One of the more common complaints from patients who wear scleral lenses is that their vision is “foggy” or “cloudy.” When a patient has this complaint, it is prudent to systematically rule out possible causes.
Possible Causes of Scleral Lens Fogging
Lens Power While this may seem obvious, the first step is to ensure that the lens power is correct by performing an over-refraction, including checking for uncorrected cylinder. If there is residual astigmatism, front-surface-toric optical correction may be needed.
If a patient is still not achieving the expected visual acuity, and particularly if the patient complains that the lenses start out clear in the morning but the fogginess progressively worsens throughout the day, move on to the next possible cause.
Lens Surface Take a moment to evaluate the surface of the lens. If you see poor wetting or deposits, there are many ways to address this. Start with the patients themselves. For patients who wear makeup or who use creams/lotions near their eyes, remind them to avoid getting these often hydrophobic substances on the lens surface by using them after applying their lenses.
Patients may need to perform additional cleaning of their lenses beyond daily disinfection to remove stubborn deposits, so you may recommend extra strength cleaners or treatments. Do not forget to check application plungers, which can leave residue on the lens surface if not in good condition (Figure 1).
Fluid Reservoir In my experience, the two most common causes of tear reservoir debris clouding are excessive corneal vault and haptic misalignment due to asymmetric scleral shape.
To check for haptic misalignment, apply fluorescein to the surface of the lens, then watch behind the slit lamp to see where it rapidly uptakes under the lens (Figure 2). If not addressed, this may lead to debris entrapment under the lens, resulting in symptoms of cloudy vision (Figure 3). This problem can be remedied by using a toric or quadrant-specific haptic design.
Lid and Ocular Surface Disease While the tendency is to focus on the fit of a scleral lens when there is cloudy vision, remember that many scleral lens patients wear scleral lenses for ocular surface disease. I encourage you to take a moment to evaluate the lids and lashes while remembering that sometimes meibomian gland dysfunction (MGD) is non-obvious (Figure 4). Poor tear film quality can significantly alter the stability of vision over the scleral lens surface. Reminding these patients to perform appropriate home therapy can greatly improve their success with scleral lens wear. CLS