropriate filling solutions and also steepened the landing zone in the superior and inferior portions of the lens. She was able to wear this lens without needing to take it out during the day and became “fog free.”
A number of factors can cause post-lens fogging. Although this is not a comprehensive list, it highlights some of the most common reasons that it can occur. If post-lens fogging is the new norm, we don’t want to be normal. CLS